Subsections

# 38 Overview of Infrastructure Utility Classes

The ESMF utilities are a set of tools for quickly assembling modeling applications.

The ESMF Info class enables models to be self-describing via metadata, which are instances of JSON-compatible key-value pairs.

The Time Management Library provides utilities for time and time interval representation and calculation, and higher-level utilities that control model time stepping, via clocks, as well as alarming.

The ESMF Config class provides configuration management based on NASA DAO's Inpak package, a collection of methods for accessing files containing input parameters stored in an ASCII format.

The ESMF LogErr class consists of a variety of methods for writing error, warning, and informational messages to log files. A default Log is created during ESMF initialization. Other Logs can be created later in the code by the user.

The DELayout class provides a layer of abstraction on top of the Virtual Machine (VM) layer. DELayout does this by introducing DEs (Decomposition Elements) as logical resource units. The DELayout object keeps track of the relationship between its DEs and the resources of the associated VM object. A DELayout can be shaped by the user at creation time to best match the computational problem or other design criteria.

The ESMF VM (Virtual Machine) class is a generic representation of hardware and system software resources. There is exactly one VM object per ESMF Component, providing the execution environment for the Component code. The VM class handles all resource management tasks for the Component class and provides a description of the underlying configuration of the compute resources used by a Component. In addition to resource description and management, the VM class offers the lowest level of ESMF communication methods.

The ESMF Fortran I/O utilities provide portable methods to access capabilities which are often implemented in different ways amongst different environments. Currently, two utility methods are implemented: one to find an unopened unit number, and one to flush an I/O buffer.

# 39 Info Class (Object Attributes)

All ESMF base objects (i.e. Array, ArrayBundle, Field, FieldBundle, Grid, Mesh, DistGrid) contain a key-value attribute storage object called ESMF_Info. ESMF_Info objects may also be created independent of a base object. ESMF_Info supports setting and getting key-value pairs where the key is a string and the value is a scalar or a list of common data types. An ESMF_Info object may have a flat or nested data structure. The purpose of ESMF_Info is to support I/O-compatible metadata structures (i.e. netCDF), internal record-keeping for model execution (NUOPC), and provide a mechanism for custom user metadata attributes.

ESMF_Info is designed for interoperability. To achieve this goal, ESMF_Info adopted the JSON (Javascript Object Notation) specification. Internally, ESMF_Info uses JSON for Modern C++ [1] to manage its storage map. There are numerous resources for JSON on the web [11]. Quoting from the json.org site [11] when it introduces the format:

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language Standard ECMA-262 3rd Edition - December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language. JSON is built on two structures:
• A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
• An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.
These are universal data structures. Virtually all modern programming languages support them in one form or another. It makes sense that a data format that is interchangeable with programming languages also be based on these structures.

By adopting JSON compliance for ESMF_Info, ESMF made its core metadata capabilities explicitly interoperable with a widely used data structure. If data may be represented with JSON, then it is compatible with ESMF_Info.

There are some aspects of the ESMF_Info implementation related to JSON and JSON for Modern C++ that should be noted:

1. JSON supports 64-bit data types for integers and reals ([3], [2]). I4/R4 is converted to I8/R8 and vice versa. ESMF_Info internally tracks 32-bit sets to ensure the data type may be appropriately queried.
2. The memory overhead per JSON object (e.g. a key-value pair) requires an additional allocator pointer for type generalization [6]. Hence, the JSON map is not suited for big data storage, offering flexibility in exchange.
3. Keys are stored in an unordered map sorted in lexicographical order.

## 39.1 Migrating from Attribute

The ESMF_Info class is a replacement for the ESMF_Attribute class and is the preferred way of managing metadata attributes in ESMF moving forward. It is recommended that users migrate existing ESMF_Attribute calls to the new ESMF_Info API. The ESMF_Info class provides the backend for ESMF_Attribute since ESMF version 8.1. The ESMF_Attribute docs are located in appendix 55. In practice, users should experience no friction when migrating client code. Please email ESMF support in the case of a migration issue. Some structural changes to ESMF_Attribute did occur:
• Changed behavior when getting fixed-size lists. List size in storage must match the size of the outgoing list.
• Removed ability to use a default value with list gets.
• Removed attPackInstanceName from all interfaces.
• Removed attcopyFlag from all interfaces.
• Modified ESMF_AttributeAdd to set the target key to a null JSON value.
• Modified ESMF_AttributeSet to not require an attribute added to an ESMF_AttPack be added through ESMF_AttributeAdd before setting.
• Removed support for attribute XML I/O.
• Removed ability to add multiple nested Attribute packages.
• Removed retrieval of "internal" ESMF object Attributes.

Below are examples for setting and getting an attribute using ESMF_Info and the legacy ESMF_Attribute. The ESMF_Info interfaces are not overloaded for ESMF object types but rather work off a handle retrieved via a get call.

### 39.1.1 Setting an Attribute

With ESMF_Attribute:
call ESMF_AttributeSet(array, "aKey", 15, rc=rc)

With ESMF_Info:
call ESMF_InfoGetFromHost(array, info, rc=rc)
call ESMF_InfoSet(info, "aKey", 15, rc=rc)


### 39.1.2 Getting an Attribute

With ESMF_Attribute:
call ESMF_AttributeGet(array, "aKey", aKeyValue, rc=rc)

With ESMF_Info:
call ESMF_InfoGetFromHost(array, info, rc=rc)
call ESMF_InfoGet(info, "aKey", aKeyValue, rc=rc)


## 39.2 Key Format Overview

A key in the ESMF_Info interface provides the location of a value to retrieve from the key-value storage. Keys in the ESMF_Info class use the JSON Pointer syntax [5]. A forward slash is prepended to string keys if it does not exist. Hence, "aKey" and "/aKey" are equivalent. Note the indexing aspect of the JSON Pointer syntax is not supported.

Every "key" argument in the ESMF_Info class uses pathing following the JSON Pointer syntax [6]. A forward slash is prepended to string keys if it does not exist. Hence, "aKey" and "/aKey" are equivalent. Note the indexing aspect of the JSON Pointer syntax is not supported (i.e. "/my_list 1").

Some examples for valid "key" arguments:

• altitude :: A simple key argument with no nesting.
• /altitude :: A simple key argument with no nesting with the prepended pointer forward slash.
• /altitude/height_above_mean_sea_level :: A key for an attribute "height_above_mean_sea_level" nested in a map identified with key "altitude".

## 39.3 Usage and Examples

### 39.3.1 Retrieve an Info Handle

This example demonstrates how to retrieve an ESMF_Info object handle from an ESMF object. ESMF_Info handles are a view into the object's ESMF_Info storage and should not be created/destroyed as the ESMF_Info's lifetime is determined by its host object's lifetime. Destroying the host object will leave a handle in an undefined state.

Variable declarations:

    type(ESMF_DistGrid) :: distgrid
type(ESMF_Array) :: array
type(ESMF_Info) :: infoh
real(ESMF_KIND_R8), dimension(10,10) :: farray
integer :: rc


Create an ESMF Array.

    distgrid = ESMF_DistGridCreate(minIndex=(/1,1/), maxIndex=(/10,10/), rc=rc)


    array = ESMF_ArrayCreate(distgrid, farray, indexflag=ESMF_INDEX_DELOCAL, rc=rc)


Get the ESMF_Info handle from the object. See example 39.3.2 for additional usage examples.

    call ESMF_InfoGetFromHost(array, infoh, rc=rc)


Destroy everything except the ESMF_Info object. Attempting to destroy the ESMF_Info handle will result in an error.

    call ESMF_ArrayDestroy(array, rc=rc)


    call ESMF_DistGridDestroy(distgrid, rc=rc)


### 39.3.2 General Usage Examples

General usage examples for the ESMF_Info class. The demonstrated capabilities are:
• Creating an ESMF_Info object.
• Setting/getting a key-value pair.
• Setting/getting a list value and a list value by index.
• Printing and dumping ESMF_Info contents.
• Checking for key presence and set state (null value check).
• Setting/getting with nesting (hierarchies).
• Inquiring the ESMF_Info object for general item metadata and iteration purposes.
• Copying ESMF_Info contents.
• Removing a key-value pair from the ESMF_Info storage.
• Destroying the ESMF_Info object.

Variable declarations:

    type(ESMF_Info) :: info, infoCopy, infoFromCh
type(ESMF_TypeKind_Flag) :: typekind
character(len=ESMF_MAXSTR) :: ikey
character(:), allocatable :: output, getCh
real(ESMF_KIND_R8), dimension(4) :: realList
real(ESMF_KIND_R8), dimension(:), allocatable :: realListAlloc
integer(ESMF_KIND_I4) :: getInt
real(ESMF_KIND_R8) :: getReal
integer :: rc, infoSize, ii
logical :: isPresent, isSet


Create an ESMF_Info object. This object contains an empty key-value store called a JSON object [8].

An ESMF_Info handle may also be retrieved from an ESMF object as opposed to creating a standalone ESMF_Info object. See example 39.3.1.

    info = ESMF_InfoCreate(rc=rc)


    call ESMF_InfoSet(info, "myIntegerKey", 54, rc=rc)


Get the integer value we just set.

    call ESMF_InfoGet(info, "myIntegerKey", getInt, rc=rc)


Set a list of reals.

    call ESMF_InfoSet(info, "myListOfReals", (/ 33.3, 44.4, 0.0, 99.0 /), rc=rc)


Set an index in the new list then retrieve the value.

    call ESMF_InfoSet(info, "myListOfReals", 1234.0, idx=3, rc=rc)


    call ESMF_InfoGet(info, "myListOfReals", getReal, idx=3, rc=rc)


Get the values from a list.

    call ESMF_InfoGet(info, "myListOfReals", realList, rc=rc)


Allocatable lists may be used through a specific interface.

    call ESMF_InfoGetAlloc(info, "myListOfReals", realListAlloc, rc=rc)


The storage contents may be printed directly or dumped to a character.

    call ESMF_InfoPrint(info, indent=4, rc=rc)


    output = ESMF_InfoDump(info, rc=rc)


    print *, "the Info dump: "//output


Check if a key is present.

    isPresent = ESMF_InfoIsPresent(info, "myIntegerKey", rc=rc)


    if (.not. isPresent) call ESMF_Finalize(endflag=ESMF_END_ABORT)


Add a null value and check if it is set (has a non-null value).

    call ESMF_InfoSetNULL(info, "aNullKey", rc=rc)


    isSet = ESMF_InfoIsSet(info, "aNullKey", rc=rc)


    if (isSet) call ESMF_Finalize(endflag=ESMF_END_ABORT)

isSet = ESMF_InfoIsSet(info, "myIntegerKey", rc=rc)


    if (.not. isSet) call ESMF_Finalize(endflag=ESMF_END_ABORT)


The force flag, when set to false, will cause an error if the key exists in the map. The force flag is set to true by default.

    call ESMF_InfoSet(info, "myIntegerKey", 33, force=.false., rc=rc)
if (rc .ne. ESMC_RC_CANNOT_SET) call ESMF_Finalize(endflag=ESMF_END_ABORT)


Nesting uses the JSON Pointer 39.2 syntax. All key arguments in ESMF_Info may use this syntax unless noted otherwise. When creating a nested object, objects are created if they do not exist. Hence, it is not necessary to create the individual nested elements for deep hierarchies.

    call ESMF_InfoSet(info, "/Universe/Galaxy/Star/Planet", "Venus", rc=rc)


Using the get interface, it is possible to iterate over the storage contents. In the call below, we are retrieving the number of elements (key-value pairs) that exist in our root storage object. We then select the target element in root using an index and retrieve some additional metadata for the target object.

    call ESMF_InfoGet(info, size=infoSize, rc=rc)


    do ii=1,infoSize
call ESMF_InfoGet(info, idx=ii, ikey=ikey, typekind=typekind, rc=rc)


      if (localPet == 0) then
print *, "ESMF_Info inquire loop: "
print *, "       idx= ", ii
print *, "      ikey= ", trim(ikey)
print *, "  typekind= ", typekind
endif
enddo


Copying the ESMF_Info object requires the copy to be destroyed/deallocated.

    infoCopy = ESMF_InfoCreate(info, rc=rc)


Comparison operators = and /= are implemented for ESMF_Info objects.

    if (infoCopy /= info) call ESMF_Finalize(endflag=ESMF_END_ABORT)


After removing a key from the copied ESMF_Info object, the two objects will no longer be equal.

    call ESMF_InfoRemove(infoCopy, "myIntegerKey", rc=rc)


    if (infoCopy == info) call ESMF_Finalize(endflag=ESMF_END_ABORT)


Destroy the copied object.

    call ESMF_InfoDestroy(infoCopy, rc=rc)


An ESMF_Info object may be created from a JSON string. Note the usage of quotes is required as below.

    infoFromCh = ESMF_InfoCreate('{"hello":"world"}', rc=rc)


The contents of an ESMF_Info object may be set in another ESMF_Info object.

    call ESMF_InfoSet(info, "infoFromCh", infoFromCh, rc=rc)


    call ESMF_InfoDestroy(infoFromCh, rc=rc)


An allocatable character get interface is available.

    call ESMF_InfoGetCharAlloc(info, "/infoFromCh/hello", getCh, rc=rc)


Destroy the ESMF_Info object.

    call ESMF_InfoDestroy(info, rc=rc)


## 39.4 Class API

### 39.4.1 ESMF_InfoAssignment(=) - Info assignment

INTERFACE:

     interface assignment(=)
info1 = info2

ARGUMENTS:
     type(ESMF_Info) :: info1
type(ESMF_Info) :: info2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign info1 as an alias to the same ESMF Info object in memory as info2. If info2 is invalid, then info1 will be equally invalid after the assignment.

The arguments are:

info1
The ESMF_Info object on the left hand side of the assignment.
info2
The ESMF_Info object on the right hand side of the assignment.

### 39.4.2 ESMF_InfoOperator(==) - Info equality operator

INTERFACE:

 interface operator(==)

RETURN VALUE:
     logical :: result

ARGUMENTS:
      type(ESMF_Info), intent(in) :: info1
type(ESMF_Info), intent(in) :: info2

DESCRIPTION:

Test if the contents of two ESMF_Info objects are equal.

The arguments are:

info1
The ESMF_Info object on the left hand side of the operation.
info1
The ESMF_Info object on the right hand side of the operation.

### 39.4.3 ESMF_InfoOperator(/=) - Info not equal operator

INTERFACE:

 interface operator(/=)

RETURN VALUE:
     logical :: result

ARGUMENTS:
      type(ESMF_Info), intent(in) :: info1
type(ESMF_Info), intent(in) :: info2

DESCRIPTION:

Test if the contents of two ESMF_Info objects are not equal.

The arguments are:

info1
The ESMF_Info object on the left hand side of the operation.
info1
The ESMF_Info object on the right hand side of the operation.

INTERFACE:

 subroutine ESMF_InfoBroadcast(info, rootPet, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: info
integer, intent(in) :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

DESCRIPTION:

Broadcast an ESMF_Info object collectively across the current VM.

Users wishing to synchronize via broadcast an attribute hierarchy associated with an ESMF object should consult the ESMF_InfoSync documentation 39.4.28

The arguments are:

info
The ESMF_Info object that is the source (on rootPet) or the destination object to populate (on all other PETs). On destination PETs, the structure of info is overwritten with data from rootPet.
rootPet
The root PET identifier.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.5 ESMF_InfoCreate - Create a new Info object

INTERFACE:

   ! Private name; call using ESMF_InfoCreate()
function ESMF_InfoCreateEmpty(rc)

ARGUMENTS:
   integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_Info) :: ESMF_InfoCreateEmpty

DESCRIPTION:

Create an ESMF_Info object. This object must be destroyed using ESMF_InfoDestroy to free its memory allocation

The arguments are:

[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.6 ESMF_InfoCreate - Create a new Info object using a key

INTERFACE:

   ! Private name; call using ESMF_InfoCreate()
function ESMF_InfoCreateByKey(info, key, rc)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_Info) :: ESMF_InfoCreateByKey

DESCRIPTION:

Create an ESMF_Info object from a location in info defined by key. Returned object is a deep copy. The value associated with key must be a nested object (i.e. a collection of key/value pairs).

The arguments are:

info
The ESMF_Info object providing source data.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.7 ESMF_InfoCreate - Create an Info object from another Info object

INTERFACE:

   ! Private name; call using ESMF_InfoCreate()
function ESMF_InfoCreateFromInfo(info, rc)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_Info) :: ESMF_InfoCreateFromInfo

DESCRIPTION:

Create an ESMF_Info object from another ESMF_Info object. The returned object is a deep copy of the source object.

The arguments are:

info
The ESMF_Info object acting as the source data.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.8 ESMF_InfoCreate - Create a new Info object by string parsing

INTERFACE:

   ! Private name; call using ESMF_InfoCreate()
function ESMF_InfoCreateByParse(jsonString, rc)

ARGUMENTS:
   character(len=*), intent(in) :: jsonString
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_Info) :: ESMF_InfoCreateByParse

DESCRIPTION:

Create an ESMF_Info object by parsing a JSON-formatted string.

The arguments are:

jsonString
The string to parse.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.9 ESMF_InfoDestroy - Destroy an Info object

INTERFACE:

 subroutine ESMF_InfoDestroy(info, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

DESCRIPTION:

Destroy an ESMF_Info object. Destroying an ESMF_Info object created internally by an ESMF object results in an error

The arguments are:

info
Target ESMF_Info object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.10 ESMF_InfoDump - Dump Info contents to string

INTERFACE:

 function ESMF_InfoDump(info, key, indent, rc) result(output)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(*), intent(in), optional :: key
integer, intent(in), optional :: indent
integer, intent(out), optional :: rc
RESULT:
character(:), allocatable :: output

DESCRIPTION:

Dump the contents of an ESMF_Info object as a JSON string.

The arguments are:

info
Target ESMF_Info object.
[key]
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[indent]
Default is 0. Specifying an indentation greater than 0 will result in a "pretty print" for JSON output string (string includes new line breaks).
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.11 ESMF_InfoGet - Get a numeric, logical, or fixed-size character value

INTERFACE:

  subroutine ESMF_InfoGet(info, key, value, default, idx, attnestflag, rc)

ARGUMENTS:
    type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
<value>, see below for supported value
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
<default, optional> see below for supported default value
integer, intent(in), optional :: idx
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
integer, intent(out), optional :: rc

DESCRIPTION:

Get a value from an ESMF_Info object using a key. If the key is not found, rc will not equal ESMF_SUCCESS. The returned value is always a copy including gets with a default.

Overloaded value for the following types:

• integer(kind=ESMF_KIND_I4)
• integer(kind=ESMF_KIND_I8)
• real(kind=ESMF_KIND_R4)
• real(kind=ESMF_KIND_R8)
• logical
• character(:)

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
value
The output value associated with the key.
[default]
A default value to use if the key is not present in the target ESMF_Info object. Must be the same typekind and size as value.
[idx]
An integer index to get if the target key's value is a list.
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search. The first instance of the key (searching by depth) will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.12 ESMF_InfoGetCharAlloc - Get an allocatable character value

INTERFACE:

  subroutine ESMF_InfoGetCharAlloc(info, key, value, default, idx, attnestflag, rc)

ARGUMENTS:
    type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
character(:), allocatable, intent(out) :: value
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in), optional :: default
integer, intent(in), optional :: idx
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
integer, intent(out), optional :: rc

DESCRIPTION:

Get a value from an ESMF_Info object using a key. If the key is not found, rc will not equal ESMF_SUCCESS. The returned value is always a copy including gets with a default.

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
value
The output value associated with the key.
[default]
A default value to use if the key is not present in the target ESMF_Info object. Must be the same typekind and size as value.
[idx]
An integer index to get if the target key's value is a list.
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search. The first instance of the key (searching by depth) will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.13 ESMF_InfoGet - Get a list

INTERFACE:

  subroutine ESMF_InfoGet(info, key, values, itemCount, attnestflag, scalarToArray, rc)

ARGUMENTS:
    type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
<values>, see below for supported values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: itemCount
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
logical, intent(in), optional :: scalarToArray
integer, intent(out), optional :: rc

DESCRIPTION:

Get a value list from an ESMF_Info object using a key. If the key is not found, rc will not equal ESMF_SUCCESS. The returned value is always a copy.

The length of values must match its length in storage.

Overloaded values for the following types:

• integer(kind=ESMF_KIND_I4), dimension(:)
• integer(kind=ESMF_KIND_I8), dimension(:)
• real(kind=ESMF_KIND_R4), dimension(:)
• real(kind=ESMF_KIND_R8), dimension(:)
• logical, dimension(:)
• character(:), dimension(:)

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
values
The output value list associated with the key.
[itemCount]
The number of items in values.
[attnestflag]
Default is ESMF_ATTNEST_OFF. Setting to ESMF_ATTNEST_ON triggers a recursive search. The first instance of the key will be found in the hierarchy.
[scalarToArray]
Default is false. If true, allow conversion of scalar values in storage to single-valued lists.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.14 ESMF_InfoGetAlloc - Get an allocatable list

INTERFACE:

  subroutine ESMF_InfoGetAlloc(info, key, values, itemCount, attnestflag, scalarToArray, rc)

ARGUMENTS:
    type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
<values>, see below for supported values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: itemCount
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
logical, intent(in), optional :: scalarToArray
integer, intent(out), optional :: rc

DESCRIPTION:

Get a value list from an ESMF_Info object using a key. If the key is not found, rc will not equal ESMF_SUCCESS. The returned value is always a copy.

Overloaded values for the following types:

• integer(kind=ESMF_KIND_I4), dimension(:), allocatable
• integer(kind=ESMF_KIND_I8), dimension(:), allocatable
• real(kind=ESMF_KIND_R4), dimension(:), allocatable
• real(kind=ESMF_KIND_R8), dimension(:), allocatable
• logical, dimension(:), allocatable
• character(:), dimension(:), allocatable

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
values
The output value list associated with the key.
[itemCount]
The number of items in values.
[attnestflag]
Default is ESMF_ATTNEST_OFF. Setting to ESMF_ATTNEST_ON triggers a recursive search. The first instance of the key will be found in the hierarchy.
[scalarToArray]
Default is false. If true, allow conversion of scalar values in storage to single-valued lists.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.15 ESMF_InfoGet - Inquire an Info object for metadata

INTERFACE:

   ! Private name; call using ESMF_InfoGet()
subroutine ESMF_InfoInquire(info, size, key, jsonType, isArray, &
isDirty, idx, typekind, ikey, isPresent, isStructured, isNull, rc)

ARGUMENTS:
    type(ESMF_Info), intent(in) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: size
character(len=*), intent(in), optional :: key
character(len=*), intent(out), optional :: jsonType
logical, intent(out), optional :: isArray
logical, intent(out), optional :: isDirty
integer, intent(in), optional :: idx
type(ESMF_TypeKind_Flag), intent(out), optional :: typekind
character(len=*), intent(out), optional :: ikey
logical, intent(out), optional :: isPresent
logical, intent(out), optional :: isStructured
logical, intent(out), optional :: isNull
integer, intent(out), optional :: rc

DESCRIPTION:

Inquire an ESMF_Info object for metadata.

The arguments are:

info
Target ESMF_Info object.
[size]
Returns the size of the target. The following rules apply:
• If the target is an object, return the number of key-value pairs.
• If the target is a scalar, return 1.
• If the target is an array, return its length.
[key]
If provided, use this location as the origin instead of root. See section 39.2 for an overview of the key format.
[jsonType]
Returns the JSON object type name [9].
[isArray]
Returns true if the target is an array.
[isDirty]
Returns true if the ESMF_Info object should be synchronized during an ESMF_InfoSync operation.
[idx]
An integer index to use. This will index into an object type providing the primary mechanism for iteration.
[typekind]
Get the ESMF typekind for the target. The minimum typekind required to hold the value is returned.
[ikey]
If present, this will be set to the key's name for the current inquire. Useful when iterating using an index. This does not return the full key path if nested.
[isPresent]
Returns true if the key exists in storage. If no key is provided, this will return true.
[isStructured]
Returns true if the target is structured [4]. This means it is either an object (a map) or an array.
[isNull]
Returns true if the target is null [7].
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.16 ESMF_InfoGetFromHost - Get an Info handle from an ESMF object

INTERFACE:

  subroutine ESMF_InfoGetFromHost(host, info, rc)

ARGUMENTS:
    type(ESMF_*), intent(inout) :: host
type(ESMF_Info), intent(out) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

DESCRIPTION:

Get an ESMF_Info object handle from a host ESMF object. The returned handle should not be destroyed.

The arguments are:

host
• ESMF_Array
• ESMF_ArrayBundle
• ESMF_CplComp
• ESMF_GridComp
• ESMF_SciComp
• ESMF_DistGrid
• ESMF_Field
• ESMF_FieldBundle
• ESMF_Grid
• ESMF_State
• ESMF_LocStream
• ESMF_Mesh
info
Outgoing ESMF_Info object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.17 ESMF_InfoGetTK - Retrieve the ESMF TypeKind for a key

INTERFACE:

 function ESMF_InfoGetTK(info, key, attnestflag, rc) result(typekind)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_TypeKind_Flag) :: typekind

DESCRIPTION:

Return a value's ESMF TypeKind using a key.

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search for keyParent. The first instance of the key will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.18 ESMF_InfoGetArrayMeta - Retrieve array metadata information

INTERFACE:

 subroutine ESMF_InfoGetArrayMeta(info, key, isArray, size, attnestflag, rc)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
logical, intent(out) :: isArray
integer(C_INT), intent(out) :: size
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
integer, intent(out), optional :: rc

DESCRIPTION:

Return a value's array status and size using a key.

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
isArray
Set to true if the target is an array in storage.
size
Set to the size of the target object in storage (i.e. length of the array).
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search for keyParent. The first instance of the key will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.19 ESMF_InfoIsPresent - Check for key presence

INTERFACE:

 function ESMF_InfoIsPresent(info, key, attnestflag, isPointer, rc) result(is_present)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
logical, intent(in), optional :: isPointer
integer, intent(out), optional :: rc

RETURN VALUE:
   logical :: is_present

DESCRIPTION:

Return true if key exists in ESMF_Info's storage.

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search for keyParent. The first instance of the key will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[isPointer]
Default is true. If true, expect the key is using JSON Pointer syntax (see section 39.2). Setting to false will trigger a slightly faster search.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.20 ESMF_InfoIsSet - Check if a value is null

INTERFACE:

 function ESMF_InfoIsSet(info, key, rc) result(is_set)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: key
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

RETURN VALUE:
   logical :: is_set

DESCRIPTION:

Returns true if the target value is not null [7].

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.21 ESMF_InfoPrint - Print contents of an Info object

INTERFACE:

 subroutine ESMF_InfoPrint(info, indent, preString, unit, rc)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(*), intent(in), optional :: preString
character(*), intent(out), optional :: unit
integer, intent(in), optional :: indent
integer, intent(out), optional :: rc

DESCRIPTION:

Print ESMF_Info contents in JSON format.

The arguments are:

info
Target ESMF_Info object.
[indent]
Default is 0. Specify a "pretty print" indentation for the JSON output string.
[preString]
Optionally prepended string. Default to empty string.
[unit]
Internal unit, i.e. a string. Default to printing to stdout.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

INTERFACE:

 function ESMF_InfoReadJSON(filename, rc) result(info_r)

ARGUMENTS:
   character(len=*), intent(in) :: filename
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

RETURN VALUE:
   type(ESMF_Info) :: info_r

DESCRIPTION:

Read JSON data from a file and return a new ESMF_Info object.

The arguments are:

filename
Path to the input file.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.23 ESMF_InfoRemove - Remove a key-value pair from an Info object

INTERFACE:

 subroutine ESMF_InfoRemove(info, keyParent, keyChild, attnestflag, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: info
character(len=*), intent(in) :: keyParent
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in), optional :: keyChild
type(ESMF_AttNest_Flag), intent(in), optional :: attnestflag
integer, intent(out), optional :: rc

DESCRIPTION:

Remove a key-value pair from an ESMF_Info object.

The arguments are:

info
Target ESMF_Info object.
keyParent
String key to identify the parent location for the removal. If no keyChild is specified, then the root location is assumed. See section 39.2 for an overview of the key format.
[keyChild]
String key to identify the value for the removal. This may not be a path.
[attnestflag]
Setting to ESMF_ATTNEST_ON triggers a recursive search for keyParent. The first instance of the key will be found in the hierarchy. Default is ESMF_ATTNEST_OFF.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.24 ESMF_InfoSet - Set a value

INTERFACE:

  subroutine ESMF_InfoSet(info, key, value, force, idx, pkey, rc)

ARGUMENTS:
    type(ESMF_Info), intent(inout) :: info
character(len=*), intent(in) :: key
<value>, see below for supported value
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: force
integer, intent(in), optional :: idx
character(len=*), intent(in), optional :: pkey
integer, intent(out), optional :: rc

DESCRIPTION:

Set a value in an ESMF_Info object using a key.

Overloaded value for the following types:

• integer(kind=ESMF_KIND_I4)
• integer(kind=ESMF_KIND_I8)
• real(kind=ESMF_KIND_R4)
• real(kind=ESMF_KIND_R8)
• logical
• character(:)

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
value
The input value associated with the key.
[force]
Default is true. When true, insert the key even if it already exists in storage. If false, rc will not return ESMF_SUCCESS if the key already exists.
[idx]
An integer index to set if the target key's value is a list.
[pkey]
Use this key's location as the origin for the set call.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.25 ESMF_InfoSet - Set a key to the contents of an Info object

INTERFACE:

   ! Private name; call using ESMF_InfoSet
subroutine ESMF_InfoSetINFO(info, key, value, force, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: info
character(len=*), intent(in) :: key
type(ESMF_Info), intent(in) :: value
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: force
integer, intent(out), optional :: rc

DESCRIPTION:

Set a value to the contents of an ESMF_Info object. A copy of the source contents is made.

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
value
The ESMF_Info object to use as source data.
[force]
Default is true. When true, insert the key even if it already exists in storage. If false, rc will not return ESMF_SUCCESS if the key already exists.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.26 ESMF_InfoSet - Set a value list

INTERFACE:

  subroutine ESMF_InfoSet(info, key, values, force, pkey, rc)

ARGUMENTS:
    type(ESMF_Info), intent(inout) :: info
character(len=*), intent(in) :: key
<values>, see below for supported values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: force
character(len=*), intent(in), optional :: pkey
integer, intent(out), optional :: rc

DESCRIPTION:

Set a value list in an ESMF_Info object using a key. List values are initialized to null.

Overloaded values for the following types:

• integer(kind=ESMF_KIND_I4), dimension(:)
• integer(kind=ESMF_KIND_I8), dimension(:)
• real(kind=ESMF_KIND_R4), dimension(:)
• real(kind=ESMF_KIND_R8), dimension(:)
• logical, dimension(:)
• character(:), dimension(:)

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
values
The input value list associated with the key.
[force]
Default is true. When true, insert the key even if it already exists in storage. If false, rc will not return ESMF_SUCCESS if the key already exists.
[pkey]
Use this key's location as the origin for the set call. Used primarily for recursive requirements related to ESMF_Attribute.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.27 ESMF_InfoSetNULL - Set a value to null

INTERFACE:

 subroutine ESMF_InfoSetNULL(info, key, force, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: info
character(len=*), intent(in) :: key
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: force
integer, intent(out), optional :: rc

DESCRIPTION:

Set a value to null [7].

The arguments are:

info
Target ESMF_Info object.
key
String key to access in ESMF_Info storage. See section 39.2 for an overview of the key format.
[force]
Default is true. When true, insert the key even if it already exists in storage. If false, rc will not return ESMF_SUCCESS if the key already exists.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.28 ESMF_InfoSync - Synchronize Info contents across a VM

INTERFACE:

  subroutine ESMF_InfoSync(host, rootPet, vm, markClean, &
rc)

ARGUMENTS:
    type(ESMF_*), intent(inout) :: host
integer, intent(in) :: rootPet
type(ESMF_VM), intent(in) :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: markClean
integer, intent(out), optional :: rc

DESCRIPTION:

Synchronize ESMF_Info contents collectively across the current VM. Contents on the rootPet are set as the contents on matching objects sharing the VM. An attempt is made to optimize by only communicating updated contents (i.e. something set or modified). This subroutine will traverse the ESMF object hierarchy associated with host (i.e. Arrays in an ArrayBundle, Fields in a FieldBundle, etc.).

Users interested in broadcasting only the ESMF_Info object should consult the ESMF_InfoBroadcast documentation 39.4.4.

The arguments are:

host
• ESMF_State
• ESMF_CplComp
• ESMF_GridComp
• ESMF_SciComp
• ESMF_Field
• ESMF_FieldBundle
rootPet
The root PET to use for the synchronization.
vm
The VM to synchronize across.
[markClean]
Default is false. If true, mark changed ESMF_Info contents as clean once synchronized. These contents will no longer be broadcast in consecutive calls to ESMF_InfoSync.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.29 ESMF_InfoUpdate - Update the contents of an Info object

INTERFACE:

 subroutine ESMF_InfoUpdate(lhs, rhs, recursive, overwrite, rc)

ARGUMENTS:
   type(ESMF_Info), intent(inout) :: lhs
type(ESMF_Info), intent(in) :: rhs
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical, intent(in), optional :: recursive
logical, intent(in), optional :: overwrite
integer, intent(out), optional :: rc

DESCRIPTION:

Update the contents of lhs using the contents of rhs. The operation inserts or overwrites any key in lhs if it exists in rhs. Otherwise, the contents of lhs is left unaltered. See the JSON documentation for implementation details [10]. If recursive is .true. (default is .false.), nested objects will be updated by their component key/values. Otherwise, the first instance or top-level key is replaced without the child contents being updated element-by-element.

The arguments are:

lhs
The ESMF_Info object to update.
rhs
The ESMF_Info object whose contents are used to update lhs.
[recursive]
Default is .false.. If .true., descend into nested objects and recursively update the contents.
[overwrite]
Default is .false.. If .true., key-values that exist in lhs will be overwritten by key-values in rhs. Flag is only applicable when recursive is .true..
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 39.4.30 ESMF_InfoWriteJSON - Write Info contents to file

INTERFACE:

 subroutine ESMF_InfoWriteJSON(info, filename, rc)

ARGUMENTS:
   type(ESMF_Info), intent(in) :: info
character(len=*), intent(in) :: filename
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

DESCRIPTION:

Write ESMF_Info contents to file using the JSON format.

The arguments are:

info
Target ESMF_Info object.
filename
Path to the output file.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 40 Time Manager Utility

The ESMF Time Manager utility includes software for time and date representation and calculations, model time advancement, and the identification of unique and periodic events. Since multi-component geophysical applications often require synchronization across the time management schemes of the individual components, the Time Manager's standard calendars and consistent time representation promote component interoperability.

 Key Features Drift-free timekeeping through an integer-based internal time representation. Both integers and reals can be specified at the interface. The ability to represent time as a rational fraction, to support exact timekeeping in applications that involve grid refinement. Support for many calendar kinds, including user-customized calendars. Support for both concurrent and sequential modes of component execution. Support for varying and negative time steps.

## 40.1 Time Manager Classes

There are five ESMF classes that represent time concepts:
• Calendar A Calendar can be used to keep track of the date as an ESMF Gridded Component advances in time. Standard calendars (such as Gregorian and 360-day) and user-specified calendars are supported. Calendars can be queried for quantities such as seconds per day, days per month, and days per year.
• Time A Time represents a time instant in a particular calendar, such as November 28, 1964, at 7:31pm EST in the Gregorian calendar. The Time class can be used to represent the start and stop time of a time integration.
• TimeInterval TimeIntervals represent a period of time, such as 300 milliseconds. Time steps can be represented using TimeIntervals.
• Clock Clocks collect the parameters and methods used for model time advancement into a convenient package. A Clock can be queried for quantities such as start time, stop time, current time, and time step. Clock methods include incrementing the current time, and determining if it is time to stop.
• Alarm Alarms identify unique or periodic events by “ringing” - returning a true value - at specified times. For example, an Alarm might be set to ring on the day of the year when leaves start falling from the trees in a climate model.

In the remainder of this section, we briefly summarize the functionality that the Time Manager classes provide. Detailed descriptions and usage examples precede the API listing for each class.

## 40.2 Calendar

An ESMF Calendar can be queried for seconds per day, days per month and days per year. The flexible definition of Calendars allows them to be defined for planetary bodies other than Earth. The set of supported calendars includes:
Gregorian
The standard Gregorian calendar.
no-leap
The Gregorian calendar with no leap years.
Julian
The standard Julian date calendar.
Julian Day
The standard Julian days calendar.
Modified Julian Day
The Modified Julian days calendar.
360-day
A 30-day-per-month, 12-month-per-year calendar.
no calendar
Tracks only elapsed model time in hours, minutes, seconds.
See Section 41.1 for more details on supported standard calendars, and how to create a customized ESMF Calendar.

## 40.3 Time Instants and TimeIntervals

TimeIntervals and Time instants (simply called Times) are the computational building blocks of the Time Manager utility. TimeIntervals support operations such as add, subtract, compare size, reset value, copy value, and subdivide by a scalar. Times, which are moments in time associated with specific Calendars, can be incremented or decremented by TimeIntervals, compared to determine which of two Times is later, differenced to obtain the TimeInterval between two Times, copied, reset, and manipulated in other useful ways. Times support a host of different queries, both for values of individual Time components such as year, month, day, and second, and for derived values such as day of year, middle of current month and Julian day. It is also possible to retrieve the value of the hardware realtime clock in the form of a Time. See Sections 42.1 and 43.1, respectively, for use and examples of Times and TimeIntervals.

Since climate modeling, numerical weather prediction and other Earth and space applications have widely varying time scales and require different sorts of calendars, Times and TimeIntervals must support a wide range of time specifiers, spanning nanoseconds to years. The interfaces to these time classes are defined so that the user can specify a time using a combination of units selected from the list shown in Table 40.4.

## 40.4 Clocks and Alarms

Although it is possible to repeatedly step a Time forward by a TimeInterval using arithmetic on these basic types, it is useful to identify a higher-level concept to represent this function. We refer to this capability as a Clock, and include in its required features the ability to store the start and stop times of a model run, to check when time advancement should cease, and to query the value of quantities such as the current time and the time at the previous time step. The Time Manager includes a class with methods that return a true value when a periodic or unique event has taken place; we refer to these as Alarms. Applications may contain temporary or multiple Clocks and Alarms. Sections 44.1 and 45.1 describe the use of Clocks and Alarms in detail.

 Unit Meaning Year. mm Month of the year. dd Day of the month. Julian or Modified Julian day. Hour. Minute. Second. Millisecond. Microsecond. Nanosecond. O Time zone offset in integer number of hours and minutes. Numerator for times of the form s , where s is seconds and s, sN, and sD are integers. This format provides a mechanism for supporting exact behavior.

## 40.5 Design and Implementation Notes

1. Base TimeIntervals and Times on the same integer representation. It is useful to allow both TimeIntervals and Times to inherit from a single class, BaseTime. In C++, this can be implemented by using inheritance. In Fortran, it can be implemented by having the derived types TimeIntervals and Times contain a derived type BaseTime. In both cases, the BaseTime class can be made private and invisible to the user.

The result of this strategy is that Time Intervals and Times gain a consistent core representation of time as well a set of basic methods.

The BaseTime class can be designed with a minimum number of elements to represent any required time. The design is based on the idea used in the real-time POSIX 1003.1b-1993 standard. That is, to represent time simply as a pair of integers: one for seconds (whole) and one for nanoseconds (fractional). These can then be converted at the interface level to any desired format.

For ESMF, this idea can be modified and extended, in order to handle the requirements for a large time range (> 200,000 years) and to exactly represent any rational fraction, not just nanoseconds. To handle the large time range, a 64-bit or greater integer is used for whole seconds. Any rational fractional second is expressed using two additional integers: a numerator and a denominator. Both the whole seconds and fractional numerator are signed to handle negative time intervals and instants. For arithmetic consistency both must carry the same sign (both positive or both negative), except, of course, for zero values. The fractional seconds element (numerator) is bounded with respect to whole seconds. If the absolute value of the numerator becomes greater than or equal to the denominator, whole seconds are incremented or decremented accordingly and the numerator is reset to the remainder. Conversions are performed upon demand by interface methods within the TimeInterval and Time classes. This is done because different applications require different representations of time intervals and time instances. Floating point values as well as integers can be specified for the various time units in the interfaces, see Table 40.4. Floating point values are represented internally as integer-based rational fractions.

The BaseTime class defines increment and decrement methods for basic TimeInterval calculations between Time instants. It is done here rather than in the Calendar class because it can be done with simple second-based arithmetic that is calendar independent.

Comparison methods can also be defined in the BaseTime class. These perform equality/inequality, less than, and greater than comparisons between any two TimeIntervals or Times. These methods capture the common comparison logic between TimeIntervals and Times and hence are defined here for sharing.

2. The Time class depends on a calendar. The Time class contains an internal Calendar class. Upon demand by a user, the results of an increment or decrement operation are converted to user units, which may be calendar-dependent, via methods obtained from their internal Calendar.

## 40.6 Object Model

The following is a simplified UML diagram showing the structure of the Time Manager utility. See Appendix A, A Brief Introduction to UML, for a translation table that lists the symbols in the diagram and their meaning.

# 41 Calendar Class

## 41.1 Description

The Calendar class represents the standard calendars used in geophysical modeling: Gregorian, Julian, Julian Day, Modified Julian Day, no-leap, 360-day, and no-calendar. It also supports a user-customized calendar. Brief descriptions are provided for each calendar below. For more information on standard calendars, see [33] and [29].

## 41.2 Constants

### 41.2.1 ESMF_CALKIND

DESCRIPTION:
Supported calendar kinds.

The type of this flag is:

type(ESMF_CalKind_Flag)

The valid values are:

ESMF_CALKIND_360DAY
Valid range: machine limits
In the 360-day calendar, there are 12 months, each of which has 30 days. Like the no-leap calendar, this is a simple approximation to the Gregorian calendar sometimes used by modelers.

ESMF_CALKIND_CUSTOM
Valid range: machine limits
The user can set calendar parameters in the generic calendar.

ESMF_CALKIND_GREGORIAN
Valid range: 3/1/4801 BC to 10/29/292,277,019,914
The Gregorian calendar is the calendar currently in use throughout Western countries. Named after Pope Gregory XIII, it is a minor correction to the older Julian calendar. In the Gregorian calendar every fourth year is a leap year in which February has 29 and not 28 days; however, years divisible by 100 are not leap years unless they are also divisible by 400. As in the Julian calendar, days begin at midnight.

ESMF_CALKIND_JULIAN
Valid range: 3/1/4713 BC to 4/24/292,271,018,333
The Julian calendar was introduced by Julius Caesar in 46 B.C., and reached its final form in 4 A.D. The Julian calendar differs from the Gregorian only in the determination of leap years, lacking the correction for years divisible by 100 and 400 in the Gregorian calendar. In the Julian calendar, any year is a leap year if divisible by 4. Days are considered to begin at midnight.

ESMF_CALKIND_JULIANDAY
Valid range: +/- 1x10
Julian days simply enumerate the days and fraction of a day which have elapsed since the start of the Julian era, defined as beginning at noon on Monday, 1st January of year 4713 B.C. in the Julian calendar. Julian days, unlike the dates in the Julian and Gregorian calendars, begin at noon.

ESMF_CALKIND_MODJULIANDAY
Valid range: +/- 1x10
The Modified Julian Day (MJD) was introduced by space scientists in the late 1950's. It is defined as an offset from the Julian Day (JD):

MJD = JD - 2400000.5

The half day is subtracted so that the day starts at midnight.

ESMF_CALKIND_NOCALENDAR
Valid range: machine limits
The no-calendar option simply tracks the elapsed model time in seconds.

ESMF_CALKIND_NOLEAP
Valid range: machine limits
The no-leap calendar is the Gregorian calendar with no leap years - February is always assumed to have 28 days. Modelers sometimes use this calendar as a simple, close approximation to the Gregorian calendar.

## 41.3 Use and Examples

In most multi-component Earth system applications, the timekeeping in each component must refer to the same standard calendar in order for the components to properly synchronize. It therefore makes sense to create as few ESMF Calendars as possible, preferably one per application. A typical strategy would be to create a single Calendar at the start of an application, and use that Calendar in all subsequent calls that accept a Calendar, such as ESMF_TimeSet.

The following example shows how to set up an ESMF Calendar.

! !PROGRAM: ESMF_CalendarEx - Calendar creation examples
!
! !DESCRIPTION:
!
! This program shows examples of how to create different calendar kinds
!-----------------------------------------------------------------------------
#include "ESMF.h"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! instantiate calendars
type(ESMF_Calendar) :: gregorianCalendar
type(ESMF_Calendar) :: julianDayCalendar
type(ESMF_Calendar) :: marsCalendar

! local variables for Get methods
integer :: sols
integer(ESMF_KIND_I8) :: dl
type(ESMF_Time) :: time, marsTime
type(ESMF_TimeInterval) :: marsTimeStep

! return code
integer:: rc


      ! initialize ESMF framework
call ESMF_Initialize(defaultlogfilename="CalendarEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


### 41.3.1 Calendar creation

This example shows how to create three ESMF_Calendars.

      ! create a Gregorian calendar
gregorianCalendar = ESMF_CalendarCreate(ESMF_CALKIND_GREGORIAN, &
name="Gregorian", rc=rc)


      ! create a Julian Day calendar
julianDayCalendar = ESMF_CalendarCreate(ESMF_CALKIND_JULIANDAY, &
name="JulianDay", rc=rc)


      ! create a Custom calendar for the planet Mars
! 1 Mars solar day = 24 hours, 39 minutes, 35 seconds = 88775 seconds
! 1 Mars solar year = 668.5921 Mars solar days = 668 5921/10000 sols/year
! http://www.giss.nasa.gov/research/briefs/allison_02
! http://www.giss.nasa.gov/tools/mars24/help/notes.html
marsCalendar = ESMF_CalendarCreate(secondsPerDay=88775, &
daysPerYear=668, &
daysPerYearDn=5921, &
daysPerYearDd=10000, &
name="MarsCalendar", rc=rc)


### 41.3.2 Calendar comparison

This example shows how to compare an ESMF_Calendar with a known calendar kind.

      ! compare calendar kind against a known type
if (gregorianCalendar == ESMF_CALKIND_GREGORIAN) then
print *, "gregorianCalendar is of type ESMF_CALKIND_GREGORIAN."
else
print *, "gregorianCalendar is not of type ESMF_CALKIND_GREGORIAN."
end if


### 41.3.3 Time conversion between Calendars

This example shows how to convert a time from one ESMF_Calendar to another.

      call ESMF_TimeSet(time, yy=2004, mm=4, dd=17, &
calendar=gregorianCalendar, rc=rc)


      ! switch time's calendar to perform conversion
call ESMF_TimeSet(time, calendar=julianDayCalendar, rc=rc)


      call ESMF_TimeGet(time, d_i8=dl, rc=rc)
print *, "Gregorian date 2004/4/17 is ", dl, &
" days in the Julian Day calendar."


### 41.3.4 Add a time interval to a time on a Calendar

This example shows how to increment a time using a custom ESMF_Calendar.

      ! Set a time to Mars solar year 3, sol 100
call ESMF_TimeSet(marsTime, yy=3, d=100, &
calendar=marsCalendar, rc=rc)


      ! Set a 1 solar year time step
call ESMF_TimeIntervalSet(marsTimeStep, yy=1, rc=rc)


      ! Perform the increment
marsTime = marsTime + marsTimeStep


      ! Get the result in sols (2774 = (3+1)*668.5921 + 100)
call ESMF_TimeGet(marsTime, d=sols, rc=rc)
print *, "For Mars, 3 solar years, 100 sols + 1 solar year = ", &
sols, "sols."


