MPIWaitany(3OpenMPI) MPIWaitany(3OpenMPI)

NAME
       MMPPIIWWaaiittaannyy - Waits for any specified send or receive to complete.


SSYYNNTTAAXX
CC SSyynnttaaxx
       #include 
       int MPIWaitany(int count, MPIRequest *arrayofrequests,
            int *index, MPIStatus *status)


FFoorrttrraann SSyynnttaaxx
       INCLUDE 'mpif.h'
       MPIWAITANY(COUNT, ARRAYOFREQUESTS, INDEX, STATUS, IERROR)
            INTEGER   COUNT, ARRAYOFREQUESTS(*), INDEX
            INTEGER   STATUS(MPISTATUSSIZE), IERROR


CC++++ SSyynnttaaxx
       #include 
       static int Request::Waitany(int count, Request
            arrayofrequests[], Status& status)

       static int Request::Waitany(int count, Request arrayofrequests[])


IINNPPUUTT PPAARRAAMMEETTEERRSS
       count     List length (integer).

       arrayofrequests
                 Array of requests (array of handles).



OOUUTTPPUUTT PPAARRAAMMEETTEERRSS
       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).


       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       A call to MPIWaitany can be used to wait for the completion of one out
       of several requests.

       The arrayofrequests list may contain null or inactive handles. If the
       list  contains  no  active handles (list has length zero or all entries
       are null or inactive), then the call returns immediately with  index  =
       MPIUNDEFINED, and an empty status.

       The  execution  of MPIWaitany(count, arrayofrequests, index, status)
       has the same effect as the execution of MPIWait(&arrayofrequests[i],
       status),  where  i  is the value returned by index (unless the value of
       index is MPIUNDEFINED).  MPIWaitany  with  an  array  containing  one
       active entry is equivalent to MPIWait.

       If  your application does not need to examine the status field, you can
       save resources by using the predefined constant MPISTATUSIGNORE as  a
       special value for the status argument.

       EExxaammppllee:: Client-server code (starvation can occur).

           CALL MPICOMMSIZE(comm, size, ierr)
           CALL MPICOMMRANK(comm, rank, ierr)
           IF(rank .GT 0) THEN         ! client code
               DO WHILE(.TRUE.)
                  CALL MPIISEND(a, n, MPIREAL, 0, tag, comm, request, ierr)
                  CALL MPIWAIT(request, status, ierr)
               END DO
           ELSE         ! rank=0 - server code
                  DO i=1, size-1
                     CALL MPIIRECV(a(1,i), n, MPIREAL, i tag,
                              comm, requestlist(i), ierr)
                  END DO
                  DO WHILE(.TRUE.)
                     CALL MPIWAITANY(size-1, requestlist, index, status, ierr)
                     CALL DOSERVICE(a(1,index))  ! handle one message
                     CALL MPIIRECV(a(1, index), n, MPIREAL, index, tag,
                               comm, requestlist(index), ierr)
                  END DO
           END IF



EERRRROORRSS
       Almost  all MPI routines return an error value; C routines as the value
       of the function and Fortran routines in the last  argument.  C++  func-
       tions  do  not  return  errors.  If the default error handler is set to
       MPI::ERRORSTHROWEXCEPTIONS, then on error the C++ exception mechanism
       will be used to throw an MPI::Exception object.

       Before  the  error  value is returned, the current MPI error handler is
       called. By default, this error handler aborts the MPI job,  except  for
       I/O   function   errors.   The   error  handler  may  be  changed  with
       MPICommseterrhandler,          MPIFileseterrhandler,           or
       MPIWinseterrhandler (depending on the type of MPI handle that gener-
       ated the request); the predefined error handler  MPIERRORSRETURN  may
       be  used  to  cause error values to be returned. Note that MPI does not
       guarantee that an MPI program can continue past an error.

       Note that per MPI-1 section 3.2.5, MPI exceptions on requests passed to
       MPIWAITANY  do not set the status.MPIERROR field in the returned sta-
       tus.  The error code is passed to the back-end error handler and may be
       passed  back  to  the caller through the return value of MPIWAITANY if
       the back-end error handler returns it.  The pre-defined MPI error  han-
       dler MPIERRORSRETURN exhibits this behavior, for example.


SEE ALSO
       MPICommseterrhandler
       MPIFileseterrhandler
       MPITest
       MPITestall
       MPITestany
       MPITestsome
       MPIWait
       MPIWaitall
       MPIWaitsome
       MPIWinseterrhandler




Open MPI 1.2                    September 2006           MPIWaitany(3OpenMPI)