.\" -*- nroff -*-
.\" Copyright 2010 Cisco Systems, Inc.  All rights reserved.
.\" Copyright 2007-2008 Sun Microsystems, Inc.
.\" Copyright (c) 1996 Thinking Machines Corporation
.\" $COPYRIGHT$
.TH MPI_Win_test 3 "May 26, 2022" ""4.1.4"" "Open MPI"
.SH NAME
\fBMPI_Win_test\fP \- Attempts to complete an RMA exposure epoch; a nonblocking version of MPI_Win_wait

.SH SYNTAX
.ft R
.SH C Syntax
.nf
#include <mpi.h>
int MPI_Win_test(MPI_Win \fIwin\fP, int *\fIflag\fP)

.fi
.SH Fortran Syntax
.nf
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_WIN_TEST(\fI WIN, FLAG, IERROR\fP)
	INTEGER \fI WIN, IERROR\fP

.fi
.SH Fortran 2008 Syntax
.nf
USE mpi_f08
MPI_Win_test(\fIwin\fP, \fIflag\fP, \fIierror\fP)
	TYPE(MPI_Win), INTENT(IN) :: \fIwin\fP
	LOGICAL, INTENT(OUT) :: \fIflag\fP
	INTEGER, OPTIONAL, INTENT(OUT) :: \fIierror\fP

.fi
.SH C++ Syntax
.nf
#include <mpi.h>
bool MPI::Win::Test() const

.fi
.SH INPUT PARAMETERS
.ft R
.TP 1i
win
Window object (handle)


.SH OUTPUT PARAMETERS
.ft R
.TP 1i
IERROR
Fortran only: Error status (integer).
.TP 1i
flag
The returning state of the test for epoch closure.


.SH DESCRIPTION
.ft R
MPI_Win_test is a one-sided MPI communication synchronization call, a
nonblocking version of MPI_Win_wait. It returns \fIflag = true\fP if
MPI_Win_wait would return, \fIflag = false\fP otherwise. The effect of return of MPI_Win_test with \fIflag = true\fP is the same as the effect of a return of MPI_Win_wait. If \fIflag = false\fP is returned, then the call has no visible effect.
.sp
Invoke MPI_Win_test only where MPI_Win_wait can be invoked. Once
the call has returned \fIflag = true\fP, it must not be invoked anew, until the window is posted anew.


.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_Win_set_errhandler; 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.

.SH SEE ALSO
MPI_Win_post
MPI_Win_wait
.br