/*-
 * 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: src/lib/libpthread/thread/thr_barrier.c,v 1.1 2003/09/04 14:06:43 davidxu Exp $
 */

#include "namespace.h"
#include <machine/tls.h>
#include <errno.h>
#include <stdlib.h>
#include <pthread.h>
#include "un-namespace.h"

#include "thr_private.h"

int
_pthread_barrier_destroy(pthread_barrier_t *barrier)
{
        pthread_barrier_t bar;

        if (barrier == NULL || *barrier == NULL)
                return (EINVAL);

        bar = *barrier;
        if (bar->b_waiters > 0)
                return (EBUSY);
        *barrier = NULL;
        __free(bar);
        return (0);
}

int
_pthread_barrier_init(pthread_barrier_t * __restrict barrier,
                      const pthread_barrierattr_t * __restrict attr __unused,
                      unsigned count)
{
        pthread_barrier_t bar;

        if (barrier == NULL || count == 0 || count > INT_MAX)
                return (EINVAL);

        bar = __malloc(sizeof(struct __pthread_barrier_s));
        if (bar == NULL)
                return (ENOMEM);

        _thr_umtx_init(&bar->b_lock);
        bar->b_cycle    = 0;
        bar->b_waiters  = 0;
        bar->b_count    = count;
        *barrier        = bar;

        return (0);
}

int
_pthread_barrier_wait(pthread_barrier_t *barrier)
{
        pthread_t curthread;
        pthread_barrier_t bar;
        int64_t cycle;
        int ret;

        if (barrier == NULL || *barrier == NULL)
                return (EINVAL);

        bar = *barrier;
        curthread = tls_get_curthread();
        THR_UMTX_LOCK(curthread, &bar->b_lock);
        if (++bar->b_waiters == bar->b_count) {
                /* Current thread is lastest thread */
                bar->b_waiters = 0;
                bar->b_cycle++;
                _thr_umtx_wake(&bar->b_cycle, 0);
                THR_UMTX_UNLOCK(curthread, &bar->b_lock);
                ret = PTHREAD_BARRIER_SERIAL_THREAD;
        } else {
                cycle = bar->b_cycle;
                THR_UMTX_UNLOCK(curthread, &bar->b_lock);
                do {
                        _thr_umtx_wait(&bar->b_cycle, cycle, NULL, 0);
                        /* test cycle to avoid bogus wakeup */
                } while (cycle == bar->b_cycle);
                ret = 0;
        }
        return (ret);
}

__strong_reference(_pthread_barrier_init,       pthread_barrier_init);
__strong_reference(_pthread_barrier_wait,       pthread_barrier_wait);
__strong_reference(_pthread_barrier_destroy,    pthread_barrier_destroy);