### 41.3.5 Calendar destruction

This example shows how to destroy three ESMF_Calendars.

      call ESMF_CalendarDestroy(julianDayCalendar, rc=rc)


      call ESMF_CalendarDestroy(gregorianCalendar, rc=rc)


      call ESMF_CalendarDestroy(marsCalendar, rc=rc)


      ! finalize ESMF framework
call ESMF_Finalize(rc=rc)


      end program ESMF_CalendarEx


## 41.4 Restrictions and Future Work

1. Months per year set to 12. Due to the requirement of only Earth modeling, the number of months per year is hard-coded at 12. However, for easy modification, this is implemented via a C preprocessor #define MONTHS_PER_YEAR in ESMCI_Calendar.h.

2. Calendar date conversions. Date conversions are currently defined between the Gregorian, Julian, Julian Day, and Modified Julian Day calendars. Further research and work would need to be done to determine conversion algorithms with and between the other calendars: No Leap, 360 Day, and Custom.

3. ESMF_CALKIND_CUSTOM. Currently, there is no provision for a custom calendar to define a leap year rule, so ESMF_CalendarIsLeapYear() will always return .false. in this case. However, the arguments daysPerYear, daysPerYearDn, and daysPerYearDd in ESMF_CalendarCreate() and ESMF_CalendarSet() can be used to set a fractional number of days per year, for example, 365.25 = 365 25/100. Also, if further timekeeping precision is required, fractional and/or floating point secondsPerDay and secondsPerYear could be added to the interfaces ESMF_CalendarCreate(), ESMF_CalendarSet(), and ESMF_CalendarGet() and implemented.

## 41.5 Class API

### 41.5.1 ESMF_CalendarAssignment(=) - Assign a Calendar to another Calendar

INTERFACE:

       interface assignment(=)
calendar1 = calendar2

ARGUMENTS:
       type(ESMF_Calendar) :: calendar1
type(ESMF_Calendar) :: calendar2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign calendar1 as an alias to the same ESMF_Calendar object in memory as calendar2. If calendar2 is invalid, then calendar1 will be equally invalid after the assignment.

The arguments are:

calendar1
The ESMF_Calendar object on the left hand side of the assignment.
calendar2
The ESMF_Calendar object on the right hand side of the assignment.

### 41.5.2 ESMF_CalendarOperator(==) - Test if Calendar argument 1 is equal to Calendar argument 2

INTERFACE:

       interface operator(==)
if (<calendar argument 1> == <calendar argument 2>) then ... endif
OR
result = (<calendar argument 1> == <calendar argument 2>)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       <calendar argument 1>, see below for supported values
<calendar argument 2>, see below for supported values

DESCRIPTION:

Overloads the (==) operator for the ESMF_Calendar class. Compare an ESMF_Calendar object or ESMF_CalKind_Flag with another calendar object or calendar kind for equality. Return .true. if equal, .false. otherwise. Comparison is based on calendar kind, which is a property of a calendar object.

If both arguments are ESMF_Calendar objects, and both are of type ESMF_CALKIND_CUSTOM, then all the calendar's properties, except name, are compared.

If both arguments are ESMF_Calendar objects, and either of them is not in the ESMF_INIT_CREATED status, an error will be logged. However, this does not affect the return value, which is .true. when both arguments are in the same status, and .false. otherwise.

If one argument is an ESMF_Calendar object, and the other is an ESMF_CalKind_Flag, and the calendar object is not in the ESMF_INIT_CREATED status, an error will be logged and .false. will be returned.

Supported values for <calendar argument 1> are:

type(ESMF_Calendar), intent(in) :: calendar1
type(ESMF_CalKind_Flag), intent(in) :: calkindflag1
Supported values for <calendar argument 2> are:
type(ESMF_Calendar), intent(in) :: calendar2
type(ESMF_CalKind_Flag), intent(in) :: calkindflag2

The arguments are:

<calendar argument 1>
The ESMF_Calendar object or ESMF_CalKind_Flag on the left hand side of the equality operation.
<calendar argument 2>
The ESMF_Calendar object or ESMF_CalKind_Flag on the right hand side of the equality operation.

### 41.5.3 ESMF_CalendarOperator(/=) - Test if Calendar argument 1 is not equal to Calendar argument 2

INTERFACE:

       interface operator(/=)
if (<calendar argument 1> /= <calendar argument 2>) then ... endif
OR
result = (<calendar argument 1> /= <calendar argument 2>)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       <calendar argument 1>, see below for supported values
<calendar argument 2>, see below for supported values

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Calendar class. Compare a ESMF_Calendar object or ESMF_CalKind_Flag with another calendar object or calendar kind for inequality. Return .true. if not equal, .false. otherwise. Comparison is based on calendar kind, which is a property of a calendar object.

If both arguments are ESMF_Calendar objects, and both are of type ESMF_CALKIND_CUSTOM, then all the calendar's properties, except name, are compared.

If both arguments are ESMF_Calendar objects, and either of them is not in the ESMF_INIT_CREATED status, an error will be logged. However, this does not affect the return value, which is .true. when both arguments are not in the same status, and .false. otherwise.

If one argument is an ESMF_Calendar object, and the other is an ESMF_CalKind_Flag, and the calendar object is not in the ESMF_INIT_CREATED status, an error will be logged and .true. will be returned.

Supported values for <calendar argument 1> are:

type(ESMF_Calendar), intent(in) :: calendar1
type(ESMF_CalKind_Flag), intent(in) :: calkindflag1
Supported values for <calendar argument 2> are:
type(ESMF_Calendar), intent(in) :: calendar2
type(ESMF_CalKind_Flag), intent(in) :: calkindflag2

The arguments are:

<calendar argument 1>
The ESMF_Calendar object or ESMF_CalKind_Flag on the left hand side of the non-equality operation.
<calendar argument 2>
The ESMF_Calendar object or ESMF_CalKind_Flag on the right hand side of the non-equality operation.

### 41.5.4 ESMF_CalendarCreate - Create a new ESMF Calendar of built-in type

INTERFACE:

       ! Private name; call using ESMF_CalendarCreate()
function ESMF_CalendarCreateBuiltIn(calkindflag, &
name, rc)

RETURN VALUE:
       type(ESMF_Calendar) :: ESMF_CalendarCreateBuiltIn

ARGUMENTS:
       type(ESMF_CalKind_Flag), intent(in)            :: calkindflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates and sets a calendar to the given built-in ESMF_CalKind_Flag.

The arguments are:

calkindflag
The built-in ESMF_CalKind_Flag. Valid values are:
ESMF_CALKIND_360DAY,
ESMF_CALKIND_GREGORIAN,
ESMF_CALKIND_JULIAN,
ESMF_CALKIND_JULIANDAY,
ESMF_CALKIND_MODJULIANDAY,
ESMF_CALKIND_NOCALENDAR,
and ESMF_CALKIND_NOLEAP.
See Section 41.2 for a description of each calendar kind.
[name]
The name for the newly created calendar. If not specified, a default unique name will be generated: "CalendarNNN" where NNN is a unique sequence number from 001 to 999.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.5 ESMF_CalendarCreate - Create a copy of an ESMF Calendar

INTERFACE:

       ! Private name; call using ESMF_CalendarCreate()
function ESMF_CalendarCreateCopy(calendar, rc)

RETURN VALUE:
       type(ESMF_Calendar) :: ESMF_CalendarCreateCopy

ARGUMENTS:
       type(ESMF_Calendar), intent(in)            :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates a complete (deep) copy of a given ESMF_Calendar.

The arguments are:

calendar
The ESMF_Calendar to copy.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.6 ESMF_CalendarCreate - Create a new custom ESMF Calendar

INTERFACE:

       ! Private name; call using ESMF_CalendarCreate()
function ESMF_CalendarCreateCustom(&
daysPerMonth, secondsPerDay, &
daysPerYear, daysPerYearDn, daysPerYearDd, name, rc)

RETURN VALUE:
       type(ESMF_Calendar) :: ESMF_CalendarCreateCustom

ARGUMENTS:
 -- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,               intent(in),  optional :: daysPerMonth(:)
integer(ESMF_KIND_I4), intent(in),  optional :: secondsPerDay
integer(ESMF_KIND_I4), intent(in),  optional :: daysPerYear
integer(ESMF_KIND_I4), intent(in),  optional :: daysPerYearDn
integer(ESMF_KIND_I4), intent(in),  optional :: daysPerYearDd
character (len=*),     intent(in),  optional :: name
integer,               intent(out), optional :: rc

DESCRIPTION:

Creates a custom ESMF_Calendar and sets its properties.

The arguments are:

[daysPerMonth]
Integer array of days per month, for each month of the year. The number of months per year is variable and taken from the size of the array. If unspecified, months per year = 0, with the days array undefined.
[secondsPerDay]
Integer number of seconds per day. Defaults to 0 if not specified.
[daysPerYear]
Integer number of days per year. Use with daysPerYearDn and daysPerYearDd (see below) to specify a days-per-year calendar for any planetary body. Default = 0.
[daysPerYearDn]
Integer numerator portion of fractional number of days per year (daysPerYearDn/daysPerYearDd). Use with daysPerYear (see above) and daysPerYearDd (see below) to specify a days-per-year calendar for any planetary body. Default = 0.
[daysPerYearDd]
Integer denominator portion of fractional number of days per year (daysPerYearDn/daysPerYearDd). Use with daysPerYear and daysPerYearDn (see above) to specify a days-per-year calendar for any planetary body. Default = 1.
[name]
The name for the newly created calendar. If not specified, a default unique name will be generated: "CalendarNNN" where NNN is a unique sequence number from 001 to 999.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.7 ESMF_CalendarDestroy - Release resources associated with a Calendar

INTERFACE:

       subroutine ESMF_CalendarDestroy(calendar, rc)

ARGUMENTS:
       type(ESMF_Calendar), intent(inout)          :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Releases resources associated with this ESMF_Calendar.

The arguments are:

calendar
Release resources associated with this ESMF_Calendar and mark the object as invalid. It is an error to pass this object into any other routines after being destroyed.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.8 ESMF_CalendarGet - Get Calendar properties

INTERFACE:

       subroutine ESMF_CalendarGet(calendar, &
name, calkindflag, daysPerMonth, monthsPerYear, &
secondsPerDay, secondsPerYear, &
daysPerYear, daysPerYearDn, daysPerYearDd, rc)

ARGUMENTS:
       type(ESMF_Calendar),    intent(in)            :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_CalKind_Flag),intent(out), optional :: calkindflag
integer,                intent(out), optional :: daysPerMonth(:)
integer,                intent(out), optional :: monthsPerYear
integer(ESMF_KIND_I4),  intent(out), optional :: secondsPerDay
integer(ESMF_KIND_I4),  intent(out), optional :: secondsPerYear
integer(ESMF_KIND_I4),  intent(out), optional :: daysPerYear
integer(ESMF_KIND_I4),  intent(out), optional :: daysPerYearDn
integer(ESMF_KIND_I4),  intent(out), optional :: daysPerYearDd
character (len=*),      intent(out), optional :: name
integer,                intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets one or more of an ESMF_Calendar's properties.

The arguments are:

calendar
The object instance to query.
[calkindflag]
The CalKind_Flag ESMF_CALKIND_GREGORIAN, ESMF_CALKIND_JULIAN, etc.
[daysPerMonth]
Integer array of days per month, for each month of the year.
[monthsPerYear]
Integer number of months per year; the size of the daysPerMonth array.
[secondsPerDay]
Integer number of seconds per day.
[secondsPerYear]
Integer number of seconds per year.
[daysPerYear]
Integer number of days per year. For calendars with intercalations, daysPerYear is the number of days for years without an intercalation. For other calendars, it is the number of days in every year.
[daysPerYearDn]
Integer fractional number of days per year (numerator). For calendars with intercalations, daysPerYearDn/daysPerYearDd is the average fractional number of days per year (e.g. 25/100 for Julian 4-year intercalation). For other calendars, it is zero.
[daysPerYearDd]
Integer fractional number of days per year (denominator). See daysPerYearDn above.
[name]
The name of this calendar.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.9 ESMF_CalendarIsCreated - Check whether a Calendar object has been created

INTERFACE:

   function ESMF_CalendarIsCreated(calendar, rc)

RETURN VALUE:
     logical :: ESMF_CalendarIsCreated

ARGUMENTS:
     type(ESMF_Calendar), intent(in)            :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

DESCRIPTION:

Return .true. if the calendar has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

calendar
ESMF_Calendar queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.10 ESMF_CalendarIsLeapYear - Determine if given year is a leap year

INTERFACE:

       ! Private name; call using ESMF_CalendarIsLeapYear()
function ESMF_CalendarIsLeapYear<kind>(calendar, yy, rc)

RETURN VALUE:
       logical :: ESMF_CalendarIsLeapYear<kind>

ARGUMENTS:
       type(ESMF_Calendar),       intent(in)            :: calendar
integer(ESMF_KIND_<kind>), intent(in)            :: yy
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,                   intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns .true. if the given year is a leap year within the given calendar, and .false. otherwise. Custom calendars do not define leap years, so .false. will always be returned in this case; see Section 41.4. See also ESMF_TimeIsLeapYear().

The arguments are:

calendar
ESMF_Calendar to determine leap year within.
yy
Year to check for leap year. The type is integer and the <kind> can be either I4 or I8: ESMF_KIND_I4 or ESMF_KIND_I8.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.11 ESMF_CalendarPrint - Print Calendar information

INTERFACE:

       subroutine ESMF_CalendarPrint(calendar, options, rc)

ARGUMENTS:
       type(ESMF_Calendar), intent(in)            :: calendar
character (len=*),   intent(in),  optional :: options
integer,             intent(out), optional :: rc

DESCRIPTION:

Prints out an ESMF_Calendar's properties to stdio, in support of testing and debugging. The options control the type of information and level of detail.

The arguments are:

calendar
ESMF_Calendar to be printed out.
[options]
Print options. If none specified, prints all calendar property values.
"calkindflag" - print the calendar's type (e.g. ESMF_CALKIND_GREGORIAN).
"daysPerMonth" - print the array of number of days for each month.
"daysPerYear" - print the number of days per year (integer and fractional parts).
"monthsPerYear" - print the number of months per year.
"name" - print the calendar's name.
"secondsPerDay" - print the number of seconds in a day.
"secondsPerYear" - print the number of seconds in a year.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.12 ESMF_CalendarSet - Set a Calendar to a built-in type

INTERFACE:

       ! Private name; call using ESMF_CalendarSet()
subroutine ESMF_CalendarSetBuiltIn(calendar, calkindflag, &
name, rc)

ARGUMENTS:
       type(ESMF_Calendar),     intent(inout)         :: calendar
type(ESMF_CalKind_Flag), intent(in)            :: calkindflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets calendar to the given built-in ESMF_CalKind_Flag.

The arguments are:

calendar
The object instance to initialize.
calkindflag
The built-in CalKind_Flag. Valid values are:
ESMF_CALKIND_360DAY,
ESMF_CALKIND_GREGORIAN,
ESMF_CALKIND_JULIAN,
ESMF_CALKIND_JULIANDAY,
ESMF_CALKIND_MODJULIANDAY,
ESMF_CALKIND_NOCALENDAR,
and ESMF_CALKIND_NOLEAP.
See Section 41.2 for a description of each calendar kind.
[name]
The new name for this calendar.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.13 ESMF_CalendarSet - Set properties of a custom Calendar

INTERFACE:

       ! Private name; call using ESMF_CalendarSet()
subroutine ESMF_CalendarSetCustom(calendar, &
daysPerMonth, secondsPerDay, &
daysPerYear, daysPerYearDn, daysPerYearDd, name, rc)

ARGUMENTS:
       type(ESMF_Calendar),  intent(inout)         :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(in),  optional :: daysPerMonth(:)
integer(ESMF_KIND_I4),intent(in),  optional :: secondsPerDay
integer(ESMF_KIND_I4),intent(in),  optional :: daysPerYear
integer(ESMF_KIND_I4),intent(in),  optional :: daysPerYearDn
integer(ESMF_KIND_I4),intent(in),  optional :: daysPerYearDd
character (len=*),    intent(in),  optional :: name
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets properties in a custom ESMF_Calendar.

The arguments are:

calendar
The object instance to initialize.
[daysPerMonth]
Integer array of days per month, for each month of the year. The number of months per year is variable and taken from the size of the array. If unspecified, months per year = 0, with the days array undefined.
[secondsPerDay]
Integer number of seconds per day. Defaults to 0 if not specified.
[daysPerYear]
Integer number of days per year. Use with daysPerYearDn and daysPerYearDd (see below) to specify a days-per-year calendar for any planetary body. Default = 0.
[daysPerYearDn]
Integer numerator portion of fractional number of days per year (daysPerYearDn/daysPerYearDd). Use with daysPerYear (see above) and daysPerYearDd (see below) to specify a days-per-year calendar for any planetary body. Default = 0.
[daysPerYearDd]
Integer denominator portion of fractional number of days per year (daysPerYearDn/daysPerYearDd). Use with daysPerYear and daysPerYearDn (see above) to specify a days-per-year calendar for any planetary body. Default = 1.
[name]
The new name for this calendar.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.14 ESMF_CalendarSetDefault - Set the default Calendar kind

INTERFACE:

       ! Private name; call using ESMF_CalendarSetDefault()
subroutine ESMF_CalendarSetDefaultKind(calkindflag, rc)

ARGUMENTS:
       type(ESMF_CalKind_Flag), intent(in)            :: calkindflag
integer,                 intent(out), optional :: rc

DESCRIPTION:

Sets the default calendar to the given type. Subsequent Time Manager operations requiring a calendar where one isn't specified will use the internal calendar of this type.

The arguments are:

calkindflag
The calendar kind to be the default.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.15 ESMF_CalendarSetDefault - Set the default Calendar

INTERFACE:

       ! Private name; call using ESMF_CalendarSetDefault()
subroutine ESMF_CalendarSetDefaultCal(calendar, rc)

ARGUMENTS:
       type(ESMF_Calendar),     intent(in)            :: calendar
integer,                 intent(out), optional :: rc

DESCRIPTION:

Sets the default calendar to the one given. Subsequent Time Manager operations requiring a calendar where one isn't specified will use this calendar.

The arguments are:

calendar
The object instance to be the default.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 41.5.16 ESMF_CalendarValidate - Validate a Calendar's properties

INTERFACE:

       subroutine ESMF_CalendarValidate(calendar, rc)

ARGUMENTS:
       type(ESMF_Calendar), intent(in)            :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Checks whether a calendar is valid. Must be one of the defined calendar kinds. daysPerMonth, daysPerYear, secondsPerDay must all be greater than or equal to zero.

The arguments are:

calendar
ESMF_Calendar to be validated.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 42 Time Class

## 42.1 Description

A Time represents a specific point in time. In order to accommodate the range of time scales in Earth system applications, Times in the ESMF can be specified in many different ways, from years to nanoseconds. The Time interface is designed so that you select one or more options from a list of time units in order to specify a Time. The options for specifying a Time are shown in Table 40.4.

There are Time methods defined for setting and getting a Time, incrementing and decrementing a Time by a TimeInterval, taking the difference between two Times, and comparing Times. Special quantities such as the middle of the month and the day of the year associated with a particular Time can be retrieved. There is a method for returning the Time value as a string in the ISO 8601 format YYYY-MM-DDThh:mm:ss [26].

A Time that is specified in hours, minutes, seconds, or subsecond intervals does not need to be associated with a standard calendar; a Time whose specification includes time units of a day and greater must be. The ESMF representation of a calendar, the Calendar class, is described in Section 41.1. The ESMF_TimeSet method is used to initialize a Time as well as associate it with a Calendar. If a Time method is invoked in which a Calendar is necessary and one has not been set, the ESMF method will return an error condition.

In the ESMF the TimeInterval class is used to represent time periods. This class is frequently used in combination with the Time class. The Clock class, for example, advances model time by incrementing a Time with a TimeInterval.

## 42.2 Use and Examples

Times are most frequently used to represent start, stop, and current model times. The following examples show how to create, initialize, and manipulate Time.

! !PROGRAM: ESMF_TimeEx - Time initialization and manipulation examples
!
! !DESCRIPTION:
!
! This program shows examples of Time initialization and manipulation
!-----------------------------------------------------------------------------
#include "ESMF.h"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! instantiate two times
type(ESMF_Time) :: time1, time2

type(ESMF_VM) :: vm

! instantiate a time interval
type(ESMF_TimeInterval) :: timeinterval1

! local variables for Get methods
integer :: YY, MM, DD, H, M, S

! return code
integer:: rc


      ! initialize ESMF framework
call ESMF_Initialize(vm=vm, defaultCalKind=ESMF_CALKIND_GREGORIAN, &
defaultlogfilename="TimeEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


### 42.2.1 Time initialization

This example shows how to initialize an ESMF_Time.

      ! initialize time1 to 2/28/2000 2:24:45
call ESMF_TimeSet(time1, yy=2000, mm=2, dd=28, h=2, m=24, s=45, rc=rc)


      print *, "Time1 = "
call ESMF_TimePrint(time1, options="string", rc=rc)


### 42.2.2 Time increment

This example shows how to increment an ESMF_Time by an ESMF_TimeInterval.

      ! initialize a time interval to 2 days, 8 hours, 36 minutes, 15 seconds
call ESMF_TimeIntervalSet(timeinterval1, d=2, h=8, m=36, s=15, rc=rc)


      print *, "Timeinterval1 = "
call ESMF_TimeIntervalPrint(timeinterval1, options="string", rc=rc)


      ! increment time1 with timeinterval1
time2 = time1 + timeinterval1

call ESMF_TimeGet(time2, yy=YY, mm=MM, dd=DD, h=H, m=M, s=S, rc=rc)
print *, "time2 = time1 + timeinterval1 = ", YY, "/", MM, "/", DD, &
" ",  H, ":", M, ":", S


### 42.2.3 Time comparison

This example shows how to compare two ESMF_Times.

      if (time2 > time1) then
print *, "time2 is larger than time1"
else
print *, "time1 is smaller than or equal to time2"
endif


      ! finalize ESMF framework
call ESMF_Finalize(rc=rc)


      end program ESMF_TimeEx


## 42.3 Restrictions and Future Work

1. Limits on size and resolution of Time. The limits on the size and resolution of the time representation are based on the 64-bit integer types used. For seconds, a signed 64-bit integer will have a range of +/- -1, or +/- 9,223,372,036,854,775,807. This corresponds to a maximum size of +/- (-1)/(86400 * 365.25) or +/- 292,271,023,045 years.

For fractional seconds, a signed 64-bit integer will handle a resolution of +/- -1, or +/- 9,223,372,036,854,775,807 parts of a second.

## 42.4 Class API

### 42.4.1 ESMF_TimeAssignment(=) - Assign a Time to another Time

INTERFACE:

       interface assignment(=)
time1 = time2

ARGUMENTS:
       type(ESMF_Time) :: time1
type(ESMF_Time) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Set time1 equal to time2. This is the default Fortran assignment, which creates a complete, independent copy of time2 as time1. If time2 is an invalid ESMF_Time object then time1 will be equally invalid after the assignment.

The arguments are:

time1
The ESMF_Time to be set.
time2
The ESMF_Time to be copied.

### 42.4.2 ESMF_TimeOperator(+) - Increment a Time by a TimeInterval

INTERFACE:

       interface operator(+)
time2 = time1 + timeinterval

RETURN VALUE:
       type(ESMF_Time) :: time2

ARGUMENTS:
       type(ESMF_Time),         intent(in) :: time1
type(ESMF_TimeInterval), intent(in) :: timeinterval

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (+) operator for the ESMF_Time class to increment time1 with timeinterval and return the result as an ESMF_Time.

The arguments are:

time1
The ESMF_Time to increment.
timeinterval
The ESMF_TimeInterval to add to the given ESMF_Time.

### 42.4.3 ESMF_TimeOperator(-) - Decrement a Time by a TimeInterval

INTERFACE:

       interface operator(-)
time2 = time1 - timeinterval

RETURN VALUE:
       type(ESMF_Time) :: time2

ARGUMENTS:
       type(ESMF_Time),         intent(in) :: time1
type(ESMF_TimeInterval), intent(in) :: timeinterval

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (-) operator for the ESMF_Time class to decrement time1 with timeinterval, and return the result as an ESMF_Time.

The arguments are:

time1
The ESMF_Time to decrement.
timeinterval
The ESMF_TimeInterval to subtract from the given ESMF_Time.

### 42.4.4 ESMF_TimeOperator(-) - Return the difference between two Times

INTERFACE:

       interface operator(-)
timeinterval = time1 - time2

RETURN VALUE:
       type(ESMF_TimeInterval) :: timeinterval

ARGUMENTS:
       type(ESMF_Time),         intent(in) :: time1
type(ESMF_Time),         intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (-) operator for the ESMF_Time class to return the difference between time1 and time2 as an ESMF_TimeInterval. It is assumed that time1 is later than time2; if not, the resulting ESMF_TimeInterval will have a negative value.

The arguments are:

time1
The first ESMF_Time in comparison.
time2
The second ESMF_Time in comparison.

### 42.4.5 ESMF_TimeOperator(==) - Test if Time 1 is equal to Time 2

INTERFACE:

       interface operator(==)
if (time1 == time2) then ... endif
OR
result = (time1 == time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (==) operator for the ESMF_Time class to return .true. if time1 and time2 represent the same instant in time, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.6 ESMF_TimeOperator(/=) - Test if Time 1 is not equal to Time 2

INTERFACE:

       interface operator(/=)
if (time1 /= time2) then ... endif
OR
result = (time1 /= time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Time class to return .true. if time1 and time2 do not represent the same instant in time, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.7 ESMF_TimeOperator(<) - Test if Time 1 is less than Time 2

INTERFACE:

       interface operator(<)
if (time1 < time2) then ... endif
OR
result = (time1 < time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (<) operator for the ESMF_Time class to return .true. if time1 is earlier in time than time2, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.8 ESMF_TimeOperator(<=) - Test if Time 1 is less than or equal to Time 2

INTERFACE:

       interface operator(<=)
if (time1 <= time2) then ... endif
OR
result = (time1 <= time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (<=) operator for the ESMF_Time class to return .true. if time1 is earlier in time or the same time as time2, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.9 ESMF_TimeOperator(>) - Test if Time 1 is greater than Time 2

INTERFACE:

       interface operator(>)
if (time1 > time2) then ... endif
OR
result = (time1 > time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (>) operator for the ESMF_Time class to return .true. if time1 is later in time than time2, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.10 ESMF_TimeOperator(>=) - Test if Time 1 is greater than or equal to Time 2

INTERFACE:

       interface operator(>=)
if (time1 >= time2) then ... endif
OR
result = (time1 >= time2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Time), intent(in) :: time1
type(ESMF_Time), intent(in) :: time2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (>=) operator for the ESMF_Time class to return .true. if time1 is later in time or the same time as time2, and .false. otherwise.

The arguments are:

time1
First ESMF_Time in comparison.
time2
Second ESMF_Time in comparison.

### 42.4.11 ESMF_TimeGet - Get a Time value

INTERFACE:

       subroutine ESMF_TimeGet(time, &
yy, yy_i8, &
mm, dd, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
calendar, calkindflag, timeZone, &
timeString, timeStringISOFrac, &
dayOfWeek, midMonth, &
dayOfYear,  dayOfYear_r8, &
dayOfYear_intvl, rc)

ARGUMENTS:
       type(ESMF_Time),         intent(in)            :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(out), optional :: yy
integer(ESMF_KIND_I8),   intent(out), optional :: yy_i8
integer,                 intent(out), optional :: mm
integer,                 intent(out), optional :: dd
integer(ESMF_KIND_I4),   intent(out), optional :: d
integer(ESMF_KIND_I8),   intent(out), optional :: d_i8
integer(ESMF_KIND_I4),   intent(out), optional :: h
integer(ESMF_KIND_I4),   intent(out), optional :: m
integer(ESMF_KIND_I4),   intent(out), optional :: s
integer(ESMF_KIND_I8),   intent(out), optional :: s_i8
integer(ESMF_KIND_I4),   intent(out), optional :: ms
integer(ESMF_KIND_I4),   intent(out), optional :: us
integer(ESMF_KIND_I4),   intent(out), optional :: ns
real(ESMF_KIND_R8),      intent(out), optional :: d_r8
real(ESMF_KIND_R8),      intent(out), optional :: h_r8
real(ESMF_KIND_R8),      intent(out), optional :: m_r8
real(ESMF_KIND_R8),      intent(out), optional :: s_r8
real(ESMF_KIND_R8),      intent(out), optional :: ms_r8
real(ESMF_KIND_R8),      intent(out), optional :: us_r8
real(ESMF_KIND_R8),      intent(out), optional :: ns_r8
integer(ESMF_KIND_I4),   intent(out), optional :: sN
integer(ESMF_KIND_I8),   intent(out), optional :: sN_i8
integer(ESMF_KIND_I4),   intent(out), optional :: sD
integer(ESMF_KIND_I8),   intent(out), optional :: sD_i8
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
integer,                 intent(out), optional :: timeZone ! not imp
character (len=*),       intent(out), optional :: timeString
character (len=*),       intent(out), optional :: timeStringISOFrac
integer,                 intent(out), optional :: dayOfWeek
type(ESMF_Time),         intent(out), optional :: midMonth
integer(ESMF_KIND_I4),   intent(out), optional :: dayOfYear
real(ESMF_KIND_R8),      intent(out), optional :: dayOfYear_r8
type(ESMF_TimeInterval), intent(out), optional :: dayOfYear_intvl
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the value of time in units specified by the user via Fortran optional arguments. See ESMF_TimeSet() above for a description of time units and calendars.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally from integers. For example, if a time value is 5 and 3/8 seconds (s=5, sN=3, sD=8), and you want to get it as floating point seconds, you would get 5.375 (s_r8=5.375).

Units are bound (normalized) by the next larger unit specified. For example, if a time is defined to be 2:00 am on February 2, 2004, then ESMF_TimeGet(dd=day, h=hours, s=seconds) would return day = 2, hours = 2, seconds = 0, whereas ESMF_TimeGet(dd = day, s=seconds) would return day = 2, seconds = 7200. Note that hours and seconds are bound by a day. If bound by a month, ESMF_TimeGet(mm=month, h=hours, s=seconds) would return month = 2, hours = 26, seconds = 0, and ESMF_TimeGet(mm = month, s=seconds) would return month = 2, seconds = 93600 (26 * 3600). Similarly, if bound to a year, ESMF_TimeGet(yy=year, h=hours, s=seconds) would return year = 2004, hours = 770 (32*24 + 2), seconds = 0, and ESMF_TimeGet(yy = year, s=seconds) would return year = 2004, seconds = 2772000 (770 * 3600).

For timeString, timeStringISOFrac, dayOfWeek, midMonth, dayOfYear, dayOfYear_intvl, and dayOfYear_r8 described below, valid calendars are Gregorian, Julian, No Leap, 360 Day and Custom calendars. Not valid for Julian Day, Modified Julian Day, or No Calendar.

For timeString and timeStringISOFrac, YYYY format returns at least 4 digits; years <= 999 are padded on the left with zeroes and years >= 10000 return the number of digits required.

For timeString, convert ESMF_Time's value into partial ISO 8601 format YYYY-MM-DDThh:mm:ss[:n/d]. See [26] and [14]. See also method ESMF_TimePrint().

For timeStringISOFrac, convert ESMF_Time's value into full ISO 8601 format YYYY-MM-DDThh:mm:ss[.f]. See [26] and [14]. See also method ESMF_TimePrint().

For dayOfWeek, gets the day of the week the given ESMF_Time instant falls on. ISO 8601 standard: Monday = 1 through Sunday = 7. See [26] and [14].

For midMonth, gets the middle time instant of the month that the given ESMF_Time instant falls on.

For dayOfYear, gets the day of the year that the given ESMF_Time instant falls on. See range discussion in argument list below. Return as an integer value.

For dayOfYear_r8, gets the day of the year the given ESMF_Time instant falls on. See range discussion in argument list below. Return as floating point value; fractional part represents the time of day.

For dayOfYear_intvl, gets the day of the year the given ESMF_Time instant falls on. Return as an ESMF_TimeInterval.

The arguments are:

time
The object instance to query.
[yy]
Integer year (32-bit).
[yy_i8]
Integer year (large, 64-bit).
[mm]
Integer month.
[dd]
Integer day of the month.
[d]
Integer Julian date, or Modified Julian date (32-bit).
[d_i8]
Integer Julian date, or Modified Julian date (large, 64-bit).
[h]
Integer hour.
[m]
Integer minute.
[s]
Integer second (32-bit).
[s_i8]
Integer second (large, 64-bit).
[ms]
Integer millisecond.
[us]
Integer microsecond.
[ns]
Integer nanosecond.
[d_r8]
Double precision day.
[h_r8]
Double precision hour.
[m_r8]
Double precision minute.
[s_r8]
Double precision second.
[ms_r8]
Double precision millisecond.
[us_r8]
Double precision microsecond.
[ns_r8]
Double precision nanosecond.
[sN]
Integer numerator of fractional second (sN/sD).
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, <= 64-bit).
[sD]
Integer denominator of fractional second (sN/sD).
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, <= 64-bit).
[calendar]
Associated Calendar.
[calkindflag]
Associated CalKind_Flag.
[timeZone]
Associated timezone (hours offset from UCT, e.g. EST = -5). (Not implemented yet).
[timeString]
Convert time value to format string YYYY-MM-DDThh:mm:ss[:n/d], where n/d is numerator/denominator of any fractional seconds and all other units are in ISO 8601 format. See [26] and  [14]. See also method ESMF_TimePrint().
[timeStringISOFrac]
Convert time value to strict ISO 8601 format string YYYY-MM-DDThh:mm:ss[.f], where f is decimal form of any fractional seconds. See [26] and [14]. See also method ESMF_TimePrint().
[dayOfWeek]
The time instant's day of the week [1-7].
[MidMonth]
The given time instant's middle-of-the-month time instant.
[dayOfYear]
The ESMF_Time instant's integer day of the year. [1-366] for Gregorian and Julian calendars, [1-365] for No-Leap calendar. [1-360] for 360-Day calendar. User-defined range for Custom calendar.
[dayOfYear_r8]
The ESMF_Time instant's floating point day of the year. [1.x-366.x] for Gregorian and Julian calendars, [1.x-365.x] for No-Leap calendar. [1.x-360.x] for 360-Day calendar. User-defined range for Custom calendar.
[dayOfYear_intvl]
The ESMF_Time instant's day of the year as an ESMF_TimeInterval.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.12 ESMF_TimeIsLeapYear - Determine if a Time is in a leap year

INTERFACE:

       function ESMF_TimeIsLeapYear(time, rc)

RETURN VALUE:
       logical :: ESMF_TimeIsLeapYear

ARGUMENTS:
       type(ESMF_Time), intent(in)            :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,         intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns .true. if given time is in a leap year, and .false. otherwise. See also ESMF_CalendarIsLeapYear().

The arguments are:

time
The ESMF_Time to check for leap year.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.13 ESMF_TimeIsSameCalendar - Compare Calendars of two Times

INTERFACE:

       function ESMF_TimeIsSameCalendar(time1, time2, rc)

RETURN VALUE:
       logical :: ESMF_TimeIsSameCalendar

ARGUMENTS:
       type(ESMF_Time), intent(in)            :: time1
type(ESMF_Time), intent(in)            :: time2
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,         intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns .true. if the Calendars in these Times are the same, .false. otherwise.

The arguments are:

time1
The first ESMF_Time in comparison.
time2
The second ESMF_Time in comparison.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.14 ESMF_TimePrint - Print Time information

INTERFACE:

       subroutine ESMF_TimePrint(time, options, preString, unit, rc)

ARGUMENTS:
       type(ESMF_Time),   intent(in)            :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character (len=*), intent(in),  optional :: options
character(*),      intent(in),  optional :: preString
character(*),      intent(out), optional :: unit
integer,           intent(out), optional :: rc

DESCRIPTION:

Prints out the contents of an ESMF_Time to stdout, in support of testing and debugging. The options control the type of information and level of detail. For options "string" and "string isofrac", YYYY format returns at least 4 digits; years <= 999 are padded on the left with zeroes and years >= 10000 return the number of digits required.

The arguments are:

time
The ESMF_Time to be printed out.
[options]
Print options. If none specified, prints all Time property values.
"string" - prints time's value in ISO 8601 format for all units through seconds. For any non-zero fractional seconds, prints in integer rational fraction form n/d. Format is YYYY-MM-DDThh:mm:ss[:n/d], where [:n/d] is the integer numerator and denominator of the fractional seconds value, if present. See [26] and  [14]. See also method ESMF_TimeGet(..., timeString= , ...)
"string isofrac" - prints time's value in strict ISO 8601 format for all units, including any fractional seconds part. Format is YYYY-MM-DDThh:mm:ss[.f] where [.f] represents fractional seconds in decimal form, if present. See [26] and [14]. See also method ESMF_TimeGet(..., timeStringISOFrac= , ...)
[preString]
Optionally prepended string. Default to empty string.
[unit]
Internal unit, i.e. a string. Default to printing to stdout.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.15 ESMF_TimeSet - Initialize or set a Time

INTERFACE:

   ! Private name; call using ESMF_TimeSet()
subroutine ESMF_TimeSetDefault(time, &
yy, yy_i8, &
mm, dd, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
calendar, calkindflag, &
timeZone, rc)

ARGUMENTS:
       type(ESMF_Time),         intent(inout)         :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(in),  optional :: yy
integer(ESMF_KIND_I8),   intent(in),  optional :: yy_i8
integer,                 intent(in),  optional :: mm
integer,                 intent(in),  optional :: dd
integer(ESMF_KIND_I4),   intent(in),  optional :: d
integer(ESMF_KIND_I8),   intent(in),  optional :: d_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: h
integer(ESMF_KIND_I4),   intent(in),  optional :: m
integer(ESMF_KIND_I4),   intent(in),  optional :: s
integer(ESMF_KIND_I8),   intent(in),  optional :: s_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: ms
integer(ESMF_KIND_I4),   intent(in),  optional :: us
integer(ESMF_KIND_I4),   intent(in),  optional :: ns
real(ESMF_KIND_R8),      intent(in),  optional :: d_r8
real(ESMF_KIND_R8),      intent(in),  optional :: h_r8
real(ESMF_KIND_R8),      intent(in),  optional :: m_r8
real(ESMF_KIND_R8),      intent(in),  optional :: s_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ms_r8
real(ESMF_KIND_R8),      intent(in),  optional :: us_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ns_r8
integer(ESMF_KIND_I4),   intent(in),  optional :: sN
integer(ESMF_KIND_I8),   intent(in),  optional :: sN_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: sD
integer(ESMF_KIND_I8),   intent(in),  optional :: sD_i8
type(ESMF_Calendar),     intent(in),  optional :: calendar
type(ESMF_CalKind_Flag), intent(in),  optional :: calkindflag
integer,                 intent(in),  optional :: timeZone ! not imp
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Initializes an ESMF_Time with a set of user-specified units via Fortran optional arguments.

The range of valid values for mm and dd depend on the calendar used. For Gregorian, Julian, and No-Leap calendars, mm is [1-12] and dd is [1-28,29,30, or 31], depending on the value of mm and whether yy or yy_i8 is a leap year. For the 360-day calendar, mm is [1-12] and dd is [1-30]. For Julian Day, Modified Julian Day, and No-Calendar, yy, yy_i8, mm, and dd are invalid inputs, since these calendars do not define them. When valid, the yy and yy_i8 arguments should be fully specified, e.g. 2003 instead of 03. yy and yy_i8 ranges are only limited by machine word size, except for the Gregorian and Julian calendars, where the lowest (proleptic) date limits are 3/1/-4800 and 3/1/-4712, respectively. This is a limitation of the Gregorian date-to-Julian day and Julian date-to-Julian day conversion algorithms used to convert Gregorian and Julian dates to the internal representation of seconds. See [22] for a description of the Gregorian date-to-Julian day algorithm and [25] for a description of the Julian date-to-Julian day algorithm. The Custom calendar will have user-defined values for yy, yy_i8, mm, and dd.

The Julian day specifier, d or d_i8, can only be used with the Julian Day and Modified Julian Day calendars, and has a valid range depending on the word size. For a signed 32-bit d, the range for Julian day is [+/- 24855]. For a signed 64-bit d_i8, the valid range for Julian day is [+/- 106,751,991,167,300]. The Julian day number system adheres to the conventional standard where the reference day of d=0 corresponds to 11/24/-4713 in the proleptic Gregorian calendar and 1/1/-4712 in the proleptic Julian calendar. See [30] and  [12].

The Modified Julian Day system, introduced by space scientists in the late 1950's, is defined as Julian Day - 2400000.5. See [34].

Note that d and d_i8 are not valid for the No-Calendar. To remain consistent with non-Earth calendars added to ESMF in the future, ESMF requires a calendar to be planet-specific. Hence the No-Calendar does not know what a day is; it cannot assume an Earth day of 86400 seconds.

Hours, minutes, seconds, and sub-seconds can be used with any calendar, since they are standardized units that are the same for any planet.

Time manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally to integers. Sub-second values are represented internally with an integer numerator and denominator fraction (sN/sD). The smallest required resolution is nanoseconds (denominator). For example, pi can be represented as s=3, sN=141592654, sD=1000000000. However, via sN_i8 and sD_i8, larger values can be used. If specifying a constant floating point value, be sure to provide at least 16 digits to take full advantage of double precision, for example s_r8=2.718281828459045d0 for 'e' seconds.

The arguments are:

time
The object instance to initialize.
[yy]
Integer year (32-bit). Default = 0.
[yy_i8]
Integer year (large, 64-bit). Default = 0.
[mm]
Integer month. Default = 1.
[dd]
Integer day of the month. Default = 1.
[d]
Integer Julian Day, or Modified Julian Day (32-bit). Must not be specified with Gregorian calendars. Default = 0.
[d_i8]
Integer Julian Day, or Modified Julian Day (large, 64-bit). Must not be specified with Gregorian calendars. Default = 0.
[h]
Integer hour. Default = 0.
[m]
Integer minute. Default = 0.
[s]
Integer second (32-bit). Default = 0.
[s_i8]
Integer second (large, 64-bit). Default = 0.
[ms]
Integer millisecond. Default = 0.
[us]
Integer microsecond. Default = 0.
[ns]
Integer nanosecond. Default = 0.
[d_r8]
Double precision day. Default = 0.0.
[h_r8]
Double precision hour. Default = 0.0.
[m_r8]
Double precision minute. Default = 0.0.
[s_r8]
Double precision second. Default = 0.0.
[ms_r8]
Double precision millisecond. Default = 0.0.
[us_r8]
Double precision microsecond. Default = 0.0.
[ns_r8]
Double precision nanosecond. Default = 0.0.
[sN]
Integer numerator of fractional second (sN/sD). Default = 0.
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 0.
[sD]
Integer denominator of fractional second (sN/sD). Default = 1.
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 1.
[calendar]
Associated Calendar. Defaults to calendar ESMF_CALKIND_NOCALENDAR or default specified in ESMF_Initialize() or ESMF_CalendarSetDefault(). Alternate to, and mutually exclusive with, calkindflag below. Primarily for specifying a custom calendar kind.
[calkindflag]
Alternate to, and mutually exclusive with, calendar above. More convenient way of specifying a built-in calendar kind.
[timeZone]
Associated timezone (hours offset from UTC, e.g. EST = -5). Default = 0 (UTC). (Not implemented yet).
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.16 ESMF_TimeSet - Initialize or set a Time from ISO format string

INTERFACE:

   ! Private name; call using ESMF_TimeSet()
subroutine ESMF_TimeSetString(time, timeString, rc)

ARGUMENTS:
       type(ESMF_Time),         intent(inout)         :: time
character(*),            intent(in)            :: timeString
integer,                 intent(out), optional :: rc

DESCRIPTION:

Initializes an ESMF_Time with a set of user-specified string.

The arguments are:

time
The object instance to initialize.
timeString
ISO format time string. E.g. 2012-10-24T18:00:00.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.17 ESMF_TimeSyncToRealTime - Get system real time (wall clock time)

INTERFACE:

       subroutine ESMF_TimeSyncToRealTime(time, rc)

ARGUMENTS:
       type(ESMF_Time), intent(inout) :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the system real time (wall clock time), and returns it as an ESMF_Time. Accurate to the nearest second.

The arguments are:

time
The object instance to receive the real time.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 42.4.18 ESMF_TimeValidate - Validate a Time

INTERFACE:

       subroutine ESMF_TimeValidate(time, options, rc)

ARGUMENTS:
       type(ESMF_Time),   intent(in)            :: time
character (len=*), intent(in),  optional :: options
integer,           intent(out), optional :: rc

DESCRIPTION:

Checks whether an ESMF_Time is valid. Must be a valid date/time on a valid calendar. The options control the type of validation.

The arguments are:

time
ESMF_Time instant to be validated.
[options]
Validation options. If none specified, validates all time property values.
"calendar" - validate only the time's calendar.
"timezone" - validate only the time's timezone.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 43 TimeInterval Class

## 43.1 Description

A TimeInterval represents a period between time instants. It can be either positive or negative. Like the Time interface, the TimeInterval interface is designed so that you can choose one or more options from a list of time units in order to specify a TimeInterval. See Section 40.3, Table 40.4 for the available options.

There are TimeInterval methods defined for setting and getting a TimeInterval, for incrementing and decrementing a TimeInterval by another TimeInterval, and for multiplying and dividing TimeIntervals by integers, reals, fractions and other TimeIntervals. Methods are also defined to take the absolute value and negative absolute value of a TimeInterval, and for comparing the length of two TimeIntervals.

The class used to represent time instants in ESMF is Time, and this class is frequently used in operations along with TimeIntervals. For example, the difference between two Times is a TimeInterval.

When a TimeInterval is used in calculations that involve an absolute reference time, such as incrementing a Time with a TimeInterval, calendar dependencies may be introduced. The length of the time period that the TimeInterval represents will depend on the reference Time and the standard calendar that is associated with it. The calendar dependency becomes apparent when, for example, adding a TimeInterval of 1 day to the Time of February 28, 1996, at 4:00pm EST. In a 360 day calendar, the resulting date would be February 29, 1996, at 4:00pm EST. In a no-leap calendar, the result would be March 1, 1996, at 4:00pm EST.

TimeIntervals are used by other parts of the ESMF timekeeping system, such as Clocks (Section 44.1) and Alarms (Section 45.1).

## 43.2 Use and Examples

A typical use for a TimeInterval in a geophysical model is representation of the time step by which the model is advanced. Some models change the size of their time step as the model run progresses; this could be done by incrementing or decrementing the original time step by another TimeInterval, or by dividing or multiplying the time step by an integer value. An example of advancing model time using a TimeInterval representation of a time step is shown in Section 44.1.

The following brief example shows how to create, initialize and manipulate TimeInterval.

! !PROGRAM: ESMF_TimeIntervalEx - Time Interval initialization and
!                                 manipulation examples
!
! !DESCRIPTION:
!
! This program shows examples of Time Interval initialization and manipulation
!-----------------------------------------------------------------------------
#include "ESMF.h"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! instantiate some time intervals
type(ESMF_TimeInterval) :: timeinterval1, timeinterval2, timeinterval3

! local variables
integer :: d, h, m, s

! return code
integer:: rc


      ! initialize ESMF framework
call ESMF_Initialize(defaultCalKind=ESMF_CALKIND_GREGORIAN, &
defaultlogfilename="TimeIntervalEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


### 43.2.1 TimeInterval initialization

This example shows how to initialize two ESMF_TimeIntervals.

