1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate * CDDL HEADER START
3*0Sstevel@tonic-gate *
4*0Sstevel@tonic-gate * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate * (the "License"). You may not use this file except in compliance
7*0Sstevel@tonic-gate * with the License.
8*0Sstevel@tonic-gate *
9*0Sstevel@tonic-gate * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate * and limitations under the License.
13*0Sstevel@tonic-gate *
14*0Sstevel@tonic-gate * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate *
20*0Sstevel@tonic-gate * CDDL HEADER END
21*0Sstevel@tonic-gate */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate * Copyright 2002 Sun Microsystems, Inc. All rights reserved.
24*0Sstevel@tonic-gate * Use is subject to license terms.
25*0Sstevel@tonic-gate */
26*0Sstevel@tonic-gate
27*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI"
28*0Sstevel@tonic-gate
29*0Sstevel@tonic-gate /*
30*0Sstevel@tonic-gate * This file implements a barrier, a synchronization primitive designed to allow
31*0Sstevel@tonic-gate * threads to wait for each other at given points. Barriers are initialized
32*0Sstevel@tonic-gate * with a given number of threads, n, using barrier_init(). When a thread calls
33*0Sstevel@tonic-gate * barrier_wait(), that thread blocks until n - 1 other threads reach the
34*0Sstevel@tonic-gate * barrier_wait() call using the same barrier_t. When n threads have reached
35*0Sstevel@tonic-gate * the barrier, they are all awakened and sent on their way. One of the threads
36*0Sstevel@tonic-gate * returns from barrier_wait() with a return code of 1; the remaining threads
37*0Sstevel@tonic-gate * get a return code of 0.
38*0Sstevel@tonic-gate */
39*0Sstevel@tonic-gate
40*0Sstevel@tonic-gate #include <pthread.h>
41*0Sstevel@tonic-gate #include <synch.h>
42*0Sstevel@tonic-gate #include <stdio.h>
43*0Sstevel@tonic-gate
44*0Sstevel@tonic-gate #include "barrier.h"
45*0Sstevel@tonic-gate
46*0Sstevel@tonic-gate void
barrier_init(barrier_t * bar,int nthreads)47*0Sstevel@tonic-gate barrier_init(barrier_t *bar, int nthreads)
48*0Sstevel@tonic-gate {
49*0Sstevel@tonic-gate pthread_mutex_init(&bar->bar_lock, NULL);
50*0Sstevel@tonic-gate sema_init(&bar->bar_sem, 0, USYNC_THREAD, NULL);
51*0Sstevel@tonic-gate
52*0Sstevel@tonic-gate bar->bar_numin = 0;
53*0Sstevel@tonic-gate bar->bar_nthr = nthreads;
54*0Sstevel@tonic-gate }
55*0Sstevel@tonic-gate
56*0Sstevel@tonic-gate int
barrier_wait(barrier_t * bar)57*0Sstevel@tonic-gate barrier_wait(barrier_t *bar)
58*0Sstevel@tonic-gate {
59*0Sstevel@tonic-gate pthread_mutex_lock(&bar->bar_lock);
60*0Sstevel@tonic-gate
61*0Sstevel@tonic-gate if (++bar->bar_numin < bar->bar_nthr) {
62*0Sstevel@tonic-gate pthread_mutex_unlock(&bar->bar_lock);
63*0Sstevel@tonic-gate sema_wait(&bar->bar_sem);
64*0Sstevel@tonic-gate
65*0Sstevel@tonic-gate return (0);
66*0Sstevel@tonic-gate
67*0Sstevel@tonic-gate } else {
68*0Sstevel@tonic-gate int i;
69*0Sstevel@tonic-gate
70*0Sstevel@tonic-gate /* reset for next use */
71*0Sstevel@tonic-gate bar->bar_numin = 0;
72*0Sstevel@tonic-gate for (i = 1; i < bar->bar_nthr; i++)
73*0Sstevel@tonic-gate sema_post(&bar->bar_sem);
74*0Sstevel@tonic-gate pthread_mutex_unlock(&bar->bar_lock);
75*0Sstevel@tonic-gate
76*0Sstevel@tonic-gate return (1);
77*0Sstevel@tonic-gate }
78*0Sstevel@tonic-gate }
79