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

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.