producer-consumer.cc

#include <iostream>
#include <thread>
#include <deque>
#include <mutex>
#include <condition_variable>

struct queue {
	void put(int x) {
		std::unique_lock<std::mutex> guard(lock);
		q.push_back(x);
		if (sleepers && q.size() == 1)
			cond.notify_one();
	}
	
	int get() {
		std::unique_lock<std::mutex> guard(lock);
		while (q.size() == 0) {
			++sleepers;
			cond.wait(guard);
			--sleepers;
		}
		auto x = q.front();
		q.pop_front();
		return x;
	}
	unsigned sleepers = 0;
	std::deque<int> q;
	std::mutex lock;
	std::condition_variable cond;
};