How do I use condition variables with unique_lock?

Can you explain how to use condition variables with unique_lock in C++?

Sure! Condition variables are used for signaling between threads. When using them with unique_lock, you can safely manage access to shared resources.

What is the difference between unique_lock and lock_guard?

The main difference is that unique_lock allows more flexibility, such as deferred locking and unlocking, while lock_guard is simpler and automatically unlocks when it goes out of scope.

Can you provide a code example?

Absolutely! Here's a simple example:

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

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

void worker() {
    std::unique_lock<std::mutex> lock(mtx);
    cv.wait(lock, [] { return ready; });
    std::cout << "Worker thread is running!" << std::endl;
}

int main() {
    std::thread t(worker);
    {
        std::lock_guard<std::mutex> lock(mtx);
        ready = true;
    }
    cv.notify_one();
    t.join();
    return 0;
}

This code demonstrates a worker thread waiting for a signal to proceed.

What happens if I don't use unique_lock with condition variables?

If you don't use unique_lock, you may encounter issues with thread safety and deadlocks, as condition variables require a unique_lock to manage the mutex properly.