.. _mpi_win_test:


MPI_Win_test
============

.. include_body

:ref:`MPI_Win_test` |mdash| Attempts to complete an RMA exposure epoch; a
nonblocking version of :ref:`MPI_Win_wait`


SYNTAX
------


C Syntax
^^^^^^^^

.. code-block:: c

   #include <mpi.h>

   int MPI_Win_test(MPI_Win win, int *flag)


Fortran Syntax
^^^^^^^^^^^^^^

.. code-block:: fortran

   USE MPI
   ! or the older form: INCLUDE 'mpif.h'
   MPI_WIN_TEST( WIN, FLAG, IERROR)
   	INTEGER  WIN, IERROR


Fortran 2008 Syntax
^^^^^^^^^^^^^^^^^^^

.. code-block:: fortran

   USE mpi_f08
   MPI_Win_test(win, flag, ierror)
   	TYPE(MPI_Win), INTENT(IN) :: win
   	LOGICAL, INTENT(OUT) :: flag
   	INTEGER, OPTIONAL, INTENT(OUT) :: ierror


INPUT PARAMETERS
----------------
* ``win``: Window object (handle)

OUTPUT PARAMETERS
-----------------
* ``ierror``: Fortran only: Error status (integer).
* ``flag``: The returning state of the test for epoch closure.

DESCRIPTION
-----------

:ref:`MPI_Win_test` is a one-sided MPI communication synchronization call, a
nonblocking version of :ref:`MPI_Win_wait`. It returns *flag = true* if
:ref:`MPI_Win_wait` would return, *flag = false* otherwise. The effect of
return of :ref:`MPI_Win_test` with *flag = true* is the same as the effect of a
return of :ref:`MPI_Win_wait`. If *flag = false* is returned, then the call has
no visible effect.

Invoke :ref:`MPI_Win_test` only where :ref:`MPI_Win_wait` can be invoked. Once the
call has returned *flag = true*, it must not be invoked anew, until the
window is posted anew.


ERRORS
------

.. include:: ./ERRORS.rst

.. seealso::
   * :ref:`MPI_Win_post`
   * :ref:`MPI_Win_wait`