std condition variable ex

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

std::mutex mtx;
std::condition_variable cv;
bool ready = false;

void waiter(int id) {
    std::unique_lock<std::mutex> lock(mtx);
    std::cout << "Thread " << id << " waiting\n";
    cv.wait(lock);
    std::cout << "Thread " << id << " awakened\n";
}

void signaler() {
    std::this_thread::sleep_for(std::chrono::seconds(1));
    {
        std::lock_guard<std::mutex> lock(mtx);
        ready = true;
    }
    for (int i = 0; i < 3; ++i) {
        std::cout << "Signaling...\n";
        cv.notify_one();
        std::this_thread::sleep_for(std::chrono::milliseconds(100));
    }
}

int main() {
    std::vector<std::thread> threads;
    for (int i = 0; i < 5; ++i) {
        threads.emplace_back(waiter, i);
    }
    std::thread s(signaler);

    for (auto& t : threads) t.join();
    s.join();

    return 0;
}