Code snippet with elementary stuff needed to send messages throug a queue to a thread to dispatch tasks.

producer-consumer-queue.cc

#include <iostream>
#include <thread>
#include <future>
#include <functional>
#include <queue>
#include <format>

#include <csignal>

using namespace std::chrono_literals;

template<typename T>
void Consumer(std::mutex& mutex, std::queue<T>& queue) {
    while (1) {
        mutex.lock();
        if (!queue.empty()) {
            auto msg = queue.front();
            std::cout << msg << std::endl;
            queue.pop();
        }
        mutex.unlock();
        std::this_thread::sleep_for(5ms);
    }
}

template<typename T>
void Producer(std::mutex& mutex, std::queue<T>& queue) {
    int count = 0;
    while (1) {
        mutex.lock();
        queue.push(count++);
        mutex.unlock();
        std::this_thread::sleep_for(100ms);
    }
}

std::queue<int> queue;

int main() {
    std::mutex mutex;

    auto producer   = std::thread(Producer<int>, std::ref(mutex), std::ref(queue));
    auto consumer_1 = std::thread(Consumer<int>, std::ref(mutex), std::ref(queue));
    auto consumer_2 = std::thread(Consumer<int>, std::ref(mutex), std::ref(queue));

    signal(SIGINT, [](int sig) {
            std::cout << std::format("SIGINT - queue.size()={}\n", queue.size());
            abort();
    });

    consumer_1.detach();
    consumer_2.detach();
    producer.join();
    return 0;
}