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129 lines
3.4 KiB
C
129 lines
3.4 KiB
C
/* POSIX barrier implementation for LinuxThreads.
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Copyright (C) 2000, 2003 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include "pthread.h"
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#include "internals.h"
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#include "spinlock.h"
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#include "queue.h"
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#include "restart.h"
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int
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pthread_barrier_wait(pthread_barrier_t *barrier)
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{
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pthread_descr self = thread_self();
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pthread_descr temp_wake_queue, th;
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int result = 0;
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__pthread_lock(&barrier->__ba_lock, self);
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/* If the required number of threads have achieved rendezvous... */
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if (barrier->__ba_present >= barrier->__ba_required - 1)
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{
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/* ... then this last caller shall be the serial thread */
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result = PTHREAD_BARRIER_SERIAL_THREAD;
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/* Copy and clear wait queue and reset barrier. */
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temp_wake_queue = barrier->__ba_waiting;
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barrier->__ba_waiting = NULL;
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barrier->__ba_present = 0;
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}
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else
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{
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result = 0;
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barrier->__ba_present++;
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enqueue(&barrier->__ba_waiting, self);
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}
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__pthread_unlock(&barrier->__ba_lock);
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if (result == 0)
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{
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/* Non-serial threads have to suspend */
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suspend(self);
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/* We don't bother dealing with cancellation because the POSIX
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spec for barriers doesn't mention that pthread_barrier_wait
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is a cancellation point. */
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}
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else
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{
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/* Serial thread wakes up all others. */
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while ((th = dequeue(&temp_wake_queue)) != NULL)
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restart(th);
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}
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return result;
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}
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int
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pthread_barrier_init(pthread_barrier_t *barrier,
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const pthread_barrierattr_t *attr,
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unsigned int count)
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{
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if (count == 0)
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return EINVAL;
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__pthread_init_lock(&barrier->__ba_lock);
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barrier->__ba_required = count;
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barrier->__ba_present = 0;
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barrier->__ba_waiting = NULL;
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return 0;
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}
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int
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pthread_barrier_destroy(pthread_barrier_t *barrier)
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{
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if (barrier->__ba_waiting != NULL) return EBUSY;
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return 0;
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}
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int
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pthread_barrierattr_init(pthread_barrierattr_t *attr)
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{
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attr->__pshared = PTHREAD_PROCESS_PRIVATE;
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return 0;
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}
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int
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pthread_barrierattr_destroy(pthread_barrierattr_t *attr)
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{
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return 0;
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}
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int
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__pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr,
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int *pshared)
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{
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*pshared = PTHREAD_PROCESS_PRIVATE;
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return 0;
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}
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int
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pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared)
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{
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if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
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return EINVAL;
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/* For now it is not possible to shared a conditional variable. */
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if (pshared != PTHREAD_PROCESS_PRIVATE)
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return ENOSYS;
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return 0;
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}
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