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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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* Copyright 2002 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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#pragma ident "%Z%%M% %I% %E% SMI"
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* This file implements a barrier, a synchronization primitive designed to allow
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* threads to wait for each other at given points. Barriers are initialized
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* with a given number of threads, n, using barrier_init(). When a thread calls
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* barrier_wait(), that thread blocks until n - 1 other threads reach the
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* barrier_wait() call using the same barrier_t. When n threads have reached
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* the barrier, they are all awakened and sent on their way. One of the threads
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* returns from barrier_wait() with a return code of 1; the remaining threads
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* get a return code of 0.
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barrier_init(barrier_t *bar, int nthreads)
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pthread_mutex_init(&bar->bar_lock, NULL);
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sema_init(&bar->bar_sem, 0, USYNC_THREAD, NULL);
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sem_init(&bar->bar_sem, 0, 0);
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bar->bar_nthr = nthreads;
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barrier_wait(barrier_t *bar)
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pthread_mutex_lock(&bar->bar_lock);
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if (++bar->bar_numin < bar->bar_nthr) {
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pthread_mutex_unlock(&bar->bar_lock);
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sema_wait(&bar->bar_sem);
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sem_wait(&bar->bar_sem);
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/* reset for next use */
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for (i = 1; i < bar->bar_nthr; i++)
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sema_post(&bar->bar_sem);
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sem_post(&bar->bar_sem);
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pthread_mutex_unlock(&bar->bar_lock);