      ! initialize time interval1 to 1 day
call ESMF_TimeIntervalSet(timeinterval1, d=1, rc=rc)


      call ESMF_TimeIntervalPrint(timeinterval1, options="string", rc=rc)


      ! initialize time interval2 to 4 days, 1 hour, 30 minutes, 10 seconds
call ESMF_TimeIntervalSet(timeinterval2, d=4, h=1, m=30, s=10, rc=rc)


      call ESMF_TimeIntervalPrint(timeinterval2, options="string", rc=rc)


### 43.2.2 TimeInterval conversion

This example shows how to convert ESMF_TimeIntervals into different units.

      call ESMF_TimeIntervalGet(timeinterval1, s=s, rc=rc)
print *, "Time Interval1 = ", s, " seconds."


      call ESMF_TimeIntervalGet(timeinterval2, h=h, m=m, s=s, rc=rc)
print *, "Time Interval2 = ", h, " hours, ", m, " minutes, ", &
s, " seconds."


### 43.2.3 TimeInterval difference

This example shows how to calculate the difference between two ESMF_TimeIntervals.

      ! difference between two time intervals
timeinterval3 = timeinterval2 - timeinterval1
call ESMF_TimeIntervalGet(timeinterval3, d=d, h=h, m=m, s=s, rc=rc)
print *, "Difference between TimeInterval2 and TimeInterval1 = ", &
d, " days, ", h, " hours, ", m, " minutes, ", s, " seconds."


### 43.2.4 TimeInterval multiplication

This example shows how to multiply an ESMF_TimeInterval.

      ! multiply time interval by an integer
timeinterval3 = timeinterval2 * 3
call ESMF_TimeIntervalGet(timeinterval3, d=d, h=h, m=m, s=s, rc=rc)
print *, "TimeInterval2 multiplied by 3 = ", d, " days, ", h, &
" hours, ", m, " minutes, ", s, " seconds."


### 43.2.5 TimeInterval comparison

This example shows how to compare two ESMF_TimeIntervals.

      ! comparison
if (timeinterval1 < timeinterval2) then
print *, "TimeInterval1 is smaller than TimeInterval2"
else
print *, "TimeInterval1 is larger than or equal to TimeInterval2"
end if


      end program ESMF_TimeIntervalEx


## 43.3 Restrictions and Future Work

1. Limits on time span. The limits on the time span that can be represented are based on the 64-bit integer types used. For seconds, a signed 64-bit integer will have a range of +/- -1, or +/- 9,223,372,036,854,775,807. This corresponds to a range of +/- (-1)/(86400 * 365.25) or +/- 292,271,023,045 years.

For fractional seconds, a signed 64-bit integer will handle a resolution of +/- -1, or +/- 9,223,372,036,854,775,807 parts of a second.

## 43.4 Class API

### 43.4.1 ESMF_TimeIntervalAssignment(=) - Assign a TimeInterval to another TimeInterval

INTERFACE:

       interface assignment(=)
timeinterval1 = timeinterval2

ARGUMENTS:
       type(ESMF_TimeInterval) :: timeinterval1
type(ESMF_TimeInterval) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Set timeinterval1 equal to timeinterval2. This is the default Fortran assignment, which creates a complete, independent copy of timeinterval2 as timeinterval1. If timeinterval2 is an invalid ESMF_TimeInterval object then timeinterval1 will be equally invalid after the assignment.

The arguments are:

timeinterval1
The ESMF_TimeInterval to be set.
timeinterval2
The ESMF_TimeInterval to be copied.

### 43.4.2 ESMF_TimeIntervalOperator(+) - Add two TimeIntervals

INTERFACE:

       interface operator(+)
sum = timeinterval1 + timeinterval2

RETURN VALUE:
       type(ESMF_TimeInterval) :: sum

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (+) operator for the ESMF_TimeInterval class to add timeinterval1 to timeinterval2 and return the sum as an ESMF_TimeInterval.

The arguments are:

timeinterval1
The augend.
timeinterval2

### 43.4.3 ESMF_TimeIntervalOperator(-) - Subtract one TimeInterval from another

INTERFACE:

       interface operator(-)
difference = timeinterval1 - timeinterval2

RETURN VALUE:
       type(ESMF_TimeInterval) :: difference

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (-) operator for the ESMF_TimeInterval class to subtract timeinterval2 from timeinterval1 and return the difference as an ESMF_TimeInterval.

The arguments are:

timeinterval1
The minuend.
timeinterval2
The subtrahend.

### 43.4.4 ESMF_TimeIntervalOperator(-) - Perform unary negation on a TimeInterval

INTERFACE:

       interface operator(-)
timeinterval = -timeinterval

RETURN VALUE:
       type(ESMF_TimeInterval) :: -timeInterval

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (-) operator for the ESMF_TimeInterval class to perform unary negation on timeinterval and return the result.

The arguments are:

timeinterval
The time interval to be negated.

### 43.4.5 ESMF_TimeIntervalOperator(/) - Divide two TimeIntervals, return double precision quotient

INTERFACE:

       interface operator(/)
quotient = timeinterval1 / timeinterval2

RETURN VALUE:
       real(ESMF_KIND_R8) :: quotient

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (/) operator for the ESMF_TimeInterval class to return timeinterval1 divided by timeinterval2 as a double precision quotient.

The arguments are:

timeinterval1
The dividend.
timeinterval2
The divisor.

### 43.4.6 ESMF_TimeIntervalOperator(/) - Divide a TimeInterval by an integer, return TimeInterval quotient

INTERFACE:

       interface operator(/)
quotient = timeinterval / divisor

RETURN VALUE:
       type(ESMF_TimeInterval) :: quotient

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval
integer(ESMF_KIND_I4),   intent(in) :: divisor

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (/) operator for the ESMF_TimeInterval class to divide a timeinterval by an integer divisor, and return the quotient as an ESMF_TimeInterval.

The arguments are:

timeinterval
The dividend.
divisor
Integer divisor.

### 43.4.7 ESMF_TimeIntervalFunction(MOD) - Divide two TimeIntervals, return TimeInterval remainder

INTERFACE:

       interface MOD
function MOD(timeinterval1, timeinterval2)

RETURN VALUE:
       type(ESMF_TimeInterval) :: MOD

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the Fortran intrinsic MOD() function for the ESMF_TimeInterval class to return the remainder of timeinterval1 divided by timeinterval2 as an ESMF_TimeInterval.

The arguments are:

timeinterval1
The dividend.
timeinterval2
The divisor.

### 43.4.8 ESMF_TimeIntervalOperator(*) - Multiply a TimeInterval by an integer

INTERFACE:

       interface operator(*)
product = timeinterval * multiplier
OR
product = multiplier * timeinterval

RETURN VALUE:
       type(ESMF_TimeInterval) :: product

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval
integer(ESMF_KIND_I4),   intent(in) :: multiplier

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (*) operator for the ESMF_TimeInterval class to multiply a timeinterval by an integer multiplier, and return the product as an ESMF_TimeInterval.

The arguments are:

timeinterval
The multiplicand.
multiplier
The integer multiplier.

### 43.4.9 ESMF_TimeIntervalOperator(==) - Test if TimeInterval 1 is equal to TimeInterval 2

INTERFACE:

       interface operator(==)
if (timeinterval1 == timeinterval2) then ... endif
OR
result = (timeinterval1 == timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (==) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 and timeinterval2 represent an equal duration of time, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.10 ESMF_TimeIntervalOperator(/=) - Test if TimeInterval 1 is not equal to TimeInterval 2

INTERFACE:

       interface operator(/=)
if (timeinterval1 /= timeinterval2) then ... endif
OR
result = (timeinterval1 /= timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (/=) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 and timeinterval2 do not represent an equal duration of time, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.11 ESMF_TimeIntervalOperator(<) - Test if TimeInterval 1 is less than TimeInterval 2

INTERFACE:

       interface operator(<)
if (timeinterval1 < timeinterval2) then ... endif
OR
result = (timeinterval1 < timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (<) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 is a lesser duration of time than timeinterval2, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.12 ESMF_TimeIntervalOperator(<=) - Test if TimeInterval 1 is less than or equal to TimeInterval 2

INTERFACE:

       interface operator(<=)
if (timeinterval1 <= timeinterval2) then ... endif
OR
result = (timeinterval1 <= timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (<=) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 is a lesser or equal duration of time than timeinterval2, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.13 ESMF_TimeIntervalOperator(>) - Test if TimeInterval 1 is greater than TimeInterval 2

INTERFACE:

       interface operator(>)
if (timeinterval1 > timeinterval2) then ... endif
OR
result = (timeinterval1 > timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (>) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 is a greater duration of time than timeinterval2, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.14 ESMF_TimeIntervalOperator(>=) - Test if TimeInterval 1 is greater than or equal to TimeInterval 2

INTERFACE:

       interface operator(>=)
if (timeinterval1 >= timeinterval2) then ... endif
OR
result = (timeinterval1 >= timeinterval2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval1
type(ESMF_TimeInterval), intent(in) :: timeinterval2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Overloads the (>=) operator for the ESMF_TimeInterval class to return .true. if timeinterval1 is a greater or equal duration of time than timeinterval2, and .false. otherwise.

The arguments are:

timeinterval1
First ESMF_TimeInterval in comparison.
timeinterval2
Second ESMF_TimeInterval in comparison.

### 43.4.15 ESMF_TimeIntervalAbsValue - Get the absolute value of a TimeInterval

INTERFACE:

       function ESMF_TimeIntervalAbsValue(timeinterval)

RETURN VALUE:
       type(ESMF_TimeInterval) :: ESMF_TimeIntervalAbsValue

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns the absolute value of timeinterval.

The argument is:

timeinterval
The object instance to take the absolute value of. Absolute value is returned as the value of the function.

### 43.4.16 ESMF_TimeIntervalGet - Get a TimeInterval value

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalGet()
subroutine ESMF_TimeIntervalGetDur(timeinterval, &
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
startTime, calendar, calkindflag, &
timeString, timeStringISOFrac, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(out), optional :: yy
integer(ESMF_KIND_I8),   intent(out), optional :: yy_i8
integer(ESMF_KIND_I4),   intent(out), optional :: mm
integer(ESMF_KIND_I8),   intent(out), optional :: mm_i8
integer(ESMF_KIND_I4),   intent(out), optional :: d
integer(ESMF_KIND_I8),   intent(out), optional :: d_i8
integer(ESMF_KIND_I4),   intent(out), optional :: h
integer(ESMF_KIND_I4),   intent(out), optional :: m
integer(ESMF_KIND_I4),   intent(out), optional :: s
integer(ESMF_KIND_I8),   intent(out), optional :: s_i8
integer(ESMF_KIND_I4),   intent(out), optional :: ms
integer(ESMF_KIND_I4),   intent(out), optional :: us
integer(ESMF_KIND_I4),   intent(out), optional :: ns
real(ESMF_KIND_R8),      intent(out), optional :: d_r8
real(ESMF_KIND_R8),      intent(out), optional :: h_r8
real(ESMF_KIND_R8),      intent(out), optional :: m_r8
real(ESMF_KIND_R8),      intent(out), optional :: s_r8
real(ESMF_KIND_R8),      intent(out), optional :: ms_r8
real(ESMF_KIND_R8),      intent(out), optional :: us_r8
real(ESMF_KIND_R8),      intent(out), optional :: ns_r8
integer(ESMF_KIND_I4),   intent(out), optional :: sN
integer(ESMF_KIND_I8),   intent(out), optional :: sN_i8
integer(ESMF_KIND_I4),   intent(out), optional :: sD
integer(ESMF_KIND_I8),   intent(out), optional :: sD_i8
type(ESMF_Time),         intent(out), optional :: startTime
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
character (len=*),       intent(out), optional :: timeString
character (len=*),       intent(out), optional :: timeStringISOFrac
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the value of timeinterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally from integers.

Units are bound (normalized) to the next larger unit specified. For example, if a time interval is defined to be one day, then ESMF_TimeIntervalGet(d = days, s = seconds) would return days = 1, seconds = 0, whereas ESMF_TimeIntervalGet(s = seconds) would return seconds = 86400.

For timeString, converts ESMF_TimeInterval's value into partial ISO 8601 format PyYmMdDThHmMs[:n/d]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

For timeStringISOFrac, converts ESMF_TimeInterval's value into full ISO 8601 format PyYmMdDThHmMs[.f]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

The arguments are:

timeinterval
The object instance to query.
[yy]
Integer year (32-bit).
[yy_i8]
Integer year (large, 64-bit).
[mm]
Integer month (32-bit).
[mm_i8]
Integer month (large, 64-bit).
[d]
Integer Julian day, or Modified Julian day (32-bit).
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit).
[h]
Integer hour.
[m]
Integer minute.
[s]
Integer second (32-bit).
[s_i8]
Integer second (large, 64-bit).
[ms]
Integer millisecond.
[us]
Integer microsecond.
[ns]
Integer nanosecond.
[d_r8]
Double precision day.
[h_r8]
Double precision hour.
[m_r8]
Double precision minute.
[s_r8]
Double precision second.
[ms_r8]
Double precision millisecond.
[us_r8]
Double precision microsecond.
[ns_r8]
Double precision nanosecond.
[sN]
Integer numerator of fractional second (sN/sD).
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[sD]
Integer denominator of fractional second (sN/sD).
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[startTime]
Starting time, if set, of an absolute calendar interval (yy, mm, and/or d).
[calendar]
Associated Calendar, if any.
[calkindflag]
Associated CalKind_Flag, if any.
[timeString]
Convert time interval value to format string PyYmMdDThHmMs[:n/d]S, where n/d is numerator/denominator of any fractional seconds and all other units are in ISO 8601 format. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().
[timeStringISOFrac]
Convert time interval value to strict ISO 8601 format string PyYmMdDThHmMs[.f], where f is decimal form of any fractional seconds. See [26] and [14]. See also method ESMF_TimeIntervalPrint().
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.17 ESMF_TimeIntervalGet - Get a TimeInterval value

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalGet()
subroutine ESMF_TimeIntervalGetDurStart(timeinterval, startTimeIn, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
startTime, &
calendar, calkindflag, &
timeString, timeStringISOFrac, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
type(ESMF_Time),         intent(in)            :: startTimeIn ! Input
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(out), optional :: yy
integer(ESMF_KIND_I8),   intent(out), optional :: yy_i8
integer(ESMF_KIND_I4),   intent(out), optional :: mm
integer(ESMF_KIND_I8),   intent(out), optional :: mm_i8
integer(ESMF_KIND_I4),   intent(out), optional :: d
integer(ESMF_KIND_I8),   intent(out), optional :: d_i8
integer(ESMF_KIND_I4),   intent(out), optional :: h
integer(ESMF_KIND_I4),   intent(out), optional :: m
integer(ESMF_KIND_I4),   intent(out), optional :: s
integer(ESMF_KIND_I8),   intent(out), optional :: s_i8
integer(ESMF_KIND_I4),   intent(out), optional :: ms
integer(ESMF_KIND_I4),   intent(out), optional :: us
integer(ESMF_KIND_I4),   intent(out), optional :: ns
real(ESMF_KIND_R8),      intent(out), optional :: d_r8
real(ESMF_KIND_R8),      intent(out), optional :: h_r8
real(ESMF_KIND_R8),      intent(out), optional :: m_r8
real(ESMF_KIND_R8),      intent(out), optional :: s_r8
real(ESMF_KIND_R8),      intent(out), optional :: ms_r8
real(ESMF_KIND_R8),      intent(out), optional :: us_r8
real(ESMF_KIND_R8),      intent(out), optional :: ns_r8
integer(ESMF_KIND_I4),   intent(out), optional :: sN
integer(ESMF_KIND_I8),   intent(out), optional :: sN_i8
integer(ESMF_KIND_I4),   intent(out), optional :: sD
integer(ESMF_KIND_I8),   intent(out), optional :: sD_i8
type(ESMF_Time),         intent(out), optional :: startTime
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
character (len=*),       intent(out), optional :: timeString
character (len=*),       intent(out), optional :: timeStringISOFrac
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the value of timeinterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally from integers.

Units are bound (normalized) to the next larger unit specified. For example, if a time interval is defined to be one day, then ESMF_TimeIntervalGet(d = days, s = seconds) would return days = 1, seconds = 0, whereas ESMF_TimeIntervalGet(s = seconds) would return seconds = 86400.

For timeString, converts ESMF_TimeInterval's value into partial ISO 8601 format PyYmMdDThHmMs[:n/d]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

For timeStringISOFrac, converts ESMF_TimeInterval's value into full ISO 8601 format PyYmMdDThHmMs[.f]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

The arguments are:

timeinterval
The object instance to query.
startTimeIn
INPUT argument: pins a calendar interval to a specific point in time to allow conversion between relative units (yy, mm, d) and absolute units (d, h, m, s). Overrides any startTime and/or endTime previously set. Mutually exclusive with endTimeIn and calendarIn.
[yy]
Integer year (32-bit).
[yy_i8]
Integer year (large, 64-bit).
[mm]
Integer month (32-bit).
[mm_i8]
Integer month (large, 64-bit).
[d]
Integer Julian day, or Modified Julian day (32-bit).
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit).
[h]
Integer hour.
[m]
Integer minute.
[s]
Integer second (32-bit).
[s_i8]
Integer second (large, 64-bit).
[ms]
Integer millisecond.
[us]
Integer microsecond.
[ns]
Integer nanosecond.
[d_r8]
Double precision day.
[h_r8]
Double precision hour.
[m_r8]
Double precision minute.
[s_r8]
Double precision second.
[ms_r8]
Double precision millisecond.
[us_r8]
Double precision microsecond.
[ns_r8]
Double precision nanosecond.
[sN]
Integer numerator of fractional second (sN/sD).
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[sD]
Integer denominator of fractional second (sN/sD).
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[startTime]
Starting time, if set, of an absolute calendar interval (yy, mm, and/or d).
[calendar]
Associated Calendar, if any.
[calkindflag]
Associated CalKind_Flag, if any.
[timeString]
Convert time interval value to format string PyYmMdDThHmMs[:n/d]S, where n/d is numerator/denominator of any fractional seconds and all other units are in ISO 8601 format. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().
[timeStringISOFrac]
Convert time interval value to strict ISO 8601 format string PyYmMdDThHmMs[.f], where f is decimal form of any fractional seconds. See [26] and [14]. See also method ESMF_TimeIntervalPrint().
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.18 ESMF_TimeIntervalGet - Get a TimeInterval value

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalGet()
subroutine ESMF_TimeIntervalGetDurCal(timeinterval, calendarIn, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
startTime, &
calendar, calkindflag, &
timeString, timeStringISOFrac, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
type(ESMF_Calendar),     intent(in)            :: calendarIn ! Input
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(out), optional :: yy
integer(ESMF_KIND_I8),   intent(out), optional :: yy_i8
integer(ESMF_KIND_I4),   intent(out), optional :: mm
integer(ESMF_KIND_I8),   intent(out), optional :: mm_i8
integer(ESMF_KIND_I4),   intent(out), optional :: d
integer(ESMF_KIND_I8),   intent(out), optional :: d_i8
integer(ESMF_KIND_I4),   intent(out), optional :: h
integer(ESMF_KIND_I4),   intent(out), optional :: m
integer(ESMF_KIND_I4),   intent(out), optional :: s
integer(ESMF_KIND_I8),   intent(out), optional :: s_i8
integer(ESMF_KIND_I4),   intent(out), optional :: ms
integer(ESMF_KIND_I4),   intent(out), optional :: us
integer(ESMF_KIND_I4),   intent(out), optional :: ns
real(ESMF_KIND_R8),      intent(out), optional :: d_r8
real(ESMF_KIND_R8),      intent(out), optional :: h_r8
real(ESMF_KIND_R8),      intent(out), optional :: m_r8
real(ESMF_KIND_R8),      intent(out), optional :: s_r8
real(ESMF_KIND_R8),      intent(out), optional :: ms_r8
real(ESMF_KIND_R8),      intent(out), optional :: us_r8
real(ESMF_KIND_R8),      intent(out), optional :: ns_r8
integer(ESMF_KIND_I4),   intent(out), optional :: sN
integer(ESMF_KIND_I8),   intent(out), optional :: sN_i8
integer(ESMF_KIND_I4),   intent(out), optional :: sD
integer(ESMF_KIND_I8),   intent(out), optional :: sD_i8
type(ESMF_Time),         intent(out), optional :: startTime
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
character (len=*),       intent(out), optional :: timeString
character (len=*),       intent(out), optional :: timeStringISOFrac
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the value of timeinterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally from integers.

Units are bound (normalized) to the next larger unit specified. For example, if a time interval is defined to be one day, then ESMF_TimeIntervalGet(d = days, s = seconds) would return days = 1, seconds = 0, whereas ESMF_TimeIntervalGet(s = seconds) would return seconds = 86400.

For timeString, converts ESMF_TimeInterval's value into partial ISO 8601 format PyYmMdDThHmMs[:n/d]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

For timeStringISOFrac, converts ESMF_TimeInterval's value into full ISO 8601 format PyYmMdDThHmMs[.f]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

The arguments are:

timeinterval
The object instance to query.
calendarIn
INPUT argument: pins a calendar interval to a specific calendar to allow conversion between relative units (yy, mm, d) and absolute units (d, h, m, s). Mutually exclusive with startTimeIn and endTimeIn since they contain a calendar. Alternate to, and mutually exclusive with, calkindflagIn below. Primarily for specifying a custom calendar kind.
[yy]
Integer year (32-bit).
[yy_i8]
Integer year (large, 64-bit).
[mm]
Integer month (32-bit).
[mm_i8]
Integer month (large, 64-bit).
[d]
Integer Julian day, or Modified Julian day (32-bit).
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit).
[h]
Integer hour.
[m]
Integer minute.
[s]
Integer second (32-bit).
[s_i8]
Integer second (large, 64-bit).
[ms]
Integer millisecond.
[us]
Integer microsecond.
[ns]
Integer nanosecond.
[d_r8]
Double precision day.
[h_r8]
Double precision hour.
[m_r8]
Double precision minute.
[s_r8]
Double precision second.
[ms_r8]
Double precision millisecond.
[us_r8]
Double precision microsecond.
[ns_r8]
Double precision nanosecond.
[sN]
Integer numerator of fractional second (sN/sD).
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[sD]
Integer denominator of fractional second (sN/sD).
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[startTime]
Starting time, if set, of an absolute calendar interval (yy, mm, and/or d).
[calendar]
Associated Calendar, if any.
[calkindflag]
Associated CalKind_Flag, if any.
[timeString]
Convert time interval value to format string PyYmMdDThHmMs[:n/d]S, where n/d is numerator/denominator of any fractional seconds and all other units are in ISO 8601 format. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().
[timeStringISOFrac]
Convert time interval value to strict ISO 8601 format string PyYmMdDThHmMs[.f], where f is decimal form of any fractional seconds. See [26] and [14]. See also method ESMF_TimeIntervalPrint().
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.19 ESMF_TimeIntervalGet - Get a TimeInterval value

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalGet()
subroutine ESMF_TimeIntervalGetDurCalTyp(timeinterval, calkindflagIn, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
startTime, &
calendar, calkindflag, &
timeString, &
timeStringISOFrac, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
type(ESMF_CalKind_Flag), intent(in)            :: calkindflagIn ! Input
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(out), optional :: yy
integer(ESMF_KIND_I8),   intent(out), optional :: yy_i8
integer(ESMF_KIND_I4),   intent(out), optional :: mm
integer(ESMF_KIND_I8),   intent(out), optional :: mm_i8
integer(ESMF_KIND_I4),   intent(out), optional :: d
integer(ESMF_KIND_I8),   intent(out), optional :: d_i8
integer(ESMF_KIND_I4),   intent(out), optional :: h
integer(ESMF_KIND_I4),   intent(out), optional :: m
integer(ESMF_KIND_I4),   intent(out), optional :: s
integer(ESMF_KIND_I8),   intent(out), optional :: s_i8
integer(ESMF_KIND_I4),   intent(out), optional :: ms
integer(ESMF_KIND_I4),   intent(out), optional :: us
integer(ESMF_KIND_I4),   intent(out), optional :: ns
real(ESMF_KIND_R8),      intent(out), optional :: d_r8
real(ESMF_KIND_R8),      intent(out), optional :: h_r8
real(ESMF_KIND_R8),      intent(out), optional :: m_r8
real(ESMF_KIND_R8),      intent(out), optional :: s_r8
real(ESMF_KIND_R8),      intent(out), optional :: ms_r8
real(ESMF_KIND_R8),      intent(out), optional :: us_r8
real(ESMF_KIND_R8),      intent(out), optional :: ns_r8
integer(ESMF_KIND_I4),   intent(out), optional :: sN
integer(ESMF_KIND_I8),   intent(out), optional :: sN_i8
integer(ESMF_KIND_I4),   intent(out), optional :: sD
integer(ESMF_KIND_I8),   intent(out), optional :: sD_i8
type(ESMF_Time),         intent(out), optional :: startTime
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
character (len=*),       intent(out), optional :: timeString
character (len=*),       intent(out), optional :: timeStringISOFrac
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the value of timeinterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally from integers.

Units are bound (normalized) to the next larger unit specified. For example, if a time interval is defined to be one day, then ESMF_TimeIntervalGet(d = days, s = seconds) would return days = 1, seconds = 0, whereas ESMF_TimeIntervalGet(s = seconds) would return seconds = 86400.

For timeString, converts ESMF_TimeInterval's value into partial ISO 8601 format PyYmMdDThHmMs[:n/d]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

For timeStringISOFrac, converts ESMF_TimeInterval's value into full ISO 8601 format PyYmMdDThHmMs[.f]S. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().

The arguments are:

timeinterval
The object instance to query.
calkindflagIn
INPUT argument: Alternate to, and mutually exclusive with, calendarIn above. More convenient way of specifying a built-in calendar kind.
[yy]
Integer year (32-bit).
[yy_i8]
Integer year (large, 64-bit).
[mm]
Integer month (32-bit).
[mm_i8]
Integer month (large, 64-bit).
[d]
Integer Julian day, or Modified Julian day (32-bit).
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit).
[h]
Integer hour.
[m]
Integer minute.
[s]
Integer second (32-bit).
[s_i8]
Integer second (large, 64-bit).
[ms]
Integer millisecond.
[us]
Integer microsecond.
[ns]
Integer nanosecond.
[d_r8]
Double precision day.
[h_r8]
Double precision hour.
[m_r8]
Double precision minute.
[s_r8]
Double precision second.
[ms_r8]
Double precision millisecond.
[us_r8]
Double precision microsecond.
[ns_r8]
Double precision nanosecond.
[sN]
Integer numerator of fractional second (sN/sD).
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[sD]
Integer denominator of fractional second (sN/sD).
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit).
[startTime]
Starting time, if set, of an absolute calendar interval (yy, mm, and/or d).
[calendar]
Associated Calendar, if any.
[calkindflag]
Associated CalKind_Flag, if any.
[timeString]
Convert time interval value to format string PyYmMdDThHmMs[:n/d]S, where n/d is numerator/denominator of any fractional seconds and all other units are in ISO 8601 format. See [26] and  [14]. See also method ESMF_TimeIntervalPrint().
[timeStringISOFrac]
Convert time interval value to strict ISO 8601 format string PyYmMdDThHmMs[.f], where f is decimal form of any fractional seconds. See [26] and [14]. See also method ESMF_TimeIntervalPrint().
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.20 ESMF_TimeIntervalNegAbsValue - Return the negative absolute value of a TimeInterval

INTERFACE:

       function ESMF_TimeIntervalNegAbsValue(timeinterval)

RETURN VALUE:
       type(ESMF_TimeInterval) :: ESMF_TimeIntervalNegAbsValue

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in) :: timeinterval

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns the negative absolute value of timeinterval.

The argument is:

timeinterval
The object instance to take the negative absolute value of. Negative absolute value is returned as the value of the function.

### 43.4.21 ESMF_TimeIntervalPrint - Print TimeInterval information

INTERFACE:

       subroutine ESMF_TimeIntervalPrint(timeinterval, options, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
character (len=*),       intent(in),  optional :: options
integer,                 intent(out), optional :: rc

DESCRIPTION:

Prints out the contents of an ESMF_TimeInterval to stdout, in support of testing and debugging. The options control the type of information and level of detail.

The arguments are:

timeinterval
Time interval to be printed out.
[options]
Print options. If none specified, prints all timeinterval property values.
"string" - prints timeinterval's value in ISO 8601 format for all units through seconds. For any non-zero fractional seconds, prints in integer rational fraction form n/d. Format is PyYmMdDThHmMs[:n/d]S, where [:n/d] is the integer numerator and denominator of the fractional seconds value, if present. See [26] and [14]. See also method ESMF_TimeIntervalGet(..., timeString= , ...)
"string isofrac" - prints timeinterval's value in strict ISO 8601 format for all units, including any fractional seconds part. Format is PyYmMdDThHmMs[.f]S, where [.f] represents fractional seconds in decimal form, if present. See [26] and [14]. See also method ESMF_TimeIntervalGet(..., timeStringISOFrac= , ...)
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.22 ESMF_TimeIntervalSet - Initialize or set a TimeInterval

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalSet()
subroutine ESMF_TimeIntervalSetDur(timeinterval, &
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(inout)         :: timeinterval
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(in),  optional :: yy
integer(ESMF_KIND_I8),   intent(in),  optional :: yy_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: mm
integer(ESMF_KIND_I8),   intent(in),  optional :: mm_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: d
integer(ESMF_KIND_I8),   intent(in),  optional :: d_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: h
integer(ESMF_KIND_I4),   intent(in),  optional :: m
integer(ESMF_KIND_I4),   intent(in),  optional :: s
integer(ESMF_KIND_I8),   intent(in),  optional :: s_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: ms
integer(ESMF_KIND_I4),   intent(in),  optional :: us
integer(ESMF_KIND_I4),   intent(in),  optional :: ns
real(ESMF_KIND_R8),      intent(in),  optional :: d_r8
real(ESMF_KIND_R8),      intent(in),  optional :: h_r8
real(ESMF_KIND_R8),      intent(in),  optional :: m_r8
real(ESMF_KIND_R8),      intent(in),  optional :: s_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ms_r8
real(ESMF_KIND_R8),      intent(in),  optional :: us_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ns_r8
integer(ESMF_KIND_I4),   intent(in),  optional :: sN
integer(ESMF_KIND_I8),   intent(in),  optional :: sN_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: sD
integer(ESMF_KIND_I8),   intent(in),  optional :: sD_i8
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets the value of the ESMF_TimeInterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally to integers.

Ranges are limited only by machine word size. Numeric defaults are 0, except for sD, which is 1.

The arguments are:

timeinterval
The object instance to initialize.
[yy]
Integer year (32-bit). Default = 0.
[yy_i8]
Integer year (large, 64-bit). Default = 0.
[mm]
Integer month (32-bit). Default = 0.
[mm_i8]
Integer month (large, 64-bit). Default = 0.
[d]
Integer Julian day, or Modified Julian day (32-bit). Default = 0.
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit). Default = 0.
[h]
Integer hour. Default = 0.
[m]
Integer minute. Default = 0.
[s]
Integer second (32-bit). Default = 0.
[s_i8]
Integer second (large, 64-bit). Default = 0.
[ms]
Integer millisecond. Default = 0.
[us]
Integer microsecond. Default = 0.
[ns]
Integer nanosecond. Default = 0.
[d_r8]
Double precision day. Default = 0.0.
[h_r8]
Double precision hour. Default = 0.0.
[m_r8]
Double precision minute. Default = 0.0.
[s_r8]
Double precision second. Default = 0.0.
[ms_r8]
Double precision millisecond. Default = 0.0.
[us_r8]
Double precision microsecond. Default = 0.0.
[ns_r8]
Double precision nanosecond. Default = 0.0.
[sN]
Integer numerator of fractional second (sN/sD). Default = 0.
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 0.
[sD]
Integer denominator of fractional second (sN/sD). Default = 1.
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 1.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.23 ESMF_TimeIntervalSet - Initialize or set a TimeInterval

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalSet()
subroutine ESMF_TimeIntervalSetDurStart(timeinterval, startTime, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(inout)         :: timeinterval
type(ESMF_Time),         intent(in)            :: startTime
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(in),  optional :: yy
integer(ESMF_KIND_I8),   intent(in),  optional :: yy_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: mm
integer(ESMF_KIND_I8),   intent(in),  optional :: mm_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: d
integer(ESMF_KIND_I8),   intent(in),  optional :: d_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: h
integer(ESMF_KIND_I4),   intent(in),  optional :: m
integer(ESMF_KIND_I4),   intent(in),  optional :: s
integer(ESMF_KIND_I8),   intent(in),  optional :: s_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: ms
integer(ESMF_KIND_I4),   intent(in),  optional :: us
integer(ESMF_KIND_I4),   intent(in),  optional :: ns
real(ESMF_KIND_R8),      intent(in),  optional :: d_r8
real(ESMF_KIND_R8),      intent(in),  optional :: h_r8
real(ESMF_KIND_R8),      intent(in),  optional :: m_r8
real(ESMF_KIND_R8),      intent(in),  optional :: s_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ms_r8
real(ESMF_KIND_R8),      intent(in),  optional :: us_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ns_r8
integer(ESMF_KIND_I4),   intent(in),  optional :: sN
integer(ESMF_KIND_I8),   intent(in),  optional :: sN_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: sD
integer(ESMF_KIND_I8),   intent(in),  optional :: sD_i8
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets the value of the ESMF_TimeInterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally to integers.

Ranges are limited only by machine word size. Numeric defaults are 0, except for sD, which is 1.

The arguments are:

timeinterval
The object instance to initialize.
startTime
Starting time of an absolute calendar interval (yy, mm, and/or d); pins a calendar interval to a specific point in time. If not set, and calendar also not set, calendar interval "floats" across all calendars and times.
[yy]
Integer year (32-bit). Default = 0.
[yy_i8]
Integer year (large, 64-bit). Default = 0.
[mm]
Integer month (32-bit). Default = 0.
[mm_i8]
Integer month (large, 64-bit). Default = 0.
[d]
Integer Julian day, or Modified Julian day (32-bit). Default = 0.
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit). Default = 0.
[h]
Integer hour. Default = 0.
[m]
Integer minute. Default = 0.
[s]
Integer second (32-bit). Default = 0.
[s_i8]
Integer second (large, 64-bit). Default = 0.
[ms]
Integer millisecond. Default = 0.
[us]
Integer microsecond. Default = 0.
[ns]
Integer nanosecond. Default = 0.
[d_r8]
Double precision day. Default = 0.0.
[h_r8]
Double precision hour. Default = 0.0.
[m_r8]
Double precision minute. Default = 0.0.
[s_r8]
Double precision second. Default = 0.0.
[ms_r8]
Double precision millisecond. Default = 0.0.
[us_r8]
Double precision microsecond. Default = 0.0.
[ns_r8]
Double precision nanosecond. Default = 0.0.
[sN]
Integer numerator of fractional second (sN/sD). Default = 0.
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 0.
[sD]
Integer denominator of fractional second (sN/sD). Default = 1.
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8). (large, 64-bit). Default = 1.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.24 ESMF_TimeIntervalSet - Initialize or set a TimeInterval

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalSet()
subroutine ESMF_TimeIntervalSetDurCal(timeinterval, calendar, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(inout)         :: timeinterval
type(ESMF_Calendar),     intent(in)            :: calendar
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(in),  optional :: yy
integer(ESMF_KIND_I8),   intent(in),  optional :: yy_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: mm
integer(ESMF_KIND_I8),   intent(in),  optional :: mm_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: d
integer(ESMF_KIND_I8),   intent(in),  optional :: d_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: h
integer(ESMF_KIND_I4),   intent(in),  optional :: m
integer(ESMF_KIND_I4),   intent(in),  optional :: s
integer(ESMF_KIND_I8),   intent(in),  optional :: s_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: ms
integer(ESMF_KIND_I4),   intent(in),  optional :: us
integer(ESMF_KIND_I4),   intent(in),  optional :: ns
real(ESMF_KIND_R8),      intent(in),  optional :: d_r8
real(ESMF_KIND_R8),      intent(in),  optional :: h_r8
real(ESMF_KIND_R8),      intent(in),  optional :: m_r8
real(ESMF_KIND_R8),      intent(in),  optional :: s_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ms_r8
real(ESMF_KIND_R8),      intent(in),  optional :: us_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ns_r8
integer(ESMF_KIND_I4),   intent(in),  optional :: sN
integer(ESMF_KIND_I8),   intent(in),  optional :: sN_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: sD
integer(ESMF_KIND_I8),   intent(in),  optional :: sD_i8
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets the value of the ESMF_TimeInterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally to integers.

Ranges are limited only by machine word size. Numeric defaults are 0, except for sD, which is 1.

The arguments are:

timeinterval
The object instance to initialize.
calendar
Calendar used to give better definition to calendar interval (yy, mm, and/or d) for arithmetic, comparison, and conversion operations. Allows calendar interval to "float" across all times on a specific calendar. Default = NULL; if startTime also not specified, calendar interval "floats" across all calendars and times. Mutually exclusive with startTime since it contains a calendar. Alternate to, and mutually exclusive with, calkindflag below. Primarily for specifying a custom calendar kind.
[yy]
Integer year (32-bit). Default = 0.
[yy_i8]
Integer year (large, 64-bit). Default = 0.
[mm]
Integer month (32-bit). Default = 0.
[mm_i8]
Integer month (large, 64-bit). Default = 0.
[d]
Integer Julian day, or Modified Julian day (32-bit). Default = 0.
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit). Default = 0.
[h]
Integer hour. Default = 0.
[m]
Integer minute. Default = 0.
[s]
Integer second (32-bit). Default = 0.
[s_i8]
Integer second (large, 64-bit). Default = 0.
[ms]
Integer millisecond. Default = 0.
[us]
Integer microsecond. Default = 0.
[ns]
Integer nanosecond. Default = 0.
[d_r8]
Double precision day. Default = 0.0.
[h_r8]
Double precision hour. Default = 0.0.
[m_r8]
Double precision minute. Default = 0.0.
[s_r8]
Double precision second. Default = 0.0.
[ms_r8]
Double precision millisecond. Default = 0.0.
[us_r8]
Double precision microsecond. Default = 0.0.
[ns_r8]
Double precision nanosecond. Default = 0.0.
[sN]
Integer numerator of fractional second (sN/sD). Default = 0.
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8). (large, 64-bit). Default = 0.
[sD]
Integer denominator of fractional second (sN/sD). Default = 1.
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8). (large, 64-bit). Default = 1.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.25 ESMF_TimeIntervalSet - Initialize or set a TimeInterval

INTERFACE:

       ! Private name; call using ESMF_TimeIntervalSet()
subroutine ESMF_TimeIntervalSetDurCalTyp(timeinterval, calkindflag, &
&
yy, yy_i8, &
mm, mm_i8, &
d, d_i8, &
h, m, &
s, s_i8, &
ms, us, ns, &
d_r8, h_r8, m_r8, s_r8, &
ms_r8, us_r8, ns_r8, &
sN, sN_i8, sD, sD_i8, &
rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(inout)         :: timeinterval
type(ESMF_CalKind_Flag), intent(in)            :: calkindflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer(ESMF_KIND_I4),   intent(in),  optional :: yy
integer(ESMF_KIND_I8),   intent(in),  optional :: yy_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: mm
integer(ESMF_KIND_I8),   intent(in),  optional :: mm_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: d
integer(ESMF_KIND_I8),   intent(in),  optional :: d_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: h
integer(ESMF_KIND_I4),   intent(in),  optional :: m
integer(ESMF_KIND_I4),   intent(in),  optional :: s
integer(ESMF_KIND_I8),   intent(in),  optional :: s_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: ms
integer(ESMF_KIND_I4),   intent(in),  optional :: us
integer(ESMF_KIND_I4),   intent(in),  optional :: ns
real(ESMF_KIND_R8),      intent(in),  optional :: d_r8
real(ESMF_KIND_R8),      intent(in),  optional :: h_r8
real(ESMF_KIND_R8),      intent(in),  optional :: m_r8
real(ESMF_KIND_R8),      intent(in),  optional :: s_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ms_r8
real(ESMF_KIND_R8),      intent(in),  optional :: us_r8
real(ESMF_KIND_R8),      intent(in),  optional :: ns_r8
integer(ESMF_KIND_I4),   intent(in),  optional :: sN
integer(ESMF_KIND_I8),   intent(in),  optional :: sN_i8
integer(ESMF_KIND_I4),   intent(in),  optional :: sD
integer(ESMF_KIND_I8),   intent(in),  optional :: sD_i8
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets the value of the ESMF_TimeInterval in units specified by the user via Fortran optional arguments.

The ESMF Time Manager represents and manipulates time internally with integers to maintain precision. Hence, user-specified floating point values are converted internally to integers.

Ranges are limited only by machine word size. Numeric defaults are 0, except for sD, which is 1.

The arguments are:

timeinterval
The object instance to initialize.
calkindflag
Alternate to, and mutually exclusive with, calendar above. More convenient way of specifying a built-in calendar kind.
[yy]
Integer year (32-bit). Default = 0.
[yy_i8]
Integer year (large, 64-bit). Default = 0.
[mm]
Integer month (32-bit). Default = 0.
[mm_i8]
Integer month (large, 64-bit). Default = 0.
[d]
Integer Julian day, or Modified Julian day (32-bit). Default = 0.
[d_i8]
Integer Julian day, or Modified Julian day (large, 64-bit). Default = 0.
[h]
Integer hour. Default = 0.
[m]
Integer minute. Default = 0.
[s]
Integer second (32-bit). Default = 0.
[s_i8]
Integer second (large, 64-bit). Default = 0.
[ms]
Integer millisecond. Default = 0.
[us]
Integer microsecond. Default = 0.
[ns]
Integer nanosecond. Default = 0.
[d_r8]
Double precision day. Default = 0.0.
[h_r8]
Double precision hour. Default = 0.0.
[m_r8]
Double precision minute. Default = 0.0.
[s_r8]
Double precision second. Default = 0.0.
[ms_r8]
Double precision millisecond. Default = 0.0.
[us_r8]
Double precision microsecond. Default = 0.0.
[ns_r8]
Double precision nanoseconds. Default = 0.0.
[sN]
Integer numerator of fractional second (sN/sD). Default = 0.
[sN_i8]
Integer numerator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 0.
[sD]
Integer denominator of fractional second (sN/sD). Default = 1.
[sD_i8]
Integer denominator of fractional second (sN_i8/sD_i8) (large, 64-bit). Default = 1.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 43.4.26 ESMF_TimeIntervalValidate - Validate a TimeInterval

INTERFACE:

       subroutine ESMF_TimeIntervalValidate(timeinterval, rc)

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeinterval
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Checks whether a timeinterval is valid. If fractional value, denominator must be non-zero.

The arguments are:

timeinterval
ESMF_TimeInterval to be validated.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 44 Clock Class

## 44.1 Description

The Clock class advances model time and tracks its associated date on a specified Calendar. It stores start time, stop time, current time, previous time, and a time step. It can also store a reference time, typically the time instant at which a simulation originally began. For a restart run, the reference time can be different than the start time, when the application execution resumes.

A user can call the ESMF_ClockSet method and reset the time step as desired.

A Clock also stores a list of Alarms, which can be set to flag events that occur at a specified time instant or at a specified time interval. See Section 45.1 for details on how to use Alarms.

There are methods for setting and getting the Times and Alarms associated with a Clock. Methods are defined for advancing the Clock's current time, checking if the stop time has been reached, reversing direction, and synchronizing with a real clock.

## 44.2 Constants

### 44.2.1 ESMF_DIRECTION

DESCRIPTION:
Specifies the time-stepping direction of a clock. Use with "direction" argument to methods ESMF_ClockSet() and ESMF_ClockGet(). Cannot be used with method ESMF_ClockCreate(), since it only initializes a clock in the default forward mode; a clock must be advanced (timestepped) at least once before reversing direction via ESMF_ClockSet(). This also holds true for negative timestep clocks which are initialized (created) with stopTime < startTime, since "forward" means timestepping from startTime towards stopTime (see ESMF_DIRECTION_FORWARD below).

"Forward" and "reverse" directions are distinct from positive and negative timesteps. "Forward" means timestepping in the direction established at ESMF_ClockCreate(), from startTime towards stopTime, regardless of the timestep sign. "Reverse" means timestepping in the opposite direction, back towards the clock's startTime, regardless of the timestep sign.

Clocks and alarms run in reverse in such a way that the state of a clock and its alarms after each time step is precisely replicated as it was in forward time-stepping mode. All methods which query clock and alarm state will return the same result for a given timeStep, regardless of the direction of arrival.

The type of this flag is:

type(ESMF_Direction_Flag)

The valid values are:

ESMF_DIRECTION_FORWARD
Upon calling ESMF_ClockAdvance(), the clock will timestep from its startTime toward its stopTime. This is the default direction. A user can use either ESMF_ClockIsStopTime() or ESMF_ClockIsDone() methods to determine when stopTime is reached. This forward behavior also holds for negative timestep clocks which are initialized (created) with stopTime < startTime.

ESMF_DIRECTION_REVERSE
Upon calling ESMF_ClockAdvance(), the clock will timestep backwards toward its startTime. Use method ESMF_ClockIsDone() to determine when startTime is reached. This reverse behavior also holds for negative timestep clocks which are initialized (created) with stopTime < startTime.

## 44.3 Use and Examples

The following is a typical sequence for using a Clock in a geophysical model.

At initialize:

• Set a Calendar.
• Set start time, stop time and time step as Times and Time Intervals.
• Create and Initialize a Clock using the start time, stop time and time step.
• Define Times and Time Intervals associated with special events, and use these to set Alarms.

At run:

• Advance the Clock, checking for ringing alarms as needed.
• Check if it is time to stop.

At finalize:

• Since Clocks and Alarms are deep classes, they need to be explicitly destroyed at finalization. Times and TimeIntervals are lightweight classes, so they don't need explicit destruction.

The following code example illustrates Clock usage.

! !PROGRAM: ESMF_ClockEx - Clock initialization and time-stepping
!
! !DESCRIPTION:
!
! This program shows an example of how to create, initialize, advance, and
! examine a basic clock
!-----------------------------------------------------------------------------
#include "ESMF.h"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! instantiate a clock
type(ESMF_Clock) :: clock

! instantiate time_step, start and stop times
type(ESMF_TimeInterval) :: timeStep
type(ESMF_Time) :: startTime
type(ESMF_Time) :: stopTime

! local variables for Get methods
type(ESMF_Time) :: currTime
integer :: YY, MM, DD, H, M, S

! return code
integer :: rc


      ! initialize ESMF framework
call ESMF_Initialize(defaultCalKind=ESMF_CALKIND_GREGORIAN, &
defaultlogfilename="ClockEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


### 44.3.1 Clock creation

This example shows how to create and initialize an ESMF_Clock.

      ! initialize time interval to 2 days, 4 hours (6 timesteps in 13 days)
call ESMF_TimeIntervalSet(timeStep, d=2, h=4, rc=rc)


      ! initialize start time to 4/1/2003 2:24:00 ( 1/10 of a day )
call ESMF_TimeSet(startTime, yy=2003, mm=4, dd=1, h=2, m=24, rc=rc)


      ! initialize stop time to 4/14/2003 2:24:00 ( 1/10 of a day )
call ESMF_TimeSet(stopTime, yy=2003, mm=4, dd=14, h=2, m=24, rc=rc)


      ! initialize the clock with the above values
clock = ESMF_ClockCreate(timeStep, startTime, stopTime=stopTime, &
name="Clock 1", rc=rc)


This example shows how to time-step an ESMF_Clock.

