std::try_lock

 

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lock_guard (C++11) unique_lock (C++11) defer_lock_t try_to_lock_t adopt_lock_t (C++11) (C++11) (C++11)	lock (C++11) try_lock (C++11) defer_lock try_to_lock adopt_lock (C++11) (C++11) (C++11)
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Defined in header <mutex>
template< class Lockable1, class Lockable2, class LockableN... > int try_lock( Lockable1& lock1, Lockable2& lock2, LockableN& lockn... );		(depuis C++11)

Essaie de verrouiller chacun des objets donnés Lockable lock1, lock2, ..., lockn en appelant try_lock ordre en commençant avec le premier .

Original:

Tries to lock each of the given Lockable objects lock1, lock2, ..., lockn by calling try_lock in order beginning with the first.

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Si un appel à try_lock échoue, unlock est appelée pour tous les objets verrouillés et un indice basé sur 0 de l'objet qui a échoué à verrouiller est retourné .

Original:

If a call to try_lock fails, unlock is called for any locked objects and a 0-based index of the object that failed to lock is returned.

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Si un appel aux résultats try_lock une exception, unlock est appelée pour tous les objets verrouillés avant rethrowing .

Original:

If a call to try_lock results in an exception, unlock is called for any locked objects before rethrowing.

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Paramètres

lock1, lock2, ... , lockn

-

l'Lockable objets à verrouiller Original: the Lockable objects to lock The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Retourne la valeur

-1 en cas de succès, ou la valeur d'index basée sur 0 de l'objet qui a échoué pour verrouiller .

Original:

-1 on success, or 0-based index value of the object that failed to lock.

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Exemple

L'exemple suivant utilise std::try_lock périodiquement de pointage et compteurs de reset en cours d'exécution dans des threads séparés .

Original:

The following example uses std::try_lock to periodically tally and reset counters running in separate threads.

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#include <mutex>
#include <vector>
#include <thread>
#include <iostream>
#include <functional>
#include <chrono>
 
int main()
{
    int foo_count = 0;
    std::mutex foo_count_mutex;
    int bar_count = 0;
    std::mutex bar_count_mutex;
    int overall_count = 0;
    bool done = false;
    std::mutex done_mutex;
 
    auto increment = [](int &counter, std::mutex &m,  const char *desc) {
        for (int i = 0; i < 10; ++i) {
            std::unique_lock<std::mutex> lock(m);
            ++counter;
            std::cout << desc << ": " << counter << '\n';
            lock.unlock();
            std::this_thread::sleep_for(std::chrono::seconds(1));
        }
    };
 
    std::thread increment_foo(increment, std::ref(foo_count), 
        std::ref(foo_count_mutex), "foo");
    std::thread increment_bar(increment, std::ref(bar_count), 
        std::ref(bar_count_mutex), "bar");
 
    std::thread update_overall([&]() {
        done_mutex.lock();
        while (!done) {
            done_mutex.unlock();
            int result = std::try_lock(foo_count_mutex, bar_count_mutex);
            if (result == -1) {
                overall_count += foo_count + bar_count;
                foo_count = 0;
                bar_count = 0;
                std::cout << "overall: " << overall_count << '\n';
                foo_count_mutex.unlock();
                bar_count_mutex.unlock();
            }
            std::this_thread::sleep_for(std::chrono::seconds(2));
            done_mutex.lock();
        }
        done_mutex.unlock();
    });
 
    increment_foo.join();
    increment_bar.join();
    done_mutex.lock();
    done = true;
    done_mutex.unlock();
    update_overall.join();
 
    std::cout << "Done processing\n"
              << "foo: " << foo_count << '\n'
              << "bar: " << bar_count << '\n'
              << "overall: " << overall_count << '\n';
}

Résultat possible :

bar: 1
foo: 1
foo: 2
bar: 2
foo: 3
overall: 5
bar: 1
foo: 1
bar: 2
foo: 2
bar: 3
overall: 10
bar: 1
foo: 1
bar: 2
foo: 2
overall: 14
bar: 1
foo: 1
bar: 2
overall: 17
foo: 1
bar: 1
foo: 2
overall: 20
Done processing
foo: 0
bar: 0
overall: 20

Voir aussi

lock (C++11)	verrouille les mutex, les blocs spécifiés le cas échéant ne sont pas disponibles Original: locks specified mutexes, blocks if any are unavailable The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (fonction générique)