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MPI_Comm_get_attr.3.rst

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MPI_Comm_get_attr

MPI_Comm_get_attr - Retrieves attribute value by key.

SYNTAX

C Syntax

#include <mpi.h>

int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
 void *attribute_val, int *flag)

Fortran Syntax

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, FLAG, IERROR)
 INTEGER COMM, COMM_KEYVAL, IERROR
 INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
 LOGICAL FLAG

Fortran 2008 Syntax

USE mpi_f08
MPI_Comm_get_attr(comm, comm_keyval, attribute_val, flag, ierror)
 TYPE(MPI_Comm), INTENT(IN) :: comm
 INTEGER, INTENT(IN) :: comm_keyval
 INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: attribute_val
 LOGICAL, INTENT(OUT) :: flag
 INTEGER, OPTIONAL, INTENT(OUT) :: ierror

INPUT PARAMETERS

  • comm: Communicator to which the attribute is attached (handle).
  • comm_keyval: Key value (integer).

OUTPUT PARAMETER

  • attribute_val: Attribute value, unless flag = false.
  • flag: False if no attribute is associated with the key (logical).
  • ierror: Fortran only: Error status (integer).

DESCRIPTION

MPI_Comm_get_attr retrieves an attribute value by key. The call is erroneous if there is no key with value keyval. On the other hand, the call is correct if the key value exists, but no attribute is attached on comm for that key; in that case, the call returns flag = false. In particular, MPI_KEYVAL_INVALID is an erroneous key value.

This function replaces MPI_Attr_get, the use of which is deprecated. The C binding is identical. The Fortran binding differs in that attribute_val is an address-sized integer.

ERRORS