      ! time step clock from start time to stop time
do while (.not.ESMF_ClockIsStopTime(clock, rc=rc))


        call ESMF_ClockPrint(clock, options="currTime string", rc=rc)


        call ESMF_ClockAdvance(clock, rc=rc)


      end do


### 44.3.3 Clock examination

This example shows how to examine an ESMF_Clock.

      ! get the clock's final current time
call ESMF_ClockGet(clock, currTime=currTime, rc=rc)


      call ESMF_TimeGet(currTime, yy=YY, mm=MM, dd=DD, h=H, m=M, s=S, rc=rc)
print *, "The clock's final current time is ", YY, "/", MM, "/", DD, &
" ", H, ":", M, ":", S


      ! get the number of times the clock was advanced


### 44.3.4 Clock reversal

This example shows how to time-step an ESMF_Clock in reverse mode.

      call ESMF_ClockSet(clock, direction=ESMF_DIRECTION_REVERSE, rc=rc)


      ! time step clock in reverse from stop time back to start time;
!  note use of ESMF_ClockIsDone() rather than ESMF_ClockIsStopTime()
do while (.not.ESMF_ClockIsDone(clock, rc=rc))


        call ESMF_ClockPrint(clock, options="currTime string", rc=rc)


        call ESMF_ClockAdvance(clock, rc=rc)


      end do


### 44.3.5 Clock destruction

This example shows how to destroy an ESMF_Clock.

      ! destroy clock
call ESMF_ClockDestroy(clock, rc=rc)


      ! finalize ESMF framework
call ESMF_Finalize(rc=rc)


      end program ESMF_ClockEx


## 44.4 Restrictions and Future Work

1. Alarm list allocation factor The alarm list within a clock is dynamically allocated automatically, 200 alarm references at a time. This constant is defined in both Fortran and C++ with a #define for ease of modification.

2. Clock variable timesteps in reverse In order for a clock with variable timesteps to be run in ESMF_DIRECTION_REVERSE, the user must supply those timesteps to ESMF_ClockAdvance(). Essentially, the user must save the timesteps while in forward mode. In a future release, the Time Manager will assume this responsibility by saving the clock state (including the timeStep) at every timestep while in forward mode.

## 44.5 Class API

### 44.5.1 ESMF_ClockAssignment(=) - Assign a Clock to another Clock

INTERFACE:

       interface assignment(=)
clock1 = clock2

ARGUMENTS:
       type(ESMF_Clock) :: clock1
type(ESMF_Clock) :: clock2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign clock1 as an alias to the same ESMF_Clock object in memory as clock2. If clock2 is invalid, then clock1 will be equally invalid after the assignment.

The arguments are:

clock1
The ESMF_Clock object on the left hand side of the assignment.
clock2
The ESMF_Clock object on the right hand side of the assignment.

### 44.5.2 ESMF_ClockOperator(==) - Test if Clock 1 is equal to Clock 2

INTERFACE:

       interface operator(==)
if (clock1 == clock2) then ... endif
OR
result = (clock1 == clock2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Clock), intent(in) :: clock1
type(ESMF_Clock), intent(in) :: clock2

DESCRIPTION:

Overloads the (==) operator for the ESMF_Clock class. Compare two clocks for equality; return .true. if equal, .false. otherwise. Comparison is based on IDs, which are distinct for newly created clocks and identical for clocks created as copies.

If either side of the equality test is not in the ESMF_INIT_CREATED status an error will be logged. However, this does not affect the return value, which is .true. when both sides are in the same status, and .false. otherwise.

The arguments are:

clock1
The ESMF_Clock object on the left hand side of the equality operation.
clock2
The ESMF_Clock object on the right hand side of the equality operation.

### 44.5.3 ESMF_ClockOperator(/=) - Test if Clock 1 is not equal to Clock 2

INTERFACE:

       interface operator(/=)
if (clock1 /= clock2) then ... endif
OR
result = (clock1 /= clock2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Clock), intent(in) :: clock1
type(ESMF_Clock), intent(in) :: clock2

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Clock class. Compare two clocks for inequality; return .true. if not equal, .false. otherwise. Comparison is based on IDs, which are distinct for newly created clocks and identical for clocks created as copies.

If either side of the equality test is not in the ESMF_INIT_CREATED status an error will be logged. However, this does not affect the return value, which is .true. when both sides are not in the same status, and .false. otherwise.

The arguments are:

clock1
The ESMF_Clock object on the left hand side of the non-equality operation.
clock2
The ESMF_Clock object on the right hand side of the non-equality operation.

### 44.5.4 ESMF_ClockAdvance - Advance a Clock's current time by one time step

INTERFACE:

       subroutine ESMF_ClockAdvance(clock, &
timeStep, ringingAlarmList, ringingAlarmCount, rc)

ARGUMENTS:
       type(ESMF_Clock),        intent(inout)         :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(in),  optional :: timeStep
type(ESMF_Alarm),        intent(out), optional :: ringingAlarmList(:)
integer,                 intent(out), optional :: ringingAlarmCount
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Advances the clock's current time by one time step: either the clock's, or the passed-in timeStep (see below). When the clock is in ESMF_DIRECTION_FORWARD (default), this method adds the timeStep to the clock's current time. In ESMF_DIRECTION_REVERSE, timeStep is subtracted from the current time. In either case, timeStep can be positive or negative. See the "direction" argument in method ESMF_ClockSet(). ESMF_ClockAdvance() optionally returns a list and number of ringing ESMF_Alarms. See also method ESMF_ClockGetRingingAlarms().

The arguments are:

clock
[timeStep]
Time step is performed with given timeStep, instead of the ESMF_Clock's. Does not replace the ESMF_Clock's timeStep; use ESMF_ClockSet(clock, timeStep, ...) for this purpose. Supports applications with variable time steps. timeStep can be positive or negative.
[ringingAlarmList]
Returns the array of alarms that are ringing after the time step.
[ringingAlarmCount]
The number of alarms ringing after the time step.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.5 ESMF_ClockCreate - Create a new ESMF Clock

INTERFACE:

       ! Private name; call using ESMF_ClockCreate()
function ESMF_ClockCreateNew(timeStep, startTime, &
stopTime, runDuration, runTimeStepCount, refTime, name, rc)

RETURN VALUE:
       type(ESMF_Clock) :: ESMF_ClockCreateNew

ARGUMENTS:
       type(ESMF_TimeInterval), intent(in)            :: timeStep
type(ESMF_Time),         intent(in)            :: startTime
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Time),         intent(in),  optional :: stopTime
type(ESMF_TimeInterval), intent(in),  optional :: runDuration
integer,                 intent(in),  optional :: runTimeStepCount
type(ESMF_Time),         intent(in),  optional :: refTime
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates and sets the initial values in a new ESMF_Clock.

The arguments are:

timeStep
The ESMF_Clock's time step interval, which can be positive or negative.
startTime
The ESMF_Clock's starting time. Can be less than or or greater than stopTime, depending on a positive or negative timeStep, respectively, and whether a stopTime is specified; see below.
[stopTime]
The ESMF_Clock's stopping time. Can be greater than or less than the startTime, depending on a positive or negative timeStep, respectively. If neither stopTime, runDuration, nor runTimeStepCount is specified, clock runs "forever"; user must use other means to know when to stop (e.g. ESMF_Alarm or ESMF_ClockGet(clock, currTime)). Mutually exclusive with runDuration and runTimeStepCount.
[runDuration]
Alternative way to specify ESMF_Clock's stopping time; stopTime = startTime + runDuration. Can be positive or negative, consistent with the timeStep's sign. Mutually exclusive with stopTime and runTimeStepCount.
[runTimeStepCount]
Alternative way to specify ESMF_Clock's stopping time; stopTime = startTime + (runTimeStepCount * timeStep). stopTime can be before startTime if timeStep is negative. Mutually exclusive with stopTime and runDuration.
[refTime]
The ESMF_Clock's reference time. Provides reference point for simulation time (see currSimTime in ESMF_ClockGet() below).
[name]
The name for the newly created clock. If not specified, a default unique name will be generated: "ClockNNN" where NNN is a unique sequence number from 001 to 999.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.6 ESMF_ClockCreate - Create a copy of an existing ESMF Clock

INTERFACE:

       ! Private name; call using ESMF_ClockCreate()
function ESMF_ClockCreateCopy(clock, rc)

RETURN VALUE:
       type(ESMF_Clock) :: ESMF_ClockCreateCopy

ARGUMENTS:
       type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates a deep copy of a given ESMF_Clock, but does not copy its list of ESMF_Alarms (pointers), since an ESMF_Alarm can only be associated with one ESMF_Clock. Hence, the returned ESMF_Clock copy has no associated ESMF_Alarms, the same as with a newly created ESMF_Clock. If desired, new ESMF_Alarms must be created and associated with this copied ESMF_Clock via ESMF_AlarmCreate(), or existing ESMF_Alarms must be re-associated with this copied ESMF_Clock via ESMF_AlarmSet(...clock=...).

The arguments are:

clock
The ESMF_Clock to copy.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.7 ESMF_ClockDestroy - Release resources associated with a Clock

INTERFACE:

       subroutine ESMF_ClockDestroy(clock, rc)

ARGUMENTS:
       type(ESMF_Clock), intent(inout)          :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Releases resources associated with this ESMF_Clock. This releases the list of associated ESMF_Alarms (pointers), but not the ESMF_Alarms themselves; the user must explicitly call ESMF_AlarmDestroy() on each ESMF_Alarm to release its resources. ESMF_ClockDestroy() and corresponding ESMF_AlarmDestroy()s can be called in either order.

If ESMF_ClockDestroy() is called before ESMF_AlarmDestroy(), any ESMF_Alarms that were in the ESMF_Clock's list will no longer be associated with any ESMF_Clock. If desired, these "orphaned" ESMF_Alarms can be associated with a different ESMF_Clock via a call to ESMF_AlarmSet(...clock=...).

The arguments are:

clock
Release resources associated with this ESMF_Clock and mark the object as invalid. It is an error to pass this object into any other routines after being destroyed.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.8 ESMF_ClockGet - Get a Clock's properties

INTERFACE:

       subroutine ESMF_ClockGet(clock, &
timeStep, startTime, stopTime, &
runDuration, runTimeStepCount, refTime, currTime, prevTime, &
currSimTime, prevSimTime, calendar, calkindflag, timeZone, &

ARGUMENTS:
       type(ESMF_Clock),        intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(out), optional :: timeStep
type(ESMF_Time),         intent(out), optional :: startTime
type(ESMF_Time),         intent(out), optional :: stopTime
type(ESMF_TimeInterval), intent(out), optional :: runDuration
real(ESMF_KIND_R8),      intent(out), optional :: runTimeStepCount
type(ESMF_Time),         intent(out), optional :: refTime
type(ESMF_Time),         intent(out), optional :: currTime
type(ESMF_Time),         intent(out), optional :: prevTime
type(ESMF_TimeInterval), intent(out), optional :: currSimTime
type(ESMF_TimeInterval), intent(out), optional :: prevSimTime
type(ESMF_Calendar),     intent(out), optional :: calendar
type(ESMF_CalKind_Flag), intent(out), optional :: calkindflag
integer,                 intent(out), optional :: timeZone
integer,                 intent(out), optional :: alarmCount
type(ESMF_Direction_Flag),    intent(out), optional :: direction
character (len=*),       intent(out), optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets one or more of the properties of an ESMF_Clock.

The arguments are:

clock
The object instance to query.
[timeStep]
The ESMF_Clock's time step interval.
[startTime]
The ESMF_Clock's starting time.
[stopTime]
The ESMF_Clock's stopping time.
[runDuration]
Alternative way to get ESMF_Clock's stopping time; runDuration = stopTime - startTime.
[runTimeStepCount]
Alternative way to get ESMF_Clock's stopping time; runTimeStepCount = (stopTime - startTime) / timeStep.
[refTime]
The ESMF_Clock's reference time.
[currTime]
The ESMF_Clock's current time.
[prevTime]
The ESMF_Clock's previous time. Equals currTime at the previous time step.
[currSimTime]
The current simulation time (currTime - refTime).
[prevSimTime]
The previous simulation time. Equals currSimTime at the previous time step.
[calendar]
The Calendar on which all the Clock's times are defined.
[calkindflag]
The CalKind_Flag on which all the Clock's times are defined.
[timeZone]
The timezone within which all the Clock's times are defined.
The number of times the ESMF_Clock has been advanced. Increments in ESMF_DIRECTION_FORWARD and decrements in ESMF_DIRECTION_REVERSE; see "direction" argument below and in ESMF_ClockSet().
[alarmCount]
The number of ESMF_Alarms in the ESMF_Clock's ESMF_Alarm list.
[direction]
The ESMF_Clock's time stepping direction. See also ESMF_ClockIsReverse(), an alternative for convenient use in "if" and "do while" constructs.
[name]
The name of this clock.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.9 ESMF_ClockGetAlarm - Get an Alarm in a Clock's Alarm list

INTERFACE:

       subroutine ESMF_ClockGetAlarm(clock, alarmname, alarm, &
rc)

ARGUMENTS:
       type(ESMF_Clock),  intent(in)            :: clock
character (len=*), intent(in)            :: alarmname
type(ESMF_Alarm),  intent(out)           :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the alarm whose name is the value of alarmname in the clock's ESMF_Alarm list.

The arguments are:

clock
The object instance to get the ESMF_Alarm from.
alarmname
The name of the desired ESMF_Alarm.
alarm
The desired alarm.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.10 ESMF_ClockGetAlarmList - Get a list of Alarms from a Clock

INTERFACE:

       subroutine ESMF_ClockGetAlarmList(clock, alarmlistflag, &
timeStep, alarmList, alarmCount, rc)

ARGUMENTS:
       type(ESMF_Clock),          intent(in)            :: clock
type(ESMF_AlarmList_Flag), intent(in)            :: alarmlistflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval),   intent(in),  optional :: timeStep
type(ESMF_Alarm),          intent(out), optional :: alarmList(:)
integer,                   intent(out), optional :: alarmCount
integer,                   intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the clock's list of alarms and/or number of alarms.

The arguments are:

clock
The object instance from which to get an ESMF_Alarm list and/or count of ESMF_Alarms.
alarmlistflag
The kind of list to get:

ESMF_ALARMLIST_ALL : Returns the ESMF_Clock's entire list of alarms.

ESMF_ALARMLIST_NEXTRINGING : Return only those alarms that will ring upon the next clock time step. Can optionally specify argument timeStep (see below) to use instead of the clock's. See also method ESMF_AlarmWillRingNext() for checking a single alarm.

ESMF_ALARMLIST_PREVRINGING : Return only those alarms that were ringing on the previous ESMF_Clock time step. See also method ESMF_AlarmWasPrevRinging() for checking a single alarm.

ESMF_ALARMLIST_RINGING : Returns only those clock alarms that are currently ringing. See also method ESMF_ClockAdvance() for getting the list of ringing alarms subsequent to a time step. See also method ESMF_AlarmIsRinging() for checking a single alarm.

[timeStep]
Optional time step to be used instead of the clock's. Only used with ESMF_ALARMLIST_NEXTRINGING alarmlistflag (see above); ignored if specified with other alarmlistflags.
[alarmList]
The array of returned alarms. If given, the array must be large enough to hold the number of alarms of the specified alarmlistflag in the specified clock.
[alarmCount]
If specified, returns the number of ESMF_Alarms of the specified alarmlistflag in the specified clock.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.11 ESMF_ClockGetNextTime - Calculate a Clock's next time

INTERFACE:

       subroutine ESMF_ClockGetNextTime(clock, nextTime, &
timeStep, rc)

ARGUMENTS:
       type(ESMF_Clock),        intent(in)            :: clock
type(ESMF_Time),         intent(out)           :: nextTime
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(in),  optional :: timeStep
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Calculates what the next time of the clock will be, based on the clock's current time step or an optionally passed-in timeStep.

The arguments are:

clock
The object instance for which to get the next time.
nextTime
The resulting ESMF_Clock's next time.
[timeStep]
The time step interval to use instead of the clock's.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.12 ESMF_ClockIsCreated - Check whether a Clock object has been created

INTERFACE:

   function ESMF_ClockIsCreated(clock, rc)

RETURN VALUE:
     logical :: ESMF_ClockIsCreated

ARGUMENTS:
     type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

DESCRIPTION:

Return .true. if the clock has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

clock
ESMF_Clock queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.13 ESMF_ClockIsDone - Based on its direction, test if the Clock has reached or exceeded its stop time or start time

INTERFACE:

       function ESMF_ClockIsDone(clock, rc)

RETURN VALUE:
       logical :: ESMF_ClockIsDone

ARGUMENTS:
       type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns true if currentTime is greater than or equal to stopTime in ESMF_DIRECTION_FORWARD, or if currentTime is less than or equal to startTime in ESMF_DIRECTION_REVERSE. It returns false otherwise.

The arguments are:

clock
The object instance to check.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.14 ESMF_ClockIsReverse - Test if the Clock is in reverse mode

INTERFACE:

       function ESMF_ClockIsReverse(clock, rc)

RETURN VALUE:
       logical :: ESMF_ClockIsReverse

ARGUMENTS:
       type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns true if clock is in ESMF_DIRECTION_REVERSE, and false if in ESMF_DIRECTION_FORWARD. Allows convenient use in "if" and "do while" constructs. Alternative to ESMF_ClockGet(...direction=...).

The arguments are:

clock
The object instance to check.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.15 ESMF_ClockIsStopTime - Test if the Clock has reached or exceeded its stop time

INTERFACE:

       function ESMF_ClockIsStopTime(clock, rc)

RETURN VALUE:
       logical :: ESMF_ClockIsStopTime

ARGUMENTS:
       type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns true if the clock has reached or exceeded its stop time, and false otherwise.

The arguments are:

clock
The object instance to check.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.16 ESMF_ClockIsStopTimeEnabled - Test if the Clock's stop time is enabled

INTERFACE:

       function ESMF_ClockIsStopTimeEnabled(clock, rc)

RETURN VALUE:
       logical :: ESMF_ClockIsStopTimeEnabled

ARGUMENTS:
       type(ESMF_Clock), intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns true if the clock's stop time is set and enabled, and false otherwise.

The arguments are:

clock
The object instance to check.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.17 ESMF_ClockPrint - Print Clock information

INTERFACE:

       subroutine ESMF_ClockPrint(clock, options, preString, unit, rc)

ARGUMENTS:
       type(ESMF_Clock),  intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character (len=*), intent(in),  optional :: options
character(*),      intent(in),  optional :: preString
character(*),      intent(out), optional :: unit
integer,           intent(out), optional :: rc

DESCRIPTION:

Prints out an ESMF_Clock's properties to stdout, in support of testing and debugging. The options control the type of information and level of detail.

The arguments are:

clock
ESMF_Clock to be printed out.
[options]
Print options. If none specified, prints all clock property values.
"advanceCount" - print the number of times the clock has been advanced.
"alarmCount" - print the number of alarms in the clock's list.
"alarmList" - print the clock's alarm list.
"currTime" - print the current clock time.
"direction" - print the clock's timestep direction.
"name" - print the clock's name.
"prevTime" - print the previous clock time.
"refTime" - print the clock's reference time.
"startTime" - print the clock's start time.
"stopTime" - print the clock's stop time.
"timeStep" - print the clock's time step.
[preString]
Optionally prepended string. Default to empty string.
[unit]
Internal unit, i.e. a string. Default to printing to stdout.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.18 ESMF_ClockSet - Set one or more properties of a Clock

INTERFACE:

       subroutine ESMF_ClockSet(clock, &
timeStep, startTime, stopTime, &
runDuration, runTimeStepCount, refTime, currTime, advanceCount, &
direction, name, rc)

ARGUMENTS:
       type(ESMF_Clock),        intent(inout)         :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(in),  optional :: timeStep
type(ESMF_Time),         intent(in),  optional :: startTime
type(ESMF_Time),         intent(in),  optional :: stopTime
type(ESMF_TimeInterval), intent(in),  optional :: runDuration
integer,                 intent(in),  optional :: runTimeStepCount
type(ESMF_Time),         intent(in),  optional :: refTime
type(ESMF_Time),         intent(in),  optional :: currTime
type(ESMF_Direction_Flag),    intent(in),  optional :: direction
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets/resets one or more of the properties of an ESMF_Clock that was previously initialized via ESMF_ClockCreate().

The arguments are:

clock
The object instance to set.
[timeStep]
The ESMF_Clock's time step interval, which can be positive or negative. This is used to change a clock's timestep property for those applications that need variable timesteps. See ESMF_ClockAdvance() below for specifying variable timesteps that are NOT saved as the clock's internal time step property. See "direction" argument below for behavior with
t ESMF_DIRECTION_REVERSE direction.
[startTime]
The ESMF_Clock's starting time. Can be less than or or greater than stopTime, depending on a positive or negative timeStep, respectively, and whether a stopTime is specified; see below.
[stopTime]
The ESMF_Clock's stopping time. Can be greater than or less than the startTime, depending on a positive or negative timeStep, respectively. If neither stopTime, runDuration, nor runTimeStepCount is specified, clock runs "forever"; user must use other means to know when to stop (e.g. ESMF_Alarm or ESMF_ClockGet(clock, currTime)). Mutually exclusive with runDuration and runTimeStepCount.
[runDuration]
Alternative way to specify ESMF_Clock's stopping time; stopTime = startTime + runDuration. Can be positive or negative, consistent with the timeStep's sign. Mutually exclusive with stopTime and runTimeStepCount.
[runTimeStepCount]
Alternative way to specify ESMF_Clock's stopping time; stopTime = startTime + (runTimeStepCount * timeStep). stopTime can be before startTime if timeStep is negative. Mutually exclusive with stopTime and runDuration.
[refTime]
The ESMF_Clock's reference time. See description in ESMF_ClockCreate() above.
[currTime]
The current time.
The number of times the clock has been timestepped.
[direction]
Sets the clock's time-stepping direction. If called with ESMF_DIRECTION_REVERSE, sets the clock in "reverse" mode, causing it to timestep back towards its startTime. If called with ESMF_DIRECTION_FORWARD, sets the clock in normal, "forward" mode, causing it to timestep in the direction of its startTime to stopTime. This holds true for negative timestep clocks as well, which are initialized (created) with stopTime < startTime. The default mode is ESMF_DIRECTION_FORWARD, established at ESMF_ClockCreate(). timeStep can also be specified as an argument at the same time, which allows for a change in magnitude and/or sign of the clock's timeStep. If not specified with ESMF_DIRECTION_REVERSE, the clock's current timeStep is effectively negated. If timeStep is specified, its sign is used as specified; it is not negated internally. E.g., if the specified timeStep is negative and the clock is placed in ESMF_DIRECTION_REVERSE, subsequent calls to ESMF_ClockAdvance() will cause the clock's current time to be decremented by the new timeStep's magnitude.
[name]
The new name for this clock.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.19 ESMF_ClockStopTimeDisable - Disable a Clock's stop time

INTERFACE:

       subroutine ESMF_ClockStopTimeDisable(clock, rc)

ARGUMENTS:
       type(ESMF_Clock), intent(inout)         :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Disables a ESMF_Clock's stop time; ESMF_ClockIsStopTime() will always return false, allowing a clock to run past its stopTime.

The arguments are:

clock
The object instance whose stop time to disable.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.20 ESMF_ClockStopTimeEnable - Enable an Clock's stop time

INTERFACE:

       subroutine ESMF_ClockStopTimeEnable(clock, stopTime, rc)

ARGUMENTS:
       type(ESMF_Clock), intent(inout)         :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Time),  intent(in),  optional :: stopTime
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Enables a ESMF_Clock's stop time, allowing ESMF_ClockIsStopTime() to respect the stopTime.

The arguments are:

clock
The object instance whose stop time to enable.
[stopTime]
The stop time to set or reset.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.21 ESMF_ClockSyncToRealTime - Set Clock's current time to wall clock time

INTERFACE:

       subroutine ESMF_ClockSyncToRealTime(clock, rc)

ARGUMENTS:
       type(ESMF_Clock), intent(inout)         :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets a clock's current time to the wall clock time. It is accurate to the nearest second.

The arguments are:

clock
The object instance to be synchronized with wall clock time.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 44.5.22 ESMF_ClockValidate - Validate a Clock's properties

INTERFACE:

       subroutine ESMF_ClockValidate(clock, rc)

ARGUMENTS:
       type(ESMF_Clock),  intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Checks whether a clock is valid. Must have a valid startTime and timeStep. If clock has a stopTime, its currTime must be within startTime to stopTime, inclusive; also startTime's and stopTime's calendars must be the same.

The arguments are:

clock
ESMF_Clock to be validated.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 45 Alarm Class

## 45.1 Description

The Alarm class identifies events that occur at specific Times or specific TimeIntervals by returning a true value at those times or subsequent times, and a false value otherwise.

## 45.2 Constants

### 45.2.1 ESMF_ALARMLIST

DESCRIPTION:
Specifies the characteristics of Alarms that populate a retrieved Alarm list.

The type of this flag is:

type(ESMF_AlarmList_Flag)

The valid values are:

ESMF_ALARMLIST_ALL
All alarms.

ESMF_ALARMLIST_NEXTRINGING
Alarms that will ring before or at the next timestep.

ESMF_ALARMLIST_PREVRINGING
Alarms that rang at or since the last timestep.

ESMF_ALARMLIST_RINGING
Only ringing alarms.

## 45.3 Use and Examples

Alarms are used in conjunction with Clocks (see Section 44.1). Multiple Alarms can be associated with a Clock. During the ESMF_ClockAdvance() method, a Clock iterates over its internal Alarms to determine if any are ringing. Alarms ring when a specified Alarm time is reached or exceeded, taking into account whether the time step is positive or negative. In ESMF_DIRECTION_REVERSE (see Section 44.1), alarms ring in reverse, i.e., they begin ringing when they originally ended, and end ringing when they originally began. On completion of the time advance call, the Clock optionally returns a list of ringing alarms.

Each ringing Alarm can then be processed using Alarm methods for identifying, turning off, disabling or resetting the Alarm.

Alarm methods are defined for obtaining the ringing state, turning the ringer on/off, enabling/disabling the Alarm, and getting/setting associated times.

The following example shows how to set and process Alarms.

! !PROGRAM: ESMF_AlarmEx - Alarm examples
!
! !DESCRIPTION:
!
! This program shows an example of how to create, initialize, and process
! alarms associated with a clock.
!-----------------------------------------------------------------------------
#include "ESMF.h"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! instantiate time_step, start, stop, and alarm times
type(ESMF_TimeInterval) :: timeStep, alarmInterval
type(ESMF_Time) :: alarmTime, startTime, stopTime

! instantiate a clock
type(ESMF_Clock) :: clock

! instantiate Alarm lists
integer, parameter :: NUMALARMS = 2
type(ESMF_Alarm) :: alarm(NUMALARMS)

! local variables for Get methods
integer :: ringingAlarmCount  ! at any time step (0 to NUMALARMS)

! name, loop counter, result code
character (len=ESMF_MAXSTR) :: name
integer :: i, rc, result


      ! initialize ESMF framework
call ESMF_Initialize(defaultCalKind=ESMF_CALKIND_GREGORIAN, &
defaultlogfilename="AlarmEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


### 45.3.1 Clock initialization

This example shows how to create and initialize an ESMF_Clock.

      ! initialize time interval to 1 day
call ESMF_TimeIntervalSet(timeStep, d=1, rc=rc)


      ! initialize start time to 9/1/2003
call ESMF_TimeSet(startTime, yy=2003, mm=9, dd=1, rc=rc)


      ! initialize stop time to 9/30/2003
call ESMF_TimeSet(stopTime, yy=2003, mm=9, dd=30, rc=rc)


      ! create & initialize the clock with the above values
clock = ESMF_ClockCreate(timeStep, startTime, stopTime=stopTime, &
name="The Clock", rc=rc)


### 45.3.2 Alarm initialization

This example shows how to create and initialize two ESMF_Alarms and associate them with the clock.

      ! Initialize first alarm to be a one-shot on 9/15/2003 and associate
! it with the clock
call ESMF_TimeSet(alarmTime, yy=2003, mm=9, dd=15, rc=rc)


      alarm(1) = ESMF_AlarmCreate(clock, &
ringTime=alarmTime, name="Example alarm 1", rc=rc)


      ! Initialize second alarm to ring on a 1 week interval starting 9/1/2003
! and associate it with the clock
call ESMF_TimeSet(alarmTime, yy=2003, mm=9, dd=1, rc=rc)


      call ESMF_TimeIntervalSet(alarmInterval, d=7, rc=rc)


      ! Alarm gets default name "Alarm002"
alarm(2) = ESMF_AlarmCreate(clock=clock, ringTime=alarmTime, &
ringInterval=alarmInterval, rc=rc)


### 45.3.3 Clock advance and Alarm processing

This example shows how to advance an ESMF_Clock and process any resulting ringing alarms.

      ! time step clock from start time to stop time
do while (.not.ESMF_ClockIsStopTime(clock, rc=rc))


        ! perform time step and get the number of any ringing alarms
rc=rc)


        call ESMF_ClockPrint(clock, options="currTime string", rc=rc)


        ! check if alarms are ringing
if (ringingAlarmCount > 0) then
print *, "number of ringing alarms = ", ringingAlarmCount

do i = 1, NUMALARMS
if (ESMF_AlarmIsRinging(alarm(i), rc=rc)) then


              call ESMF_AlarmGet(alarm(i), name=name, rc=rc)
print *, trim(name), " is ringing!"


              ! after processing alarm, turn it off
call ESMF_AlarmRingerOff(alarm(i), rc=rc)


            end if ! this alarm is ringing
end do ! each ringing alarm
endif ! ringing alarms
end do ! timestep clock


### 45.3.4 Alarm and Clock destruction

This example shows how to destroy ESMF_Alarms and ESMF_Clocks.

      call ESMF_AlarmDestroy(alarm(1), rc=rc)


      call ESMF_AlarmDestroy(alarm(2), rc=rc)


      call ESMF_ClockDestroy(clock, rc=rc)


      ! finalize ESMF framework
call ESMF_Finalize(rc=rc)


      end program ESMF_AlarmEx


## 45.4 Restrictions and Future Work

1. Alarm list allocation factor The alarm list within a clock is dynamically allocated automatically, 200 alarm references at a time. This constant is defined in both Fortran and C++ with a #define for ease of modification.

2. Sticky alarm end times in reverse For sticky alarms, there is an implicit limitation that in order to properly reverse timestep through a ring end time, that time must have already been traversed in the forward direction. This is due to the fact that the Time Manager cannot predict when user code will call ESMF_AlarmRingerOff(). An error message will be logged when this limitation is not satisfied.

3. Sticky alarm ring interval in reverse For repeating sticky alarms, it is currently assumed that the ringInterval is constant, so that only the time of the last call to ESMF_AlarmRingerOff() is saved. In ESMF_DIRECTION_REVERSE, this information is used to turn sticky alarms back on. In a future release, ringIntervals will be allowed to be variable, by saving alarm state at every timestep.

## 45.5 Design and Implementation Notes

The Alarm class is designed as a deep, dynamically allocatable class, based on a pointer type. This allows for both indirect and direct manipulation of alarms. Indirect alarm manipulation is where ESMF_Alarm API methods, such as ESMF_AlarmRingerOff(), are invoked on alarm references (pointers) returned from ESMF_Clock queries such as "return ringing alarms." Since the method is performed on an alarm reference, the actual alarm held by the clock is affected, not just a user's local copy. Direct alarm manipulation is the more common case where alarm API methods are invoked on the original alarm objects created by the user.

For consistency, the ESMF_Clock class is also designed as a deep, dynamically allocatable class.

An additional benefit from this approach is that Clocks and Alarms can be created and used from anywhere in a user's code without regard to the scope in which they were created. In contrast, statically created Alarms and Clocks would disappear if created within a user's routine that returns, whereas dynamically allocated Alarms and Clocks will persist until explicitly destroyed by the user.

## 45.6 Class API

### 45.6.1 ESMF_AlarmAssignment(=) - Assign an Alarm to another Alarm

INTERFACE:

       interface assignment(=)
alarm1 = alarm2

ARGUMENTS:
       type(ESMF_Alarm) :: alarm1
type(ESMF_Alarm) :: alarm2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign alarm1 as an alias to the same ESMF_Alarm object in memory as alarm2. If alarm2 is invalid, then alarm1 will be equally invalid after the assignment.

The arguments are:

alarm1
The ESMF_Alarm object on the left hand side of the assignment.
alarm2
The ESMF_Alarm object on the right hand side of the assignment.

### 45.6.2 ESMF_AlarmOperator(==) - Test if Alarm 1 is equal to Alarm 2

INTERFACE:

       interface operator(==)
if (alarm1 == alarm2) then ... endif
OR
result = (alarm1 == alarm2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Alarm), intent(in) :: alarm1
type(ESMF_Alarm), intent(in) :: alarm2

DESCRIPTION:

Overloads the (==) operator for the ESMF_Alarm class. Compare two alarms for equality; return .true. if equal, .false. otherwise. Comparison is based on IDs, which are distinct for newly created alarms and identical for alarms created as copies.

If either side of the equality test is not in the ESMF_INIT_CREATED status an error will be logged. However, this does not affect the return value, which is .true. when both sides are in the same status, and .false. otherwise.

The arguments are:

alarm1
The ESMF_Alarm object on the left hand side of the equality operation.
alarm2
The ESMF_Alarm object on the right hand side of the equality operation.

### 45.6.3 ESMF_AlarmOperator(/=) - Test if Alarm 1 is not equal to Alarm 2

INTERFACE:

       interface operator(/=)
if (alarm1 /= alarm2) then ... endif
OR
result = (alarm1 /= alarm2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Alarm), intent(in) :: alarm1
type(ESMF_Alarm), intent(in) :: alarm2

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Alarm class. Compare two alarms for inequality; return .true. if not equal, .false. otherwise. Comparison is based on IDs, which are distinct for newly created alarms and identical for alarms created as copies.

If either side of the equality test is not in the ESMF_INIT_CREATED status an error will be logged. However, this does not affect the return value, which is .true. when both sides are not in the same status, and .false. otherwise.

The arguments are:

alarm1
The ESMF_Alarm object on the left hand side of the non-equality operation.
alarm2
The ESMF_Alarm object on the right hand side of the non-equality operation.

### 45.6.4 ESMF_AlarmCreate - Create a new ESMF Alarm

INTERFACE:

       ! Private name; call using ESMF_AlarmCreate()
function ESMF_AlarmCreateNew(clock, &
ringTime, ringInterval, stopTime, ringDuration, ringTimeStepCount, &
refTime, enabled, sticky, name, rc)

RETURN VALUE:
       type(ESMF_Alarm) :: ESMF_AlarmCreateNew

ARGUMENTS:
       type(ESMF_Clock),        intent(in)            :: clock
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Time),         intent(in),  optional :: ringTime
type(ESMF_TimeInterval), intent(in),  optional :: ringInterval
type(ESMF_Time),         intent(in),  optional :: stopTime
type(ESMF_TimeInterval), intent(in),  optional :: ringDuration
integer,                 intent(in),  optional :: ringTimeStepCount
type(ESMF_Time),         intent(in),  optional :: refTime
logical,                 intent(in),  optional :: enabled
logical,                 intent(in),  optional :: sticky
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates and sets the initial values in a new ESMF_Alarm.

In ESMF_DIRECTION_REVERSE (see Section 44.1), alarms ring in reverse, i.e., they begin ringing when they originally ended, and end ringing when they originally began.

The arguments are:

clock
The clock with which to associate this newly created alarm.
[ringTime]
The ring time for a one-shot alarm or the first ring time for a repeating (interval) alarm. Must specify at least one of ringTime or ringInterval.
[ringInterval]
The ring interval for repeating (interval) alarms. If ringTime is not also specified (first ring time), it will be calculated as the clock's current time plus ringInterval. Must specify at least one of ringTime or ringInterval.
[stopTime]
The stop time for repeating (interval) alarms. If not specified, an interval alarm will repeat forever.
[ringDuration]
The absolute ring duration. If not sticky (see argument below), alarms rings for ringDuration, then turns itself off. Default is zero (unused). Mutually exclusive with ringTimeStepCount (below); used only if set to a non-zero duration and ringTimeStepCount is 1 (see below). See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[ringTimeStepCount]
The relative ring duration. If not sticky (see argument below), alarms rings for ringTimeStepCount, then turns itself off. Default is 1: a non-sticky alarm will ring for one clock time step. Mutually exclusive with ringDuration (above); used if ringTimeStepCount > 1. If ringTimeStepCount is 1 (default) and ringDuration is non-zero, ringDuration is used (see above), otherwise ringTimeStepCount is used. See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[refTime]
The reference (i.e. base) time for an interval alarm.
[enabled]
Sets the enabled state; default is on (true). If disabled, an alarm will not function at all. See also ESMF_AlarmEnable(), ESMF_AlarmDisable().
[sticky]
Sets the sticky state; default is on (true). If sticky, once an alarm is ringing, it will remain ringing until turned off manually via a user call to ESMF_AlarmRingerOff(). If not sticky, an alarm will turn itself off after a certain ring duration specified by either ringDuration or ringTimeStepCount (see above). There is an implicit limitation that in order to properly reverse timestep through a ring end time in ESMF_DIRECTION_REVERSE, that time must have already been traversed in the forward direction. This is due to the fact that the Time Manager cannot predict when user code will call ESMF_AlarmRingerOff(). An error message will be logged when this limitation is not satisfied. See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[name]
The name for the newly created alarm. If not specified, a default unique name will be generated: "AlarmNNN" where NNN is a unique sequence number from 001 to 999.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.5 ESMF_AlarmCreate - Create a copy of an existing ESMF Alarm

INTERFACE:

       ! Private name; call using ESMF_AlarmCreate()
function ESMF_AlarmCreateCopy(alarm, rc)

RETURN VALUE:
       type(ESMF_Alarm) :: ESMF_AlarmCreateCopy

ARGUMENTS:
       type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Creates a complete (deep) copy of a given ESMF_Alarm. The returned ESMF_Alarm copy is associated with the same ESMF_Clock as the original ESMF_Alarm. If desired, use ESMF_AlarmSet(...clock=...) to re-associate the ESMF_Alarm copy with a different ESMF_Clock.

The arguments are:

alarm
The ESMF_Alarm to copy.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.6 ESMF_AlarmDestroy - Release resources associated with an Alarm

INTERFACE:

       subroutine ESMF_AlarmDestroy(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)          :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Releases resources associated with this ESMF_Alarm. Also removes this ESMF_Alarm from its associated ESMF_Clock's list of ESMF_Alarms (removes the ESMF_Alarm pointer from the list).

The arguments are:

alarm
Release resources associated with this ESMF_Alarm and mark the object as invalid. It is an error to pass this object into any other routines after being destroyed.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.7 ESMF_AlarmDisable - Disable an Alarm

INTERFACE:

       subroutine ESMF_AlarmDisable(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Disables an ESMF_Alarm.

The arguments are:

alarm
The object instance to disable.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.8 ESMF_AlarmEnable - Enable an Alarm

INTERFACE:

       subroutine ESMF_AlarmEnable(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Enables an ESMF_Alarm to function.

The arguments are:

alarm
The object instance to enable.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.9 ESMF_AlarmGet - Get Alarm properties

INTERFACE:

       subroutine ESMF_AlarmGet(alarm, &
clock, ringTime, prevRingTime, ringInterval, stopTime, ringDuration, &
ringTimeStepCount, timeStepRingingCount, ringBegin, ringEnd, &
refTime, ringing, ringingOnPrevTimeStep, enabled, sticky, name, rc)

ARGUMENTS:
       type(ESMF_Alarm),        intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Clock),        intent(out), optional :: clock
type(ESMF_Time),         intent(out), optional :: ringTime
type(ESMF_Time),         intent(out), optional :: prevRingTime
type(ESMF_TimeInterval), intent(out), optional :: ringInterval
type(ESMF_Time),         intent(out), optional :: stopTime
type(ESMF_TimeInterval), intent(out), optional :: ringDuration
integer,                 intent(out), optional :: ringTimeStepCount
integer,                 intent(out), optional :: timeStepRingingCount
type(ESMF_Time),         intent(out), optional :: ringBegin
type(ESMF_Time),         intent(out), optional :: ringEnd
type(ESMF_Time),         intent(out), optional :: refTime
logical,                 intent(out), optional :: ringing
logical,                 intent(out), optional :: ringingOnPrevTimeStep
logical,                 intent(out), optional :: enabled
logical,                 intent(out), optional :: sticky
character (len=*),       intent(out), optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets one or more of an ESMF_Alarm's properties.

The arguments are:

alarm
The object instance to query.
[clock]
The associated clock.
[ringTime]
The ring time for a one-shot alarm or the next repeating alarm.
[prevRingTime]
The previous ring time.
[ringInterval]
The ring interval for repeating (interval) alarms.
[stopTime]
The stop time for repeating (interval) alarms.
[ringDuration]
The ring duration. Mutually exclusive with ringTimeStepCount (see below).
[ringTimeStepCount]
The number of time steps comprising the ring duration. Mutually exclusive with ringDuration (see above).
[timeStepRingingCount]
The number of time steps for which the alarm has been ringing thus far. Used internally for tracking ringTimeStepCount ring durations (see above). Mutually exclusive with ringBegin (see below). Increments in ESMF_DIRECTION_FORWARD and decrements in ESMF_DIRECTION_REVERSE; see Section 44.1.
[ringBegin]
The time when the alarm began ringing. Used internally for tracking ringDuration (see above). Mutually exclusive with timeStepRingingCount (see above).
[ringEnd]
The time when the alarm ended ringing. Used internally for re-ringing alarm in ESMF_DIRECTION_REVERSE.
[refTime]
The reference (i.e. base) time for an interval alarm.
[ringing]
[ringingOnPrevTimeStep]
The ringing state upon the previous time step. Same as ESMF_AlarmWasPrevRinging().
[enabled]
[sticky]
[name]
The name of this alarm.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.10 ESMF_AlarmIsCreated - Check whether a Alarm object has been created

INTERFACE:

   function ESMF_AlarmIsCreated(alarm, rc)

RETURN VALUE:
     logical :: ESMF_AlarmIsCreated

ARGUMENTS:
     type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

DESCRIPTION:

Return .true. if the alarm has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

alarm
ESMF_Alarm queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.11 ESMF_AlarmIsEnabled - Check if Alarm is enabled

INTERFACE:

       function ESMF_AlarmIsEnabled(alarm, rc)

RETURN VALUE:
       logical :: ESMF_AlarmIsEnabled

ARGUMENTS:
       type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Check if ESMF_Alarm is enabled.

The arguments are:

alarm
The object instance to check for enabled state.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.12 ESMF_AlarmIsRinging - Check if Alarm is ringing

INTERFACE:

       function ESMF_AlarmIsRinging(alarm, rc)

RETURN VALUE:
       logical :: ESMF_AlarmIsRinging

ARGUMENTS:
       type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Check if ESMF_Alarm is ringing.

See also method ESMF_ClockGetAlarmList(clock, ESMF_ALARMLIST_RINGING, ...) to get a list of all ringing alarms belonging to an ESMF_Clock.

The arguments are:

alarm
The alarm to check for ringing state.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.13 ESMF_AlarmIsSticky - Check if Alarm is sticky

INTERFACE:

       function ESMF_AlarmIsSticky(alarm, rc)

RETURN VALUE:
       logical :: ESMF_AlarmIsSticky

ARGUMENTS:
       type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Check if alarm is sticky.

The arguments are:

alarm
The object instance to check for sticky state.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.14 ESMF_AlarmNotSticky - Unset an Alarm's sticky flag

INTERFACE:

       subroutine ESMF_AlarmNotSticky(alarm, &
ringDuration, ringTimeStepCount, rc)

ARGUMENTS:
       type(ESMF_Alarm),        intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(in),  optional :: ringDuration
integer,                 intent(in),  optional :: ringTimeStepCount
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Unset an ESMF_Alarm's sticky flag; once alarm is ringing, it turns itself off after ringDuration.

The arguments are:

alarm
The object instance to unset sticky.
[ringDuration]
If not sticky, alarms rings for ringDuration, then turns itself off. Mutually exclusive with ringTimeStepCount (see below and full description in method ESMF_AlarmCreate() or ESMF_AlarmSet()).
[ringTimeStepCount]
If not sticky, alarms rings for ringTimeStepCount, then turns itself off. Mutually exclusive with ringDuration (see above and full description in method ESMF_AlarmCreate() or ESMF_AlarmSet()).
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.15 ESMF_AlarmPrint - Print Alarm information

INTERFACE:

       subroutine ESMF_AlarmPrint(alarm, options, rc)

ARGUMENTS:
       type(ESMF_Alarm),  intent(in)            :: alarm
character (len=*), intent(in),  optional :: options
integer,           intent(out), optional :: rc

DESCRIPTION:

Prints out an ESMF_Alarm's properties to stdout, in support of testing and debugging. The options control the type of information and level of detail.

The arguments are:

alarm
ESMF_Alarm to be printed out.
[options]
Print options. If none specified, prints all alarm property values.
"clock" - print the associated clock's name.
"enabled" - print the alarm's ability to ring.
"name" - print the alarm's name.
"prevRingTime" - print the alarm's previous ring time.
"ringBegin" - print time when the alarm actually begins to ring.
"ringDuration" - print how long this alarm is to remain ringing.
"ringEnd" - print time when the alarm actually ends ringing.
"ringing" - print the alarm's current ringing state.
"ringingOnPrevTimeStep" - print whether the alarm was ringing immediately after the previous clock time step.
"ringInterval" - print the alarm's periodic ring interval.
"ringTime" - print the alarm's next time to ring.
"ringTimeStepCount" - print how long this alarm is to remain ringing, in terms of a number of clock time steps.
"refTime" - print the alarm's interval reference (base) time.
"sticky" - print whether the alarm must be turned off manually.
"stopTime" - print when alarm intervals end.
"timeStepRingingCount" - print the number of time steps the alarm has been ringing thus far.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.16 ESMF_AlarmRingerOff - Turn off an Alarm

INTERFACE:

       subroutine ESMF_AlarmRingerOff(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Turn off an ESMF_Alarm; unsets ringing state. For a sticky alarm, this method must be called to turn off its ringing state. This is true for either ESMF_DIRECTION_FORWARD (default) or ESMF_DIRECTION_REVERSE. See Section 44.1.

The arguments are:

alarm
The object instance to turn off.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.17 ESMF_AlarmRingerOn - Turn on an Alarm

INTERFACE:

       subroutine ESMF_AlarmRingerOn(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Turn on an ESMF_Alarm; sets ringing state.

The arguments are:

alarm
The object instance to turn on.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.18 ESMF_AlarmSet - Set Alarm properties

INTERFACE:

       subroutine ESMF_AlarmSet(alarm, &
clock, ringTime, ringInterval, stopTime, ringDuration, &
ringTimeStepCount, refTime, ringing, enabled, sticky, name, rc)

ARGUMENTS:
       type(ESMF_Alarm),        intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Clock),        intent(in),  optional :: clock
type(ESMF_Time),         intent(in),  optional :: ringTime
type(ESMF_TimeInterval), intent(in),  optional :: ringInterval
type(ESMF_Time),         intent(in),  optional :: stopTime
type(ESMF_TimeInterval), intent(in),  optional :: ringDuration
integer,                 intent(in),  optional :: ringTimeStepCount
type(ESMF_Time),         intent(in),  optional :: refTime
logical,                 intent(in),  optional :: ringing
logical,                 intent(in),  optional :: enabled
logical,                 intent(in),  optional :: sticky
character (len=*),       intent(in),  optional :: name
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets/resets one or more of the properties of an ESMF_Alarm that was previously initialized via ESMF_AlarmCreate().

