Barrier.h

#ifndef __H_BARRIER
#define __H_BARRIER

#include <mutex>

// https://stackoverflow.com/questions/24465533/implementing-boostbarrier-in-c11
class Barrier {
public:
    explicit Barrier(std::size_t count) : mThreshold(count), mCount(count), mGeneration(0) {
    }

    void wait() {
        std::unique_lock<std::mutex> lock{mMutex};
        auto generation = mGeneration;
        if (!--mCount) {
            mGeneration++;
            mCount = mThreshold;
            mCond.notify_all();
        } else {
            mCond.wait(lock, [this, generation] { return generation != mGeneration; });
        }
    }

private:
    std::mutex mMutex;
    std::condition_variable mCond;
    std::size_t mThreshold;
    std::size_t mCount;
    std::size_t mGeneration;
};

#endif