barrier for threads

barrera.cpp

//============================================================================
// Name        : barrera.cpp
// Author      : Luis Hernandez
// Version     : 1
// Copyright   : CodeLouis
// Description : barier for threads
//============================================================================

//g++  5.4.0

#include <iostream>
#include <thread>
#include <condition_variable>
#include <mutex>
using namespace std;

class Barrier{
private:
	std::mutex bmutex;
	std::condition_variable cv;
	std::size_t count;
	std::size_t n;
	std::size_t generation;

public:
	explicit Barrier(unsigned sz =0):count{sz},n{sz},generation(0){};

	void wait(void){
		std::unique_lock<std::mutex> lck{bmutex};
		auto gen = generation;
		if(n-- ==0)
		{
			n = count;
			generation++;
			std::cout<<"generation "<< gen << endl;
			cv.notify_all();
		} else{
			std::cout << "waiting... task " << n+1 <<endl;
			cv.wait(lck,[this,gen]{return gen!= generation;});
			std::cout << "waiting... completed " << generation << endl;
		}
	}

};

int main(){
    int numberThreads = 30;
    int barrierLimit = 3;
    numberThreads++;
	std::thread mThreads[numberThreads];
	Barrier * mBarrier = new Barrier(barrierLimit);

	for(int i=0; i<numberThreads; i++){
		mThreads[i] = std::thread(&Barrier::wait,mBarrier);
	}
	for(int i=0; i<numberThreads; i++){
		mThreads[i].join();
	}

	std::cout << "End of threads" << endl;

	delete mBarrier;
	return 0;
}