std::unique_lock<Mutex>:: lock

Verrouille (c'est-à-dire prend possession de) le mutex associé. Appelle effectivement mutex ( ) - > lock ( ) .

Paramètres

(aucun)

Valeur de retour

(aucun)

Exceptions

• Toute exception levée par mutex ( ) - > lock ( ) .

• S'il n'y a pas de mutex associé, std::system_error avec un code d'erreur de std::errc::operation_not_permitted .

• Si le mutex est déjà verrouillé par ce unique_lock (en d'autres termes, owns_lock() est true ), std::system_error avec un code d'erreur de std::errc::resource_deadlock_would_occur .

Exemple

#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();
}

0, initial counter: 1
1, initial counter: 2
2, initial counter: 3
3, initial counter: 4
4, initial counter: 5
5, initial counter: 6
6, initial counter: 7
7, initial counter: 8
8, initial counter: 9
9, initial counter: 10
6, final counter: 11
3, final counter: 12
4, final counter: 13
2, final counter: 14
5, final counter: 15
0, final counter: 16
1, final counter: 17
7, final counter: 18
9, final counter: 19
8, final counter: 20

Voir aussi