freebsd-dev/lib/libkse/thread/thr_barrier.c

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/*-
* Copyright (c) 2003 David Xu <davidxu@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <errno.h>
#include <stdlib.h>
#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"
#include "thr_private.h"
__weak_reference(_pthread_barrier_init, pthread_barrier_init);
__weak_reference(_pthread_barrier_wait, pthread_barrier_wait);
__weak_reference(_pthread_barrier_destroy, pthread_barrier_destroy);
int
_pthread_barrier_destroy(pthread_barrier_t *barrier)
{
pthread_barrier_t bar;
int ret, ret2;
if (barrier == NULL || *barrier == NULL)
return (EINVAL);
bar = *barrier;
if (bar->b_waiters > 0)
return (EBUSY);
*barrier = NULL;
ret = _pthread_mutex_destroy(&bar->b_lock);
ret2 = _pthread_cond_destroy(&bar->b_cond);
free(bar);
return (ret ? ret : ret2);
}
int
_pthread_barrier_init(pthread_barrier_t *barrier,
const pthread_barrierattr_t *attr, int count)
{
pthread_barrier_t bar;
int ret;
if (barrier == NULL || count <= 0)
return (EINVAL);
bar = malloc(sizeof(struct pthread_barrier));
if (bar == NULL)
return (ENOMEM);
if ((ret = _pthread_mutex_init(&bar->b_lock, NULL)) != 0) {
free(bar);
return (ret);
}
if ((ret = _pthread_cond_init(&bar->b_cond, NULL)) != 0) {
_pthread_mutex_destroy(&bar->b_lock);
free(bar);
return (ret);
}
bar->b_waiters = 0;
bar->b_count = count;
bar->b_generation = 0;
*barrier = bar;
return (0);
}
int
_pthread_barrier_wait(pthread_barrier_t *barrier)
{
int ret, gen;
pthread_barrier_t bar;
if (barrier == NULL || *barrier == NULL)
return (EINVAL);
bar = *barrier;
if ((ret = _pthread_mutex_lock(&bar->b_lock)) != 0)
return (ret);
if (++bar->b_waiters == bar->b_count) {
/* Current thread is lastest thread */
bar->b_generation++;
bar->b_waiters = 0;
ret = _pthread_cond_broadcast(&bar->b_cond);
if (ret == 0)
ret = PTHREAD_BARRIER_SERIAL_THREAD;
} else {
gen = bar->b_generation;
do {
ret = _pthread_cond_wait(
&bar->b_cond, &bar->b_lock);
/* test generation to avoid bogus wakeup */
} while (ret == 0 && gen == bar->b_generation);
}
_pthread_mutex_unlock(&bar->b_lock);
return (ret);
}