The arguments are:

alarm
The object instance to set.
[clock]
Re-associates this alarm with a different clock.
[ringTime]
The next ring time for a one-shot alarm or a repeating (interval) alarm.
[ringInterval]
The ring interval for repeating (interval) alarms.
[stopTime]
The stop time for repeating (interval) alarms.
[ringDuration]
The absolute ring duration. If not sticky (see argument below), alarms rings for ringDuration, then turns itself off. Default is zero (unused). Mutually exclusive with ringTimeStepCount (below); used only if set to a non-zero duration and ringTimeStepCount is 1 (see below). See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[ringTimeStepCount]
The relative ring duration. If not sticky (see argument below), alarms rings for ringTimeStepCount, then turns itself off. Default is 1: a non-sticky alarm will ring for one clock time step. Mutually exclusive with ringDuration (above); used if ringTimeStepCount > 1. If ringTimeStepCount is 1 (default) and ringDuration is non-zero, ringDuration is used (see above), otherwise ringTimeStepCount is used. See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[refTime]
The reference (i.e. base) time for an interval alarm.
[ringing]
[enabled]
Sets the enabled state. If disabled, an alarm will not function at all. See also ESMF_AlarmEnable(), ESMF_AlarmDisable().
[sticky]
Sets the sticky state. If sticky, once an alarm is ringing, it will remain ringing until turned off manually via a user call to ESMF_AlarmRingerOff(). If not sticky, an alarm will turn itself off after a certain ring duration specified by either ringDuration or ringTimeStepCount (see above). There is an implicit limitation that in order to properly reverse timestep through a ring end time in ESMF_DIRECTION_REVERSE, that time must have already been traversed in the forward direction. This is due to the fact that the Time Manager cannot predict when user code will call ESMF_AlarmRingerOff(). An error message will be logged when this limitation is not satisfied. See also ESMF_AlarmSticky(), ESMF_AlarmNotSticky().
[name]
The new name for this alarm.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.19 ESMF_AlarmSticky - Set an Alarm's sticky flag

INTERFACE:

       subroutine ESMF_AlarmSticky(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm), intent(inout)         :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Set an ESMF_Alarm's sticky flag; once alarm is ringing, it remains ringing until ESMF_AlarmRingerOff() is called. There is an implicit limitation that in order to properly reverse timestep through a ring end time in ESMF_DIRECTION_REVERSE, that time must have already been traversed in the forward direction. This is due to the fact that an ESMF_Alarm cannot predict when user code will call ESMF_AlarmRingerOff(). An error message will be logged when this limitation is not satisfied.

The arguments are:

alarm
The object instance to be set sticky.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.20 ESMF_AlarmValidate - Validate an Alarm's properties

INTERFACE:

       subroutine ESMF_AlarmValidate(alarm, rc)

ARGUMENTS:
       type(ESMF_Alarm),  intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Performs a validation check on an ESMF_Alarm's properties. Must have a valid ringTime, set either directly or indirectly via ringInterval. See ESMF_AlarmCreate().

The arguments are:

alarm
ESMF_Alarm to be validated.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.21 ESMF_AlarmWasPrevRinging - Check if Alarm was ringing on the previous Clock timestep

INTERFACE:

       function ESMF_AlarmWasPrevRinging(alarm, rc)

RETURN VALUE:
       logical :: ESMF_AlarmWasPrevRinging

ARGUMENTS:
       type(ESMF_Alarm), intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Check if ESMF_Alarm was ringing on the previous clock timestep.

See also method ESMF_ClockGetAlarmList(clock, ESMF_ALARMLIST_PREVRINGING, ...) get a list of all alarms belonging to a ESMF_Clock that were ringing on the previous time step.

The arguments are:

alarm
The object instance to check for previous ringing state.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 45.6.22 ESMF_AlarmWillRingNext - Check if Alarm will ring upon the next Clock timestep

INTERFACE:

       function ESMF_AlarmWillRingNext(alarm, timeStep, rc)

RETURN VALUE:
       logical :: ESMF_AlarmWillRingNext

ARGUMENTS:
       type(ESMF_Alarm),        intent(in)            :: alarm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_TimeInterval), intent(in),  optional :: timeStep
integer,                 intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Check if ESMF_Alarm will ring on the next clock timestep, either the current clock timestep or a passed-in timestep.

See also method ESMF_ClockGetAlarmList(clock, ESMF_ALARMLIST_NEXTRINGING, ...) to get a list of all alarms belonging to a ESMF_Clock that will ring on the next time step.

The arguments are:

alarm
The alarm to check for next ringing state.
[timeStep]
Optional timestep to use instead of the clock's.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 46 Config Class

## 46.1 Description

ESMF Configuration Management is based on NASA DAO's Inpak 90 package, a Fortran 90 collection of routines/functions for accessing Resource Files in ASCII format.The package is optimized for minimizing formatted I/O, performing all of its string operations in memory using Fortran intrinsic functions.

### 46.1.1 Package history

The ESMF Configuration Management Package was evolved by Leonid Zaslavsky and Arlindo da Silva from Ipack90 package created by Arlindo da Silva at NASA DAO.

Back in the 70's Eli Isaacson wrote IOPACK in Fortran 66. In June of 1987 Arlindo da Silva wrote Inpak77 using Fortran 77 string functions; Inpak 77 is a vastly simplified IOPACK, but has its own goodies not found in IOPACK. Inpak 90 removes some obsolete functionality in Inpak77, and parses the whole resource file in memory for performance.

### 46.1.2 Resource files

A Resource File (RF) is a text file consisting of list of label-value pairs. There is a limit of 250 characters per line and the Resource File can contain a maximum of 200 records. Each label should be followed by some data, the value. An example Resource File follows. It is the file used in the example below.

 # This is an example Resource File.
# It contains a list of <label,value> pairs.
# The colon after the label is required.

# The values after the label can be an list.
# Multiple types are authorized.

my_file_names:         jan87.dat jan88.dat jan89.dat  # all strings
constants:             3.1415   25                    # float and integer
my_favorite_colors:    green blue 022

# Or, the data can be a list of single value pairs.
# It is simplier to retrieve data in this format:

parameter_1:           89
parameter_2:           78.2
input_file_name:       dummy_input.netcdf

# Or, the data can be located in a table using the following
# syntax:

my_table_name::
1000     3000     263.0
925     3000     263.0
850     3000     263.0
700     3000     269.0
500     3000     287.0
400     3000     295.8
300     3000     295.8
::


Note that the colon after the label is required and that the double colon is required to declare tabular data.

Resource files are intended for random access (except between ::'s in a table definition). This means that order in which a particular label-value pair is retrieved is not dependent upon the original order of the pairs. The only exception to this, however, is when the same label appears multiple times within the Resource File.

## 46.2 Use and Examples

This example/test code performs simple Config/Resource File routines. It does not include attaching a Config to a component. The important thing to remember there is that you can have one Config per component.

There are two methodologies for accessing data in a Resource File. This example will demonstrate both.

Note the API section contains a complete description of arguments in the methods/functions demonstrated in this example.

### 46.2.1 Variable declarations

The following are the variable declarations used as arguments in the following code fragments. They represent the locals names for the variables listed in the Resource File (RF). Note they do not need to be the same.

      character(ESMF_MAXPATHLEN) :: fname ! config file name
character(ESMF_MAXPATHLEN) :: fn1, fn2, fn3, input_file ! strings to be read in
integer       :: rc            ! error return code (0 is OK)
integer       :: i_n           ! the first constant in the RF
real          :: param_1       ! the second constant in the RF
real          :: table(7,3)    ! an array to hold the table in the RF

type(ESMF_Config)   :: cf      ! the Config itself


### 46.2.2 Creation of a Config

While there are two methodologies for accessing the data within a Resource File, there is only one way to create the initial Config and load its ASCII text into memory. This is the first step in the process.

Note that subsequent calls to ESMF_ConfigLoadFile will OVERWRITE the current Config NOT append to it. There is no means of appending to a Config.

      cf = ESMF_ConfigCreate(rc=rc)             ! Create the empty Config


      fname = "myResourceFile.rc"                ! Name the Resource File
! into the empty Config


### 46.2.3 How to retrieve a label with a single value

The first method for retrieving information from the Resource File takes advantage of the <label,value> relationship within the file and access the data in a dictionary-like manner. This is the simplest methodology, but it does imply the use of only one value per label in the Resource File.

Remember, that the order in which a particular label/value pair is retrieved is not dependent upon the order which they exist within the Resource File.

    call ESMF_ConfigGetAttribute(cf, radius, label='radius_of_the_earth:', &
default=1.0, rc=rc)


Note that the colon must be included in the label string when using this methodology. It is also important to provide a default value in case the label does not exist in the file

This methodology works for all types. The following is an example of retrieving a string:

    call ESMF_ConfigGetAttribute(cf, input_file, label='input_file_name:', &
default="./default.nc", rc=rc)


The same code fragment can be used to demonstrate what happens when the label is not present. Note that "file_name" does not exist in the Resource File. The result of its absence is the default value provided in the call.

    call ESMF_ConfigGetAttribute(cf, input_file, label='file_name:', &
default="./default.nc", rc=rc)


### 46.2.4 How to retrieve a label with multiple values

When there are multiple, mixed-typed values associated with a label, the values can be retrieved in two steps: 1) Use ESMF_ConfigFindLabel() to find the label in the Config class; 2) use ESMF_ConfigGetAttribute() without the optional 'label' argument to retrieve the values one at a time, reading from left to right in the record.

A second reminder that the order in which a particular label/value pair is retrieved is not dependent upon the order which they exist within the Resource File. The label used in this method allows the user to skip to any point in the file.

      call ESMF_ConfigFindLabel(cf, 'constants:', rc=rc) ! Step a) Find the
! label


Two constants, radius and i_n, can now be retrieved without having to specify their label or use an array. They are also different types.

      call ESMF_ConfigGetAttribute(cf, param_1, rc=rc) ! Step b) read in the
! first constant in
! the sequence
call ESMF_ConfigGetAttribute(cf, i_n, rc=rc)     ! Step c) read in the
! second constant in
! the sequence


This methodology also works with strings.

       call ESMF_ConfigFindLabel(cf, 'my_file_names:', &
rc=rc)                       ! Step a) find the label


       call ESMF_ConfigGetAttribute(cf, fn1, &
rc=rc)                    ! Step b) retrieve the 1st filename
call ESMF_ConfigGetAttribute(cf, fn2, &
rc=rc)                    ! Step c) retrieve the 2nd filename
call ESMF_ConfigGetAttribute(cf, fn3, &
rc=rc)                    ! Step d) retrieve the 3rd filename


### 46.2.5 How to retrieve a table

To access tabular data, the user must use the multi-value method.

      call ESMF_ConfigFindLabel(cf, 'my_table_name::', &
rc=rc)        ! Step a) Set the label location to the
! beginning of the table


Subsequently, call ESMF_ConfigNextLine() is used to move the location to the next row of the table. The example table in the Resource File contains 7 rows and 3 columns (7,3).

      do i = 1, 7
call ESMF_ConfigNextLine(cf, rc=rc) ! Step b) Increment the rows
do j = 1, 3                         ! Step c) Fill in the table
call ESMF_ConfigGetAttribute(cf, table(i,j), rc=rc)
enddo
enddo


### 46.2.6 Destruction of a Config

The work with the configuration file cf is finalized by call to ESMF_ConfigDestroy():

      call ESMF_ConfigDestroy(cf, rc=rc) ! Destroy the Config


## 46.3 Class API

### 46.3.1 ESMF_ConfigAssignment(=) - Config assignment

INTERFACE:

     interface assignment(=)
config1 = config2

ARGUMENTS:
     type(ESMF_Config) :: config1
type(ESMF_Config) :: config2

DESCRIPTION:

Assign config1 as an alias to the same ESMF_Config object in memory as config2. If config2 is invalid, then config1 will be equally invalid after the assignment.

The arguments are:

config1
The ESMF_Config object on the left hand side of the assignment.
config2
The ESMF_Config object on the right hand side of the assignment.

### 46.3.2 ESMF_ConfigOperator(==) - Test if Config objects are equivalent

INTERFACE:

       interface operator(==)
if (config1 == config2) then ... endif
OR
result = (config1 == config2)

RETURN VALUE:
       configical :: result

ARGUMENTS:
       type(ESMF_Config), intent(in) :: config1
type(ESMF_Config), intent(in) :: config2

DESCRIPTION:

Overloads the (==) operator for the ESMF_Config class. Compare two configs for equality; return .true. if equal, .false. otherwise. Comparison is based on whether the objects are distinct, as with two newly created objects, or are simply aliases to the same object as would be the case when assignment was involved.

The arguments are:

config1
The ESMF_Config object on the left hand side of the equality operation.
config2
The ESMF_Config object on the right hand side of the equality operation.

### 46.3.3 ESMF_ConfigOperator(/=) - Test if Config objects are not equivalent

INTERFACE:

       interface operator(/=)
if (config1 /= config2) then ... endif
OR
result = (config1 /= config2)

RETURN VALUE:
       configical :: result

ARGUMENTS:
       type(ESMF_Config), intent(in) :: config1
type(ESMF_Config), intent(in) :: config2

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Config class. Compare two configs for equality; return .true. if not equivalent, .false. otherwise. Comparison is based on whether the Config objects are distinct, as with two newly created objects, or are simply aliases to the same object as would be the case when assignment was involved.

The arguments are:

config1
The ESMF_Config object on the left hand side of the equality operation.
config2
The ESMF_Config object on the right hand side of the equality operation.

### 46.3.4 ESMF_ConfigCreate - Instantiate a Config object

INTERFACE:

       ! Private name; call using ESMF_ConfigCreate()
type(ESMF_Config) function ESMF_ConfigCreateEmpty(rc)

ARGUMENTS:
 -- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,intent(out), optional              :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Instantiates an ESMF_Config object for use in subsequent calls.

The arguments are:

[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.5 ESMF_ConfigCreate - Instantiate a new Config object from a Config section

INTERFACE:

     ! Private name; call using ESMF_ConfigCreate()
type(ESMF_Config) function ESMF_ConfigCreateFromSection(config, &
openlabel, closelabel, rc)

ARGUMENTS:
       type(ESMF_Config)             :: config
character(len=*),  intent(in) :: openlabel, closelabel
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,intent(out), optional :: rc

DESCRIPTION:

Instantiates an ESMF_Config object from a section of an existing ESMF_Config object delimited by openlabel and closelabel. An error is returned if neither of the input labels is found in input config.

Note that a section is intended as the content of a given ESMF_Config object delimited by two distinct labels. Such content, as well as each of the surrounding labels, are still within the scope of the parent ESMF_Config object. Therefore, including in a section labels used outside that section should be done carefully to prevent parsing conflicts.

The arguments are:

config
The input ESMF_Config object.
openlabel
Label marking the beginning of a section in config.
closelabel
Label marking the end of a section in config.
[rc]
Return code; equals ESMF_SUCCESS if a section is found and a new ESMF_Config object returned.

### 46.3.6 ESMF_ConfigDestroy - Destroy a Config object

INTERFACE:

     subroutine ESMF_ConfigDestroy(config, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)          :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,           intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Destroys the config object.

The arguments are:

config
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.7 ESMF_ConfigFindLabel - Find a label in a Config object

INTERFACE:

     subroutine ESMF_ConfigFindLabel(config, label, isPresent, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)           :: config
character(len=*),  intent(in)              :: label
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,           intent(out),  optional  :: isPresent
integer,           intent(out),  optional  :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
6.1.0
Added the isPresent argument. Allows detection of end-of-line condition to be separate from the rc.

DESCRIPTION:

Finds the label (key) string in the config object starting from the beginning of its content.

Since the search is done by looking for a string, possibly multi-worded, in the whole Config object, it is important to use special conventions to distinguish labels from other words. This is done in the Resource File by using the NASA/DAO convention to finish line labels with a colon (:) and table labels with a double colon (::).

The arguments are:

config
label
Identifying label.
[isPresent]
Set to .true. if the item is found.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors. If the label is not found, and the isPresent argument is not present, an error is returned.

### 46.3.8 ESMF_ConfigFindNextLabel - Find a label in Config object starting from current position

INTERFACE:

     subroutine ESMF_ConfigFindNextLabel(config, label, isPresent, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)           :: config
character(len=*),  intent(in)              :: label
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,           intent(out),  optional  :: isPresent
integer,           intent(out),  optional  :: rc

DESCRIPTION:

Finds the label (key) string in the config object, starting from the current position pointer.

This method is equivalent to ESMF_ConfigFindLabel, but the search is performed starting from the current position pointer.

The arguments are:

config
label
Identifying label.
[isPresent]
Set to .true. if the item is found.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors. If the label is not found, and the isPresent argument is not present, an error is returned.

### 46.3.9 ESMF_ConfigGetAttribute - Get an attribute value from Config object

INTERFACE:

        subroutine ESMF_ConfigGetAttribute(config, <value>, &
label, default, rc)

ARGUMENTS:
        type(ESMF_Config), intent(inout)         :: config
<value argument>, see below for supported values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*),  intent(in),  optional :: label
character(len=*),  intent(in),  optional :: default
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets a value from the config object. When the value is a sequence of characters it will be terminated by the first white space.

Supported values for <value argument> are:

character(len=*), intent(out) :: value
real(ESMF_KIND_R4), intent(out) :: value
real(ESMF_KIND_R8), intent(out) :: value
integer(ESMF_KIND_I4), intent(out) :: value
integer(ESMF_KIND_I8), intent(out) :: value
logical, intent(out) :: value

The arguments are:

config
<value argument>
Returned value.
[label]
Identifing label.
[default]
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.10 ESMF_ConfigGetAttribute - Get a list of attribute values from Config object

INTERFACE:

        subroutine ESMF_ConfigGetAttribute(config, <value list argument>, &
count, label, default, rc)

ARGUMENTS:
        type(ESMF_Config), intent(inout)         :: config
<value list argument>, see below for values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,           intent(in)   optional :: count
character(len=*),  intent(in),  optional :: label
character(len=*),  intent(in),  optional :: default
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets a list of values from the config object.

Supported values for <value list argument> are:

character(len=*), intent(out) :: valueList(:)
real(ESMF_KIND_R4), intent(inout) :: valueList(:)
real(ESMF_KIND_R8), intent(inout) :: valueList(:)
integer(ESMF_KIND_I4), intent(inout) :: valueList(:)
integer(ESMF_KIND_I8), intent(inout) :: valueList(:)
logical, intent(inout) :: valueList(:)

The arguments are:

config
<value list argument>
Returned value.
count
Number of returned values expected.
[label]
Identifing label.
[default]
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.11 ESMF_ConfigGetChar - Get a character attribute value from Config object

INTERFACE:

       subroutine ESMF_ConfigGetChar(config, value, &
label, default, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)         :: config
character,         intent(out)           :: value
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*),  intent(in),  optional :: label
character,         intent(in),  optional :: default
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets a character value from the config object.

The arguments are:

config
value
Returned value.
[label]
Identifying label.
[default]
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.12 ESMF_ConfigGetDim - Get table sizes from Config object

INTERFACE:

     subroutine ESMF_ConfigGetDim(config, lineCount, columnCount, &
label, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)         :: config
integer,           intent(out)           :: lineCount
integer,           intent(out)           :: columnCount
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*),  intent(in),  optional :: label
integer,           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Returns the number of lines in the table in lineCount and the maximum number of words in a table line in columnCount.

After the call, the line pointer is positioned to the end of the table. To reset it to the beginning of the table, use ESMF_ConfigFindLabel.

The arguments are:

config
lineCount
Returned number of lines in the table.
columnCount
Returned maximum number of words in a table line.
[label]
Identifying label (if present), otherwise current line.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.13 ESMF_ConfigGetLen - Get the length of the line in words from Config object

INTERFACE:

     integer function ESMF_ConfigGetLen(config, label, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)          :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*),  intent(in),   optional :: label
integer,           intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Gets the length of the line in words by counting words disregarding types. Returns the word count as an integer.

The arguments are:

config
[label]
Identifying label. If not specified, use the current line.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.14 ESMF_ConfigIsCreated - Check whether a Config object has been created

INTERFACE:

   function ESMF_ConfigIsCreated(config, rc)

RETURN VALUE:
     logical :: ESMF_ConfigIsCreated

ARGUMENTS:
     type(ESMF_Config), intent(in)            :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

DESCRIPTION:

Return .true. if the config has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

config
ESMF_Config queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

INTERFACE:

     subroutine ESMF_ConfigLoadFile(config, filename, &
delayout, unique, rc)

ARGUMENTS:
       type(ESMF_Config),   intent(inout)         :: config
character(len=*),    intent(in)            :: filename
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_DELayout), intent(in),  optional :: delayout
logical,             intent(in),  optional :: unique
integer,             intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Resource file with filename is loaded into memory.

The arguments are:

config
filename
Configuration file name.
[delayout]
ESMF_DELayout associated with this config object.
[unique]
If specified as true, uniqueness of labels are checked and error code set if duplicates found.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.16 ESMF_ConfigNextLine - Find next line in a Config object

INTERFACE:

     subroutine ESMF_ConfigNextLine(config, tableEnd, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)          :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,           intent(out),  optional :: tableEnd
integer,           intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Selects the next line (for tables).

The arguments are:

config
[tableEnd]
Returns .true. if end of table mark (::) is encountered.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.17 ESMF_ConfigPrint - Write content of Config object to unit

INTERFACE:

     subroutine ESMF_ConfigPrint(config, unit, rc)

ARGUMENTS:
       type(ESMF_Config), intent(in)  :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, optional, intent(in)  :: unit
integer, optional, intent(out) :: rc

DESCRIPTION:

Write content of input ESMF_Config object to unit unit. If unit not provided, writes to standard output.

The arguments are:

config
The input ESMF_Config object.
[unit]
Output unit.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.18 ESMF_ConfigSetAttribute - Set a value in Config object

INTERFACE:

       subroutine ESMF_ConfigSetAttribute(config, <value argument>, &
label, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)           :: config
<value argument>, see below for supported values
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*),  intent(in),   optional  :: label
integer,           intent(out),  optional  :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Sets a value in the config object.

Supported values for <value argument> are:

integer(ESMF_KIND_I4), intent(in) :: value

The arguments are:

config
<value argument>
Value to set.
[label]
Identifying attribute label.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 46.3.19 ESMF_ConfigValidate - Validate a Config object

INTERFACE:

     subroutine ESMF_ConfigValidate(config, &
options, rc)

ARGUMENTS:
       type(ESMF_Config), intent(inout)          :: config
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character (len=*), intent(in),   optional :: options
integer,           intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Checks whether a config object is valid.

The arguments are:

config
ESMF_Config object to be validated.
[options]
If none specified: simply check that the buffer is not full and the pointers are within range. "unusedAttributes" - Report to the default logfile all attributes not retrieved via a call to ESMF_ConfigGetAttribute() or ESMF_ConfigGetChar(). The attribute name (label) will be logged via ESMF_LogErr with the WARNING log message type. For an array-valued attribute, retrieving at least one value via ESMF_ConfigGetAttribute() or ESMF_ConfigGetChar() constitutes being "used."
[rc]
Return code; equals ESMF_SUCCESS if there are no errors. Equals ESMF_RC_ATTR_UNUSED if any unused attributes are found with option "unusedAttributes" above.

# 47 Log Class

## 47.1 Description

The Log class consists of a variety of methods for writing error, warning, and informational messages to files. A default Log is created at ESMF initialization. Other Logs can be created later in the code by the user. Most Log methods take a Log as an optional argument and apply to the default Log when another Log is not specified. A set of standard return codes and associated messages are provided for error handling.

Log provides capabilities to store message entries in a buffer, which is flushed to a file, either when the buffer is full, or when the user calls an ESMF_LogFlush() method. Currently, the default is for the Log to flush after every ten entries. This can easily be changed by using the ESMF_LogSet() method and setting the maxElements property to another value. The ESMF_LogFlush() method is automatically called when the program exits by any means (program completion, halt on error, or when the Log is closed).

The user has the capability to abort the program on conditions such as an error or on a warning by using the ESMF_LogSet() method with the logmsgAbort argument. For example if the logmsgAbort array is set to (ESMF_LOGMSG_ERROR,ESMF_LOGMSG_WARNING), the program will stop on any and all warning or errors. When the logmsgAbort argument is set to ESMF_LOGMSG_ERROR, the program will only abort on errors. Lastly, the user can choose to never abort by using ESMF_LOGMSG_NONE; this is the default.

Log will automatically put the PET number into the Log. Also, the user can either specify ESMF_LOGKIND_SINGLE which writes all the entries to a single Log or ESMF_LOGKIND_MULTI which writes entries to multiple Logs according to the PET number. To distinguish Logs from each other when using ESMF_LOGKIND_MULTI, the PET number (in the format PETx.) will be prepended to the file name where x is the PET number.

Opening multiple log files and writing log messages from all the processors may affect the application performance while running on a large number of processors. For that reason, ESMF_LOGKIND_NONE is provided to switch off the Log capability. All the Log methods have no effect in the ESMF_LOGKIND_NONE mode.

A tracing capability may be enabled by setting the trace flag by using the ESMF_LogSet() method. When tracing is enabled, calls to methods such as ESMF_LogFoundError, ESMF_LogFoundAllocError, and ESMF_LogFoundDeallocError are logged in the default log file. This can result in voluminous output. It is typically used only around areas of code which are being debugged.

Other options that are planned for Log are to adjust the verbosity of output, and to optionally write to stdout instead of file(s).

## 47.2 Constants

### 47.2.1 ESMF_LOGERR

The valid values are:

ESMF_LOGERR_PASSTHRU
A named character constant, with a predefined generic error message, that can be used for the msg argument in any ESMF_Log routine. The message indicated by this named constant is “Passing error in return code."

### 47.2.2 ESMF_LOGKIND

DESCRIPTION:
Specifies a single log file, multiple log files (one per PET), or no log files.

The type of this flag is:

type(ESMF_LogKind_Flag)

The valid values are:

ESMF_LOGKIND_SINGLE
Use a single log file, combining messages from all of the PETs. Not supported on some platforms.
ESMF_LOGKIND_MULTI
Use multiple log files -- one per PET.
ESMF_LOGKIND_MULTI_ON_ERROR
Use multiple log files -- one per PET. A log file is only opened when a message of type ESMF_LOGMSG_ERROR is encountered.
ESMF_LOGKIND_NONE
Do not issue messages to a log file.

### 47.2.3 ESMF_LOGMSG

DESCRIPTION:
Specifies a message level

The type of this flag is:

type(ESMF_LogMsg_Flag)

The valid values are:

ESMF_LOGMSG_INFO
Informational messages
ESMF_LOGMSG_WARNING
Warning messages
ESMF_LOGMSG_ERROR
Error messages
ESMF_LOGMSG_TRACE
Trace messages
ESMF_LOGMSG_DEBUG
DEBUG messages
ESMF_LOGMSG_JSON
JSON format messages

Valid predefined named array constant values are:

ESMF_LOGMSG_ALL
All messages
ESMF_LOGMSG_NONE
No messages
ESMF_LOGMSG_NOTRACE
All messages EXCEPT trace messages

## 47.3 Use and Examples

By default ESMF_Initialize() opens a default Log in ESMF_LOGKIND_MULTI mode. ESMF handles the initialization and finalization of the default Log so the user can immediately start using it. If additional Log objects are desired, they must be explicitly created or opened using ESMF_LogOpen().

ESMF_LogOpen() requires a Log object and filename argument. Additionally, the user can specify single or multi Logs by setting the logkindflag property to ESMF_LOGKIND_SINGLE or ESMF_LOGKIND_MULTI. This is useful as the PET numbers are automatically added to the Log entries. A single Log will put all entries, regardless of PET number, into a single log while a multi Log will create multiple Logs with the PET number prepended to the filename and all entries will be written to their corresponding Log by their PET number.

By default, the Log file is not truncated at the start of a new run; it just gets appended each time. Future functionality may include an option to either truncate or append to the Log file.

In all cases where a Log is opened, a Fortran unit number is assigned to a specific Log. A Log is assigned an unused unit number using the algorithm described in the ESMF_IOUnitGet() method.

The user can then set or get options on how the Log should be used with the ESMF_LogSet() and ESMF_LogGet() methods. These are partially implemented at this time.

Depending on how the options are set, ESMF_LogWrite() either writes user messages directly to a Log file or writes to a buffer that can be flushed when full or by using the ESMF_LogFlush() method. The default is to flush after every ten entries because maxElements is initialized to ten (which means the buffer reaches its full state after every ten writes and then flushes).

A message filtering option may be set with ESMF_LogSet() so that only selected message types are actually written to the log. One key use of this feature is to allow placing informational log write requests into the code for debugging or tracing. Then, when the informational entries are not needed, the messages at that level may be turned off -- leaving only warning and error messages in the logs.

For every ESMF_LogWrite(), a time and date stamp is prepended to the Log entry. The time is given in microsecond precision. The user can call other methods to write to the Log. In every case, all methods eventually make a call implicitly to ESMF_LogWrite() even though the user may never explicitly call it.

When calling ESMF_LogWrite(), the user can supply an optional line, file and method. These arguments can be passed in explicitly or with the help of cpp macros. In the latter case, a define for an ESMF_FILENAME must be placed at the beginning of a file and a define for ESMF_METHOD must be placed at the beginning of each method. The user can then use the ESMF_CONTEXT cpp macro in place of line, file and method to insert the parameters into the method. The user does not have to specify line number as it is a value supplied by cpp.

An example of Log output is given below running with logkindflag property set to ESMF_LOGKIND_MULTI (default) using the default Log:

(Log file PET0.ESMF_LogFile)

20041105 163418.472210 INFO      PET0     Running with ESMF Version 2.2.1


(Log file PET1.ESMF_LogFile)

20041105 163419.186153 ERROR     PET1     ESMF_Field.F90             812
ESMF_FieldGet No Grid or Bad Grid attached to Field


The first entry shows date and time stamp. The time is given in microsecond precision. The next item shown is the type of message (INFO in this case). Next, the PET number is added. Lastly, the content is written.

The second entry shows something slightly different. In this case, we have an ERROR. The method name (ESMF_Field.F90) is automatically provided from the cpp macros as well as the line number (812). Then the content of the message is written.

When done writing messages, the default Log is closed by calling ESMF_LogFinalize() or ESMF_LogClose() for user created Logs. Both methods will release the assigned unit number.

! !PROGRAM: ESMF_LogErrEx - Log Error examples
!
! !DESCRIPTION:
!
! This program shows examples of Log Error writing
!-----------------------------------------------------------------------------


! Macros for cpp usage
! File define
#define ESMF_FILENAME "ESMF_LogErrEx.F90"
! Method define
#define ESMF_METHOD "program ESMF_LogErrEx"
#include "ESMF_LogMacros.inc"

! ESMF Framework module
use ESMF
use ESMF_TestMod
implicit none

! return variables
integer :: rc1, rc2, rc3, rcToTest, allocRcToTest, result
type(ESMF_LOG) :: alog  ! a log object that is not the default log
type(ESMF_LogKind_Flag) :: logkindflag
type(ESMF_Time) :: time
type(ESMF_VM) :: vm
integer, pointer :: intptr(:)


### 47.3.1 Default Log

This example shows how to use the default Log. This example does not use cpp macros but does use multi Logs. A separate Log will be created for each PET.

    ! Initialize ESMF to initialize the default Log
call ESMF_Initialize(vm=vm, defaultlogfilename="LogErrEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc1)


    ! LogWrite
call ESMF_LogWrite("Log Write 2", ESMF_LOGMSG_INFO, rc=rc2)


    ! LogMsgSetError
rcToReturn=rc2)


    ! LogMsgFoundError
call ESMF_TimeSet(time, calkindflag=ESMF_CALKIND_NOCALENDAR)
call ESMF_TimeSyncToRealTime(time, rc=rcToTest)
if (ESMF_LogFoundError(rcToTest, msg="getting wall clock time", &
rcToReturn=rc2)) then
! Error getting time. The previous call will have printed the error
! (This call is expected to provoke an error from the Time Manager.)
endif

! LogMsgFoundAllocError
allocate(intptr(10), stat=allocRcToTest)
if (ESMF_LogFoundAllocError(allocRcToTest, msg="integer array", &
rcToReturn=rc2)) then
! Error during allocation.  The previous call will have logged already
! an error message into the log.
endif
deallocate(intptr)


### 47.3.2 User created Log

This example shows how to use a user created Log. This example uses cpp macros.

    ! Open a Log named "Testlog.txt" associated with alog.
call ESMF_LogOpen(alog, "TestLog.txt", rc=rc1)



%/////////////////////////////////////////////////////////////

\begin{verbatim}
! LogWrite
call ESMF_LogWrite("Log Write 2", ESMF_LOGMSG_INFO, &
line=__LINE__, file=ESMF_FILENAME, &
method=ESMF_METHOD, log=alog, rc=rc2)


    ! LogMsgSetError
line=__LINE__, file=ESMF_FILENAME, &
method=ESMF_METHOD, rcToReturn=rc2, log=alog)


### 47.3.3 Get and Set

This example shows how to use Get and Set routines, on both the default Log and the user created Log from the previous examples.

    ! This is an example showing a query of the default Log.  Please note that
! no Log is passed in the argument list, so the default Log will be used.
call ESMF_LogGet(logkindflag=logkindflag, rc=rc3)


    ! This is an example setting a property of a Log that is not the default.
! It was opened in a previous example, and the handle for it must be
! passed in the argument list.
call ESMF_LogSet(log=alog, logmsgAbort=(/ESMF_LOGMSG_ERROR/), rc=rc2)


    ! Close the user log.
call ESMF_LogClose(alog, rc=rc3)


    ! Finalize ESMF to close the default log
call ESMF_Finalize(rc=rc1)


## 47.4 Restrictions and Future Work

1. Line, file and method are only available when using the C preprocessor Message writing methods are expanded using the ESMF macro ESMF_CONTEXT that adds the predefined symbolic constants __LINE__ and __FILE__ (or the ESMF constant ESMF_FILENAME if defined) and the ESMF constant ESMF_METHOD to the argument list. Using these constants, we can associate a file name, line number and method name with the message. If the CPP preprocessor is not used, this expansion will not be done and hence the ESMF macro ESMF_CONTEXT can not be used, leaving the file name, line number and method out of the Log text.

2. Get and set methods are partially implemented. Currently, the ESMF_LogGet() and ESMF_LogSet() methods are partially implemented.

3. Log only appends entries. All writing to the Log is appended rather than overwriting the Log. Future enhancements include the option to either append to an existing Log or overwrite the existing Log.

4. Avoiding conflicts with the default Log. The private methods ESMF_LogInitialize() and ESMF_LogFinalize() are called during ESMF_Initialize() and ESMF_Finalize() respectively, so they do not need to be called if the default Log is used. If a new Log is required, ESMF_LogOpen() is used with a new Log object passed in so that there are no conflicts with the default Log.

5. ESMF_LOGKIND_SINGLE does not work properly. When the ESMF_LogKind_Flag is set to ESMF_LOGKIND_SINGLE, different system may behave differently. The log messages from some processors may be lost or overwritten by other processors. Users are advised not to use this mode. The MPI-based I/O will be implemented to fix the problem in the future release.

## 47.5 Design and Implementation Notes

1. The Log class was implemented in Fortran and uses the Fortran I/O libraries when the class methods are called from Fortran. The C/C++ Log methods use the Fortran I/O library by calling utility functions that are written in Fortran. These utility functions call the standard Fortran write, open and close functions. At initialization an ESMF_LOG is created. The ESMF_LOG stores information for a specific Log file. When working with more than one Log file, multiple ESMF_LOG's are required (one ESMF_LOG for each Log file). For each Log, a handle is returned through the ESMF_LogInitialize method for the default log or ESMF_LogOpen for a user created log. The user can specify single or multi logs by setting the logkindflag property in the ESMF_LogInitialize or ESMF_Open method to ESMF_LOGKIND_SINGLE or ESMF_LOGKIND_MULTI. Similarly, the user can set the logkindflag property for the default Log with the ESMF_Initialize method call. The logkindflag is useful as the PET numbers are automatically added to the log entries. A single log will put all entries, regardless of PET number, into a single log while a multi log will create multiple logs with the PET number prepended to the filename and all entries will be written to their corresponding log by their PET number.

The properties for a Log are set with the ESMF_LogSet() method and retrieved with the ESMF_LogGet() method.

Additionally, buffering is enabled. Buffering allows ESMF to manage output data streams in a desired way. Writing to the buffer is transparent to the user because all the Log entries are handled automatically by the ESMF_LogWrite() method. All the user has to do is specify the buffer size (the default is ten) by setting the maxElements property. Every time the ESMF_LogWrite() method is called, a LogEntry element is populated with the ESMF_LogWrite() information. When the buffer is full (i.e., when all the LogEntry elements are populated), the buffer will be flushed and all the contents will be written to file. If buffering is not needed, that is maxElements=1 or flushImmediately=ESMF_TRUE, the ESMF_LogWrite() method will immediately write to the Log file(s).

## 47.6 Object Model

The following is a simplified UML diagram showing the structure of the Log class. See Appendix A, A Brief Introduction to UML, for a translation table that lists the symbols in the diagram and their meaning.

## 47.7 Class API

### 47.7.1 ESMF_LogAssignment(=) - Log assignment

INTERFACE:

     interface assignment(=)
log1 = log2

ARGUMENTS:
     type(ESMF_Log) :: log1
type(ESMF_Log) :: log2

DESCRIPTION:

Assign log1 as an alias to the same ESMF_Log object in memory as log2. If log2 is invalid, then log1 will be equally invalid after the assignment.

The arguments are:

log1
The ESMF_Log object on the left hand side of the assignment.
log2
The ESMF_Log object on the right hand side of the assignment.

### 47.7.2 ESMF_LogOperator(==) - Test if Log 1 is equivalent to Log 2

INTERFACE:

       interface operator(==)
if (log1 == log2) then ... endif
OR
result = (log1 == log2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Log), intent(in) :: log1
type(ESMF_Log), intent(in) :: log2

DESCRIPTION:

Overloads the (==) operator for the ESMF_Log class. Compare two logs for equality; return .true. if equal, .false. otherwise. Comparison is based on whether the objects are distinct, as with two newly created logs, or are simply aliases to the same log as would be the case when assignment was involved.

The arguments are:

log1
The ESMF_Log object on the left hand side of the equality operation.
log2
The ESMF_Log object on the right hand side of the equality operation.

### 47.7.3 ESMF_LogOperator(/=) - Test if Log 1 is not equivalent to Log 2

INTERFACE:

       interface operator(/=)
if (log1 /= log2) then ... endif
OR
result = (log1 /= log2)

RETURN VALUE:
       logical :: result

ARGUMENTS:
       type(ESMF_Log), intent(in) :: log1
type(ESMF_Log), intent(in) :: log2

DESCRIPTION:

Overloads the (/=) operator for the ESMF_Log class. Compare two logs for inequality; return .true. if equal, .false. otherwise. Comparison is based on whether the objects are distinct, as with two newly created logs, or are simply aliases to the same log as would be the case when assignment was involved.

The arguments are:

log1
The ESMF_Log object on the left hand side of the non-equality operation.
log2
The ESMF_Log object on the right hand side of the non-equality operation.

### 47.7.4 ESMF_LogClose - Close Log file(s)

INTERFACE:

       subroutine ESMF_LogClose(log, rc)

ARGUMENTS:
       type(ESMF_Log), intent(inout), optional :: log
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,        intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This routine closes the log file(s) associated with log. If the log is not explicitly closed, it will be closed by ESMF_Finalize.

The arguments are:

[log]
An ESMF_Log object. If not specified, the default log is closed.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.5 ESMF_LogFlush - Flush the Log file(s)

INTERFACE:

       subroutine ESMF_LogFlush(log, rc)

ARGUMENTS:
       type(ESMF_Log), intent(inout), optional :: log
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,        intent(out),   optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This subroutine flushes the file buffer associated with log.

The arguments are:

[log]
An optional ESMF_Log object that can be used instead of the default Log.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.6 ESMF_LogFoundAllocError - Check Fortran allocation status error and write message

INTERFACE:

       function ESMF_LogFoundAllocError(statusToCheck,  &
msg,line,file, &
method,rcToReturn,log)

RETURN VALUE:
       logical                                    :: ESMF_LogFoundAllocError

ARGUMENTS:
       integer,          intent(in)              :: statusToCheck
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),    optional :: msg
integer,          intent(in),    optional :: line
character(len=*), intent(in),    optional :: file
character(len=*), intent(in),    optional :: method
integer,          intent(inout), optional :: rcToReturn
type(ESMF_Log),   intent(inout), optional :: log

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This function returns .true. when statusToCheck indicates an allocation error, otherwise it returns .false.. The status value is typically returned from a Fortran ALLOCATE statement. If an error is indicated, a ESMF memory allocation error message will be written to the ESMF_Log along with a user added msg, line, file and method.

The arguments are:

statusToCheck
Fortran allocation status to check. Fortran specifies that a status of 0 (zero) indicates success.
[msg]
User-provided message string.
[line]
Integer source line number. Expected to be set by using the preprocessor __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[rcToReturn]
If specified, when the allocation status indicates an error, set the rcToReturn value to ESMF_RC_MEM. Otherwise, rcToReturn is not modified.
[log]
An optional ESMF_Log object that can be used instead of the default Log.

### 47.7.7 ESMF_LogFoundDeallocError - Check Fortran deallocation status error and write message

INTERFACE:

       function ESMF_LogFoundDeallocError(statusToCheck,  &
msg,line,file, &
method,rcToReturn,log)

RETURN VALUE:
       logical ::ESMF_LogFoundDeallocError

ARGUMENTS:
       integer,          intent(in)              :: statusToCheck
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),    optional :: msg
integer,          intent(in),    optional :: line
character(len=*), intent(in),    optional :: file
character(len=*), intent(in),    optional :: method
integer,          intent(inout), optional :: rcToReturn
type(ESMF_Log),   intent(inout), optional :: log

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This function returns .true. when statusToCheck indicates a deallocation error, otherwise it returns .false.. The status value is typically returned from a Fortran DEALLOCATE statement. If an error is indicated, a ESMF memory allocation error message will be written to the ESMF_Log along with a user added msg, line, file and method.

The arguments are:

statusToCheck
Fortran deallocation status to check. Fortran specifies that a status of 0 (zero) indicates success.
[msg]
User-provided message string.
[line]
Integer source line number. Expected to be set by using the preprocessor __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[rcToReturn]
If specified, when the deallocation status indicates an error, set the rcToReturn value to ESMF_RC_MEM. Otherwise, rcToReturn is not modified.
[log]
An optional ESMF_Log object that can be used instead of the default Log.

### 47.7.8 ESMF_LogFoundError - Check ESMF return code for error and write message

INTERFACE:

   recursive function ESMF_LogFoundError(rcToCheck,   &
msg, line, file, method, &
rcToReturn, log) result (LogFoundError)

RETURN VALUE:
       logical :: LogFoundError

ARGUMENTS:
       integer,          intent(in),    optional :: rcToCheck
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),    optional :: msg
integer,          intent(in),    optional :: line
character(len=*), intent(in),    optional :: file
character(len=*), intent(in),    optional :: method
integer,          intent(inout), optional :: rcToReturn
type(ESMF_Log),   intent(inout), optional :: log

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This function returns .true. when rcToCheck indicates an return code other than ESMF_SUCCESS, otherwise it returns .false.. If an error is indicated, a ESMF predefined error message will be written to the ESMF_Log along with a user added msg, line, file and method.

The arguments are:

[rcToCheck]
Return code to check. Default is ESMF_SUCCESS.
[msg]
User-provided message string.
[line]
Integer source line number. Expected to be set by using the preprocessor __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[rcToReturn]
If specified, when rcToCheck indicates an error, set the rcToReturn to the value of rcToCheck. Otherwise, rcToReturn is not modified. This is not the return code for this function; it allows the calling code to do an assignment of the error code at the same time it is testing the value.
[log]
An optional ESMF_Log object that can be used instead of the default Log.

### 47.7.9 ESMF_LogFoundNetCDFError - Check NetCDF status code for success or log the associated NetCDF error message.

INTERFACE:

 function ESMF_LogFoundNetCDFError(ncerrToCheck, msg, line, &
file, method, rcToReturn, log)

#if defined ESMF_NETCDF
use netcdf
#elif defined ESMF_PNETCDF
use pnetcdf
#endif

RETURN VALUE:
   logical :: ESMF_LogFoundNetCDFError

ARGUMENTS:
   integer,          intent(in)              :: ncerrToCheck
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),    optional :: msg
integer,          intent(in),    optional :: line
character(len=*), intent(in),    optional :: file
character(len=*), intent(in),    optional :: method
integer,          intent(inout), optional :: rcToReturn
type(ESMF_Log),   intent(inout), optional :: log

DESCRIPTION:

This function returns .true. when ncerrToCheck indicates an return code other than 0 (the success code from NetCDF Fortran) or NF_NOERR (the success code for PNetCDF). Otherwise it returns .false.. If an error is indicated, a predefined ESMF error message will be written to the ESMF_Log along with a user added msg, line, file and method. The NetCDF string error representation will also be logged.

The arguments are:

[ncerrToCheck]
NetCDF error code to check.
[msg]
User-provided message string.
[line]
Integer source line number. Expected to be set by using the preprocessor __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[rcToReturn]
If specified, when ncerrToCheck indicates an error, set rcToReturn to ESMF_RC_NETCDF_ERROR. The string representation for the error code will be retrieved from the NetCDF Fortran library and logged alongside any user-provided message string. Otherwise, rcToReturn is not modified. This is not the return code for this function; it allows the calling code to do an assignment of the error code at the same time it is testing the value.
[log]
An optional ESMF_Log object that can be used instead of the default Log.

### 47.7.10 ESMF_LogGet - Return information about a log object

INTERFACE:

       subroutine ESMF_LogGet(log,  &
flush,    &
logmsgAbort, logkindflag, &
maxElements, trace, fileName,  &
highResTimestampFlag, indentCount,  &
noPrefix, rc)

ARGUMENTS:
       type(ESMF_Log),          intent(in),  optional :: log
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,                 intent(out), optional :: flush
type(ESMF_LogMsg_Flag),  pointer,     optional :: logmsgAbort(:)
type(ESMF_LogKind_Flag), intent(out), optional :: logkindflag
integer,                 intent(out), optional :: maxElements
logical,                 intent(out), optional :: trace
character(*),            intent(out), optional :: fileName
logical,                 intent(out), optional :: highResTimestampFlag
integer,                 intent(out), optional :: indentCount
logical,                 intent(out), optional :: noPrefix
integer,                 intent(out), optional :: rc

DESCRIPTION:

This subroutine returns properties about a Log object.

The arguments are:

[log]
An optional ESMF_Log object that can be used instead of the default Log.
[flush]
Flush flag.
[logmsgAbort]
Returns an array containing current message halt settings. If the array is not pre-allocated, ESMF_LogGet will allocate an array of the correct size. If no message types are defined, an array of length zero is returned. It is the callers responsibility to deallocate the array.
[logkindflag]
Defines either single or multilog.
[maxElements]
Maximum number of elements in the Log.
[trace]
Current setting of the Log call tracing flag.
[fileName]
Current file name. When the log has been opened with ESMF_LOGKIND_MULTI, the filename has a PET number prefix.
[highResTimestampFlag]
Current setting of the extended elapsed timestamp flag.
[indentCount]
[noPrefix]
Current setting of the message prefix enable/disable flag.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.11 ESMF_LogOpen - Open Log file(s)

INTERFACE:

     subroutine ESMF_LogOpen(log, filename,  &
appendflag, logkindflag, noPrefix, rc)

ARGUMENTS:
     type(ESMF_Log),          intent(inout)         :: log
character(len=*),        intent(in)            :: filename
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,                 intent(in),  optional :: appendFlag
type(ESMF_LogKind_Flag), intent(in),  optional :: logkindFlag
logical,                 intent(in),  optional :: noPrefix
integer,                 intent(out), optional :: rc

DESCRIPTION:

This routine opens a file named filename and associates it with the ESMF_Log. When logkindflag is set to ESMF_LOGKIND_MULTI or ESMF_LOGKIND_MULTI_ON_ERROR the file name is prepended with PET number identification. If the incoming log is already open, an error is returned.

