105 lines
3.4 KiB
C
105 lines
3.4 KiB
C
|
/*
|
||
|
|
* 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.,
|
||
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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_LONGPTR)&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);
|
||
|
|
}
|