* This translation unit implements barrier primitives.
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
* Contact Email: firstname.lastname@example.org
* The current list of contributors is contained
* in the file CONTRIBUTORS included with the source
* code distribution. The list can also be seen at the
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* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public
* License along with this library in the file COPYING.LIB;
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* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
pthread_barrier_wait (pthread_barrier_t * barrier)
if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID)
b = *barrier;
step = b->iStep;
if (0 == InterlockedDecrement ((long *) &(b->nCurrentBarrierHeight)))
/* Must be done before posting the semaphore. */
b->nCurrentBarrierHeight = b->nInitialBarrierHeight;
* There is no race condition between the semaphore wait and post
* because we are using two alternating semas and all threads have
* entered barrier_wait and checked nCurrentBarrierHeight before this
* barrier's sema can be posted. Any threads that have not quite
* entered sem_wait below when the multiple_post has completed
* will nevertheless continue through the semaphore (barrier)
* and will not be left stranded.
result = (b->nInitialBarrierHeight > 1
? sem_post_multiple (&(b->semBarrierBreeched[step]),
b->nInitialBarrierHeight - 1) : 0);
* Use the non-cancelable version of sem_wait().
result = ptw32_semwait (&(b->semBarrierBreeched[step]));
* The first thread across will be the PTHREAD_BARRIER_SERIAL_THREAD.
* This also sets up the alternate semaphore as the next barrier.
if (0 == result)
result = ((PTW32_INTERLOCKED_LONG) step ==
(1L - step),
PTHREAD_BARRIER_SERIAL_THREAD : 0);