//----------------------------------------------------
// mq.cc
//----------------------------------------------------

#include <iostream> // std::cout
#include <mqueue.h> // mq_open, mq_close, mq_recv, mq_send
#include <random>   // std::random_device
#include <string>   // std::string, std::to_string
#include <thread>   // std::thread

//----------------------------------------------------

using namespace std::literals;

//----------------------------------------------------

const size_t N = 8;

//----------------------------------------------------

class mq_mutex
{
public:
    mq_mutex(): path("/mq" + std::to_string(std::random_device{}()))
    {
        mq_attr attr = {.mq_maxmsg = 1, .mq_msgsize = sizeof(buffer)};
        mq_unlink(path.c_str());
        id = mq_open(path.c_str(), O_CREAT | O_RDWR, 0600, &attr);
        unlock();
    }

    ~mq_mutex()
    {
        mq_close(id);
        mq_unlink(path.c_str());
    }

    void lock() { mq_receive(id, &buffer, 1, NULL); }

    void unlock() { mq_send(id, &buffer, 1, 0); }

private:
    std::string path;
    mqd_t id;
    char buffer;
} m;

//----------------------------------------------------

void seccion_critica()
{
    std::cout << "[" << std::this_thread::get_id() << "]: ";
    for (size_t i = 0; i < 10; ++i)
        std::cout << i;
    std::cout << std::endl;
}

//----------------------------------------------------

void hebra()
{
    while (true)
    {
        m.lock();
        seccion_critica();
        m.unlock();
    }
}

//----------------------------------------------------

int main()
{
    std::jthread threads[N];

    for (auto &i : threads)
        i = std::jthread(hebra);
}

//----------------------------------------------------