1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2002 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 /* 30 * This file implements a barrier, a synchronization primitive designed to allow 31 * threads to wait for each other at given points. Barriers are initialized 32 * with a given number of threads, n, using barrier_init(). When a thread calls 33 * barrier_wait(), that thread blocks until n - 1 other threads reach the 34 * barrier_wait() call using the same barrier_t. When n threads have reached 35 * the barrier, they are all awakened and sent on their way. One of the threads 36 * returns from barrier_wait() with a return code of 1; the remaining threads 37 * get a return code of 0. 38 */ 39 40 #include <pthread.h> 41 #include <stdio.h> 42 43 #include "barrier.h" 44 45 void 46 barrier_init(barrier_t *bar, int nthreads) 47 { 48 pthread_mutex_init(&bar->bar_lock, NULL); 49 pthread_cond_init(&bar->bar_cv, NULL); 50 bar->bar_numin = 0; 51 bar->bar_nthr = nthreads; 52 } 53 54 int 55 barrier_wait(barrier_t *bar) 56 { 57 pthread_mutex_lock(&bar->bar_lock); 58 59 if (++bar->bar_numin < bar->bar_nthr) { 60 pthread_cond_wait(&bar->bar_cv, &bar->bar_lock); 61 pthread_mutex_unlock(&bar->bar_lock); 62 63 return (0); 64 } else { 65 /* reset for next use */ 66 bar->bar_numin = 0; 67 pthread_cond_broadcast(&bar->bar_cv); 68 pthread_mutex_unlock(&bar->bar_lock); 69 70 return (1); 71 } 72 } 73