The arguments are:

log
An ESMF_Log object.
filename
Name of log file to be opened.
[appendFlag]
If the log file exists, setting to .false. will set the file position to the beginning of the file. Otherwise, new records will be appended to the end of the file. If not specified, defaults to .true..
[logkindFlag]
Set the logkindflag. See section 47.2.2 for a list of valid options. When the ESMF_LOGKIND_MULTI_ON_ERROR is selected, the log opening is deferred until a ESMF_LogWrite with log message of type ESMF_LOGMSG_ERROR is written. If not specified, defaults to ESMF_LOGKIND_MULTI.
[noPrefix]
Set the noPrefix flag. If set to .false., log messages are prefixed with time stamps, message type, and PET number. If set to .true. the messages will be written without prefixes. If not specified, defaults to .false..
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.12 ESMF_LogOpen - Open Default Log file(s)

INTERFACE:

   ! Private name; call using ESMF_LogOpen ()
subroutine ESMF_LogOpenDefault (filename,  &
appendflag, logkindflag, rc)

ARGUMENTS:
     character(len=*),        intent(in)            :: filename
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,                 intent(in),  optional :: appendflag
type(ESMF_LogKind_Flag), intent(in),  optional :: logkindflag
integer,                 intent(out), optional :: rc

DESCRIPTION:

This routine opens a file named filename and associates it with the default log. When logkindflag is set to ESMF_LOGKIND_MULTI the file name is prepended with PET number identification. If the incoming default log is already open, an error is returned.

The arguments are:

filename
Name of DEFAULT log file to be opened.
[appendflag]
If the log file exists, setting to .false. will set the file position to the beginning of the file. Otherwise, new records will be appended to the end of the file. If not specified, defaults to .true..
[logkindflag]
Set the logkindflag. See section 47.2.2 for a list of valid options. If not specified, defaults to ESMF_LOGKIND_MULTI.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.13 ESMF_LogSet - Set Log parameters

INTERFACE:

     subroutine ESMF_LogSet(log,  &
flush,  &
logmsgAbort, maxElements, logmsgList,  &
noPrefix, rc)

ARGUMENTS:
       type(ESMF_Log),         intent(inout), optional :: log
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,                intent(in),    optional :: flush
type(ESMF_LogMsg_Flag), intent(in),    optional :: logmsgAbort(:)
integer,                intent(in),    optional :: maxElements
type(ESMF_LogMsg_Flag), intent(in),    optional :: logmsgList(:)
logical,                intent(in),    optional :: trace
logical,                intent(in),    optional :: highResTimestampFlag
integer,                intent(in),    optional :: indentCount
logical,                intent(in),    optional :: noPrefix
integer,                intent(out),   optional :: rc

DESCRIPTION:

This subroutine sets the properties for the Log object.

The arguments are:

[log]
An optional ESMF_Log object. The default is to use the default log that was opened at ESMF_Initialize time.
[flush]
If set to .true., flush log messages immediately, rather than buffering them. Default is to flush after maxElements messages.
[logmsgAbort]
Sets the condition on which ESMF aborts. The array can contain any combination of ESMF_LOGMSG named constants. These named constants are described in section 47.2.3. Default is to always continue processing.
[maxElements]
Maximum number of elements in the Log buffer before flushing occurs. Default is to flush when 10 messages have been accumulated.
[logmsgList]
An array of message types that will be logged. Log write requests not matching the list will be ignored. If an empty array is provided, no messages will be logged. See section 47.2.3 for a list of valid message types. By default, all non-trace messages will be logged.
List of error codes that will not be logged as errors. Default is to log all error codes.
[trace]
If set to .true., calls such as ESMF_LogFoundError(), ESMF_LogFoundAllocError(), and ESMF_LogFoundDeallocError() will be logged in the default log files. This option is intended to be used as a tool for debugging and program flow tracing within the ESMF library. Voluminous output may appear in the log, with a consequent slowdown in performance. Therefore, it is recommended that this option only be enabled before a problematic call to a ESMF method, and disabled afterwards. Default is to not trace these calls.
[highResTimestampFlag]
Sets the extended elapsed timestamp flag. If set to .true., a timestamp from ESMF_VMWtime will be included in each log message. Default is to not add the additional timestamps.
[indentCount]
[noPrefix]
If set to .false., log messages are prefixed with time stamps, message type and PET number. If set to .true. the messages will be written without the prefixes.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 47.7.14 ESMF_LogSetError - Set ESMF return code for error and write msg

INTERFACE:

       subroutine ESMF_LogSetError(rcToCheck,  &
msg, line, file, method, &
rcToReturn, log)

ARGUMENTS:
       integer,          intent(in)              :: rcToCheck
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),    optional :: msg
integer,          intent(in),    optional :: line
character(len=*), intent(in),    optional :: file
character(len=*), intent(in),    optional :: method
integer,          intent(out),   optional :: rcToReturn
type(ESMF_Log),   intent(inout), optional :: log

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This subroutine sets the rcToReturn value to rcToCheck if rcToReturn is present and writes this error code to the ESMF_Log if an error is generated. A predefined error message will added to the ESMF_Log along with a user added msg, line, file and method.

The arguments are:

rcToCheck
rc value for set
[msg]
User-provided message string.
[line]
Integer source line number. Expected to be set by using the preprocessor macro __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[rcToReturn]
If specified, copy the rcToCheck value to rcToreturn. This is not the return code for this function; it allows the calling code to do an assignment of the error code at the same time it is testing the value.
[log]
An optional ESMF_Log object that can be used instead of the default Log.

### 47.7.15 ESMF_LogWrite - Write to Log file(s)

INTERFACE:

       recursive subroutine ESMF_LogWrite(msg, logmsgFlag, &
logmsgList,      & ! DEPRECATED ARGUMENT
line, file, method, log, rc)

ARGUMENTS:
       character(len=*),      intent(in)             :: msg
type(ESMF_LogMsg_Flag),intent(in),optional    :: logmsgFlag
type(ESMF_LogMsg_Flag),intent(in),optional::logmsgList ! DEPRECATED ARG
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,               intent(in),   optional :: line
character(len=*),      intent(in),   optional :: file
character(len=*),      intent(in),   optional :: method
type(ESMF_Log),        intent(inout),optional :: log
integer,               intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
5.2.0rp1
Added argument logmsgFlag. Started to deprecate argument logmsgList. This corrects inconsistent use of the List suffix on the argument name. In ESMF this suffix indicates one-dimensional array arguments.

DESCRIPTION:

This subroutine writes to the file associated with an ESMF_Log. A message is passed in along with the logmsgFlag, line, file and method. If the write to the ESMF_Log is successful, the function will return a logical true. This function is the base function used by all the other ESMF_Log writing methods.

The arguments are:

msg
User-provided message string.
[logmsgFlag]
The type of message. See Section 47.2.3 for possible values. If not specified, the default is ESMF_LOGMSG_INFO.
[logmsgList]
[line]
Integer source line number. Expected to be set by using the preprocessor macro __LINE__ macro.
[file]
User-provided source file name.
[method]
User-provided method string.
[log]
An optional ESMF_Log object that can be used instead of the default Log.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 48 DELayout Class

## 48.1 Description

The DELayout class provides an additional layer of abstraction on top of the Virtual Machine (VM) layer. DELayout does this by introducing DEs (Decomposition Elements) as logical resource units. The DELayout object keeps track of the relationship between its DEs and the resources of the associated VM object.

The relationship between DEs and VM resources (PETs (Persistent Execution Threads) and VASs (Virtual Address Spaces)) contained in a DELayout object is defined during its creation and cannot be changed thereafter. There are, however, a number of hint and specification arguments that can be used to shape the DELayout during its creation.

Contrary to the number of PETs and VASs contained in a VM object, which are fixed by the available resources, the number of DEs contained in a DELayout can be chosen freely to best match the computational problem or other design criteria. Creating a DELayout with less DEs than there are PETs in the associated VM object can be used to share resources between decomposed objects within an ESMF component. Creating a DELayout with more DEs than there are PETs in the associated VM object can be used to evenly partition the computation over the available resources.

The simplest case, however, is where the DELayout contains the same number of DEs as there are PETs in the associated VM context. In this case the DELayout may be used to re-label the hardware and operating system resources held by the VM. For instance, it is possible to order the resources so that specific DEs have best available communication paths. The DELayout will map the DEs to the PETs of the VM according to the resource details provided by the VM instance.

Furthermore, general DE to PET mapping can be used to offer computational resources with finer granularity than the VM does. The DELayout can be queried for computational and communication capacities of DEs and DE pairs, respectively. This information can be used to best utilize the DE resources when partitioning the computational problem. In combination with other ESMF classes, general DE to PET mapping can be used to realize cache blocking, communication hiding and dynamic load balancing.

Finally, the DELayout layer offers primitives that allow a work queue style dynamic load balancing between DEs.

## 48.2 Constants

### 48.2.1 ESMF_PIN

DESCRIPTION:
Specifies which VM resource DEs are pinned to (PETs, VASs, SSIs).

The type of this flag is:

type(ESMF_Pin_Flag)

The valid values are:

ESMF_PIN_DE_TO_PET
Pin DEs to PETs. Only the owning PET has access to a DE.
ESMF_PIN_DE_TO_VAS
Pin DEs to virtual address spaces (VAS). DEs are accessible from all PETs within the same VAS.
ESMF_PIN_DE_TO_SSI
Pin DEs to single system images (SSI) - typically shared memory nodes. DEs are accessible from all PETs within the same SSI. The memory allocation between different DEs is allowed to be non-contiguous.
ESMF_PIN_DE_TO_SSI_CONTIG
Same as ESMF_PIN_DE_TO_SSI, but the shared memory allocation across DEs located on the same SSI must be contigous throughout.

DESCRIPTION:
Reply when a PET offers to service a DE.

The type of this flag is:

The valid values are:

The service offer has been accepted. The PET is expected to service the DE.
The service offer has been denied. The PET is expected to not service the DE.

## 48.3 Use and Examples

The following examples demonstrate how to create, use and destroy DELayout objects.

### 48.3.1 Default DELayout

Without specifying any of the optional parameters the created ESMF_DELayout defaults into having as many DEs as there are PETs in the associated VM object. Consequently the resulting DELayout describes a simple 1-to-1 DE to PET mapping.

  delayout = ESMF_DELayoutCreate(rc=rc)


The default DE to PET mapping is simply:

   DE 0  -> PET 0
DE 1  -> PET 1
...


DELayout objects that are not used any longer should be destroyed.

  call ESMF_DELayoutDestroy(delayout, rc=rc)


The optional vm argument can be provided to DELayoutCreate() to lower the method's overhead by the amount it takes to determine the current VM.

  delayout = ESMF_DELayoutCreate(vm=vm, rc=rc)


By default all PETs of the associated VM will be considered. However, if the optional argument petList is present DEs will only be mapped against the PETs contained in the list. When the following example is executed on four PETs it creates a DELayout with four DEs by default that are mapped to the provided PETs in their given order. It is erroneous to specify PETs that are not part of the VM context on which the DELayout is defined.

  delayout = ESMF_DELayoutCreate(petList=(/(i,i=petCount-1,1,-1)/), rc=rc)


Once the end of the petList has been reached the DE to PET mapping continues from the beginning of the list. For a 4 PET VM the above created DELayout will end up with the following DE to PET mapping:

   DE 0  -> PET 3
DE 1  -> PET 2
DE 2  -> PET 1
DE 2  -> PET 3


### 48.3.2 DELayout with specified number of DEs

The deCount argument can be used to specify the number of DEs. In this example a DELayout is created that contains four times as many DEs as there are PETs in the VM.

  delayout = ESMF_DELayoutCreate(deCount=4*petCount, rc=rc)


Cyclic DE to PET mapping is the default. For 4 PETs this means:

   DE 0, 4,  8, 12  -> PET 0
DE 1, 5,  9, 13  -> PET 1
DE 2, 6, 10, 14  -> PET 2
DE 3, 7, 11, 15  -> PET 3

The default DE to PET mapping can be overridden by providing the deGrouping argument. This argument provides a positive integer group number for each DE in the DELayout. All of the DEs of a group will be mapped against the same PET. The actual group index is arbitrary (but must be positive) and its value is of no consequence.

  delayout = ESMF_DELayoutCreate(deCount=4*petCount, &
deGrouping=(/(i/4,i=0,4*petCount-1)/), rc=rc)


This will achieve blocked DE to PET mapping. For 4 PETs this means:

   DE  0,  1,  2,  3  -> PET 0
DE  4,  5,  6,  7  -> PET 1
DE  8,  9, 10, 11  -> PET 2
DE 12, 13, 14, 15  -> PET 3


### 48.3.3 DELayout with computational and communication weights

The quality of the partitioning expressed by the DE to PET mapping depends on the amount and quality of information provided during DELayout creation. In the following example the compWeights argument is used to specify relative computational weights for all DEs and communication weights for DE pairs are provided by the commWeights argument. The example assumes four DEs.

  allocate(compWeights(4))
allocate(commWeights(4, 4))
! setup compWeights and commWeights according to computational problem
delayout = ESMF_DELayoutCreate(deCount=4, compWeights=compWeights, &
commWeights=commWeights, rc=rc)
deallocate(compWeights, commWeights)


The resulting DE to PET mapping depends on the specifics of the VM object and the provided compWeights and commWeights arrays.

### 48.3.4 DELayout from petMap

Full control over the DE to PET mapping is provided via the petMap argument. This example maps the DEs to PETs in reverse order. In the 4-PET case this will result in the following mapping:

   DE 0 -> PET 3
DE 1 -> PET 2
DE 2 -> PET 1
DE 3 -> PET 0


  delayout = ESMF_DELayoutCreate(petMap=(/(i,i=petCount-1,0,-1)/), rc=rc)


### 48.3.5 DELayout from petMap with multiple DEs per PET

The petMap argument gives full control over DE to PET mapping. The following example run on 4 or more PETs maps DEs to PETs according to the following table:

   DE 0 -> PET 3
DE 1 -> PET 3
DE 2 -> PET 1
DE 3 -> PET 0
DE 4 -> PET 2
DE 5 -> PET 1
DE 6 -> PET 3
DE 7 -> PET 1


  delayout = ESMF_DELayoutCreate(petMap=(/3, 3, 1, 0, 2, 1, 3, 1/), rc=rc)


### 48.3.6 Working with a DELayout - simple 1-to-1 DE-to-PET mapping

The simplest case is a DELayout where there is exactly one DE for every PET. Of course this implies that the number of DEs equals the number of PETs. This special 1-to-1 DE-to-PET mapping is very common and many applications assume it. The following example shows how a DELayout can be queried about its mapping.

First a default DELayout is created where the number of DEs equals the number of PETs, and are associated 1-to-1.

  delayout = ESMF_DELayoutCreate(rc=rc)


Next the DELayout is queried for the oneToOneFlag, and the user code makes a decision based on its value.

  call ESMF_DELayoutGet(delayout, oneToOneFlag=oneToOneFlag, rc=rc)
if (rc /= ESMF_SUCCESS) call ESMF_Finalize(endflag=ESMF_END_ABORT)
if (.not. oneToOneFlag) then
! handle the unexpected case of not dealing with a 1-to-1 mapping
else


1-to-1 mapping is guaranteed in this branch and the following code can work under the simplifying assumption that every PET holds exactly one DE:

    allocate(localDeToDeMap(1))
call ESMF_DELayoutGet(delayout, localDeToDeMap=localDeToDeMap, rc=rc)
if (rc /= ESMF_SUCCESS) finalrc=rc
myDe = localDeToDeMap(1)
deallocate(localDeToDeMap)
if (finalrc /= ESMF_SUCCESS) call ESMF_Finalize(endflag=ESMF_END_ABORT)
endif


### 48.3.7 Working with a DELayout - general DE-to-PET mapping

In general a DELayout may map any number (including zero) of DEs against a single PET. The exact situation can be detected by querying the DELayout for the oneToOneFlag. If this flag comes back as .true. then the DELayout maps exactly one DE against each PET, but if it comes back as .false. the DELayout describes a more general DE-to-PET layout. The following example shows how code can be be written to work for a general DELayout.

First a DELayout is created with two more DEs than there are PETs. The DELayout will consequently map some DEs to the same PET.

  delayout = ESMF_DELayoutCreate(deCount=petCount+2, rc=rc)


The first piece of information needed on each PET is the localDeCount. This number may be different on each PET and indicates how many DEs are mapped against the local PET.

  call ESMF_DELayoutGet(delayout, localDeCount=localDeCount, rc=rc)


The DELayout can further be queried for a list of DEs that are held by the local PET. This information is provided by the localDeToDeMap argument. In ESMF a localDe is an index that enumerates the DEs that are associated with the local PET. In many cases the exact bounds of the localDe index range, e.g. , or does not matter, since it only affects how user code indexes into variables the user allocated, and therefore set the specific bounds. However, there are a few Array and Field level calls that take localDe input arguments. In all those cases where the localDe index variable is passed into an ESMF call as an input argument, it must be defined with a range starting at zero, i.e. .

For consistency with Array and Field, the following code uses a range for the localDe index variable, although it is not strictly necessary here:

  allocate(localDeToDeMap(0:localDeCount-1))
call ESMF_DELayoutGet(delayout, localDeToDeMap=localDeToDeMap, rc=rc)
if (rc /= ESMF_SUCCESS) finalrc=rc
do localDe=0, localDeCount-1
workDe = localDeToDeMap(localDe)
!    print *, "I am PET", localPET, " and I am working on DE ", workDe
enddo
deallocate(localDeToDeMap)
if (finalrc /= ESMF_SUCCESS) call ESMF_Finalize(endflag=ESMF_END_ABORT)


### 48.3.8 Work queue dynamic load balancing

The DELayout API includes two calls that can be used to easily implement work queue dynamic load balancing. The workload is broken up into DEs (more than there are PETs) and processed by the PETs. Load balancing is only possible for ESMF multi-threaded VMs and requires that DEs are pinned to VASs instead of the PETs (default). The following example will run for any VM and DELayout, however, load balancing will only occur under the mentioned conditions.

  delayout = ESMF_DELayoutCreate(deCount=petCount+2, &
pinflag=ESMF_PIN_DE_TO_VAS, rc=rc)


  call ESMF_DELayoutGet(delayout, vasLocalDeCount=localDeCount, rc=rc)
if (rc /= ESMF_SUCCESS) finalrc=rc
allocate(localDeToDeMap(localDeCount))
call ESMF_DELayoutGet(delayout, vasLocalDeToDeMap=localDeToDeMap, rc=rc)
if (rc /= ESMF_SUCCESS) finalrc=rc
do i=1, localDeCount
workDe = localDeToDeMap(i)
print *, "I am PET", localPET, &
" and I am offering service for DE ", workDe
if (rc /= ESMF_SUCCESS) finalrc=rc
! process work associated with workDe
print *, "I am PET", localPET, ", service offer for DE ", workDe, &
" was accepted."
call ESMF_DELayoutServiceComplete(delayout, de=workDe, rc=rc)
if (rc /= ESMF_SUCCESS) finalrc=rc
endif
enddo
deallocate(localDeToDeMap)
if (finalrc /= ESMF_SUCCESS) call ESMF_Finalize(endflag=ESMF_END_ABORT)


## 48.5 Design and Implementation Notes

The DELayout class is a light weight object. It stores the DE to PET and VAS mapping for all DEs within all PET instances and a list of local DEs for each PET instance. The DELayout does not store the computational and communication weights optionally provided as arguments to the create method. These hints are only used during create while they are available in user owned arrays.

## 48.6 Class API

### 48.6.1 ESMF_DELayoutAssignment(=) - DELayout assignment

INTERFACE:

     interface assignment(=)
delayout1 = delayout2

ARGUMENTS:
     type(ESMF_DELayout) :: delayout1
type(ESMF_DELayout) :: delayout2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign delayout1 as an alias to the same ESMF DELayout object in memory as delayout2. If delayout2 is invalid, then delayout1 will be equally invalid after the assignment.

The arguments are:

delayout1
The ESMF_DELayout object on the left hand side of the assignment.
delayout2
The ESMF_DELayout object on the right hand side of the assignment.

### 48.6.2 ESMF_DELayoutOperator(==) - DELayout equality operator

INTERFACE:

   interface operator(==)
if (delayout1 == delayout2) then ... endif
OR
result = (delayout1 == delayout2)

RETURN VALUE:
     logical :: result

ARGUMENTS:
     type(ESMF_DELayout), intent(in) :: delayout1
type(ESMF_DELayout), intent(in) :: delayout2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Test whether delayout1 and delayout2 are valid aliases to the same ESMF DELayout object in memory. For a more general comparison of two ESMF DELayouts, going beyond the simple alias test, the ESMF_DELayoutMatch() function (not yet implemented) must be used.

The arguments are:

delayout1
The ESMF_DELayout object on the left hand side of the equality operation.
delayout2
The ESMF_DELayout object on the right hand side of the equality operation.

### 48.6.3 ESMF_DELayoutOperator(/=) - DELayout not equal operator

INTERFACE:

   interface operator(/=)
if (delayout1 /= delayout2) then ... endif
OR
result = (delayout1 /= delayout2)

RETURN VALUE:
     logical :: result

ARGUMENTS:
     type(ESMF_DELayout), intent(in) :: delayout1
type(ESMF_DELayout), intent(in) :: delayout2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Test whether delayout1 and delayout2 are not valid aliases to the same ESMF DELayout object in memory. For a more general comparison of two ESMF DELayouts, going beyond the simple alias test, the ESMF_DELayoutMatch() function (not yet implemented) must be used.

The arguments are:

delayout1
The ESMF_DELayout object on the left hand side of the non-equality operation.
delayout2
The ESMF_DELayout object on the right hand side of the non-equality operation.

### 48.6.4 ESMF_DELayoutCreate - Create DELayout object

INTERFACE:

   ! Private name; call using ESMF_DELayoutCreate()
recursive function ESMF_DELayoutCreateDefault(deCount, &
deGrouping, pinflag, petList, vm, rc)

RETURN VALUE:
     type(ESMF_DELayout) :: ESMF_DELayoutCreateDefault

ARGUMENTS:
 -- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,                      intent(in),  optional :: deCount
integer, target,              intent(in),  optional :: deGrouping(:)
type(ESMF_Pin_Flag),          intent(in),  optional :: pinflag
integer, target,              intent(in),  optional :: petList(:)
type(ESMF_VM),                intent(in),  optional :: vm
integer,                      intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Create an ESMF_DELayout object on the basis of optionally provided restrictions. By default a DELayout with deCount equal to petCount will be created, each DE mapped to a single PET. However, the number of DEs as well grouping of DEs and PETs can be specified via the optional arguments.

The arguments are:

[deCount]
Number of DEs to be provided by the created DELayout. By default the number of DEs equals the number of PETs in the associated VM context. Specifying a deCount smaller than the number of PETs will result in unassociated PETs. This may be used to share VM resources between DELayouts within the same ESMF component. Specifying a deCount greater than the number of PETs will result in multiple DE to PET mapping.
[deGrouping]
This optional argument must be of size deCount. Its content assigns a DE group index to each DE of the DELayout. A group index of -1 indicates that the associated DE isn't member of any particular group. The significance of DE groups is that all the DEs belonging to a certain group will be mapped against the same PET. This does not, however, mean that DEs belonging to different DE groups must be mapped to different PETs.
[pinflag]
This flag specifies which type of resource DEs are pinned to. The default is to pin DEs to PETs. Alternatively it is also possible to pin DEs to VASs. See section 48.2.1 for a list of valid pinning options.
[petList]
List specifying PETs to be used by this DELayout. This can be used to control the PET overlap between DELayouts within the same ESMF component. It is erroneous to specify PETs that are not within the provided VM context. The default is to include all the PETs of the VM.
[vm]
If present, the DELayout object is created on the specified ESMF_VM object. The default is to create on the VM of the current context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.5 ESMF_DELayoutCreate - Create DELayout from petMap

INTERFACE:

   ! Private name; call using ESMF_DELayoutCreate()
recursive function ESMF_DELayoutCreateFromPetMap(petMap, &
pinflag, vm, rc)

RETURN VALUE:
     type(ESMF_DELayout) :: ESMF_DELayoutCreateFromPetMap

ARGUMENTS:
     integer,                      intent(in)            :: petMap(:)
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Pin_Flag),          intent(in),  optional :: pinflag
type(ESMF_VM),                intent(in),  optional :: vm
integer,                      intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Create an ESMF_DELayout with exactly specified DE to PET mapping.

This ESMF method must be called in unison by all PETs of the VM. Calling this method from a PET not part of the VM or not calling it from a PET that is part of the VM will result in undefined behavior. ESMF does not guard against violation of the unison requirement. The call is not collective, there is no communication between PETs.

The arguments are:

petMap
List specifying the DE-to-PET mapping. The list elements correspond to DE 0, 1, 2, ... and map against the specified PET of the VM context. The size of the petMap argument determines the number of DEs in the created DELayout. It is erroneous to specify a PET identifier that lies outside the VM context.
[pinflag]
This flag specifies which type of resource DEs are pinned to. The default is to pin DEs to PETs. Alternatively it is also possible to pin DEs to VASs. See section 48.2.1 for a list of valid pinning options.
[vm]
If present, the DELayout object is created on the specified ESMF_VM object. The default is to create on the VM of the current context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.6 ESMF_DELayoutDestroy - Release resources associated with DELayout object

INTERFACE:

   recursive subroutine ESMF_DELayoutDestroy(delayout, noGarbage, rc)

ARGUMENTS:
     type(ESMF_DELayout),  intent(inout)          :: delayout
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,              intent(in),   optional :: noGarbage
integer,              intent(out),  optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
7.0.0
Added argument noGarbage. The argument provides a mechanism to override the default garbage collection mechanism when destroying an ESMF object.

DESCRIPTION:

Destroy an ESMF_DELayout object, releasing the resources associated with the object.

By default a small remnant of the object is kept in memory in order to prevent problems with dangling aliases. The default garbage collection mechanism can be overridden with the noGarbage argument.

The arguments are:

delayout
ESMF_DELayout object to be destroyed.
[noGarbage]
If set to .TRUE. the object will be fully destroyed and removed from the ESMF garbage collection system. Note however that under this condition ESMF cannot protect against accessing the destroyed object through dangling aliases - a situation which may lead to hard to debug application crashes.

It is generally recommended to leave the noGarbage argument set to .FALSE. (the default), and to take advantage of the ESMF garbage collection system which will prevent problems with dangling aliases or incorrect sequences of destroy calls. However this level of support requires that a small remnant of the object is kept in memory past the destroy call. This can lead to an unexpected increase in memory consumption over the course of execution in applications that use temporary ESMF objects. For situations where the repeated creation and destruction of temporary objects leads to memory issues, it is recommended to call with noGarbage set to .TRUE., fully removing the entire temporary object from memory.

[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.7 ESMF_DELayoutGet - Get object-wide DELayout information

INTERFACE:

   recursive subroutine ESMF_DELayoutGet(delayout, vm, deCount,&
petMap, vasMap, oneToOneFlag, pinflag, localDeCount, localDeToDeMap, &
localDeList, &      ! DEPRECATED ARGUMENT
vasLocalDeCount, vasLocalDeToDeMap, &
vasLocalDeList, &   ! DEPRECATED ARGUMENT
rc)

ARGUMENTS:
     type(ESMF_DELayout),      intent(in)            :: delayout
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_VM),            intent(out), optional :: vm
integer,                  intent(out), optional :: deCount
integer, target,          intent(out), optional :: petMap(:)
integer, target,          intent(out), optional :: vasMap(:)
logical,                  intent(out), optional :: oneToOneFlag
type(ESMF_Pin_Flag),      intent(out), optional :: pinflag
integer,                  intent(out), optional :: localDeCount
integer, target,          intent(out), optional :: localDeToDeMap(:)
integer, target, intent(out), optional :: localDeList(:)  !DEPRECATED ARG
integer,                  intent(out), optional :: vasLocalDeCount
integer, target,          intent(out), optional :: vasLocalDeToDeMap(:)
integer, target, intent(out), optional :: vasLocalDeList(:) !DEPRECATED ARG
integer,                  intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
5.2.0rp1
Added arguments localDeToDeMap and vasLocalDeToDeMap. Started to deprecate arguments localDeList and vasLocalDeList. The new argument names correctly use the Map suffix and better describe the returned information. This was pointed out by user request.

DESCRIPTION:

The arguments are:

delayout
Queried ESMF_DELayout object.
[vm]
The ESMF_VM object on which delayout is defined.
[deCount]
The total number of DEs in the DELayout.
[petMap]
List of PETs against which the DEs are mapped. The petMap argument must at least be of size deCount.
[vasMap]
List of VASs against which the DEs are mapped. The vasMap argument must at least be of size deCount.
[oneToOneFlag]
A value of .TRUE. indicates that delayout maps each DE to a single PET, and each PET maps to a single DE. All other layouts return a value of .FALSE..
[pinflag]
The type of DE pinning. See section 48.2.1 for a list of valid pinning options.
[localDeCount]
The number of DEs in the DELayout associated with the local PET.
[localDeToDeMap]
Mapping between localDe indices and the (global) DEs associated with the local PET. The localDe index variables are discussed in sections 48.3.7 and 28.2.5. The provided actual argument must be of size localDeCount.
[localDeList]
[vasLocalDeCount]
The number of DEs in the DELayout associated with the local VAS.
[vasLocalDeToDeMap]
Mapping between localDe indices and the (global) DEs associated with the local VAS. The localDe index variables are discussed in sections 48.3.7 and 28.2.5. The provided actual argument must be of size localDeCount.
[vasLocalDeList]
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.8 ESMF_DELayoutIsCreated - Check whether a DELayout object has been created

INTERFACE:

   function ESMF_DELayoutIsCreated(delayout, rc)

RETURN VALUE:
     logical :: ESMF_DELayoutIsCreated

ARGUMENTS:
     type(ESMF_DELayout), intent(in)            :: delayout
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,             intent(out), optional :: rc

DESCRIPTION:

Return .true. if the delayout has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

delayout
ESMF_DELayout queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.9 ESMF_DELayoutPrint - Print DELayout information

INTERFACE:

   subroutine ESMF_DELayoutPrint(delayout, rc)

ARGUMENTS:
     type(ESMF_DELayout),  intent(in)            :: delayout
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Prints internal information about the specified ESMF_DELayout object to stdout.

The arguments are:

delayout
Specified ESMF_DELayout object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.10 ESMF_DELayoutServiceComplete - Close service window

INTERFACE:

   recursive subroutine ESMF_DELayoutServiceComplete(delayout, de, rc)

ARGUMENTS:
     type(ESMF_DELayout),  intent(in)            :: delayout
integer,              intent(in)            :: de
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

The PET who's service offer was accepted for de must use ESMF_DELayoutServiceComplete to close the service window.

The arguments are:

delayout
Specified ESMF_DELayout object.
de
DE for which to close service window.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.11 ESMF_DELayoutServiceOffer - Offer service for a DE in DELayout

INTERFACE:

   recursive function ESMF_DELayoutServiceOffer(delayout, de, rc)

RETURN VALUE:
     type(ESMF_ServiceReply_Flag) :: ESMF_DELayoutServiceOffer

ARGUMENTS:
     type(ESMF_DELayout),  intent(in)            :: delayout
integer,              intent(in)            :: de
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Offer service for a DE in the ESMF_DELayout object. This call together with ESMF_DELayoutServiceComplete() provides the synchronization primitives between the PETs of an ESMF multi-threaded VM necessary for dynamic load balancing via a work queue approach.

The calling PET will either receive ESMF_SERVICEREPLY_ACCEPT if the service offer has been accepted by DELayout or ESMF_SERVICEREPLY_DENY if the service offer was denied. The service offer paradigm is different from a simple mutex approach in that the DELayout keeps track of the number of service offers issued for each DE by each PET and accepts only one PET's offer for each offer increment. This requires that all PETs use ESMF_DELayoutServiceOffer() in unison. See section 48.2.2 for the potential return values.

The arguments are:

delayout
Specified ESMF_DELayout object.
de
DE for which service is offered by the calling PET.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 48.6.12 ESMF_DELayoutValidate - Validate DELayout internals

INTERFACE:

   subroutine ESMF_DELayoutValidate(delayout, rc)

ARGUMENTS:
     type(ESMF_DELayout),  intent(in)            :: delayout
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Validates that the delayout is internally consistent. The method returns an error code if problems are found.

The arguments are:

delayout
Specified ESMF_DELayout object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 49 VM Class

## 49.1 Description

The ESMF VM (Virtual Machine) class is a generic representation of hardware and system software resources. There is exactly one VM object per ESMF Component, providing the execution environment for the Component code. The VM class handles all resource management tasks for the Component class and provides a description of the underlying configuration of the compute resources used by a Component.

In addition to resource description and management, the VM class offers the lowest level of ESMF communication methods. The VM communication calls are very similar to MPI. Data references in VM communication calls must be provided as raw, language-specific, one-dimensional, contiguous data arrays. The similarity between VM and MPI communication calls is striking and there are many equivalent point-to-point and collective communication calls. However, unlike MPI, the VM communication calls support communication between threaded PETs in a completely transparent fashion.

Many ESMF applications do not interact with the VM class directly very much. The resource management aspect is wrapped completely transparent into the ESMF Component concept. Often the only reason that user code queries a Component object for the associated VM object is to inquire about resource information, such as the localPet or the petCount. Further, for most applications the use of higher level communication APIs, such as provided by Array and Field, are much more convenient than using the low level VM communication calls.

The basic elements of a VM are called PETs, which stands for Persistent Execution Threads. These are equivalent to OS threads with a lifetime of at least that of the associated component. All VM functionality is expressed in terms of PETs. In the simplest, and most common case, a PET is equivalent to an MPI process. However, ESMF also supports multi-threading, where multiple PETs run as Pthreads inside the same virtual address space (VAS).

The resource management functions of the VM class become visible when a component, or the driver code, creates sub-components. Section 16.4.8 discusses this aspect from the Superstructure perspective and provides links to the relevant Component examples in the documentation.

There are two parts to resource management, the parent and the child. When the parent component creates a child component, the parent VM object provides the resources on which the child is created with ESMF_GridCompCreate() or ESMF_CplCompCreate(). The optional petList argument to these calls limits the resources that the parent gives to a specific child. The child component, may specify - during its optional ESMF_<Grid/Cpl>CompSetVM() method - how it wants to arrange the inherited resources in its own VM. After this, all standard ESMF methods of the Component, including ESMF_<Grid/Cpl>CompSetServices(), will execute in the child VM. Notice that the ESMF_<Grid/Cpl>CompSetVM() routine, although part of the child Component, must execute before the child VM has been started up. It runs in the parent VM context. The child VM is created and started up just before the user-written set services routine, specified as an argument to ESMF_<Grid/Cpl>CompSetServices(), is entered.

## 49.2 Constants

### 49.2.1 ESMF_VMEPOCH

DESCRIPTION:
Specifies the kind of VM Epoch being entered.

The type of this flag is:

type(ESMF_VMEpoch_Flag)

The valid values are:

ESMF_VMEPOCH_NONE
An epoch wihout special behavior.
ESMF_VMEPOCH_BUFFER
This option must only be used for parts of the code with distinct sending and receiving PETs, i.e. where no PETs are both sender and receiver. All non-blocking messages are being buffered. A single message is sent between unique pairs of src-dst PETs. This can significantly improve performance for cases with a large imbalance in the number of sending versus receiving PETs. The extra buffering also improves the overall asynchronous behavior between the sending and receiving side.

## 49.3 Use and Examples

The concept of the ESMF Virtual Machine (VM) is so fundamental to the framework that every ESMF application uses it. However, for many user applications the VM class is transparently hidden behind the ESMF Component concept and higher data classes (e.g. Array, Field). The interaction between user code and VM is often only indirect. The following examples provide an overview of where the VM class can come into play in user code.

### 49.3.1 Global VM

This complete example program demonstrates the simplest ESMF application, consisting of only a main program without any Components. The global VM, which is automatically created during the ESMF_Initialize() call, is obtained using two different methods. First the global VM will be returned by ESMF_Initialize() if the optional vm argument is specified. The example uses the VM object obtained this way to call the VM print method. Second, the global VM can be obtained anywhere in the user application using the ESMF_VMGetGlobal() call. The identical VM is returned and several VM query methods are called to inquire about the associated resources.

program ESMF_VMDefaultBasicsEx
#include "ESMF.h"

use ESMF
use ESMF_TestMod

implicit none

! local variables
integer:: rc
type(ESMF_VM):: vm
integer:: localPet, petCount, peCount, ssiId, vas


  call ESMF_Initialize(vm=vm, defaultlogfilename="VMDefaultBasicsEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)
! Providing the optional vm argument to ESMF_Initialize() is one way of
! obtaining the global VM.


  call ESMF_VMPrint(vm, rc=rc)


  call ESMF_VMGetGlobal(vm=vm, rc=rc)
! Calling ESMF_VMGetGlobal() anywhere in the user application is the other
! way to obtain the global VM object.


  call ESMF_VMGet(vm, localPet=localPet, petCount=petCount, peCount=peCount, &
rc=rc)
! The VM object contains information about the associated resources. If the
! user code requires this information it must query the VM object.


  print *, "This PET is localPet: ", localPet
print *, "of a total of ",petCount," PETs in this VM."
print *, "There are ", peCount," PEs referenced by this VM"

call ESMF_VMGet(vm, localPet, peCount=peCount, ssiId=ssiId, vas=vas, rc=rc)


  print *, "This PET is executing in virtual address space (VAS) ", vas
print *, "located on single system image (SSI) ", ssiId
print *, "and is associated with ", peCount, " PEs."


end program


### 49.3.2 VM and Components

The following example shows the role that the VM plays in connection with ESMF Components. A single Component is created in the main program. Through the optional petList argument the driver code specifies that only resources associated with PET 0 are given to the gcomp object.

When the Component code is invoked through the standard ESMF Component methods Initialize, Run, or Finalize the Component's VM is automatically entered. Inside of the user-written Component code the Component VM can be obtained by querying the Component object. The VM object will indicate that only a single PET is executing the Component code.

module ESMF_VMComponentEx_gcomp_mod


  recursive subroutine mygcomp_init(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp)   :: gcomp
type(ESMF_State)      :: istate, estate
type(ESMF_Clock)      :: clock
integer, intent(out)  :: rc

! local variables
type(ESMF_VM):: vm

! get this Component's vm
call ESMF_GridCompGet(gcomp, vm=vm)

! the VM object contains information about the execution environment of
! the Component

call ESMF_VMPrint(vm, rc=rc)

rc = 0
end subroutine !--------------------------------------------------------------

recursive subroutine mygcomp_run(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp)   :: gcomp
type(ESMF_State)      :: istate, estate
type(ESMF_Clock)      :: clock
integer, intent(out)  :: rc

! local variables
type(ESMF_VM):: vm

! get this Component's vm
call ESMF_GridCompGet(gcomp, vm=vm)

! the VM object contains information about the execution environment of
! the Component

call ESMF_VMPrint(vm, rc=rc)

rc = 0
end subroutine !--------------------------------------------------------------

recursive subroutine mygcomp_final(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp)   :: gcomp
type(ESMF_State)      :: istate, estate
type(ESMF_Clock)      :: clock
integer, intent(out)  :: rc

! local variables
type(ESMF_VM):: vm

! get this Component's vm
call ESMF_GridCompGet(gcomp, vm=vm)

! the VM object contains information about the execution environment of
! the Component

call ESMF_VMPrint(vm, rc=rc)

rc = 0
end subroutine !--------------------------------------------------------------

end module


program ESMF_VMComponentEx
#include "ESMF.h"
use ESMF
use ESMF_TestMod
use ESMF_VMComponentEx_gcomp_mod
implicit none

! local variables


  gcomp = ESMF_GridCompCreate(petList=(/0/), rc=rc)


  call ESMF_GridCompSetServices(gcomp, userRoutine=mygcomp_register, rc=rc)


  call ESMF_GridCompInitialize(gcomp, rc=rc)


  call ESMF_GridCompRun(gcomp, rc=rc)


  call ESMF_GridCompFinalize(gcomp, rc=rc)


  call ESMF_GridCompDestroy(gcomp, rc=rc)


  call ESMF_Finalize(rc=rc)


end program


### 49.3.3 Getting the MPI Communicator from an VM object

Sometimes user code requires access to the MPI communicator, e.g. to support legacy code that contains explict MPI communication calls. The correct way of wrapping such code into ESMF is to obtain the MPI intra-communicator out of the VM object. In order not to interfere with ESMF communications it is advisable to duplicate the communicator before using it in user-level MPI calls. In this example the duplicated communicator is used for a user controlled MPI_Barrier().

  integer:: mpic


  integer:: mpic2


  call ESMF_VMGet(vm, mpiCommunicator=mpic, rc=rc)
! The returned MPI communicator spans the same MPI processes that the VM
! is defined on.


  call MPI_Comm_dup(mpic, mpic2, ierr)
! Duplicate the MPI communicator not to interfere with ESMF communications.
! The duplicate MPI communicator can be used in any MPI call in the user
! code. Here the MPI_Barrier() routine is called.
call MPI_Barrier(mpic2, ierr)


### 49.3.4 Nesting ESMF inside a user MPI application

It is possible to nest an ESMF application inside a user application that explicitly calls MPI_Init() and MPI_Finalize(). The ESMF_Initialize() call automatically checks whether MPI has already been initialized, and if so does not call MPI_Init() internally. On the finalize side, ESMF_Finalize() can be instructed to not call MPI_Finalize(), making it the responsibility of the outer code to finalize MPI.

  ! For cases where ESMF resource management is desired (e.g. for threading),
! ESMF_InitializePreMPI() must be called before MPI_Init().
call ESMF_InitializePreMPI(rc=rc)


  ! User code initializes MPI.
call MPI_Init(ierr)


  ! ESMF_Initialize() does not call MPI_Init() if it finds MPI initialized.
call ESMF_Initialize(defaultlogfilename="VMUserMpiEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


  ! Use ESMF here...


  ! Calling ESMF_Finalize() with endflag=ESMF_END_KEEPMPI instructs ESMF
! to keep MPI active.
call ESMF_Finalize(endflag=ESMF_END_KEEPMPI, rc=rc)


  ! It is the responsibility of the outer user code to finalize MPI.
call MPI_Finalize(ierr)


### 49.3.5 Nesting ESMF inside a user MPI application on a subset of MPI ranks

The previous example demonstrated that it is possible to nest an ESMF application, i.e. ESMF_Initialize()...ESMF_Finalize() inside MPI_Init()...MPI_Finalize(). It is not necessary that all MPI ranks enter the ESMF application. The following example shows how the user code can pass an MPI communicator to ESMF_Initialize(), and enter the ESMF application on a subset of MPI ranks.

  ! User code initializes MPI.
call MPI_Init(ierr)


  ! User code determines the local rank.
call MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr)


  ! User code prepares MPI communicator "esmfComm", that allows rank 0 and 1
! to be grouped together.
if (rank < 2) then
! first communicator split with color=0
call MPI_Comm_split(MPI_COMM_WORLD, 0, 0, esmfComm, ierr)
else
! second communicator split with color=1
call MPI_Comm_split(MPI_COMM_WORLD, 1, 0, esmfComm, ierr)
endif


  if (rank < 2) then
! Only call ESMF_Initialize() on rank 0 and 1, passing the prepared MPI
! communicator that spans these ranks.
call ESMF_Initialize(mpiCommunicator=esmfComm, &
defaultlogfilename="VMUserMpiCommEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


    ! Use ESMF here...


    ! Calling ESMF_Finalize() with endflag=ESMF_END_KEEPMPI instructs ESMF
! to keep MPI active.
call ESMF_Finalize(endflag=ESMF_END_KEEPMPI, rc=rc)


  else
! Ranks 2 and above do non-ESMF work...


  endif


  ! Free the MPI communicator before finalizing MPI.
call MPI_Comm_free(esmfComm, ierr)

! It is the responsibility of the outer user code to finalize MPI.
call MPI_Finalize(ierr)


### 49.3.6 Multiple concurrent instances of ESMF under separate MPI communicators

Multiple instances of ESMF can run concurrently under the same user main program on separate MPI communicators. The user program first splits MPI_COMM_WORLD into separate MPI communicators. Each communicator is then used to run a separate ESMF instance by passing it into ESMF_Initialize() on the appropriate MPI ranks.

Care must be taken to set the defaultlogfilename to be unique on each ESMF instances. This prevents concurrent ESMF instances from writing to the same log file. Further, each ESMF instances must call ESMF_Finalize() with the endflag=ESMF_END_KEEPMPI option in order to hand MPI control back to the user program. The outer user program is ultimately responsible for destroying the MPI communicators and to cleanly shut down MPI.

  ! User code initializes MPI.
call MPI_Init(ierr)


  ! User code determines the local rank and overall size of MPI_COMM_WORLD
call MPI_Comm_rank(MPI_COMM_WORLD, rank, ierr)
call MPI_Comm_size(MPI_COMM_WORLD, size, ierr)


  ! User code prepares different MPI communicators.
! Here a single MPI_Comm_split() call is used to split MPI_COMM_WORLD
! into two non-overlapping communicators:
! One communicator for ranks 0 and 1, and the other for ranks 2 and above.
if (rank < 2) then
! first communicator split with color=0
call MPI_Comm_split(MPI_COMM_WORLD, 0, 0, esmfComm, ierr)
else
! second communicator split with color=1
call MPI_Comm_split(MPI_COMM_WORLD, 1, 0, esmfComm, ierr)
endif


  if (rank < 2) then
! Ranks 0 and 1 enter ESMF_Initialize() with the prepared communicator.
! Care is taken to set a unique log file name.
call ESMF_Initialize(mpiCommunicator=esmfComm, &
defaultlogfilename="VMUserMpiCommMultiEx1.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


    ! Use ESMF here...


    ! Finalize ESMF without finalizing MPI. The user application will call
! MPI_Finalize() on all ranks.
call ESMF_Finalize(endflag=ESMF_END_KEEPMPI, rc=rc)


  else
! Ranks 2 and above enter ESMF_Initialize() with the prepared communicator.
! Care is taken to set a unique log file name.
call ESMF_Initialize(mpiCommunicator=esmfComm, &
defaultlogfilename="VMUserMpiCommMultiEx2.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


    ! Use ESMF here...


    ! Finalize ESMF without finalizing MPI. The user application will call
! MPI_Finalize() on all ranks.
call ESMF_Finalize(endflag=ESMF_END_KEEPMPI, rc=rc)


  endif


  ! Free the MPI communicator(s) before finalizing MPI.
call MPI_Comm_free(esmfComm, ierr)

! It is the responsibility of the outer user code to finalize MPI.
call MPI_Finalize(ierr)


### 49.3.7 Communication - Send and Recv

The VM layer provides MPI-like point-to-point communication. Use ESMF_VMSend() and ESMF_VMRecv() to pass data between two PETs. The following code sends data from PET 'src' and receives it on PET 'dst'. Both PETs must be part of the same VM.

