Ubuntu Manpage: MPI_Testany - Tests for completion of any one previously initiated communication in a

NAME

       MPI_Testany  -  Tests  for  completion  of any one previously initiated communication in a
       list.

SYNTAX

C Syntax

       #include <mpi.h>
       int MPI_Testany(int count, MPI_Request *array_of_requests,
            int *index, int *flag, MPI_Status *status)

Fortran Syntax

       INCLUDE 'mpif.h'
       MPI_TESTANY(COUNT, ARRAY_OF_REQUESTS, INDEX, FLAG, STATUS, IERROR)
            LOGICAL   FLAG
            INTEGER   COUNT, ARRAY_OF_REQUESTS(*), INDEX
            INTEGER   STATUS(MPI_STATUS_SIZE), IERROR

C++ Syntax

       #include <mpi.h>
       static bool Request::Testany(int count, Request array_of_requests[],
            int& index, Status& status)

       static bool Request::Testany(int count, Request array_of_requests[],
            int& index)

INPUT PARAMETERS

       count     List length (integer).

       array_of_requests
                 Array of requests (array of handles).

OUTPUT PARAMETERS

       index     Index of operation that completed, or MPI_UNDEFINED if none completed (integer).

       flag      True if one of the operations is complete (logical).

       status    Status object (status).

       IERROR    Fortran only: Error status (integer).

DESCRIPTION

MPI_Testany tests for completion of either one or none of the operations associated with
active handles. In the former case, it returns flag = true, returns in index the index of
this request in the array, and returns in status the status of that operation; if the
request was allocated by a nonblocking communication call then the request is deallocated
and the handle is set to MPI_REQUEST_NULL. (The array is indexed from 0 in C, and from 1
in Fortran.) In the latter case (no operation completed), it returns flag = false, returns
a value of MPI_UNDEFINED in index, and status is undefined.

The array may contain null or inactive handles. If the array contains no active handles
then the call returns immediately with flag = true, index = MPI_UNDEFINED, and an empty
status.

If the array of requests contains active handles then the execution of MPI_Testany(count,
array_of_requests, index, status) has the same effect as the execution of
MPI_Test(&array_of_requests[i], flag, status), for i=0,1,...,count-1, in some arbitrary
order, until one call returns flag = true, or all fail. In the former case, index is set
to the last value of i, and in the latter case, it is set to MPI_UNDEFINED. MPI_Testany
with an array containing one active entry is equivalent to MPI_Test.

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

ERRORS

       Almost all MPI routines return an error value; C routines as the value of the function and
       Fortran routines in the last argument. C++ functions do not return errors. If the  default
       error  handler  is  set  to  MPI::ERRORS_THROW_EXCEPTIONS, 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    MPI_Comm_set_errhandler,    MPI_File_set_errhandler,    or
       MPI_Win_set_errhandler  (depending  on the type of MPI handle that generated the request);
       the predefined error handler MPI_ERRORS_RETURN 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 MPI_TESTANY do not
       set the status.MPI_ERROR field in the returned status.  The error code is  passed  to  the
       back-end  error  handler  and may be passed back to the caller through the return value of
       MPI_TESTANY if the back-end error handler returns it.  The pre-defined MPI  error  handler
       MPI_ERRORS_RETURN exhibits this behavior, for example.