/*
 * Copyright (c) 2015, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  * Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *  * 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.
 *  * Neither the name of Intel Corporation nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 */

/**
 * \file
 * \brief Simple thread barrier.
 */

#ifndef TOOLS_THREAD_BARRIER_H
#define TOOLS_THREAD_BARRIER_H

#include <condition_variable>
#include <mutex>

/**
 * \brief Simple thread barrier class.
 *
 * Blocks until wait() has been called N times.
 */
class thread_barrier {
public:
    explicit thread_barrier(unsigned int n) : max(n) {
        if (max == 0) {
            throw std::runtime_error("invalid barrier");
        }
    }

    void wait() {
        std::unique_lock<std::mutex> lock(mtx);
        count++;
        if (count >= max) {
            count = 0;
            condvar.notify_all();
        } else {
            condvar.wait(lock);
        }
    }

private:
    std::mutex mtx;
    std::condition_variable condvar;
    unsigned int count = 0;
    unsigned int max;
};

#endif // TOOLS_THREAD_BARRIER_H
