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 #if defined(sun) 42 #include <synch.h> 43 #else 44 #define USYNC_THREAD 1 45 #define sema_init(a, b, c, d) sem_init((a), (c) != USYNC_THREAD, (b)) 46 #define sema_wait(a) sem_wait(a) 47 #define sema_post(a) sem_post(a) 48 #endif 49 #include <stdio.h> 50 51 #include "barrier.h" 52 53 void 54 barrier_init(barrier_t *bar, int nthreads) 55 { 56 pthread_mutex_init(&bar->bar_lock, NULL); 57 sema_init(&bar->bar_sem, 0, USYNC_THREAD, NULL); 58 bar->bar_numin = 0; 59 bar->bar_nthr = nthreads; 60 } 61 62 int 63 barrier_wait(barrier_t *bar) 64 { 65 pthread_mutex_lock(&bar->bar_lock); 66 67 if (++bar->bar_numin < bar->bar_nthr) { 68 pthread_mutex_unlock(&bar->bar_lock); 69 sema_wait(&bar->bar_sem); 70 return (0); 71 72 } else { 73 int i; 74 75 /* reset for next use */ 76 bar->bar_numin = 0; 77 for (i = 1; i < bar->bar_nthr; i++) 78 sema_post(&bar->bar_sem); 79 pthread_mutex_unlock(&bar->bar_lock); 80 81 return (1); 82 } 83 } 84