Barrier.h

#pragma once
#include <mutex>
#include <stdint.h>
#include <condition_variable>

class ThreadBarrier {

public:
    ThreadBarrier(const uint32_t &threadCount) :
        _threadCount(threadCount),
        _incomingThreads(0),
        _threadsToGoOut(0) {}

    void wait() {
        std::unique_lock<std::mutex> lock(_mutex);

        ++_incomingThreads;
        if (_incomingThreads == _threadCount) {
            _incomingThreads = 0;
            _threadsToGoOut = _threadCount - 1; // -1 since the current thread goes out immediately
            _conditionalVar.notify_all();
        } else {
            _conditionalVar.wait(lock, [this]() {return this->_threadsToGoOut != 0; });
            --_threadsToGoOut;
        }

        lock.unlock();
    }

private:
    std::mutex _mutex;
    std::condition_variable _conditionalVar;

    const uint32_t _threadCount;

    uint32_t _incomingThreads;
    uint32_t _threadsToGoOut;
};