MPI_Grequest_start - Create and return a user-defined request
int MPI_Grequest_start( MPI_Grequest_query_function *query_fn,
void *extra_state, MPI_Request *request )
- - callback function invoked when request status is queried (function)
- - callback function invoked when request is freed (function)
- - callback function invoked when request is cancelled (function)
- - Extra state passed to the above functions.
- - Generalized request (handle)
The return values from the callback functions must be a valid MPI error code or
class. This value may either be the return value from any MPI routine (with
one exception noted below) or any of the MPI error classes. For portable
may be used; to provide more specific
information, create a new MPI error class or code with
and return that value.
The MPI standard is not clear on the return values from the callback routines.
However, there are notes in the standard that imply that these are MPI error
codes. For example, pages 169 line 46 through page 170, line 1 require that
return an MPI error code that may be used in the MPI
completion functions when they return MPI_ERR_IN_STATUS
The one special case is the error value returned by MPI_Comm_dup
attribute callback routine returns a failure. The MPI standard is not clear on
what values may be used to indicate an error return. Further, the Intel MPI
test suite made use of non-zero values to indicate failure, and expected these
values to be returned by the MPI_Comm_dup
when the attribute routines
encountered an error. Such error values may not be valid MPI error codes or
classes. Because of this, it is the user's responsibility to either use valid
MPI error codes in return from the attribute callbacks, if those error codes
are to be returned by a generalized request callback, or to detect and convert
those error codes to valid MPI error codes (recall that MPI error classes are
valid error codes).
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.
All MPI routines in Fortran (except for MPI_WTIME
have an additional argument ierr
at the end of the argument list.
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
All MPI objects (e.g., MPI_Datatype
) are of type
All MPI routines (except MPI_Wtime
) 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 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
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.
- - Invalid argument. Some argument is invalid and is not identified by a
specific error class (e.g., MPI_ERR_RANK ).