/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * 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.
 */

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

#include "thr_private.h"

_Static_assert(sizeof(struct pthread_barrier) <= THR_PAGE_SIZE_MIN,
    "pthread_barrier is too large for off-page");

__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;
        struct pthread *curthread;
        int pshared;

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

        if (*barrier == THR_PSHARED_PTR) {
                bar = __thr_pshared_offpage(barrier, 0);
                if (bar == NULL) {
                        *barrier = NULL;
                        return (0);
                }
                pshared = 1;
        } else {
                bar = *barrier;
                pshared = 0;
        }
        curthread = _get_curthread();
        THR_UMUTEX_LOCK(curthread, &bar->b_lock);
        if (bar->b_destroying) {
                THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
                return (EBUSY);
        }
        bar->b_destroying = 1;
        do {
                if (bar->b_waiters > 0) {
                        bar->b_destroying = 0;
                        THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
                        return (EBUSY);
                }
                if (bar->b_refcount != 0) {
                        _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
                        THR_UMUTEX_LOCK(curthread, &bar->b_lock);
                } else
                        break;
        } while (1);
        bar->b_destroying = 0;
        THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);

        *barrier = NULL;
        if (pshared)
                __thr_pshared_destroy(barrier);
        else
                free(bar);
        return (0);
}

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

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

        if (attr == NULL || *attr == NULL ||
            (*attr)->pshared == PTHREAD_PROCESS_PRIVATE) {
                bar = calloc(1, sizeof(struct pthread_barrier));
                if (bar == NULL)
                        return (ENOMEM);
                *barrier = bar;
                pshared = 0;
        } else {
                bar = __thr_pshared_offpage(barrier, 1);
                if (bar == NULL)
                        return (EFAULT);
                *barrier = THR_PSHARED_PTR;
                pshared = 1;
        }

        _thr_umutex_init(&bar->b_lock);
        _thr_ucond_init(&bar->b_cv);
        if (pshared) {
                bar->b_lock.m_flags |= USYNC_PROCESS_SHARED;
                bar->b_cv.c_flags |= USYNC_PROCESS_SHARED;
        }
        bar->b_count = count;
        return (0);
}

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

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

        if (*barrier == THR_PSHARED_PTR) {
                bar = __thr_pshared_offpage(barrier, 0);
                if (bar == NULL)
                        return (EINVAL);
        } else {
                bar = *barrier;
        }
        curthread = _get_curthread();
        THR_UMUTEX_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_ucond_broadcast(&bar->b_cv);
                THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
                ret = PTHREAD_BARRIER_SERIAL_THREAD;
        } else {
                cycle = bar->b_cycle;
                bar->b_refcount++;
                do {
                        _thr_ucond_wait(&bar->b_cv, &bar->b_lock, NULL, 0);
                        THR_UMUTEX_LOCK(curthread, &bar->b_lock);
                        /* test cycle to avoid bogus wakeup */
                } while (cycle == bar->b_cycle);
                if (--bar->b_refcount == 0 && bar->b_destroying)
                        _thr_ucond_broadcast(&bar->b_cv);
                THR_UMUTEX_UNLOCK(curthread, &bar->b_lock);
                ret = 0;
        }
        return (ret);
}