thr_barrier.c revision 157228 
1/*-
2 * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/lib/libkse/thread/thr_barrier.c 157228 2006-03-28 21:07:59Z deischen $
27 */
28
29#include <errno.h>
30#include <stdlib.h>
31#include "namespace.h"
32#include <pthread.h>
33#include "un-namespace.h"
34#include "thr_private.h"
35
36LT10_COMPAT_PRIVATE(_pthread_barrier_init);
37LT10_COMPAT_DEFAULT(pthread_barrier_init);
38LT10_COMPAT_PRIVATE(_pthread_barrier_wait);
39LT10_COMPAT_DEFAULT(pthread_barrier_wait);
40LT10_COMPAT_PRIVATE(_pthread_barrier_destroy);
41LT10_COMPAT_DEFAULT(pthread_barrier_destroy);
42
43__weak_reference(_pthread_barrier_init,		pthread_barrier_init);
44__weak_reference(_pthread_barrier_wait,		pthread_barrier_wait);
45__weak_reference(_pthread_barrier_destroy,	pthread_barrier_destroy);
46
47int
48_pthread_barrier_destroy(pthread_barrier_t *barrier)
49{
50	pthread_barrier_t	bar;
51	int			ret, ret2;
52
53	if (barrier == NULL || *barrier == NULL)
54		return (EINVAL);
55
56	bar = *barrier;
57	if (bar->b_waiters > 0)
58		return (EBUSY);
59	*barrier = NULL;
60	ret  = _pthread_mutex_destroy(&bar->b_lock);
61	ret2 = _pthread_cond_destroy(&bar->b_cond);
62	free(bar);
63	return (ret ? ret : ret2);
64}
65
66int
67_pthread_barrier_init(pthread_barrier_t *barrier,
68		      const pthread_barrierattr_t *attr, unsigned count)
69{
70	pthread_barrier_t	bar;
71	int			ret;
72
73	if (barrier == NULL || count <= 0)
74		return (EINVAL);
75
76	bar = malloc(sizeof(struct pthread_barrier));
77	if (bar == NULL)
78		return (ENOMEM);
79
80	if ((ret = _pthread_mutex_init(&bar->b_lock, NULL)) != 0) {
81		free(bar);
82		return (ret);
83	}
84
85	if ((ret = _pthread_cond_init(&bar->b_cond, NULL)) != 0) {
86		_pthread_mutex_destroy(&bar->b_lock);
87		free(bar);
88		return (ret);
89	}
90
91	bar->b_waiters		= 0;
92	bar->b_count		= count;
93	bar->b_generation	= 0;
94	*barrier		= bar;
95
96	return (0);
97}
98
99int
100_pthread_barrier_wait(pthread_barrier_t *barrier)
101{
102	int ret, gen;
103	pthread_barrier_t bar;
104
105	if (barrier == NULL || *barrier == NULL)
106		return (EINVAL);
107
108	bar = *barrier;
109	if ((ret = _pthread_mutex_lock(&bar->b_lock)) != 0)
110		return (ret);
111
112	if (++bar->b_waiters == bar->b_count) {
113		/* Current thread is lastest thread */
114		bar->b_generation++;
115		bar->b_waiters = 0;
116		ret = _pthread_cond_broadcast(&bar->b_cond);
117		if (ret == 0)
118			ret = PTHREAD_BARRIER_SERIAL_THREAD;
119	} else {
120		gen = bar->b_generation;
121		do {
122			ret = _pthread_cond_wait(
123				&bar->b_cond, &bar->b_lock);
124		/* test generation to avoid bogus wakeup */
125		} while (ret == 0 && gen == bar->b_generation);
126	}
127	_pthread_mutex_unlock(&bar->b_lock);
128	return (ret);
129}
130