How do I use unique_lock in C++?

What is unique_lock in C++ and how do I use it?

unique_lock is a smart pointer that manages a mutex, providing more flexibility than lock_guard. You can use it to lock and unlock a mutex manually.

Can you show me a simple example of using unique_lock?

Sure! Here's a basic example:

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

std::mutex mtx;

void printThreadId(int id) {
    std::unique_lock<std::mutex> lock(mtx);
    std::cout << "Thread ID: " << id << std::endl;
}

int main() {
    std::thread threads[5];
    for (int i = 0; i < 5; ++i) {
        threads[i] = std::thread(printThreadId, i);
    }
    for (auto& th : threads) {
        th.join();
    }
    return 0;
}

This code creates multiple threads that safely print their IDs.

What are the advantages of using unique_lock over lock_guard?

The main advantages of unique_lock are its ability to lock and unlock the mutex multiple times and its support for deferred locking, which allows you to control when the mutex is locked.

Are there any drawbacks to using unique_lock?

Yes, unique_lock has a slightly higher overhead compared to lock_guard due to its additional features. If you don't need those features, lock_guard might be a better choice.