// g++ -std=c++11 -o pub_sub pub_sub.cpp -lzmq -lpthread

#include <iostream>
#include <thread>
#include <zmq.hpp>

std::string address("tcp://127.0.0.1:5566");
zmq::context_t ctx;

void subscriber(void)
{

    zmq::socket_t socket(ctx, ZMQ_SUB);

    int timeout(5000);
    socket.setsockopt(ZMQ_RCVTIMEO, &timeout, sizeof(timeout));
    socket.setsockopt(ZMQ_SUBSCRIBE, nullptr, 0);

    socket.bind(address);

    zmq::message_t msg;

    std::cout << "Wait for message." << std::endl;
    if (socket.recv(&msg)) {
        std::cout << "Got message." << std::endl;
    }
    else {
        std::cerr << "Timeout waiting for message." << std::endl;
    }
}

int main ()
{
    std::thread sub(subscriber);

    // allow subscriber to bind() and recv()
    std::this_thread::sleep_for(std::chrono::milliseconds(1));

    zmq::socket_t socket(ctx, ZMQ_PUB);
    socket.connect(address);

    // no message is received if this sleep is removed
    std::this_thread::sleep_for(std::chrono::milliseconds(1));

    zmq::message_t msg(0);
    if (socket.send(msg)) {
        std::cout << "Sent message." << std::endl;
    }
    else {
        std::cerr << "Failed to send message." << std::endl;
    }

    sub.join();

    return 0;
}