Set up the localData array.

  count = 10
allocate(localData(count))
do i=1, count
localData(i) = localPet*100 + i
enddo


Carry out the data transfer between src PET and dst PET.

  if (localPet==src) then
call ESMF_VMSend(vm, sendData=localData, count=count, dstPet=dst, rc=rc)
endif


  if (localPet==dst) then
call ESMF_VMRecv(vm, recvData=localData, count=count, srcPet=src, rc=rc)
endif


Finally, on dst PET, test the received data for correctness.

  if (localPet==dst) then
do i=1, count
if (localData(i) /= src*100 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


### 49.3.8 Communication - Scatter and Gather

The VM layer provides MPI-like collective communication. ESMF_VMScatter() scatters data located on root PET across all the PETs of the VM. ESMF_VMGather() provides the opposite operation, gathering data from all the PETs of the VM onto root PET.

  integer, allocatable:: array1(:), array2(:)


  ! allocate data arrays
nsize = 2
nlen = nsize * petCount
allocate(array1(nlen))
allocate(array2(nsize))

! prepare data array1
do i=1, nlen
array1(i) = localPet * 100 + i
enddo


  call ESMF_VMScatter(vm, sendData=array1, recvData=array2, count=nsize, &
rootPet=scatterRoot, rc=rc)


  call ESMF_VMGather(vm, sendData=array2, recvData=array1, count=nsize, &
rootPet=gatherRoot, rc=rc)


### 49.3.9 Communication - AllReduce and AllFullReduce

Use ESMF_VMAllReduce() to reduce data distributed across the PETs of a VM into a result vector, returned on all the PETs. Further, use ESMF_VMAllFullReduce() to reduce the data into a single scalar returned on all PETs.

  integer, allocatable:: array1(:), array2(:)


  ! allocate data arrays
nsize = 2
allocate(array1(nsize))
allocate(array2(nsize))

! prepare data array1
do i=1, nsize
array1(i) = localPet * 100 + i
enddo


  call ESMF_VMAllReduce(vm, sendData=array1, recvData=array2, count=nsize, &
reduceflag=ESMF_REDUCE_SUM, rc=rc)
! Reduce distributed sendData, element by element into recvData and
! return it on all the PETs.


  call ESMF_VMAllFullReduce(vm, sendData=array1, recvData=result, &
count=nsize, reduceflag=ESMF_REDUCE_SUM, rc=rc)
! Fully reduce the distributed sendData into a single scalar and
! return it in recvData on all PETs.


### 49.3.10 Communication - Non-blocking option and VMEpochs

The VM communication methods offer the option to execute in non-blocking mode. In this mode, both sending and receving calls return immediatly on each local PET. A separate synchronization call is needed to assure completion of the data transfer.

The separation of initiation and completion of the data transfer provides the opportunity for the underlying communication system to progress concurrently with other operations on the same PET. This can be leveraged to have profound impact on the performance of an algorithm that requires both computation and communication.

Another critical application of the non-blocking communication mode is the prevention of deadlocks. In the default blocking mode, a receiving method will not return until the data transfer has completed. Sending methods may also not return, especially if the message being sent is above the implementation dependent internal buffer size. This behavior makes it often hard, if not impossible, to write safe algorithms that guarantee to not deadlock when communicating between a group of PETs. Using the communication calls in non-blocking mode simplifies this problem immensely.

The following code shows how ESMF_VMSend() and ESMF_VMRecv() are used in non-blocking mode by passing in the ESMF_SYNC_NONBLOCKING argument.

Set up the localData array.

  do i=1, count
localData(i) = localPet*100 + i
enddo


Initiate the data transfer between src PET and dst PET.

  if (localPet==src) then
call ESMF_VMSend(vm, sendData=localData, count=count, dstPet=dst, &
syncflag=ESMF_SYNC_NONBLOCKING, rc=rc)
endif


  if (localPet==dst) then
call ESMF_VMRecv(vm, recvData=localData, count=count, srcPet=src, &
syncflag=ESMF_SYNC_NONBLOCKING, rc=rc)
endif


There is no garantee at this point that the data transfer has actually started, let along completed. For this reason it is unsafe to overwrite the data in the localData array on src PET, or to access the localData array on dst PET. However both PETs are free to engage in other work while the data transfer my proceed concurrently.

  ! local computational work here, or other communications


Wait for the completion of all outstanding non-blocking communication calls by issuing the ESMF_VMCommWaitAll() call.

  call ESMF_VMCommWaitAll(vm, rc=rc)


Finally, on dst PET, test the received data for correctness.

  if (localPet==dst) then
do i=1, count
if (localData(i) /= src*100 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


Sometimes it is necessary to wait for individual outstanding communications specifically. This can be accomplished by using ESMF_CommHandle objects. To demonstrate this, first re-initialize the localData array.

  do i=1, count
localData(i) = localPet*100 + i
localData2(i) = localPet*1000 + i
enddo


Initiate the data transfer between src PET and dst PET, but this time also pass the commhandle variable of type ESMF_CommHandle. Here send two message between src and dst in order to have different outstanding messages to wait for.

  if (localPet==src) then
call ESMF_VMSend(vm, sendData=localData, count=count, dstPet=dst, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(1), rc=rc)
call ESMF_VMSend(vm, sendData=localData2, count=count, dstPet=dst, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(2), rc=rc)
endif


  if (localPet==dst) then
call ESMF_VMRecv(vm, recvData=localData, count=count, srcPet=src, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(1), rc=rc)
call ESMF_VMRecv(vm, recvData=localData2, count=count, srcPet=src, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(2), rc=rc)
endif


Now it is possible to specifically wait for the first data transfer, e.g. on the dst PET.

  if (localPet==dst) then
call ESMF_VMCommWait(vm, commhandle=commhandle(1), rc=rc)
endif


At this point there are still 2 outstanding communications on the src PET, and one outstanding communication on the dst PET. However, having returned from the specific ESMF_VMCommWait() call guarantees that the first communication on the dst PET has completed, i.e. the data has been received from the src PET, and can now be accessed in the localData array.

  if (localPet==dst) then
do i=1, count
if (localData(i) /= src*100 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


Before accessing data from the second transfer, it is necessary to wait on the associated commhandle for completion.

  if (localPet==dst) then
call ESMF_VMCommWait(vm, commhandle=commhandle(2), rc=rc)
endif


  if (localPet==dst) then
do i=1, count
if (localData2(i) /= src*1000 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


Finally the commhandle elements on the src side need to be cleared by waiting for them. This could be done using specific ESMF_VMCommWait() calls, similar to the dst side, or simply by waiting for all/any outstanding communications using ESMF_VMCommWaitAll() as in the previous example. This call can be issued without commhandle on all of the PETs.

  call ESMF_VMCommWaitAll(vm, rc=rc)


For cases where multiple messages are being sent between the same src-dst pairs using non-blocking communications, performance can often be improved by aggregating individual messages. An extra buffer is needed to hold the collected messages, resulting in only a single data transfer for each PET pair. In many cases this can significantly reduce the time spent in communications. The ESMF VM class provides access to such a buffer technique through the ESMF_VMEpoch API.

The ESMF_VMEpoch API consists of two interfaces: ESMF_VMEpochEnter() and ESMF_VMEpochExit(). When entering an epoch, the user specifies the type of epoch that is to be entered. Currently only ESMF_VMEPOCH_BUFFER is available. Inside this epoch, non-blocking communication calls are aggregated and data transfers on the src side are not issued until the epoch is exited. On the dst side a single data transfer is received, and then divided over the actual non-blocking receive calls.

The following code repeates the previous example with two messages between src and dst. It is important that every PET only must act either as sender or receiver. A sending PET can send to many different PETs, and a receiving PET can receive from many PETs, but no PET must send and receive within the same epoch!

First re-initialize the localData array.

  do i=1, count
localData(i) = localPet*100 + i
localData2(i) = localPet*1000 + i
enddo


Enter the ESMF_VMEPOCH_BUFFER.

  call ESMF_VMEpochEnter(epoch=ESMF_VMEPOCH_BUFFER, rc=rc)


Now issue non-blocking send and receive calls as usual.

  if (localPet==src) then
call ESMF_VMSend(vm, sendData=localData, count=count, dstPet=dst, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(1), rc=rc)


    call ESMF_VMSend(vm, sendData=localData2, count=count, dstPet=dst, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(2), rc=rc)


  endif
if (localPet==dst) then
call ESMF_VMRecv(vm, recvData=localData, count=count, srcPet=src, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(1), rc=rc)


    call ESMF_VMRecv(vm, recvData=localData2, count=count, srcPet=src, &
syncflag=ESMF_SYNC_NONBLOCKING, commhandle=commhandle(2), rc=rc)


  endif


No data transfer has been initiated at this point due to the fact that this code is inside the ESMF_VMEPOCH_BUFFER. On the dst side the same methods are used to wait for the data transfer. However, it is not until the exit of the epoch on the src side that data is transferred to the dst side.

  if (localPet==dst) then
call ESMF_VMCommWait(vm, commhandle=commhandle(1), rc=rc)


  endif


  if (localPet==dst) then
do i=1, count
if (localData(i) /= src*100 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


  if (localPet==dst) then
call ESMF_VMCommWait(vm, commhandle=commhandle(2), rc=rc)


  endif


  if (localPet==dst) then
do i=1, count
if (localData2(i) /= src*1000 + i) then
finalrc = ESMF_RC_VAL_WRONG
endif
enddo
endif


Now exit the epoch, to trigger the data transfer on the src side.

  call ESMF_VMEpochExit(rc=rc)


Finally clear the outstanding communication handles on the src side. This needs to happen first inside the next ESMF_VMEPOCH_BUFFER. As before, waits could be issued either for the specific commhandle elements not yet explicitly cleared, or a general call to ESMF_VMCommWaitAll() can be used for simplicity.

  call ESMF_VMEpochEnter(epoch=ESMF_VMEPOCH_BUFFER, rc=rc)


  call ESMF_VMCommWaitAll(vm, rc=rc)


  call ESMF_VMEpochExit(rc=rc)


### 49.3.11 Using VM communication methods with data of rank greater than one

In the current implementation of the VM communication methods all the data array arguments are declared as assumed shape dummy arrays of rank one. The assumed shape flavor was chosen in order to minimize the chance of copy in/out problems, associated with the other options for declaring the dummy data arguments. However, currently the interfaces are not overloaded for higher ranks. This restriction requires that users that need to communicate data arrays with rank greater than one, must only pass the first dimension of the data array into the VM communication calls. Specifying the full size of the data arrays (considering all dimensions) ensure that the complete data is transferred in or out of the contiguous array memory.

  integer, allocatable:: sendData(:,:)
integer, allocatable:: recvData(:,:,:,:)


  count1 = 5
count2 = 8
allocate(sendData(count1,count2)) ! 5 x 8 = 40 elements
do j=1, count2
do i=1, count1
sendData(i,j) = localPet*100 + i + (j-1)*count1
enddo
enddo

count1 = 2
count2 = 5
count3 = 1
count4 = 4
allocate(recvData(count1,count2,count3,count4)) ! 2 x 5 x 1 x 4 = 40 elements
do l=1, count4
do k=1, count3
do j=1, count2
do i=1, count1
recvData(i,j,k,l) = 0
enddo
enddo
enddo
enddo


  if (localPet==src) then
call ESMF_VMSend(vm, &
sendData=sendData(:,1), & ! 1st dimension as contiguous array section
count=count1*count2, &    ! total count of elements
dstPet=dst, rc=rc)
endif


  if (localPet==dst) then
call ESMF_VMRecv(vm, &
recvData=recvData(:,1,1,1), & ! 1st dimension as contiguous array section
count=count1*count2*count3*count4, &  ! total count of elements
srcPet=src, rc=rc)
endif


## 49.4 Restrictions and Future Work

1. Only array section syntax that leads to contiguous sub sections is supported. The source and destination arguments in VM communication calls must reference contiguous data arrays. Fortran array sections are not guaranteed to be contiguous in all cases.

2. Non-blocking Reduce() operations not implemented. None of the reduce communication calls have an implementation for the non-blocking feature. This affects:
• ESMF_VMAllFullReduce(),
• ESMF_VMAllReduce(),
• ESMF_VMReduce().

3. Limitations when using mpiuni mode. In mpiuni mode non-blocking communications are limited to one outstanding message per source-destination PET pair. Furthermore, in mpiuni mode the message length must be smaller than the internal ESMF buffer size.

4. Alternative communication paths not accessible. All user accessible VM communication calls are currently implemented using MPI-1.2. VM's implementation of alternative communication techniques, such as shared memory between threaded PETs and POSIX IPC between PETs located on the same single system image, are currently inaccessible to the user. (One exception to this is the mpiuni case for which the VM automatically utilizes a shared memory path.)

5. Data arrays in VM comm calls are assumed shape with rank=1. Currently all dummy arrays in VM comm calls are defined as assumed shape arrays of rank=1. The motivation for this choice is that the use of assumed shape dummy arrays guards against the Fortran copy in/out problem. However it may not be as flexible as desired from the user perspective. Alternatively all dummy arrays could be defined as assumed size arrays, as it is done in most MPI implementations, allowing arrays of various rank to be passed into the comm methods. Arrays of higher rank can be passed into the current interfaces using Fortran array syntax. This approach is explained in section 49.3.11.

## 49.5 Design and Implementation Notes

The VM class provides an additional layer of abstraction on top of the POSIX machine model, making it suitable for HPC applications. There are four key aspects the VM class deals with.

1. Encapsulation of hardware and operating system details within the concept of Persistent Execution Threads (PETs).

2. Resource management in terms of PETs with a guard against over-subscription.

3. Topological description of the underlying configuration of the compute resources in terms of PETs.

4. Transparent communication API for point-to-point and collective PET-based primitives, hiding the many different communication channels and offering best possible performance.

Definition of terms used in the diagram

• PE: A processing element (PE) is an alias for the smallest physical processing unit available on a particular hardware platform. In the language of today's microprocessor architecture technology a PE is identical to a core, however, if future microprocessor designs change the smallest physical processing unit the mapping of the PE to actual hardware will change accordingly. Thus the PE layer separates the hardware specific part of the VM from the hardware-independent part. Each PE is labeled with an id number which identifies it uniquely within all of the VM instances of an ESMF application.

• Core: A Core is the smallest physical processing unit which typically comprises a register set, an integer arithmetic unit, a floating-point unit and various control units. Each Core is labeled with an id number which identifies it uniquely within all of the VM instances of an ESMF application.

• CPU: The central processing unit (CPU) houses single or multiple cores, providing them with the interface to system memory, interconnects and I/O. Typically the CPU provides some level of caching for the instruction and data streams in and out of the Cores. Cores in a multi-core CPU typically share some caches. Each CPU is labeled with an id number which identifies it uniquely within all of the VM instances of an ESMF application.

• SSI: A single system image (SSI) spans all the CPUs controlled by a single running instance of the operating system. SMP and NUMA are typical multi-CPU SSI architectures. Each SSI is labeled with an id number which identifies it uniquely within all of the VM instances of an ESMF application.

• TOE: A thread of execution (TOE) executes an instruction sequence. TOE's come in two flavors: PET and TET.

• PET: A persistent execution thread (PET) executes an instruction sequence on an associated set of data. The PET has a lifetime at least as long as the associated data set. In ESMF the PET is the central concept of abstraction provided by the VM class. The PETs of an VM object are labeled from 0 to N-1 where N is the total number of PETs in the VM object.

• TET: A transient execution thread (TET) executes an instruction sequence on an associated set of data. A TET's lifetime might be shorter than that of the associated data set.

• OS-Instance: The OS-Instance of a TOE describes how a particular TOE is instantiated on the OS level. Using POSIX terminology a TOE will run as a single thread within a single- or multi-threaded process.

• MPI-1, MPI-2: Communication via MPI standards 1 and 2.

• armci: Communication via the aggregate remote memory copy interface.

• SHMEM: Communication via the SHMEM interface.

• OS-IPC: Communication via the operating system's inter process communication interface. Either POSIX IPC or System V IPC.

• InterCon-lib: Communication via the interconnect's library native interface. An example is the Elan library for Quadrics.

The POSIX machine abstraction, while a very powerful concept, needs augmentation when applied to HPC applications. Key elements of the POSIX abstraction are processes, which provide virtually unlimited resources (memory, I/O, sockets, ...) to possibly multiple threads of execution. Similarly POSIX threads create the illusion that there is virtually unlimited processing power available to each POSIX process. While the POSIX abstraction is very suitable for many multi-user/multi-tasking applications that need to share limited physical resources, it does not directly fit the HPC workload where over-subscription of resources is one of the most expensive modes of operation.

ESMF's virtual machine abstraction is based on the POSIX machine model but holds additional information about the available physical processing units in terms of Processing Elements (PEs). A PE is the smallest physical processing unit and encapsulates the hardware details (Cores, CPUs and SSIs).

There is exactly one physical machine layout for each application, and all VM instances have access to this information. The PE is the smallest processing unit which, in today's microprocessor technology, corresponds to a single Core. Cores are arranged in CPUs which in turn are arranged in SSIs. The setup of the physical machine layout is part of the ESMF initialization process.

On top of the PE concept the key abstraction provided by the VM is the PET. All user code is executed by PETs while OS and hardware details are hidden. The VM class contains a number of methods which allow the user to prescribe how the PETs of a desired virtual machine should be instantiated on the OS level and how they should map onto the hardware. This prescription is kept in a private virtual machine plan object which is created at the same time the associated component is being created. Each time component code is entered through one of the component's registered top-level methods (Initialize/Run/Finalize), the virtual machine plan along with a pointer to the respective user function is used to instantiate the user code on the PETs of the associated VM in form of single- or multi-threaded POSIX processes.

The process of starting, entering, exiting and shutting down a VM is very transparent, all spawning and joining of threads is handled by VM methods "behind the scenes". Furthermore, fundamental synchronization and communication primitives are provided on the PET level through a uniform API, hiding details related to the actual instantiation of the participating PETs.

Within a VM object each PE of the physical machine maps to 0 or 1 PETs. Allowing unassigned PEs provides a means to prevent over-subscription between multiple concurrently running virtual machines. Similarly a maximum of one PET per PE prevents over-subscription within a single VM instance. However, over-subscription is possible by subscribing PETs from different virtual machines to the same PE. This type of over-subscription can be desirable for PETs associated with I/O workloads expected to be used infrequently and to block often on I/O requests.

On the OS level each PET of a VM object is represented by a POSIX thread (Pthread) either belonging to a single- or multi-threaded process and maps to at least 1 PE of the physical machine, ensuring its execution. Mapping a single PET to multiple PEs provides resources for user-level multi-threading, in which case the user code inquires how many PEs are associated with its PET and if there are multiple PEs available the user code can spawn an equal number of threads (e.g. OpenMP) without risking over-subscription. Typically these user spawned threads are short-lived and used for fine-grained parallelization in form of TETs. All PEs mapped against a single PET must be part of a unique SSI in order to allow user-level multi-threading!

In addition to discovering the physical machine the ESMF initialization process sets up the default global virtual machine. This VM object, which is the ultimate parent of all VMs created during the course of execution, contains as many PETs as there are PEs in the physical machine. All of its PETs are instantiated in form of single-threaded MPI processes and a 1:1 mapping of PETs to PEs is used for the default global VM.

The VM design and implementation is based on the POSIX process and thread model as well as the MPI-1.2 standard. As a consequence of the latter standard the number of processes is static during the course of execution and is determined at start-up. The VM implementation further requires that the user starts up the ESMF application with as many MPI processes as there are PEs in the available physical machine using the platform dependent mechanism to ensure proper process placement.

All MPI processes participating in a VM are grouped together by means of an MPI_Group object and their context is defined via an MPI_Comm object (MPI intra-communicator). The PET local process id within each virtual machine is equal to the MPI_Comm_rank in the local MPI_Comm context whereas the PET process id is equal to the MPI_Comm_rank in MPI_COMM_WORLD. The PET process id is used within the VM methods to determine the virtual memory space a PET is operating in.

In order to provide a migration path for legacy MPI-applications the VM offers accessor functions to its MPI_Comm object. Once obtained this object may be used in explicit user-code MPI calls within the same context.

## 49.6 Class API

### 49.6.1 ESMF_VMAssignment(=) - VM assignment

INTERFACE:

     interface assignment(=)
vm1 = vm2

ARGUMENTS:
     type(ESMF_VM) :: vm1
type(ESMF_VM) :: vm2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Assign vm1 as an alias to the same ESMF VM object in memory as vm2. If vm2 is invalid, then vm1 will be equally invalid after the assignment.

The arguments are:

vm1
The ESMF_VM object on the left hand side of the assignment.
vm2
The ESMF_VM object on the right hand side of the assignment.

### 49.6.2 ESMF_VMOperator(==) - VM equality operator

INTERFACE:

   interface operator(==)
if (vm1 == vm2) then ... endif
OR
result = (vm1 == vm2)

RETURN VALUE:
     logical :: result

ARGUMENTS:
     type(ESMF_VM), intent(in) :: vm1
type(ESMF_VM), intent(in) :: vm2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Test whether vm1 and vm2 are valid aliases to the same ESMF VM object in memory. For a more general comparison of two ESMF VMs, going beyond the simple alias test, the ESMF_VMMatch() function (not yet implemented) must be used.

The arguments are:

vm1
The ESMF_VM object on the left hand side of the equality operation.
vm2
The ESMF_VM object on the right hand side of the equality operation.

### 49.6.3 ESMF_VMOperator(/=) - VM not equal operator

INTERFACE:

   interface operator(/=)
if (vm1 /= vm2) then ... endif
OR
result = (vm1 /= vm2)

RETURN VALUE:
     logical :: result

ARGUMENTS:
     type(ESMF_VM), intent(in) :: vm1
type(ESMF_VM), intent(in) :: vm2

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Test whether vm1 and vm2 are not valid aliases to the same ESMF VM object in memory. For a more general comparison of two ESMF VMs, going beyond the simple alias test, the ESMF_VMMatch() function (not yet implemented) must be used.

The arguments are:

vm1
The ESMF_VM object on the left hand side of the non-equality operation.
vm2
The ESMF_VM object on the right hand side of the non-equality operation.

### 49.6.4 ESMF_VMAllFullReduce - Fully reduce data across VM, result on all PETs

INTERFACE:

    subroutine ESMF_VMAllFullReduce(vm, sendData, recvData, &
count, reduceflag, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>),         intent(out)           :: recvData
integer,                          intent(in)            :: count
type(ESMF_Reduce_Flag),           intent(in)            :: reduceflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that reduces a contiguous data array of <type><kind> across the ESMF_VM object into a single value of the same <type><kind>. The result is returned on all PETs. Different reduction operations can be specified.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
recvData
Single data variable to be received. All PETs must specify a valid result variable.
count
Number of elements in sendData. Allowed to be different across the PETs, as long as count > 0.
reduceflag
Reduction operation. See section 52.47 for a list of valid reduce operations.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.5 ESMF_VMAllGather - Gather data across VM, result on all PETs

INTERFACE:

    subroutine ESMF_VMAllGather(vm, sendData, recvData, count, &
syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: count
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that gathers contiguous data of <type><kind> from all PETs of an ESMF_VM object into an array on each PET. The data received in recvData is identical across all PETs. The count elements sent from the sendData array on PET i are stored contiguously in the recvData array starting at position i count 1.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array. The first count elements on each PET are sent.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument large enough to accommodate the received data.
count
Number of elements to be gathered from each PET. Must be the same on all PETs.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.6 ESMF_VMAllGatherV - GatherV data across VM, result on all PETs

INTERFACE:

    subroutine ESMF_VMAllGatherV(vm, sendData, sendCount, &
recvData, recvCounts, recvOffsets, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCount
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCounts(:)
integer,                          intent(in)            :: recvOffsets(:)
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that gathers contiguous data of <type><kind> from all PETs of an ESMF_VM object into an array on each PET. The data received in recvData is identical across all PETs. The sendCount elements sent from the sendData array on PET i are stored contiguously in the recvData array starting at position recvOffsets(i).

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
sendCount
Number of sendData elements to send from local PET to all other PETs.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument large enough to accommodate the received data.
recvCounts
Number of recvData elements to be received from the corresponding source PET.
recvOffsets
Offsets in units of elements in recvData marking the start of element sequence to be received from source PET.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.7 ESMF_VMAllReduce - Reduce data across VM, result on all PETs

INTERFACE:

    subroutine ESMF_VMAllReduce(vm, sendData, recvData, count, &
reduceflag, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: count
type(ESMF_Reduce_Flag),           intent(in)            :: reduceflag
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that reduces a contiguous data array across the ESMF_VM object into a contiguous data array of the same <type><kind>. The result array is returned on all PETs. Different reduction operations can be specified.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument.
count
Number of elements in sendData and recvData. Must be the same on all PETs.
reduceflag
Reduction operation. See section 52.47 for a list of valid reduce operations.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.8 ESMF_VMAllToAll - AllToAll communications across VM

INTERFACE:

    subroutine ESMF_VMAllToAll(vm, sendData, sendCount, &
recvData, recvCount, syncflag, &
commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCount
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCount
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.3.0r. If code using this interface compiles with any version of ESMF starting with 5.3.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that performs a total exchange operation on the contiguous data of <type><kind>. PET i sends contiguous sendCount elements of its sendData array to every PET, including itself. The sendCount elements sent to PET j are those starting at position j sendCount 1, and are stored in recvData on PET in position i recvCount 1.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
sendCount
Number of sendData elements to send from local PET to each destination PET.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument large enough to accommodate the received data.
recvCount
Number of recvData elements to be received by local PET from each source PET.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.9 ESMF_VMAllToAllV - AllToAllV communications across VM

INTERFACE:

    subroutine ESMF_VMAllToAllV(vm, sendData, sendCounts, &
sendOffsets, recvData, recvCounts, recvOffsets, syncflag, &
commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCounts(:)
integer,                          intent(in)            :: sendOffsets(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCounts(:)
integer,                          intent(in)            :: recvOffsets(:)
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that performs a total exchange operation on the contiguous data of <type><kind>. PET i sends contiguous elements of its sendData array to all PETs, including itself. The sendCount(j) elements sent to PET j are those starting at position sendOffsets(j), and are stored in recvData on PET in position recvOffsets(i).

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
sendCounts
Number of sendData elements to send from local PET to destination PET.
sendOffsets
Offsets in units of elements in sendData marking to start of element sequence to be sent from local PET to destination PET.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument large enough to accommodate the received data.
recvCounts
Number of recvData elements to be received by local PET from source PET.
recvOffsets
Offsets in units of elements in recvData marking to start of element sequence to be received by local PET from source PET.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.10 ESMF_VMBarrier - VM wide barrier

INTERFACE:

   subroutine ESMF_VMBarrier(vm, rc)

ARGUMENTS:
     type(ESMF_VM),  intent(in),  optional :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,        intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that blocks calling PET until all PETs of the VM context have issued the call.

The arguments are:

[vm]
ESMF_VM object. Default use current VM.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

INTERFACE:

    subroutine ESMF_VMBroadcast(vm, bcstData, count, rootPet, &
syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(inout)         :: bcstData(:)
integer,                          intent(in)            :: count
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that broadcasts a contiguous data array of <type><kind> from rootPet to all other PETs of the ESMF_VM object. When the call returns, the bcstData array on all PETs contains the same data as on rootPet.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL, ESMF_TYPEKIND_CHARACTER.

The arguments are:

vm
ESMF_VM object.
bcstData
Contiguous data array. On rootPet bcstData holds data that is to be broadcasted to all other PETs. On all other PETs bcstData is used to receive the broadcasted data and must be large enough to accommodate the received data.
count
Number of elements in /bcstData. Must be the same on all PETs.
rootPet
PET that holds data that is being broadcast.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.12 ESMF_VMCommWait - Wait for non-blocking VM communication to complete

INTERFACE:

   subroutine ESMF_VMCommWait(vm, commhandle, rc)

ARGUMENTS:
     type(ESMF_VM),         intent(in)            :: vm
type(ESMF_CommHandle), intent(in)            :: commhandle
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,               intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Wait for non-blocking VM communication specified by the commhandle to complete.

The arguments are:

vm
ESMF_VM object.
commhandle
Handle specifying a previously issued non-blocking communication request.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.13 ESMF_VMCommWaitAll - Wait for all non-blocking VM comms to complete

INTERFACE:

   subroutine ESMF_VMCommWaitAll(vm, rc)

ARGUMENTS:
     type(ESMF_VM), intent(in)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Wait for all pending non-blocking VM communication within the specified VM context to complete.

The arguments are:

vm
ESMF_VM object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.14 ESMF_VMEpochEnter - Enter an ESMF epoch

INTERFACE:

   subroutine ESMF_VMEpochEnter(vm, epoch, rc)

ARGUMENTS:
 -- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_VM),            intent(in),  optional :: vm
type(ESMF_VMEpoch_Flag),  intent(in),  optional :: epoch
integer,                  intent(out), optional :: rc

DESCRIPTION:

Enter a specific VM epoch. VM epochs change low level communication behavior which can have significant performance implications. It is an error to call ESMF_VMEpochEnter() again before exiting a previous epoch with ESMF_VMEpochExit().

The arguments are:

[vm]
ESMF_VM object. Defaults to the current VM.
[epoch]
The epoch to be entered. See section 49.2.1 for a complete list of options. Defaults to ESMF_VMEPOCH_NONE.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.15 ESMF_VMEpochExit - Exit an ESMF epoch

INTERFACE:

   subroutine ESMF_VMEpochExit(vm, keepAlloc, rc)

ARGUMENTS:
 -- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_VM),            intent(in),  optional :: vm
logical,                  intent(in),  optional :: keepAlloc
integer,                  intent(out), optional :: rc

DESCRIPTION:

Exit the current VM epoch.

The arguments are:

[vm]
ESMF_VM object. Defaults to the current VM.
[keepAlloc]
For .true., keep internal allocations to be reused during the epoch phase. For .false., deallocate all internal buffers. The flag only affects the local PET. Defaults to .true..
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.16 ESMF_VMGather - Gather data from across VM

INTERFACE:

    subroutine ESMF_VMGather(vm, sendData, recvData, count, rootPet, &
syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: count
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that gathers contiguous data of <type><kind> from all PETs of an ESMF_VM object (including the rootPet itself) into an array on rootPet. The count elements sent from the sendData array on PET i are stored contiguously in the recvData array on rootPet starting at position i count 1.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
recvData
Contiguous data array for data to be received. Only recvData specified by the rootPet will be used by this method, and must be large enough to accommodate the received data.
count
Number of elements to be sent from each PET to rootPet. Must be the same on all PETs.
rootPet
PET on which data is gathereds.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.17 ESMF_VMGatherV - GatherV data from across VM

INTERFACE:

    subroutine ESMF_VMGatherV(vm, sendData, sendCount, recvData, &
recvCounts, recvOffsets, rootPet, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCount
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCounts(:)
integer,                          intent(in)            :: recvOffsets(:)
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that gathers contiguous data of <type><kind> from all PETs of an ESMF_VM object (including the rootPet itself) into an array on rootPet. The sendCount elements sent from the sendData array on PET i are stored contiguously in the recvData array on rootPet starting at position recvOffsets(i).

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
sendCount
Number of sendData elements to send from local PET to all other PETs.
recvData
Contiguous data array for data to be received. Only recvData specified by the rootPet will be used by this method, and must be large enough to accommodate the received data.
recvCounts
An integer array (of length group size, specified in VM object) containing number of recvData elements to be received from corresponding source PET. This argument is significant only at rootPet.
recvOffsets
Offsets in units of elements in recvData marking the start of element sequence to be received from source PET.
rootPet
PET on which data is gathered.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.18 ESMF_VMGet - Get information from a VM

INTERFACE:

   ! Private name; call using ESMF_VMGet()
recursive subroutine ESMF_VMGetDefault(vm, localPet, &
currentSsiPe, petCount, peCount, ssiCount, ssiMap, ssiMinPetCount, ssiMaxPetCount, &
ssiSharedMemoryEnabledFlag, rc)

ARGUMENTS:
     type(ESMF_VM),        intent(in)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,              intent(out), optional :: localPet
integer,              intent(out), optional :: currentSsiPe
integer,              intent(out), optional :: petCount
integer,              intent(out), optional :: peCount
integer,              intent(out), optional :: ssiCount
integer, allocatable, intent(out), optional :: ssiMap(:)
integer,              intent(out), optional :: ssiMinPetCount
integer,              intent(out), optional :: ssiMaxPetCount
integer,              intent(out), optional :: ssiLocalPetCount
integer,              intent(out), optional :: mpiCommunicator
logical,              intent(out), optional :: openMPEnabledFlag
logical,              intent(out), optional :: ssiSharedMemoryEnabledFlag
integer,              intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
8.0.0
Added arguments ssiCount, ssiMinPetCount, ssiMaxPetCount, and ssiLocalPetCount to provide access to information about how the VM is mapped across the single system images (SSIs) - typically synonymous to nodes - of the compute environment. This information is useful when constructing custom petLists.
Added argument ssiSharedMemoryEnabledFlag that allows the user to query whether ESMF was compiled with support for shared memory access between PETs on the same SSI.
8.1.0
Added argument currentSsiPe for easy query of the current PE within the local SSI that is executing the request.
Added argument ssiMap for a convenient way to obtain a view of the mapping of PETs to single system images across the entire VM.

DESCRIPTION:

Get internal information about the specified ESMF_VM object.

The arguments are:

vm
Queried ESMF_VM object.
[localPet]
Upon return this holds the id of the local PET that issued this call. The valid range of localPet is . A value of is returned on PETs that are not active under the specified vm.
[currentSsiPe]
Upon return this holds the id of the PE within the local SSI on which the calling PET (i.e. localPet) is currently executing. If the PET is associated with a set of PEs, or PETs are not pinned, the returned value might change each time the call is made.
[petCount]
Upon return this holds the number of PETs running under vm.
[peCount]
Upon return this holds the number of PEs referenced by vm.
[ssiCount]
Upon return this holds the number of single system images referenced by vm.
[ssiMap]
Upon return this array is allocated and holds the single system image id for each PET across the vm. The size of ssiMap is equal to petCount, with lower bound 0 and upper bound petCount-1.
[ssiMinPetCount]
Upon return this holds the smallest number of PETs running in the same single system images under vm.
[ssiMaxPetCount]
Upon return this holds the largest number of PETs running in the same single system images under vm.
[ssiLocalPetCount]
Upon return this holds the number of PETs running in the same single system as localPet.
[mpiCommunicator]
Upon return this holds the MPI intra-communicator used by the specified ESMF_VM object. This communicator may be used for user-level MPI communications. It is recommended that the user duplicates the communicator via MPI_Comm_Dup() in order to prevent any interference with ESMF communications. MPI_COMM_NULL is returned on PETs that are not active under the specified vm.
.TRUE.
ESMF has been compiled with Pthreads, and the MPI environment supports threading.
.FALSE.
ESMF has not been compiled with Pthreads, or the MPI environment does not support threading.
[openMPEnabledFlag]
.TRUE.
ESMF has been compiled with OpenMP.
.FALSE.
ESMF has not been compiled with OpenMP.
[ssiSharedMemoryEnabledFlag]
.TRUE.
ESMF has been compiled to support shared memory access between PETs that are on the same single system image (SSI).
.FALSE.
ESMF has not been compiled to support shared memory access between PETs that are on the same single system image (SSI).
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.19 ESMF_VMGet - Get PET specific VM information

INTERFACE:

   ! Private name; call using ESMF_VMGet()
subroutine ESMF_VMGetPetSpecific(vm, pet, peCount, &

ARGUMENTS:
     type(ESMF_VM), intent(in)            :: vm
integer,       intent(in)            :: pet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional :: peCount
integer,       intent(out), optional :: accDeviceCount
integer,       intent(out), optional :: ssiId
integer,       intent(out), optional :: vas
integer,       intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.
• This interface was modified since ESMF version 5.2.0r. The fact that code using this interface compiles with the current ESMF version does not guarantee that it compiles with previous versions of this interface. If user code compatibility with version 5.2.0r is desired then care must be taken to limit the use of this interface to features that were available in the 5.2.0r release.
Changes made after the 5.2.0r release:
7.0.0

DESCRIPTION:

Get internal information about a specific PET within an ESMF_VM object.

The arguments are:

vm
Queried ESMF_VM object.
pet
Queried PET id within the specified ESMF_VM object.
[peCount]
Upon return this holds the number of PEs associated with the specified PET in the ESMF_VM object.
[accDeviceCount]
Upon return this holds the number of accelerated devices accessible from the specified PET in the ESMF_VM object.
[ssiId]
Upon return this holds the id of the single-system image (SSI) the specified PET is running on.
Upon return this holds the number of PETs in the specified PET"s thread group.
Upon return this holds the thread id of the specified PET within the PET"s thread group.
[vas]
Virtual address space in which this PET operates.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.20 ESMF_VMGetGlobal - Get Global VM

INTERFACE:

   subroutine ESMF_VMGetGlobal(vm, rc)

ARGUMENTS:
     type(ESMF_VM), intent(out)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional  :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Get the global ESMF_VM object. This is the VM object that is created during ESMF_Initialize() and is the ultimate parent of all VM objects in an ESMF application. It is identical to the VM object returned by ESMF_Initialize(..., vm=vm, ...).

The ESMF_VMGetGlobal() call provides access to information about the global execution context via the global VM. This call is necessary because ESMF does not created a global ESMF Component during ESMF_Initialize() that could be queried for information about the global execution context of an ESMF application.

Usage of ESMF_VMGetGlobal() from within Component code is strongly discouraged. ESMF Components should only access their own VM objects through Component methods. Global information, if required by the Component user code, should be passed down to the Component from the driver through the Component calling interface.

The arguments are:

vm
Upon return this holds the ESMF_VM object of the global execution context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.21 ESMF_VMGetCurrent - Get Current VM

INTERFACE:

   subroutine ESMF_VMGetCurrent(vm, rc)

ARGUMENTS:
     type(ESMF_VM), intent(out)           :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Get the ESMF_VM object of the current execution context. Calling ESMF_VMGetCurrent() within an ESMF Component, will return the same VM object as ESMF_GridCompGet(..., vm=vm, ...) or ESMF_CplCompGet(..., vm=vm, ...).

The main purpose of providing ESMF_VMGetCurrent() is to simplify ESMF adoption in legacy code. Specifically, code that uses MPI_COMM_WORLD deep within its calling tree can easily be modified to use the correct MPI communicator of the current ESMF execution context. The advantage is that these modifications are very local, and do not require wide reaching interface changes in the legacy code to pass down the ESMF component object, or the MPI communicator.

The use of ESMF_VMGetCurrent() is strongly discouraged in newly written Component code. Instead, the ESMF Component object should be used as the appropriate container of ESMF context information. This object should be passed between the subroutines of a Component, and be queried for any Component specific information.

Outside of a Component context, i.e. within the driver context, the call to ESMF_VMGetCurrent() is identical to ESMF_VMGetGlobal().

The arguments are:

vm
Upon return this holds the ESMF_VM object of the current execution context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.22 ESMF_VMIsCreated - Check whether a VM object has been created

INTERFACE:

   function ESMF_VMIsCreated(vm, rc)

RETURN VALUE:
     logical :: ESMF_VMIsCreated

ARGUMENTS:
     type(ESMF_VM), intent(in)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional :: rc

DESCRIPTION:

Return .true. if the vm has been created. Otherwise return .false.. If an error occurs, i.e. rc /= ESMF_SUCCESS is returned, the return value of the function will also be .false..

The arguments are:

vm
ESMF_VM queried.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.23 ESMF_VMLog - Log

INTERFACE:

   subroutine ESMF_VMLog(vm, prefix, logMsgFlag, rc)

ARGUMENTS:
     type(ESMF_VM),          intent(in)              :: vm
character(len=*),       intent(in),   optional  :: prefix
type(ESMF_LogMsg_Flag), intent(in),   optional  :: logMsgFlag
integer, intent(out),                 optional  :: rc

DESCRIPTION:

Log the VM.

The arguments are:

vm
ESMF_VM object logged.
[prefix]
String to prefix the log message. Default is no prefix.
[logMsgFlag]
Type of log message generated. See section 47.2.3 for a list of valid message types. Default is ESMF_LOGMSG_INFO.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.24 ESMF_VMLogSystem - LogSystem

INTERFACE:

   subroutine ESMF_VMLogSystem(prefix, logMsgFlag, rc)

ARGUMENTS:
     character(len=*),       intent(in),   optional  :: prefix
type(ESMF_LogMsg_Flag), intent(in),   optional  :: logMsgFlag
integer, intent(out),                 optional  :: rc

DESCRIPTION:

Log the VM.

The arguments are:

[prefix]
String to prefix the log message. Default is no prefix.
[logMsgFlag]
Type of log message generated. See section 47.2.3 for a list of valid message types. Default is ESMF_LOGMSG_INFO.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.25 ESMF_VMPrint - Print VM information

INTERFACE:

   subroutine ESMF_VMPrint(vm, rc)

ARGUMENTS:
     type(ESMF_VM),  intent(in)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,        intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Print internal information about the specified ESMF_VM to stdout.

The arguments are:

vm
Specified ESMF_VM object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.26 ESMF_VMRecv - Receive data from srcPet

INTERFACE:

    subroutine ESMF_VMRecv(vm, recvData, count, srcPet, &
syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                     intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target,  intent(out)           :: recvData(:)
integer,                           intent(in)            :: count
integer,                           intent(in)            :: srcPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),              intent(in),  optional :: syncflag
type(ESMF_CommHandle),             intent(out), optional :: commhandle
integer,                           intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Receive contiguous data from srcPet within the same ESMF_VM object.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL, ESMF_TYPEKIND_CHARACTER.

The arguments are:

vm
ESMF_VM object.
recvData
Contiguous data array for data to be received.
count
Number of elements to be received.
srcPet
Sending PET.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.27 ESMF_VMReduce - Reduce data from across VM

INTERFACE:

    subroutine ESMF_VMReduce(vm, sendData, recvData, count, &
reduceflag, rootPet, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: count
type(ESMF_Reduce_Flag),           intent(in)            :: reduceflag
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that reduces a contiguous data array across the ESMF_VM object into a contiguous data array of the same <type><kind>. The result array is returned on rootPet. Different reduction operations can be specified.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

TODO: The current version of this method does not provide an implementation of the non-blocking feature. When calling this method with syncflag = ESMF_SYNC_NONBLOCKING, error code ESMF_RC_NOT_IMPL will be returned and an error will be logged.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. All PETs must specify a valid source array.
recvData
Contiguous data array for data to be received. Only the recvData array specified by the rootPet will be used by this method.
count
Number of elements in sendData and recvData. Must be the same on all PETs.
reduceflag
Reduction operation. See section 52.47 for a list of valid reduce operations.
rootPet
PET on which reduced data is returned.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.28 ESMF_VMScatter - Scatter data across VM

INTERFACE:

    subroutine ESMF_VMScatter(vm, sendData, recvData, count, &
rootPet, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: count
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that scatters contiguous data of <type><kind> from rootPet across all the PETs of an ESMF_VM object. Every PET, including rootPet, receives a portion of the data. The count number of elements received by PET i originate from the sendData array on rootPet, starting at position i count 1. Each PET stores the received contiguous data portion at the start of its recvData array.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. Only the sendData array specified by the rootPet will be used by this method.
recvData
Contiguous data array for data to be received. All PETs must specify a valid destination array large enough to accommodate the received data.
count
Number of elements to be sent from rootPet to each of the PETs. Must be the same on all PETs.
rootPet
PET that holds data that is being scattered.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.29 ESMF_VMScatterV - ScatterV across VM

INTERFACE:

    subroutine ESMF_VMScatterV(vm, sendData, sendCounts, &
sendOffsets, recvData, recvCount, rootPet, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCounts(:)
integer,                          intent(in)            :: sendOffsets(:)
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCount
integer,                          intent(in)            :: rootPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Collective ESMF_VM communication call that scatters contiguous data of <type><kind> from rootPet across all the PETs of an ESMF_VM object. Every PET, including rootPet, receives a portion of the data. The recvCount number of elements received by PET i originate from the sendData array on rootPet, starting at position sendOffsets(i). Each PET stores the received contiguous data portion at the start of its recvData array.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent. Only the sendData array specified by the rootPet will be used by this method.
sendCounts
Number of sendData elements to be sent to corresponding receive PET.
sendOffsets
Offsets in units of elements in sendData marking the start of element sequence to be sent to receive PET.
recvData
Contiguous data array for data to be received. All PETs must specify a valid recvData argument large enough to accommodate the received data.
recvCount
Number of recvData elements to receive by local PET from rootPet.
rootPet
PET that holds data that is being scattered.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.30 ESMF_VMSend - Send data to dstPet

INTERFACE:

    subroutine ESMF_VMSend(vm, sendData, count, dstPet, &
syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: count
integer,                          intent(in)            :: dstPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Send contiguous data to dstPet within the same ESMF_VM object.

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL, ESMF_TYPEKIND_CHARACTER.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent.
count
Number of elements to be sent.
dstPet
Receiving PET.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.31 ESMF_VMSendRecv - Send and Recv data to and from PETs

INTERFACE:

    subroutine ESMF_VMSendRecv(vm, sendData, sendCount, dstPet, &
recvData, recvCount, srcPet, syncflag, commhandle, rc)

ARGUMENTS:
      type(ESMF_VM),                    intent(in)            :: vm
<type>(ESMF_KIND_<kind>), target, intent(in)            :: sendData(:)
integer,                          intent(in)            :: sendCount
integer,                          intent(in)            :: dstPet
<type>(ESMF_KIND_<kind>), target, intent(out)           :: recvData(:)
integer,                          intent(in)            :: recvCount
integer,                          intent(in)            :: srcPet
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
type(ESMF_Sync_Flag),             intent(in),  optional :: syncflag
type(ESMF_CommHandle),            intent(out), optional :: commhandle
integer,                          intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Send contiguous data to dstPet within the same ESMF_VM object while receiving contiguous data from srcPet within the same ESMF_VM object. The sendData and recvData arrays must be disjoint!

This method is overloaded for: ESMF_TYPEKIND_I4, ESMF_TYPEKIND_I8, ESMF_TYPEKIND_R4, ESMF_TYPEKIND_R8, ESMF_TYPEKIND_LOGICAL, ESMF_TYPEKIND_CHARACTER.

The arguments are:

vm
ESMF_VM object.
sendData
Contiguous data array holding data to be sent.
sendCount
Number of elements to be sent.
dstPet
PET that holds recvData.
recvData
Contiguous data array for data to be received.
recvCount
Number of elements to be received.
srcPet
PET that holds sendData.
[syncflag]
Flag indicating whether this call behaves blocking or non-blocking. The default is ESMF_SYNC_BLOCKING. See section 52.57 for a complete list of options.
[commhandle]
If present, a communication handle will be returned in case of a non-blocking request (see argument syncflag). The commhandle can be used in ESMF_VMCommWait() to block the calling PET until the communication call has finished PET-locally. If no commhandle was supplied to a non-blocking call the VM method ESMF_VMCommWaitAll() may be used to block on all currently queued communication calls of the VM context.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.32 ESMF_VMValidate - Validate VM internals

INTERFACE:

   subroutine ESMF_VMValidate(vm, rc)

ARGUMENTS:
     type(ESMF_VM), intent(in)            :: vm
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,       intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Validates that the vm is internally consistent. The method returns an error code if problems are found.

The arguments are:

vm
Specified ESMF_VM object.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.33 ESMF_VMWtime - Get floating-point number of seconds

INTERFACE:

   subroutine ESMF_VMWtime(time, rc)

ARGUMENTS:
     real(ESMF_KIND_R8), intent(out)           :: time
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,            intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Get floating-point number of seconds of elapsed wall-clock time since the beginning of execution of the application.

