MPI_Waitany(3)

NAME
MPI_Waitany - Waits for any specified send or receive to complete

SYNOPSIS
#include "mpi.h"
int MPI_Waitany(
        int count,
        MPI_Request array_of_requests[],
        int *index,
        MPI_Status *status )

INPUT PARAMETERS
count
    - list length (integer)
array_of_requests
    - array of requests (array of handles)

OUTPUT PARAMETERS
index
    - index of handle for operation that completed (integer). In the range 0 to count-1 . In Fortran, the range is 1 to count .
status
    - status object (Status). May be MPI_STATUS_NULL .

NOTES
If all of the requests are MPI_REQUEST_NULL , then index is returned as MPI_UNDEFINED , and status is returned as an empty status.

NOTE ON STATUS FOR SEND OPERATIONS
For send operations, the only use of status is for MPI_Test_cancelled or in the case that there is an error, in which case the MPI_ERROR field of status will be set.

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_Errhandler_set ; 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.
MPI_SUCCESS
    - No error; MPI routine completed successfully.
MPI_ERR_REQUEST
    - Invalid MPI_Request . Either null or, in the case of a MPI_Start or MPI_Startall , not a persistent request.
MPI_ERR_ARG
    - Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., MPI_ERR_RANK ).

LOCATION
waitany.c