NAME

       MPI_Comm_set_attr - Stores attribute value associated with a key.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Comm_set_attr(MPI_Comm comm, int comm_keyval, void *attribute_val)

Fortran Syntax (see FORTRAN 77 NOTES)

       INCLUDE 'mpif.h'
       MPI_COMM_SET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, IERROR)
            INTEGER   COMM, COMM_KEYVAL, IERROR
            INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL

C++ Syntax

       #include <mpi.h>
       void MPI::Comm::Set_attr(int comm_keyval, const void* attribute_val) const

INPUT/OUTPUT PARAMETER

       comm      Communicator from which attribute will be attached (handle).

INPUT PARAMETERS

       comm_keyval
                 Key value (integer).

       attribute_val
                 Attribute value.

OUTPUT PARAMETER

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

       MPI_Comm_set_attr  stores  the  stipulated  attribute  value  attribute_val for subsequent
       retrieval by MPI_Comm_get_attr. If the value is already present, then the outcome is as if
       MPI_Comm_delete_attr  was  first  called  to  delete  the previous value (and the callback
       function delete_fn was executed), and a new value was next stored. The call  is  erroneous
       if  there  is  no  key  with  value  comm_keyval;  in  particular MPI_KEYVAL_INVALID is an
       erroneous key value. The call will fail if the delete_fn function returned an  error  code
       other than MPI_SUCCESS.

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

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.

NOTES

       Values of the permanent attributes MPI_TAG_UB, MPI_HOST, MPI_IO,  and  MPI_WTIME_IS_GLOBAL
       may not be changed.

       The  type  of  the attribute value depends on whether C or Fortran is being used. In C, an
       attribute value is a pointer (void *); in Fortran, it is a  single,  address-size  integer
       system for which a pointer does not fit in an integer.

       If  an attribute is already present, the delete function (specified when the corresponding
       keyval was created) will be called.

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran  routines in the last argument. C++ functions do not return errors. If the default
       error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then  on  error  the  C++  exception
       mechanism will be used to throw an MPI::Exception object.

       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.