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

mutex amutex;  
condition_variable is_not_full;
condition_variable is_not_empty; 

int main() {
  int c = 0;
  bool done = false;
  queue<int> goods;
  
  thread producer([&]() {

      for (int i = 0; i < 500; ++i) {
	unique_lock<mutex> lock(amutex);
        // wait w/ func call as 2nd argument, wait only executed if false returned
	is_not_full.wait(lock, [&goods](){return goods.empty(); });
	goods.push(i);
	c++;
	//cout << "p: " << c << " i=" << i << endl;
	is_not_empty.notify_one();
      }
      
      done = true;
    });
  
  thread consumer([&]() {
      while (!done) {
	while (!goods.empty()) {
	  unique_lock<mutex> lock(amutex);
	  is_not_empty.wait(lock, [&goods](){return !goods.empty(); });
	  goods.pop();
	  c--;
	  //cout << "c: " << c << endl;
	  is_not_full.notify_one();
	}
      }
    });
  
  producer.join();
  consumer.join();
  cout << "Net: " << c << endl;
}