| /* |
| * 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; |
| int step; |
| pthread_barrier_t b; |
| |
| if (barrier == NULL || *barrier == (pthread_barrier_t) PTW32_OBJECT_INVALID) |
| { |
| return EINVAL; |
| } |
| |
| 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); |
| } |
| else |
| { |
| /* |
| * 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 == |
| PTW32_INTERLOCKED_COMPARE_EXCHANGE ((PTW32_INTERLOCKED_LPLONG) |
| & (b->iStep), |
| (PTW32_INTERLOCKED_LONG) |
| (1L - step), |
| (PTW32_INTERLOCKED_LONG) |
| step) ? |
| PTHREAD_BARRIER_SERIAL_THREAD : 0); |
| } |
| |
| return (result); |
| } |