17.2.60. MPI_Comm_get_attr

MPI_Comm_get_attr - Retrieves attribute value by key.

17.2.60.1. SYNTAX

17.2.60.1.1. C Syntax

#include <mpi.h>

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

17.2.60.1.2. Fortran Syntax (see FORTRAN 77 NOTES)

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

17.2.60.1.3. 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

17.2.60.2. INPUT PARAMETERS

  • comm: Communicator to which the attribute is attached (handle).

  • comm_keyval: Key value (integer).

17.2.60.3. 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).

17.2.60.4. 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.

17.2.60.5. FORTRAN 77 NOTES

The MPI standard prescribes portable Fortran syntax for the ATTRIBUTE_VAL argument only for Fortran 90. Sun FORTRAN 77 users may use the non-portable syntax

INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.

17.2.60.6. ERRORS

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.