openmpi/ompi/mpi/man/man3/MPI_Testany.3in

.\" Copyright 2006-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.TH MPI_Testany 3 "#OMPI_DATE#" "#PACKAGE_VERSION#" "#PACKAGE_NAME#"
.SH NAME
\fBMPI_Testany\fP \- Tests for completion of any one previously initiated communication in a list. 

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Testany(int \fIcount\fP, MPI_Request\fI array_of_requests[]\fP, 
	int\fI *index\fP, int\fI *flag\fP, MPI_Status\fI *status\fP)

.fi
.SH Fortran Syntax
.nf
INCLUDE 'mpif.h'
MPI_TESTANY(\fICOUNT, ARRAY_OF_REQUESTS, INDEX, FLAG, STATUS, IERROR\fP)
	LOGICAL	\fIFLAG\fP 
	INTEGER	\fICOUNT, ARRAY_OF_REQUESTS(*), INDEX\fP 
	INTEGER	\fISTATUS(MPI_STATUS_SIZE), IERROR\fP 

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
static bool Request::Testany(int \fIcount\fP, Request \fIarray_of_requests\fP[], 
	int& \fIindex\fP, Status& \fIstatus\fP) 

static bool Request::Testany(int \fIcount\fP, Request \fIarray_of_requests\fP[], 
	int& \fIindex\fP) 

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
count
List length (integer).
.TP 1i
array_of_requests
Array of requests (array of handles).

.SH OUTPUT PARAMETERS
.ft R
.TP 1i
index
Index of operation that completed, or MPI_UNDEFINED if none completed
(integer).
.TP 1i
flag
True if one of the operations is complete (logical).
.TP 1i
status
Status object (status).
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer). 

.SH DESCRIPTION
.ft R
MPI_Testany tests for completion of either one or none of the operations associated with active handles. In the former case, it returns \fIflag\fP = true, returns in \fIindex\fP the index of this request in the array, and returns in \fIstatus\fP 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 \fIflag\fP = false, returns a value of MPI_UNDEFINED in \fIindex\fP, and \fIstatus\fP is undefined.
.sp
The array may contain null or inactive handles. If the array contains no active handles then the call returns immediately with \fIflag\fP = true, \fIindex\fP = MPI_UNDEFINED, and an empty \fIstatus\fP.
.sp
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(&\fIarray_of_requests[i\fP], \fIflag\fP, \fIstatus\fP), for \fIi\fP=0,1,...,count-1, in some arbitrary order, until one call returns \fIflag\fP = true, or all fail. In the former case, \fIindex\fP is set to the last value of \fIi\fP, 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.
.sp
If your application does not need to examine the \fIstatus\fP field, you can save resources by using the predefined constant MPI_STATUS_IGNORE as a special value for the \fIstatus\fP argument. 

.SH 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.
.sp
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.
.sp
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.

.SH SEE ALSO
.ft R
.sp
MPI_Comm_set_errhandler
.br
MPI_File_set_errhandler
.br
MPI_Test
.br
MPI_Testall
.br
MPI_Testsome
.br
MPI_Wait
.br
MPI_Waitall
.br
MPI_Waitany
.br
MPI_Waitsome
.br
MPI_Win_set_errhandler
.br