std::defer_lock, std::try_to_lock, std::adopt_lock

 

C++

Язык

Понятия (концепции)

Утилиты

Строки

Контейнеры

Алгоритмы

Итераторы

Работа с числами

Ввод / вывод

Локализация

Регулярные выражения (C++11)

Атомарные примитивы (C++11)

Потоки (C++11)

 

Библиотека поддержки потоков

Потоки Original: Threads The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
thread (C++11)
this_thread имен Original: this_thread namespace The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
get_id (C++11) yield (C++11)	sleep_for (C++11) sleep_until (C++11)
Взаимное исключение Original: Mutual exclusion The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
mutex (C++11) timed_mutex (C++11)	recursive_mutex (C++11) recursive_timed_mutex (C++11)
Generic управления замком Original: Generic lock management The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
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)
Условия переменных Original: Condition variables The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
condition_variable (C++11)
condition_variable_any (C++11)
notify_all_at_thread_exit (C++11)
cv_status (C++11)
Futures Original: Futures The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
promise (C++11) future (C++11) shared_future (C++11) packaged_task (C++11) async (C++11)	launch (C++11) future_status (C++11) future_error (C++11) future_category (C++11) future_errc (C++11)

 

constexpr std::defer_lock_t defer_lock = std::defer_lock_t();		(начиная с C++11)
constexpr std::try_to_lock_t try_to_lock = std::try_to_lock_t();		(начиная с C++11)
constexpr std::adopt_lock_t adopt_lock = std::adopt_lock_t();		(начиная с C++11)

std::defer_lock, std::try_to_lock and std::adopt_lock are instances of empty struct tag types std::defer_lock_t, std::try_to_lock_t and std::adopt_lock_t respectively.

They are used to specify locking strategies for std::lock_guard and std::unique_lock.

Type Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Effect(s)
defer_lock_t	не приобретают права собственности на мьютекс Original: do not acquire ownership of the mutex The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
try_to_lock_t	попробуйте приобрести в собственность мьютекса без блокирования Original: try to acquire ownership of the mutex without blocking The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.
adopt_lock_t	Предположим, вызывающий поток уже имеет собственность на мьютекс Original: assume the calling thread already has ownership of the mutex The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.

Пример

#include <mutex>
#include <thread>
 
struct bank_account {
    explicit bank_account(int balance) : balance(balance) {}
    int balance;
    std::mutex m;
};
 
void transfer(bank_account &from, bank_account &to, int amount)
{
    // attempt to lock both mutexes without deadlock
    std::lock(from.m, to.m);
 
    // make sure both already-locked mutexes are unlocked when
    // we're done; if we just used the lock_guard without std::lock
    // and std::adopt_lock, we might deadlock with other calls to transfer
    std::lock_guard lock1(from.m, std::adopt_lock);
    std::lock_guard lock2(to.m, std::adopt_lock);
 
    from.balance -= amount;
    to.balance += amount;
}
 
int main()
{
    bank_account my_account(100);
    bank_account your_account(50);
 
    std::thread t1(transfer, my_account, your_account, 10);
    std::thread t2(transfer, your_account, my_account, 5);
 
    t1.join();
    t2.join();
}

См. также

defer_lock_t try_to_lock_t adopt_lock_t	тип тега используется для указания замок стратегии Original: tag type used to specify locking strategy The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (класс)
(constructor)	строит lock_guard, необязательно блокировки данного мьютекса Original: constructs a lock_guard, optionally locking the given mutex The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (public функция-член std::lock_guard)
(constructor)	строит unique_lock, необязательно блокировки поставляется мьютекс Original: constructs a unique_lock, optionally locking the supplied mutex The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (public функция-член std::unique_lock)