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NAME

       MPI_Type_get_attr -  Retrieves attribute value by key

SYNOPSIS

       int MPI_Type_get_attr(MPI_Datatype datatype, int type_keyval, void *attribute_val, int *flag)

INPUT PARAMETERS

       datatype
              - datatype to which the attribute is attached (handle)
       type_keyval
              - key value (integer)

OUTPUT PARAMETERS

       attribute_val
              - attribute value, unless flag = false
       flag   - false if no attribute is associated with the key (logical)

NOTES

       Attributes  must  be  extracted  from  the  same  language  as  they were inserted in with
       MPI_Type_set_attr .  The notes for C and Fortran below explain why.

NOTES FOR C

       Even though the attr_value argument is declared as void * , it is really the address of  a
       void pointer.  See the rationale in the standard for more details.

THREAD AND INTERRUPT SAFETY

       This  routine is thread-safe.  This means that this routine may be safely used by multiple
       threads without the need for any user-provided thread locks.  However, the routine is  not
       interrupt  safe.   Typically, this is due to the use of memory allocation routines such as
       malloc or other non-MPICH runtime routines that are themselves not interrupt-safe.

NOTES FOR FORTRAN

       All MPI routines in Fortran (except for MPI_WTIME  and  MPI_WTICK  )  have  an  additional
       argument  ierr  at  the  end  of  the  argument list.  ierr is an integer and has the same
       meaning as the  return  value  of  the  routine  in  C.   In  Fortran,  MPI  routines  are
       subroutines, and are invoked with the call statement.

       All MPI objects (e.g., MPI_Datatype , MPI_Comm ) are of type INTEGER in Fortran.

ERRORS

       All  MPI  routines  (except MPI_Wtime and MPI_Wtick ) return an error value; C routines as
       the value of the function and Fortran routines in the last argument.  Before the value  is
       returned,  the current MPI error handler is called.  By default, this error handler aborts
       the MPI  job.   The  error  handler  may  be  changed  with  MPI_Comm_set_errhandler  (for
       communicators),  MPI_File_set_errhandler  (for files), and MPI_Win_set_errhandler (for RMA
       windows).  The MPI-1 routine MPI_Errhandler_set may be used but  its  use  is  deprecated.
       The  predefined  error  handler  MPI_ERRORS_RETURN may be used to cause error values to be
       returned.  Note that MPI does not guarentee that an  MPI  program  can  continue  past  an
       error; however, MPI implementations will attempt to continue whenever possible.

       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_KEYVAL
              - Invalid keyval
       MPI_ERR_ARG
              -  Invalid  argument.  Some argument is invalid and is not identified by a specific
              error class (e.g., MPI_ERR_RANK ).

                                            11/21/2018                       MPI_Type_get_attr(3)