MPI_Testany(3)

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.

SEE ALSO

MPI_Comm_set_errhandler
MPI_File_set_errhandler
MPI_Test
MPI_Testall
MPI_Testsome
MPI_Wait
MPI_Waitall
MPI_Waitany
MPI_Waitsome
MPI_Win_set_errhandler