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/*
* pthread_barrier_wait.c
*
* Description:
* 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: rpj@callisto.canberra.edu.au
*
* 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
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* 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;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include "pthread.h"
#include "implement.h"
int
pthread_barrier_wait (pthread_barrier_t * barrier)
{
int result;
pthread_barrier_t b;
ptw32_mcs_local_node_t node;
if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID)
{
return EINVAL;
}
ptw32_mcs_lock_acquire(&(*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.
*/
ptw32_mcs_node_transfer(&b->proxynode, &node);
/*
* 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);
}
else
{
ptw32_mcs_lock_release(&node);
/*
* 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));
}
if ((PTW32_INTERLOCKED_LONG)PTW32_INTERLOCKED_INCREMENT_LONG((PTW32_INTERLOCKED_PTR)&b->nCurrentBarrierHeight)
== (PTW32_INTERLOCKED_LONG)b->nInitialBarrierHeight)
{
/*
* We are the last thread to cross this barrier
*/
ptw32_mcs_lock_release(&b->proxynode);
if (0 == result)
{
result = PTHREAD_BARRIER_SERIAL_THREAD;
}
}
return (result);
}
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