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- /* POSIX barrier implementation for LinuxThreads.
- Copyright (C) 2000, 2003 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
- Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000.
- The GNU C 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 2.1 of the
- License, or (at your option) any later version.
- The GNU C 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 the GNU C Library; see the file COPYING.LIB. If
- not, see <http://www.gnu.org/licenses/>. */
- #include <errno.h>
- #include "pthread.h"
- #include "internals.h"
- #include "spinlock.h"
- #include "queue.h"
- #include "restart.h"
- int
- pthread_barrier_wait(pthread_barrier_t *barrier)
- {
- pthread_descr self = thread_self();
- pthread_descr temp_wake_queue, th;
- int result = 0;
- __pthread_lock(&barrier->__ba_lock, self);
- /* If the required number of threads have achieved rendezvous... */
- if (barrier->__ba_present >= barrier->__ba_required - 1)
- {
- /* ... then this last caller shall be the serial thread */
- result = PTHREAD_BARRIER_SERIAL_THREAD;
- /* Copy and clear wait queue and reset barrier. */
- temp_wake_queue = barrier->__ba_waiting;
- barrier->__ba_waiting = NULL;
- barrier->__ba_present = 0;
- }
- else
- {
- result = 0;
- barrier->__ba_present++;
- enqueue(&barrier->__ba_waiting, self);
- }
- __pthread_unlock(&barrier->__ba_lock);
- if (result == 0)
- {
- /* Non-serial threads have to suspend */
- suspend(self);
- /* We don't bother dealing with cancellation because the POSIX
- spec for barriers doesn't mention that pthread_barrier_wait
- is a cancellation point. */
- }
- else
- {
- /* Serial thread wakes up all others. */
- while ((th = dequeue(&temp_wake_queue)) != NULL)
- restart(th);
- }
- return result;
- }
- int
- pthread_barrier_init(pthread_barrier_t *barrier,
- const pthread_barrierattr_t *attr,
- unsigned int count)
- {
- if (count == 0)
- return EINVAL;
- __pthread_init_lock(&barrier->__ba_lock);
- barrier->__ba_required = count;
- barrier->__ba_present = 0;
- barrier->__ba_waiting = NULL;
- return 0;
- }
- int
- pthread_barrier_destroy(pthread_barrier_t *barrier)
- {
- if (barrier->__ba_waiting != NULL) return EBUSY;
- return 0;
- }
- int
- pthread_barrierattr_init(pthread_barrierattr_t *attr)
- {
- attr->__pshared = PTHREAD_PROCESS_PRIVATE;
- return 0;
- }
- int
- pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
- {
- return 0;
- }
- int
- __pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr,
- int *pshared)
- {
- *pshared = PTHREAD_PROCESS_PRIVATE;
- return 0;
- }
- int
- pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
- {
- if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
- return EINVAL;
- /* For now it is not possible to shared a conditional variable. */
- if (pshared != PTHREAD_PROCESS_PRIVATE)
- return ENOSYS;
- return 0;
- }
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