/*
 * Copyright (c) 2005, 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 ``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 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.
 *
 */

#include "namespace.h"
#include <pthread.h>
#include "un-namespace.h"

#include "thr_private.h"

#define ONCE_NEVER_DONE         PTHREAD_NEEDS_INIT
#define ONCE_DONE               PTHREAD_DONE_INIT
#define ONCE_IN_PROGRESS        0x02
#define ONCE_MASK               0x03

static pthread_mutex_t          once_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t           once_cv = PTHREAD_COND_INITIALIZER;

/*
 * POSIX:
 * The pthread_once() function is not a cancellation point. However,
 * if init_routine is a cancellation point and is canceled, the effect
 * on once_control shall be as if pthread_once() was never called.
 */

static void
once_cancel_handler(void *arg)
{
        pthread_once_t *once_control = arg;

        _pthread_mutex_lock(&once_lock);
        once_control->__state = ONCE_NEVER_DONE;
        _pthread_mutex_unlock(&once_lock);
        _pthread_cond_broadcast(&once_cv);
}

int
_pthread_once(pthread_once_t *once_control, void (*init_routine) (void))
{
        int wakeup = 0;

        _thr_check_init();

        if (once_control->__state == ONCE_DONE)
                return (0);
        _pthread_mutex_lock(&once_lock);
        while (*(volatile int *)&(once_control->__state) == ONCE_IN_PROGRESS)
                _pthread_cond_wait(&once_cv, &once_lock);
        /*
         * If previous thread was canceled, then the state still
         * could be ONCE_NEVER_DONE, we need to check it again.
         */
        if (*(volatile int *)&(once_control->__state) == ONCE_NEVER_DONE) {
                once_control->__state = ONCE_IN_PROGRESS;
                _pthread_mutex_unlock(&once_lock);
                _pthread_cleanup_push(once_cancel_handler, once_control);
                init_routine();
                _pthread_cleanup_pop(0);
                _pthread_mutex_lock(&once_lock);
                once_control->__state = ONCE_DONE;
                wakeup = 1;
        }
        _pthread_mutex_unlock(&once_lock);
        if (wakeup)
                _pthread_cond_broadcast(&once_cv);
        return (0);
}

__strong_reference(_pthread_once, pthread_once);