The arguments are:

time
Time in seconds.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.34 ESMF_VMWtimeDelay - Delay execution

INTERFACE:

   recursive subroutine ESMF_VMWtimeDelay(delay, rc)

ARGUMENTS:
     real(ESMF_KIND_R8), intent(in)            :: delay
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,            intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Delay execution for amount of seconds.

The arguments are:

delay
Delay time in seconds.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 49.6.35 ESMF_VMWtimePrec - Timer precision as floating-point number of seconds

INTERFACE:

   subroutine ESMF_VMWtimePrec(prec, rc)

ARGUMENTS:
     real(ESMF_KIND_R8), intent(out)           :: prec
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,            intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Get a run-time estimate of the timer precision as floating-point number of seconds. This is a relatively expensive call since the timer precision is measured several times before the maximum is returned as the estimate. The returned value is PET-specific and may differ across the VM context.

The arguments are:

prec
Timer precision in seconds.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 50 Profiling and Tracing

## 50.1 Description

### 50.1.1 Profiling

ESMF's built in profiling capability collects runtime statistics of an executing ESMF application through both automatic and manual code instrumentation. Timing information for all phases of all ESMF components executing in an application can be automatically collected using the ESMF_RUNTIME_PROFILE environment variable (see below for settings). Additionally, arbitrary user-defined code regions can be timed by manually instrumenting code with special API calls. Timing profiles of component phases and user-defined regions can be output in several different formats:

• in text at the end of ESMF Log files
• in separate text file, one per PET (if the ESMF Logs are turned off)
• in a single summary text file that aggregates timings over multiple PETs
• in a binary format for import into Cupid for detailed analysis

The following table lists important environment variables that control aspects of ESMF profiling.

 Environment Variable Description Example Values Default ESMF_RUNTIME_PROFILE Enable/disables all profiling functions ON or OFF OFF ESMF_RUNTIME_PROFILE_PETLIST Limits profiling to an explicit list of PETs “0-9 50 99” profile all PETs ESMF_RUNTIME_PROFILE_OUTPUT Controls output format of profiles; multiple can be specified in a space separated list TEXT, SUMMARY, BINARY TEXT

### 50.1.2 Tracing

Whereas profiling collects summary information from an application, tracing records a more detailed set of events for later analysis. Trace analysis can be used to understand what happened during a program's execution and is often used for diagnosing problems, debugging, and performance analysis.

ESMF has a built-in tracing capability that records events into special binary log files. Unlike log files written by the ESMF_Log class, which are primarily for human consumption (see Section 47.1), the trace output files are recorded in a compact binary representation and are processed by tools to produce various analyses. ESMF event streams are recorded in the Common Trace Format (CTF). CTF traces include one or more event streams, as well as a metadata file describing the events in the streams.

Several tools are available for reading in the CTF traces output by ESMF. Of the tools listed below, the first one is designed specifically for analyzing ESMF applications and the second two are general purpose tools for working with all CTF traces.

• Cupid is a plugin for the Eclipse Integrated Development Environment that can read and analyze ESMF traces.
• TraceCompass is a general purpose tool for reading, analyzing, and visualizing traces.
• Babeltrace is a command-line tool and library for trace conversion that can read and write CTF traces. Python bindings are available to open CTF traces are iterate through events.

Events that can be captured by the ESMF tracer include the following. Events are recorded with a high-precision timestamp to allow timing analyses.

phase_enter
indicates entry into an initialize, run, or finalize ESMF component routine
phase_exit
indicates exit from an initialize, run, or finalize ESMF component routine
region_enter
indicates entry into a user-defined code region
region_exit
indicates exit from a user-defined code region
mem
records current memory usage information

The following table lists important environment variables that control aspects of ESMF tracing.

 Environment Variable Description Example Values Default ESMF_RUNTIME_TRACE Enable/disables all tracing functions ON or OFF OFF ESMF_RUNTIME_TRACE_CLOCK Sets the type of clock for timestamping events (see Section 50.2.6). REALTIME or MONOTONIC or MONOTONIC_SYNC REALTIME ESMF_RUNTIME_TRACE_PETLIST Limits tracing to an explicit list of PETs “0-9 50 99” trace all PETs ESMF_RUNTIME_TRACE_COMPONENT Enables/disable tracing of Component phase_enter and phase_exit events ON or OFF ON ESMF_RUNTIME_TRACE_FLUSH Controls frequency of event stream flushing to file DEFAULT or EAGER DEFAULT

## 50.2 Use and Examples

### 50.2.1 Output a Timing Profile to Text

ESMF profiling is disabled by default. To profile an application, set the ESMF_RUNTIME_PROFILE variable to ON prior to executing the application. You do not need to recompile your code to enable profiling.

# csh shell
$setenv ESMF_RUNTIME_PROFILE ON # bash shell$ export ESMF_RUNTIME_PROFILE=ON

# (from now on, only the csh shell version will be shown)


Then execute the application in the usual way. At the end of the run the profile information will be available at the end of each PET log (if ESMF Logs are turned on) or in a set of separate files, one per PET, with names ESMF_Profile.XXX where XXX is the PET number. Below is an example timing profile. Some regions are left out for brevity.

Region                           Count  Total (s)   Self (s)    Mean (s)    Min (s)     Max (s)
[esm] Init 1                   1      4.0878      0.0341      4.0878      4.0878      4.0878
[OCN-TO-ATM] IPDv05p6b       1      2.6007      2.6007      2.6007      2.6007      2.6007
[ATM-TO-OCN] IPDv05p6b       1      1.4333      1.4333      1.4333      1.4333      1.4333
[ATM] IPDv00p2               1      0.0055      0.0055      0.0055      0.0055      0.0055
[OCN] IPDv00p2               1      0.0023      0.0023      0.0023      0.0023      0.0023
[ATM] IPDv00p1               1      0.0011      0.0011      0.0011      0.0011      0.0011
[OCN] IPDv00p1               1      0.0009      0.0009      0.0009      0.0009      0.0009
[ATM-TO-OCN] IPDv05p3        1      0.0008      0.0008      0.0008      0.0008      0.0008
[ATM-TO-OCN] IPDv05p1        1      0.0008      0.0008      0.0008      0.0008      0.0008
[ATM-TO-OCN] IPDv05p2b       1      0.0007      0.0007      0.0007      0.0007      0.0007
[ATM-TO-OCN] IPDv05p4        1      0.0007      0.0007      0.0007      0.0007      0.0007
[ATM-TO-OCN] IPDv05p2a       1      0.0007      0.0007      0.0007      0.0007      0.0007
[ATM-TO-OCN] IPDv05p5        1      0.0007      0.0007      0.0007      0.0007      0.0007
[OCN-TO-ATM] IPDv05p3        1      0.0006      0.0006      0.0006      0.0006      0.0006
[OCN-TO-ATM] IPDv05p4        1      0.0006      0.0006      0.0006      0.0006      0.0006
[OCN-TO-ATM] IPDv05p2b       1      0.0006      0.0006      0.0006      0.0006      0.0006
[OCN-TO-ATM] IPDv05p2a       1      0.0006      0.0006      0.0006      0.0006      0.0006
[OCN-TO-ATM] IPDv05p5        1      0.0006      0.0006      0.0006      0.0006      0.0006
[OCN-TO-ATM] IPDv05p1        1      0.0005      0.0005      0.0005      0.0005      0.0005
[esm] RunPhase1                1      2.7423      0.9432      2.7423      2.7423      2.7423
[OCN-TO-ATM] RunPhase1       864    0.6094      0.6094      0.0007      0.0006      0.0179
[ATM] RunPhase1              864    0.5296      0.2274      0.0006      0.0005      0.0011
ATM:ModelAdvance           864    0.3022      0.3022      0.0003      0.0003      0.0005
[ATM-TO-OCN] RunPhase1       864    0.3345      0.3345      0.0004      0.0002      0.0299
[OCN] RunPhase1              864    0.3256      0.3256      0.0004      0.0003      0.0010
[esm] FinalizePhase1           1      0.0029      0.0020      0.0029      0.0029      0.0029
[OCN-TO-ATM] FinalizePhase1  1      0.0006      0.0006      0.0006      0.0006      0.0006
[ATM-TO-OCN] FinalizePhase1  1      0.0002      0.0002      0.0002      0.0002      0.0002
[OCN] FinalizePhase1         1      0.0001      0.0001      0.0001      0.0001      0.0001
[ATM] FinalizePhase1         1      0.0000      0.0000      0.0000      0.0000      0.0000


A timed region is either an ESMF component phase (e.g., initialize, run, or finalize) or a user-defined region of code surrounded by calls to ESMF_TraceRegionEnter() and ESMF_TraceRegionExit(). (See section 50.2.8 for more information on instrumenting user-defined regions.) Regions are organized hierarchically with sub-regions nested. For example, in the profile above, the [OCN] RunPhase1 is a sub-region of [esm] RunPhase1 and is entirely contained inside that region. Regions with the same name may appear at multiple places in the hierarchy, and so would appear in multiple rows in the table. The statistics in that row apply to that region at that location in the hierarchy. Component names appear in square brackets, e.g., [ATM], [OCN], and [ATM-TO-OCN]. By default, timings are based on elapsed wall clock time and are collected on a per-PET basis. Therefore, regions timings may differ across PETs. Regions are sorted with the most expensive regions appearing at the top. The following describes the meaning of the statistics in each column:

 Count the number of times the region is executed Total the aggregate time spent in the region, inclusive of all sub-regions Self the aggregate time spend in the region, exclusive of all sub-regions Mean the average amount of time for one execution of the region Min time of the fastest execution of the region Max time of the slowest execution of the region

### 50.2.2 Summarize Timings across Multiple PETs

By default, separate timing profiles are generated for each PET in the application. The per-PET profiles can be aggregated together and output to a single file, ESMF_Profile.summary, by setting the ESMF_RUNTIME_PROFILE_OUTPUT environment variable as follows:

$setenv ESMF_RUNTIME_PROFILE ON # turn on profiling$ setenv ESMF_RUNTIME_PROFILE_OUTPUT SUMMARY  # specify summary output


Note the ESMF_RUNTIME_PROFILE environment variable must also be set to ON since this controls all profiling capabilities. The ESMF_Profile.summary file will contain a tree of timed regions, but aggregated across all PETs. For example:

Region                           PETs   Count    Mean (s)    Min (s)     Min PET Max (s)     Max PET
[esm] Init 1                   4      1        4.0880      4.0878      2       4.0883      1
[OCN-TO-ATM] IPDv05p6b       4      1        2.6007      2.6007      2       2.6007      3
[ATM-TO-OCN] IPDv05p6b       4      1        1.4335      1.4333      0       1.4337      3
[ATM-TO-OCN] IPDv05p4        4      1        0.0037      0.0007      0       0.0060      1
[ATM] IPDv00p2               4      1        0.0034      0.0020      1       0.0055      0
[ATM-TO-OCN] IPDv05p1        4      1        0.0020      0.0007      2       0.0033      3
[OCN] IPDv00p2               4      1        0.0019      0.0015      3       0.0024      2
[ATM-TO-OCN] IPDv05p3        4      1        0.0010      0.0008      0       0.0013      1
[ATM-TO-OCN] IPDv05p2a       4      1        0.0009      0.0007      0       0.0012      3
[ATM] IPDv00p1               4      1        0.0009      0.0007      3       0.0011      0
[ATM-TO-OCN] IPDv05p2b       4      1        0.0008      0.0007      0       0.0010      3
[ATM-TO-OCN] IPDv05p5        4      1        0.0008      0.0007      0       0.0010      3
[ATM-TO-OCN] IPDv05p6a       4      1        0.0008      0.0005      2       0.0012      3
[OCN-TO-ATM] IPDv05p3        4      1        0.0008      0.0006      2       0.0010      3
[OCN-TO-ATM] IPDv05p4        4      1        0.0008      0.0006      0       0.0009      3
[OCN-TO-ATM] IPDv05p2b       4      1        0.0007      0.0006      2       0.0009      3
[OCN] IPDv00p1               4      1        0.0007      0.0005      1       0.0009      2
[OCN-TO-ATM] IPDv05p2a       4      1        0.0007      0.0006      2       0.0009      1
[OCN-TO-ATM] IPDv05p5        4      1        0.0007      0.0006      0       0.0009      3
[OCN-TO-ATM] IPDv05p1        4      1        0.0006      0.0005      0       0.0008      1
[OCN-TO-ATM] IPDv05p6a       4      1        0.0006      0.0004      2       0.0007      1
[esm] RunPhase1                4      1        2.7444      2.7423      0       2.7454      1
[OCN-TO-ATM] RunPhase1       4      864      0.6123      0.6004      2       0.6244      1
[ATM] RunPhase1              4      864      0.5386      0.5296      0       0.5530      1
ATM:ModelAdvance           4      864      0.3038      0.3022      0       0.3065      1
[OCN] RunPhase1              4      864      0.3471      0.3256      0       0.3824      1
[ATM-TO-OCN] RunPhase1       4      864      0.2843      0.1956      1       0.3345      0
[esm] FinalizePhase1           4      1        0.0029      0.0029      1       0.0030      2
[OCN-TO-ATM] FinalizePhase1  4      1        0.0007      0.0006      0       0.0008      3
[ATM-TO-OCN] FinalizePhase1  4      1        0.0002      0.0001      3       0.0002      1
[OCN] FinalizePhase1         4      1        0.0001      0.0001      3       0.0001      0
[ATM] FinalizePhase1         4      1        0.0001      0.0000      0       0.0001      2


The meaning of the statistics in each column in as follows:
 PETs the number of reporting PETs that executed the region Count the number of times each reporting PET executed the region or “MULTIPLE” if not all PETs executed the region the same number of times Mean the mean across all reporting PETs of the total time spent in the region Min the minimum across all reporting PETs of the total time spent in the region Min PET the PET that reported the minimum time Max the maximum across all reporting PETs of the total time spent in the region Max PET the PET that reported the maximum time

Note that setting the ESMF_RUNTIME_PROFILE_PETLIST environment variable (described below) may reduce the number of reporting PETs. Only reporting PETs are included in the summary profile. To output both the per-PET and summary timing profiles, set the ESMF_RUNTIME_PROFILE_OUTPUT environment variable as follows:

$setenv ESMF_RUNTIME_PROFILE_OUTPUT "TEXT SUMMARY"  ### 50.2.3 Limit the Set of Profiled PETs By default, all PETs in an application are profiled. It may be desirable to only profile a subset of PETs to reduce the amount of output. An explicit list of PETs can be specified by setting the ESMF_RUNTIME_PROFILE_PETLIST environment variable. The syntax of this environment variable is to list PET numbers separated by spaces. PET ranges are also supported using the “X-Y” syntax where X < Y. For example: # only profile PETs 0, 20, and 35 through 39$ setenv ESMF_RUNTIME_PROFILE_PETLIST "0 20 35-39"


When used in conjunction with the SUMMARY option above, the summarized profile will only aggregate over the specified set of PETs. The one exception is that PET 0 is always profiled if ESMF_RUNTIME_PROFILE=ON, regardless of the ESMF_RUNTIME_TRACE_PETLIST setting.

### 50.2.4 Include MPI Communication in the Profile

MPI functions can be included in the timing profile to indicate how much time is spent inside communication calls. This can also help to determine load imbalance in the system, since large times spent inside MPI may indicate that communication between PETs is not tightly synchronized. This option includes all MPI calls in the application, whether or not they originate from the ESMF library. Here is a partial example summary profile that contains MPI times:

Region                           PETs   Count    Mean (s)    Min (s)     Min PET Max (s)     Max PET
[esm] RunPhase1                8      1        4.9307      4.6867      0       4.9656      1
[OCN] RunPhase1              8      1824     0.8344      0.8164      0       0.8652      1
[MED] RunPhase1              8      1824     0.8203      0.7900      5       0.8584      1
[ATM] RunPhase1              8      1824     0.6387      0.6212      5       0.6610      1
[ATM-TO-MED] RunPhase1       8      1824     0.5975      0.5317      0       0.6583      5
MPI_Bcast                  8      1824     0.0443      0.0025      4       0.1231      5
MPI_Wait                   8      MULTIPLE 0.0421      0.0032      0       0.0998      2
[MED-TO-OCN] RunPhase1       8      1824     0.4879      0.4497      0       0.5362      4
MPI_Wait                   8      MULTIPLE 0.0234      0.0030      0       0.0821      4
MPI_Bcast                  8      1824     0.0111      0.0024      4       0.0273      5
[OCN-TO-MED] RunPhase1       8      1824     0.4541      0.4075      0       0.4918      4
MPI_Wait                   8      MULTIPLE 0.0339      0.0017      0       0.0824      4
MPI_Bcast                  8      1824     0.0194      0.0026      4       0.0452      6
[MED-TO-ATM] RunPhase1       8      1824     0.4487      0.4005      0       0.4911      5
MPI_Bcast                  8      1824     0.0338      0.0026      4       0.0942      5
MPI_Wait                   8      MULTIPLE 0.0241      0.0022      1       0.0817      2
[esm] Init 1                   8      1        0.6287      0.6287      1       0.6287      4
[ATM-TO-MED] IPDv05p6b       8      1        0.1501      0.1500      1       0.1501      2
MPI_Barrier                8      242      0.0082      0.0006      3       0.0157      7
MPI_Wait                   8      MULTIPLE 0.0034      0.0010      0       0.0053      7
MPI_Allreduce              8      62       0.0030      0.0003      3       0.0063      7
MPI_Alltoall               8      6        0.0015      0.0000      1       0.0022      5
MPI_Allgather              8      21       0.0010      0.0002      1       0.0017      7
MPI_Waitall                8      MULTIPLE 0.0006      0.0001      3       0.0015      7
MPI_Send                   8      MULTIPLE 0.0004      0.0001      7       0.0008      6
MPI_Allgatherv             8      6        0.0001      0.0001      4       0.0001      0
MPI_Scatter                8      5        0.0000      0.0000      0       0.0000      7
MPI_Reduce                 8      5        0.0000      0.0000      1       0.0000      0
MPI_Recv                   8      MULTIPLE 0.0000      0.0000      0       0.0000      3
MPI_Bcast                  8      1        0.0000      0.0000      0       0.0000      7


The procedure for including MPI functions in the timing profile depends on whether the application is dynamically or statically linked. Most applications are dynamically linked, however on some systems (such as Cray), static linking may be used. Note that for either option, ESMF must be built with ESMF_TRACE_BUILD_LIB=ON, which is the default.

In dynamically linked applications, the LD_PRELOAD environment variable must be used when executing the MPI application. This instructs the dynamic linker to interpose certain MPI symbols so they can be captured by the ESMF profiler. To simplify this process, a script is provided at $(ESMF_INSTALL_LIBDIR)/preload.sh that sets the LD_PRELOAD variable. For example, if you typically execute your application as as follows: $ mpirun -np 8 ./myApp


then you should add the preload.sh script in front of the executable when starting the application as follows:

# replace $(ESMF_INSTALL_LIBDIR) with absolute path to the ESMF installation lib directory$ mpirun -np 8 $(ESMF_INSTALL_LIBDIR)/preload.sh ./myApp  An advantage of this approach is that your application does not need to be recompiled. The MPI timing information will be included in the per-PET profiles and/or the summary profile, depending on the setting of ESMF_RUNTIME_PROFILE_OUTPUT. In statically linked applications, the application must be re-linked with specific options provided to the linker. These options instruct the linker to wrap the MPI symbols with the ESMF profiling functions. The linking flags that must be provided are included in the esmf.mk Makefile fragment that is part of the ESMF installation. These link flags should be imported into your application Makefile, and included in the final link command. To do this, first import the esmf.mk file into your application Makefile. The path to this file is typically stored in the ESMFMKFILE environment variable. Then, pass the variables$(ESMF_TRACE_STATICLINKOPTS) and $(ESMF_TRACE_STATICLINKLIBS) to the final linking command. For example: # import esmf.mk include$(ESMFMKFILE)

# other makefile targets here...

# example final link command, with $(ESMF_TRACE_STATICLINKOPTS) and$(ESMF_TRACE_STATICLINKLIBS) added
myApp: myApp.o driver.o model.o
$(ESMF_F90LINKER)$(ESMF_F90LINKOPTS) $(ESMF_F90LINKPATHS)$(ESMF_F90LINKRPATHS) -o $@$^ $(ESMF_F90ESMFLINKLIBS)$(ESMF_TRACE_STATICLINKOPTS) $(ESMF_TRACE_STATICLINKLIBS)  This option will statically wrap all of the MPI functions and include them in the profile output. Execute the application in the normal way with the environment variable ESMF_RUNTIME_PROFILE set to ON. You will see the MPI functions included in the timing profile. ### 50.2.5 Output a Detailed Trace for Analysis ESMF tracing is disabled by default. To enable tracing, set the ESMF_RUNTIME_TRACE environment variable to ON. You do not need to recompile your code to enable tracing. # csh shell$ setenv ESMF_RUNTIME_TRACE ON

# bash shell
$export ESMF_RUNTIME_TRACE=ON  When enabled, the default behavior is to trace all PETs of the ESMF application. Although the ESMF tracer is designed to write events in a compact form, tracing can produce an extremely large number of events depending on the total number of PETs and the length of the run. To reduce output, it is possible to restrict the PETs that produce trace output by setting the ESMF_RUNTIME_TRACE_PETLIST environment variable. For example, this setting: $ setenv ESMF_RUNTIME_TRACE_PETLIST "0 101 192-196"


will instruct the tracer to only trace PETs 0, 101, and 192 through 196 (inclusive). The syntax of this environment variable is to list PET numbers separated by spaces. PET ranges are also supported using the “X-Y” syntax where X < Y. For PET counts greater than 100, it is recommended to set this environment variable. The one exception is that PET 0 is always traced, regardless of the ESMF_RUNTIME_TRACE_PETLIST setting.

ESMF's profiling and tracing options can be used together. A typical use would be to set ESMF_RUNTIME_PROFILE=ON for all PETs to capture summary timings, and set ESMF_RUNTIME_TRACE=ON and ESMF_RUNTIME_TRACE_PETLIST to a subset of of PETs, such as the root PET of each ESMF component. This helps to keep trace sizes small while still providing timing summaries over all PETs.

When tracing is enabled, phase_enter and phase_exit events will automatically be recorded for all initialize, run, and finalize phases of all Components in the application. To trace only user-instrumented regions (via the ESMF_TraceRegionEnter() and ESMF_TraceRegionExit() calls), Component-level tracing can be turned off by setting:

$setenv ESMF_RUNTIME_TRACE_COMPONENT OFF  After running an ESMF application with tracing enabled, a directory called traceout will be created in the run directory and it will contain a metadata file and an event stream file esmf_stream_XXXX for each PET with tracing enabled. Together these files form a valid CTF trace which may be analyzed with any of the tools listed above. Trace events are flushed to file at a regular interval. If the application crashes, some of the most recent events may not be flushed to file. To maximize the number of events appearing in the trace, an option is available to flush events to file more frequently. Because this option may have negative performance implications due to increased file I/O, it is not recommended unless needed. To turn on eager flushing use: $ setenv ESMF_RUNTIME_TRACE_FLUSH EAGER


### 50.2.6 Set the Clock used for Profiling/Tracing

There are three options for the kind of clock to use to timestamp events when profiling/tracing an application. These options are controlled by setting the environment variable ESMF_RUNTIME_TRACE_CLOCK.
 REALTIME The REALTIME clock timestamps events with the current time on the system. This is the default clock if the above environment variable is not set. This setting can be useful when tracing PETs that span multiple physical computing nodes assuming that the system clocks on each node are adequately synchronized. On most HPC systems, system clocks are periodically updated to stay in sync. A disadvantage of this clock is that periodic adjustments mean the clock is not monotonically increasing so some timings may be inaccurate if the system clock jumps forward or backward significantly. Testing has shown that this is not typically an issue on most systems. MONOTONIC The MONOTONIC clock is guaranteed to be monotonically increasing and does not suffer from periodic adjustments. The timestamps represent an amount of time since some arbitrary point in the past. There is no guarantee that these timestamps will be synchronized across physical computing nodes, so this option should only be used for tracing a set of PETs running on a single physical machine. MONOTONIC_SYNC The MONOTONIC_SYNC clock is similar to the MONOTONIC clock in that it is guaranteed to be monotonically increasing. In addition, at application startup, all PET clocks are synchronized to a common time by determining a PET-local offset to be applied to timestamps. Therefore this option can be used to compare trace streams across physical nodes.

### 50.2.7 Tracing a simple ESMF application

This example illustrates how to trace a simple ESMF application and print the event stream using Babeltrace. The first part of the code is a module representing a trivial ESMF Gridded Component. The second part is a main program that creates and executes the component.

module SimpleComp

use ESMF
implicit none

private
public SetServices

contains

subroutine SetServices(gcomp, rc)
type(ESMF_GridComp)   :: gcomp
integer, intent(out)  :: rc

call ESMF_GridCompSetEntryPoint(gcomp, ESMF_METHOD_INITIALIZE, &
userRoutine=Init, rc=rc)
call ESMF_GridCompSetEntryPoint(gcomp, ESMF_METHOD_RUN, &
userRoutine=Run, rc=rc)
call ESMF_GridCompSetEntryPoint(gcomp, ESMF_METHOD_FINALIZE, &
userRoutine=Finalize, rc=rc)

rc = ESMF_SUCCESS

end subroutine SetServices

subroutine Init(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp):: gcomp
type(ESMF_State):: istate, estate
type(ESMF_Clock):: clock
integer, intent(out):: rc

print *, "Inside Init"

end subroutine Init

subroutine Run(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp):: gcomp
type(ESMF_State):: istate, estate
type(ESMF_Clock):: clock
integer, intent(out):: rc

print *, "Inside Run"

end subroutine Run

subroutine Finalize(gcomp, istate, estate, clock, rc)
type(ESMF_GridComp):: gcomp
type(ESMF_State):: istate, estate
type(ESMF_Clock):: clock
integer, intent(out):: rc

print *, "Inside Finalize"

end subroutine Finalize

end module SimpleComp


program ESMF_TraceEx


      ! Use ESMF framework module
use ESMF
use SimpleComp, only: SetServices


      implicit none

! Local variables
integer :: rc, finalrc, i
type(ESMF_GridComp)     :: gridcomp


      ! initialize ESMF
finalrc = ESMF_SUCCESS
call ESMF_Initialize(vm=vm, defaultlogfilename="TraceEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


      ! create the component and then execute
! initialize, run, and finalize routines
gridcomp = ESMF_GridCompCreate(name="test", rc=rc)


      call ESMF_GridCompSetServices(gridcomp, userRoutine=SetServices, rc=rc)


      call ESMF_GridCompInitialize(gridcomp, rc=rc)


      do i=1, 5
call ESMF_GridCompRun(gridcomp, rc=rc)
enddo


      call ESMF_GridCompFinalize(gridcomp, rc=rc)


      call ESMF_GridCompDestroy(gridcomp, rc=rc)


      call ESMF_Finalize(rc=rc)


end program ESMF_TraceEx


Assuming the code above is executed on four PETs with the environment variable ESMF_RUNTIME_TRACE set to ON, then a folder will be created in the run directory called traceout containing a metadata file and four event stream files named esmf_stream_XXXX where XXXX is the PET number. If Babeltrace is available on the system, the list of events can be printed by executing the following from the run directory:

   \$ babeltrace ./traceout

For details about iterating over trace events and performing analyses on CTF traces, see the corresponding documentation in the tools listed in Section 50.1.2.

### 50.2.8 Profiling/Tracing User-defined Code Regions

This example illustrates how to manually instrument code with entry and exit points for user-defined code regions. Note that the API calls ESMF_TraceRegionEnter and ESMF_TraceRegionExit should always appear in pairs, wrapping a particular section of code. The environment variable ESMF_RUNTIME_TRACE or ESMF_RUNTIME_PROFILE must be set to ON to enable these regions. If not at least one is set, the calls to ESMF_TraceRegionEnter and ESMF_TraceRegionExit will simply return immediately. For this reason, it is safe to leave this instrumentation in application code, even when not being profiled.

      ! Use ESMF framework module
use ESMF


      implicit none

! Local variables
integer :: rc, finalrc
integer :: i, j, tmp


      ! initialize ESMF
finalrc = ESMF_SUCCESS
call ESMF_Initialize(vm=vm, defaultlogfilename="TraceUserEx.Log", &
logkindflag=ESMF_LOGKIND_MULTI, rc=rc)


      ! record entrance into "outer_region"
call ESMF_TraceRegionEnter("outer_region", rc=rc)

tmp = 0
do i=1, 10

! record entrance into "inner_region_1"
call ESMF_TraceRegionEnter("inner_region_1", rc=rc)
! arbitrary computation
do j=1,10000
tmp=tmp+j+i
enddo
! record exit from "inner_region_1"
call ESMF_TraceRegionExit("inner_region_1", rc=rc)

tmp = 0

! record entrance into "inner_region_2"
call ESMF_TraceRegionEnter("inner_region_2", rc=rc)
! arbitrary computation
do j=1,5000
tmp=tmp+j+i
enddo
! record exit from "inner_region_2"
call ESMF_TraceRegionExit("inner_region_2", rc=rc)
enddo

! record exit from "outer_region"
call ESMF_TraceRegionExit("outer_region", rc=rc)


      call ESMF_Finalize(rc=rc)


## 50.3 Restrictions and Future Work

1. Limited types of trace events. Currently only a few trace event types are available. The tracer may be extended in the future to record additional types of events.

## 50.4 Class API

### 50.4.1 ESMF_TraceRegionEnter - Trace user-defined region entry event

INTERFACE:

   subroutine ESMF_TraceRegionEnter(name, rc)

ARGUMENTS:
     character(len=*), intent(in) :: name
integer, intent(out), optional  :: rc

DESCRIPTION:

Record an event in the trace for this PET indicating entry into a user-defined region with the given name. This call must be paired with a call to ESMF_TraceRegionExit() with a matching name parameter. User-defined regions may be nested. If tracing is disabled on the calling PET or for the application as a whole, no event will be recorded and the call will return immediately.

The arguments are:

name
A user-defined name for the region of code being entered
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 50.4.2 ESMF_TraceRegionExit - Trace user-defined region exit event

INTERFACE:

   subroutine ESMF_TraceRegionExit(name, rc)

ARGUMENTS:
     character(len=*), intent(in) :: name
integer, intent(out), optional  :: rc

DESCRIPTION:

Record an event in the trace for this PET indicating exit from a user-defined region with the given name. This call must appear after a call to ESMF_TraceRegionEnter() with a matching name parameter. If tracing is disabled on the calling PET or for the application as a whole, no event will be recorded and the call will return immediately.

The arguments are:

name
A user-defined name for the region of code being exited
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

# 51 Fortran I/O and System Utilities

## 51.1 Description

The ESMF Fortran I/O and System utilities provide portable methods to access capabilities which are often implemented in different ways amongst different environments. These utility methods are divided into three groups: command line access, Fortran I/O, and sorting.

Command line arguments may be accessed using three methods: ESMF_UtilGetArg() returns a given command line argument, ESMF_UtilGetArgC() returns a count of the number of command line arguments available. Finally, the ESMF_UtilGetArgIndex() method returns the index of a desired argument value, given its keyword name.

Two I/O methods are implemented: ESMF_IOUnitGet(), to obtain an unopened Fortran unit number within the range of unit numbers that ESMF is allowed to use, and ESMF_IOUnitFlush() to flush the I/O buffer associated with a specific Fortran unit.

Finally, the ESMF_UtilSort() method sorts integer, floating point, and character string data types in either ascending or descending order.

## 51.2 Use and Examples

### 51.2.1 Fortran unit number management

The ESMF_UtilIOUnitGet() method is provided so that applications using ESMF can remain free of unit number conflicts -- both when combined with other third party code, or with ESMF itself. This call is typically used just prior to an OPEN statement:

  call ESMF_UtilIOUnitGet (unit=grid_unit, rc=rc)


By default, unit numbers between 50 and 99 are scanned to find an unopened unit number.

Internally, ESMF also uses ESMF_UtilIOUnitGet() when it needs to open Fortran unit numbers for file I/O. By using the same API for both user and ESMF code, unit number collisions can be avoided.

When integrating ESMF into an application where there are conflicts with other uses of the same unit number range, such as when hard-coded unit number values are used, an alternative unit number range can be specified. The ESMF_Initialize() optional arguments IOUnitLower and IOUnitUpper may be set as needed. Note that IOUnitUpper must be set to a value higher than IOUnitLower, and that both must be non-negative. Otherwise ESMF_Initialize will return a return code of ESMF_FAILURE. ESMF itself does not typically need more than about five units for internal use.

  call ESMF_Initialize (..., IOUnitLower=120, IOUnitUpper=140)


All current Fortran environments have preconnected unit numbers, such as units 5 and 6 for standard input and output, in the single digit range. So it is recommended that the unit number range is chosen to begin at unit 10 or higher to avoid these preconnected units.

### 51.2.2 Flushing output

Fortran run-time libraries generally use buffering techniques to improve I/O performance. However output buffering can be problematic when output is needed, but is “trapped” in the buffer because it is not full. This is a common occurrance when debugging a program, and inserting WRITE statements to track down the bad area of code. If the program crashes before the output buffer has been flushed, the desired debugging output may never be seen -- giving a misleading indication of where the problem occurred. It would be desirable to ensure that the output buffer is flushed at predictable points in the program in order to get the needed results. Likewise, in parallel code, predictable flushing of output buffers is a common requirement, often in conjunction with ESMF_VMBarrier() calls.

The ESMF_UtilIOUnitFlush() API is provided to flush a unit as desired. Here is an example of code which prints debug values, and serializes the output to a terminal in PET order:

  type(ESMF_VM) :: vm

integer :: tty_unit
integer :: me, npets

call ESMF_Initialize (vm=vm, rc=rc)
call ESMF_VMGet (vm, localPet=me, petCount=npes)

call ESMF_UtilIOUnitGet (unit=tty_unit)
open (unit=tty_unit, file='/dev/tty', status='old', action='write')
...
call ESMF_VMBarrier (vm=vm)
do, i=0, npets-1
if (i == me) then
write (tty_unit, *) 'PET: ', i, ', values are: ', a, b, c
call ESMF_UtilIOUnitFlush (unit=tty_unit)
end if
call ESMF_VMBarrier (vm=vm)
end do


## 51.3 Design and Implementation Notes

### 51.3.1 Fortran unit number management

When ESMF needs to open a Fortran I/O unit, it calls ESMF_IOUnitGet() to find an unopened unit number. As delivered, the range of unit numbers that are searched are between ESMF_LOG_FORTRAN_UNIT_NUMBER (normally set to 50), and ESMF_LOG_UPPER (normally set to 99.) Unopened unit numbers are found by using the Fortran INQUIRE statement.

When integrating ESMF into an application where there are conflicts with other uses of the same unit number range, an alternative range can be specified in the ESMF_Initialize() call by setting the IOUnitLower and IOUnitUpper arguments as needed. ESMF_IOUnitGet() will then search the alternate range of unit numbers. Note that IOUnitUpper must be set to a value higher than IOUnitLower, and that both must be non-negative. Otherwise ESMF_Initialize will return a return code of ESMF_FAILURE.

Fortran unit numbers are not standardized in the Fortran 90 Standard. The standard only requires that they be non-negative integers. But other than that, it is up to the compiler writers and application developers to provide and use units which work with the particular implementation. For example, units 5 and 6 are a defacto standard for “standard input” and “standard output” -- even though this is not specified in the actual Fortran standard. The Fortran standard also does not specify which unit numbers can be used, nor does it specify how many can be open simultaneously.

Since all current compilers have preconnected unit numbers, and these are typically found on units lower than 10, it is recommended that applications use unit numbers 10 and higher.

### 51.3.2 Flushing output

When ESMF needs to flush a Fortran unit, the ESMF_IOUnitFlush() API is used to centralize the file flushing capability, because Fortran has not historically had a standard mechanism for flushing output buffers. Most compilers run-time libraries support various library extensions to provide this functionality -- though, being non-standard, the spelling and number of arguments vary between implementations. Fortran 2003 also provides for a FLUSH statement which is built into the language. When possible, ESMF_IOUnitFlush() uses the F2003 FLUSH statement. With older compilers, the appropriate library call is made.

### 51.3.3 Sorting algorithms

The ESMF_UtilSort() algorithms are the same as those in the LAPACK sorting procedures SLASRT() and DLASRT(). Two algorithms are used. For small sorts, arrays with 20 or fewer elements, a simple Insertion sort is used. For larger sorts, a Quicksort algorithm is used.

Compared to the original LAPACK code, a full Fortran 90 style interface is supported for ease of use and enhanced compile time checking. Additional support is also provided for integer and character string data types.

## 51.4 Utility API

### 51.4.1 ESMF_UtilGetArg - Return a command line argument

INTERFACE:

   subroutine ESMF_UtilGetArg(argindex, argvalue, arglength, rc)

ARGUMENTS:
     integer,      intent(in)            :: argindex
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(*), intent(out), optional :: argvalue
integer,      intent(out), optional :: arglength
integer,      intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This method returns a copy of a command line argument specified when the process was started. This argument is the same as an equivalent C++ program would find in the argv array.

Some MPI implementations do not consistently provide command line arguments on PETs other than PET 0. It is therefore recommended that PET 0 call this method and broadcast the results to the other PETs by using the ESMF_VMBroadcast() method.

The arguments are:

argindex
A non-negative index into the command line argument argv array. If argindex is negative or greater than the number of user-specified arguments, ESMF_RC_ARG_VALUE is returned in the rc argument.
[argvalue]
Returns a copy of the desired command line argument. If the provided character string is longer than the command line argument, the string will be blank padded. If the string is too short, truncation will occur and ESMF_RC_ARG_SIZE is returned in the rc argument.
[arglength]
Returns the length of the desired command line argument in characters. The length result does not depend on the length of the value string. It may be used to query the length of the argument.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.2 ESMF_UtilGetArgC - Return number of command line arguments

INTERFACE:

   subroutine ESMF_UtilGetArgC(count, rc)

ARGUMENTS:
     integer, intent(out)           :: count
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This method returns the number of command line arguments specified when the process was started.

The number of arguments returned does not include the name of the command itself - which is typically returned as argument zero.

Some MPI implementations do not consistently provide command line arguments on PETs other than PET 0. It is therefore recommended that PET 0 call this method and broadcast the results to the other PETs by using the ESMF_VMBroadcast() method.

The arguments are:

count
Count of command line arguments.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.3 ESMF_UtilGetArgIndex - Return the index of a command line argument

INTERFACE:

   subroutine ESMF_UtilGetArgIndex(argvalue, argindex, rc)

ARGUMENTS:
     character(*), intent(in)            :: argvalue
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,      intent(out), optional :: argindex
integer,      intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

This method searches for, and returns the index of a desired command line argument. An example might be to find a specific keyword (e.g., -esmf_path) so that its associated value argument could be obtained by adding 1 to the argindex and calling ESMF_UtilGetArg().

Some MPI implementations do not consistently provide command line arguments on PETs other than PET 0. It is therefore recommended that PET 0 call this method and broadcast the results to the other PETs by using the ESMF_VMBroadcast() method.

The arguments are:

argvalue
A character string which will be searched for in the command line argument list.
[argindex]
If the value string is found, the position will be returned as a non-negative integer. If the string is not found, a negative value will be returned.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.4 ESMF_UtilIOGetCWD - Get the current directory

INTERFACE:

   subroutine ESMF_UtilIOGetCWD (pathName, rc)

PARAMETERS:
     character(*), intent(out)           :: pathName
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,      intent(out), optional :: rc

DESCRIPTION:

Call the system-dependent routine to get the current directory from the file system.

The arguments are:

pathName
Name of the current working directory.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.5 ESMF_UtilIOMkDir - Create a directory in the file system

INTERFACE:

    subroutine ESMF_UtilIOMkDir (pathName,  &
mode, relaxedFlag,  &
rc)

PARAMETERS:
      character(*), intent(in)            :: pathName
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,      intent(in),  optional :: mode
logical,      intent(in),  optional :: relaxedFlag
integer,      intent(out), optional :: rc

DESCRIPTION:

Call the system-dependent routine to create a directory in the file system.

The arguments are:

pathName
Name of the directory to be created.
[mode]
File permission mode. Typically an octal constant is used as a value, for example: mode=o'755'. If not specified on POSIX-compliant systems, the default is o'755' - corresponding to owner read/write/execute, group read/execute, and world read/execute. On native Windows, this argument is ignored and default security settings are used.
[relaxedFlag]
When set to .true., if the directory already exists, rc will be set to ESMF_SUCCESS instead of an error. If not specified, the default is .false..
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.6 ESMF_UtilIORmDir - Remove a directory from the file system

INTERFACE:

    subroutine ESMF_UtilIORmDir (pathName,  &
relaxedFlag, rc)

PARAMETERS:
      character(*), intent(in)            :: pathName
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
logical,      intent(in),  optional :: relaxedFlag
integer,      intent(out), optional :: rc

DESCRIPTION:

Call the system-dependent routine to remove a directory from the file system. Note that the directory must be empty in order to be successfully removed.

The arguments are:

pathName
Name of the directory to be removed.
[relaxedFlag]
If set to .true., and if the specified directory does not exist, the error is ignored and rc will be set to ESMF_SUCCESS. If not specified, the default is .false..
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.7 ESMF_UtilString2Double - Convert a string to floating point real

INTERFACE:

   function ESMF_UtilString2Double(string, rc)

RETURN VALUE:
     real(ESMF_KIND_R8) :: ESMF_UtilString2Double

ARGUMENTS:
     character(len=*), intent(in)            :: string
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

DESCRIPTION:

Return the numerical real value represented by the string.

Leading and trailing blanks in string are ignored when directly converting into integers.

This procedure may fail when used in an expression in a write statement with some older, pre-Fortran 2003, compiler environments that do not support re-entrant I/O calls.

The arguments are:

string
The string to be converted
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.8 ESMF_UtilString2Int - Convert a string to an integer

INTERFACE:

   function ESMF_UtilString2Int(string,  &
specialStringList, specialValueList, rc)

RETURN VALUE:
     integer :: ESMF_UtilString2Int

ARGUMENTS:
     character(len=*), intent(in)            :: string
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
character(len=*), intent(in),  optional :: specialStringList(:)
integer,          intent(in),  optional :: specialValueList(:)
integer,          intent(out), optional :: rc

DESCRIPTION:

Return the numerical integer value represented by the string. If string matches a string in the optional specialStringList, the corresponding special value will be returned instead.

If special strings are to be taken into account, both specialStringList and specialValueList arguments must be present and of same size.

An error is returned, and return value set to 0, if string is not found in specialStringList, and does not convert into an integer value.

Leading and trailing blanks in string are ignored when directly converting into integers.

This procedure may fail when used in an expression in a write statement with some older, pre-Fortran 2003, compiler environments that do not support re-entrant I/O calls.

The arguments are:

string
The string to be converted
[specialStringList]
List of special strings.
[specialValueList]
List of values associated with special strings.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.9 ESMF_UtilString2Real - Convert a string to floating point real

INTERFACE:

   function ESMF_UtilString2Real(string, rc)

RETURN VALUE:
     real :: ESMF_UtilString2Real

ARGUMENTS:
     character(len=*), intent(in)            :: string
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer,          intent(out), optional :: rc

DESCRIPTION:

Return the numerical real value represented by the string.

Leading and trailing blanks in string are ignored when directly converting into integers.

This procedure may fail when used in an expression in a write statement with some older, pre-Fortran 2003, compiler environments that do not support re-entrant I/O calls.

The arguments are:

string
The string to be converted
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.10 ESMF_UtilStringInt2String - convert integer to character string

INTERFACE:

     function ESMF_UtilStringInt2String (i, rc)

ARGUMENTS:
       integer, intent(in) :: i
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional  :: rc

RETURN VALUE:
       character(int2str_len (i)) :: ESMF_UtilStringInt2String

DESCRIPTION:

Converts given an integer to string representation. The returned string is sized such that it does not contain leading or trailing blanks.

This procedure may fail when used in an expression in a write statement with some older, pre-Fortran 2003, compiler environments that do not support re-entrant I/O calls.

The arguments are:

i
An integer.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.11 ESMF_UtilStringLowerCase - convert string to lowercase

INTERFACE:

     function ESMF_UtilStringLowerCase(string, rc)

ARGUMENTS:
       character(len=*), intent(in) :: string
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional  :: rc

RETURN VALUE:
       character(len (string)) :: ESMF_UtilStringLowerCase

DESCRIPTION:

Converts given string to lowercase.

The arguments are:

string
A character string.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.12 ESMF_UtilStringUpperCase - convert string to uppercase

INTERFACE:

       function ESMF_UtilStringUpperCase(string, rc)

ARGUMENTS:
       character(len=*), intent(in) :: string
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional  :: rc

RETURN VALUE:
       character(len (string)) :: ESMF_UtilStringUpperCase

DESCRIPTION:

Converts given string to uppercase.

The arguments are:

string
A character string.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.13 ESMF_UtilIOUnitFlush - Flush output on a unit number

INTERFACE:

   subroutine ESMF_UtilIOUnitFlush(unit, rc)

PARAMETERS:
     integer, intent(in)            :: unit
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Call the system-dependent routine to force output on a specific Fortran unit number.

The arguments are:

unit
A Fortran I/O unit number. If the unit is not connected to a file, no flushing occurs.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.14 ESMF_UtilIOUnitGet - Scan for a free I/O unit number

INTERFACE:

   subroutine ESMF_UtilIOUnitGet(unit, rc)

ARGUMENTS:
     integer, intent(out)           :: unit
-- The following arguments require argument keyword syntax (e.g. rc=rc). --
integer, intent(out), optional :: rc

STATUS:
• This interface is backward compatible with ESMF versions starting at 5.2.0r. If code using this interface compiles with any version of ESMF starting with 5.2.0r, then it will compile with the current version.

DESCRIPTION:

Scan for, and return, a free Fortran I/O unit number. By default, the range of unit numbers returned is between 50 and 99 (parameters ESMF_LOG_FORTRAN_UNIT_NUMBER and ESMF_LOG_UPPER respectively.) When integrating ESMF into an application where these values conflict with other usages, the range of values may be moved by setting the optional IOUnitLower and IOUnitUpper arguments in the initial ESMF_Initialize() call with values in a safe, alternate, range.

The Fortran unit number which is returned is not reserved in any way. Successive calls without intervening OPEN or CLOSE statements (or other means of connecting to units), might not return a unique unit number. It is recommended that an OPEN statement immediately follow the call to ESMF_IOUnitGet() to activate the unit.

The arguments are:

unit
A Fortran I/O unit number.
[rc]
Return code; equals ESMF_SUCCESS if there are no errors.

### 51.4.15 ESMF_UtilSort - Sort data

INTERFACE:

   subroutine ESMF_UtilSort (list, direction, rc)

ARGUMENTS:
   <list>, see below for supported values
type(ESMF_SortFlag), intent(in) :: direction
integer, intent(out), optional :: rc

DESCRIPTION:

Supported values for <list> are:

integer(ESMF_KIND_I4), intent(inout) :: list(:)
integer(ESMF_KIND_I8), intent(inout) :: list(:)
real(ESMF_KIND_R4), intent(inout) :: list(:)
real(ESMF_KIND_R8), intent(inout) :: list(:)
character(len=*), intent(inout) :: list(:)

Use Quick Sort, reverting to Insertion sort on lists of size <= 20.

This is an ESMFized version of SLASRT from LAPACK version 3.1. Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd. November 2006

The arguments are:

list
Array of data to be sorted. The original data is overwritten by the sorted data.
direction
Direction of sorting. Legal values are ESMF_SORT_ASCENDING and ESMF_SORT_DESCENDING.
[rc]
Return code; equals ESMF_SUCCESS if the sorting is successful.

esmf_support@ucar.edu