std::unique_lock<Mutex>::lock

Since C++11

Locks (i.e., takes ownership of) the associated mutex. Effectively calls mutex()->lock().

# Declarations

void lock();

(since C++11)

# Return value

(none)

# Example

#include <chrono>
#include <iostream>
#include <mutex>
#include <thread>
#include <vector>
 
int main()
{
    int counter = 0;
    std::mutex counter_mutex;
    std::vector<std::thread> threads;
 
    auto worker_task = [&](int id)
    {
        std::unique_lock<std::mutex> lock(counter_mutex);
        ++counter;
        std::cout << id << ", initial counter: " << counter << '\n';
        lock.unlock();
 
        // don't hold the lock while we simulate an expensive operation
        std::this_thread::sleep_for(std::chrono::seconds(1));
 
        lock.lock();
        ++counter;
        std::cout << id << ", final counter: " << counter << '\n';
    };
 
    for (int i = 0; i < 10; ++i)
        threads.emplace_back(worker_task, i);
 
    for (auto& thread : threads)
        thread.join();
}

# See also