debian man page for mpi_comm_create_keyval

MPI_Comm_create_keyval(3)						MPI						 MPI_Comm_create_keyval(3)

NAME
       MPI_Comm_create_keyval -  Create a new attribute key

SYNOPSIS
       int MPI_Comm_create_keyval(MPI_Comm_copy_attr_function *comm_copy_attr_fn,
				MPI_Comm_delete_attr_function *comm_delete_attr_fn,
				int *comm_keyval, void *extra_state)

INPUT PARAMETERS
       copy_fn
	      - Copy callback function for keyval

       delete_fn
	      - Delete callback function for keyval

       extra_state
	      - Extra state for callback functions

OUTPUT PARAMETER
       comm_keyval
	      - key value for future access (integer)

NOTES
       Key values are global (available for any and all communicators).

       Default copy and delete functions are available.  These are
       MPI_COMM_NULL_COPY_FN
	      - empty copy function
       MPI_COMM_NULL_DELETE_FN
	      - empty delete function
       MPI_COMM_DUP_FN
	      - simple dup function

	      There  are  subtle  differences  between	C  and	Fortran  that  require that the copy_fn be written in the same language from which
	      MPI_Comm_create_keyval is called.  This should not be a problem for most users; only programers using both Fortran and C in the same
	      program need to be sure that they follow this rule.

RETURN VALUE FROM ATTRIBUTE CALLBACKS
       The  MPI-2  versions  of the attribute callbacks should return either MPI_SUCCESS on success or a valid MPI error code or class on failure.
       The MPI standard is ambiguous on this point, but as MPI-2 provides the routines MPI_Add_error_class and MPI_Add_error_code that	allow  the
       user to define and use MPI error codes and classes.

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.

SEE ALSO
       MPI_Comm_free_keyval

LOCATION
       comm_create_keyval.c

								     7/27/2010						 MPI_Comm_create_keyval(3)