* 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: email@example.com
* 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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pthread_barrier_wait (pthread_barrier_t * barrier)
if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID)
ptw32_mcs_lock_acquire((ptw32_mcs_lock_t *)&(*barrier)->lock, &node);
b = *barrier;
if (--b->nCurrentBarrierHeight == 0)
* We are the last thread to arrive at the barrier before it releases us.
* Move our MCS local node to the global scope barrier handle so that the
* last thread out (not necessarily us) can release the lock.
* Any threads that have not quite entered sem_wait below when the
* multiple_post has completed will nevertheless continue through
* the semaphore (barrier).
result = (b->nInitialBarrierHeight > 1
? sem_post_multiple (&(b->semBarrierBreeched),
b->nInitialBarrierHeight - 1) : 0);
* Use the non-cancelable version of sem_wait().
* It is possible that all nInitialBarrierHeight-1 threads are
* at this point when the last thread enters the barrier, resets
* nCurrentBarrierHeight = nInitialBarrierHeight and leaves.
* If pthread_barrier_destroy is called at that moment then the
* barrier will be destroyed along with the semas.
result = ptw32_semwait (&(b->semBarrierBreeched));
* We are the last thread to cross this barrier
if (0 == result)
result = PTHREAD_BARRIER_SERIAL_THREAD;