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MPI_Comm_create_keyval(3) MPI MPI_Comm_create_keyval(3)
MPI_Comm_create_keyval - Create a new attribute key
int MPI_Comm_create_keyval(MPI_Comm_copy_attr_function *comm_copy_attr_fn,
int *comm_keyval, void *extra_state)
- Copy callback function for keyval
- Delete callback function for keyval
- Extra state for callback functions
- key value for future access (integer)
Key values are global (available for any and all communicators).
Default copy and delete functions are available. These are
- empty copy function
- empty delete function
- 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-
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
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.
- No error; MPI routine completed successfully.