pingpong_v2

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

std::mutex m1;
std::mutex m2;

void bar(){
    std::unique_lock <std::mutex> lock2(m2, std::defer_lock);
    std::unique_lock <std::mutex> lock1(m1, std::defer_lock);
    for(size_t i = 0; i < 500000; ++i) {
        if(lock1.try_lock()){
            printf("pong\n");
            lock2.unlock();
        }
        std::this_thread::yield();
    }
}

void foo(){
    std::unique_lock <std::mutex> lock1(m1);
    std::unique_lock <std::mutex> lock2(m2, std::defer_lock);
    for(size_t i = 0; i < 500000; ++i) {
        if(lock2.try_lock()){
            printf("ping\n");
            lock1.unlock();
        }
        std::this_thread::yield();
    }
}

int main(int argc, char const *argv[]) {
    std::thread T1 (foo);
    T1.detach();
    std::thread T2 (bar);
    T2.join();
    return 0;
}