[thread.sharedtimedmutex.requirements] (original) (raw)

32 Concurrency support library [thread]

32.6 Mutual exclusion [thread.mutex]

32.6.4 Mutex requirements [thread.mutex.requirements]

32.6.4.5 Shared timed mutex types [thread.sharedtimedmutex.requirements]

32.6.4.5.1 General [thread.sharedtimedmutex.requirements.general]

32.6.4.5.2 Class shared_timed_mutex [thread.sharedtimedmutex.class]

32.6.4.5.1 General [thread.sharedtimedmutex.requirements.general]

The standard library type shared_timed_mutex is ashared timed mutex type.

In this description,m denotes an object of a shared timed mutex type,rel_time denotes an object of an instantiation ofduration ([time.duration]), andabs_time denotes an object of an instantiation oftime_point.

The expression m.try_lock_shared_for(rel_time) is well-formed and has the following semantics:

Preconditions: The calling thread has no ownership of the mutex.

Effects: Attempts to obtain shared lock ownership for the calling thread within the relative timeout ([thread.req.timing]) specified by rel_time.

If the time specified by rel_time is less than or equal to rel_time.zero(), the function attempts to obtain ownership without blocking (as if by callingtry_lock_shared()).

The function returns within the timeout specified by rel_time only if it has obtained shared ownership of the mutex object.

[Note 2:

As with try_lock(), there is no guarantee that ownership will be obtained if the lock is available, but implementations are expected to make a strong effort to do so.

— _end note_]

If an exception is thrown then a shared lock has not been acquired for the current thread.

Synchronization: If try_lock_shared_for() returns true, priorunlock() operations on the same object synchronize with ([intro.multithread]) this operation.

Returns: true if the shared lock was acquired, otherwise false.

The expression m.try_lock_shared_until(abs_time) is well-formed and has the following semantics:

Preconditions: The calling thread has no ownership of the mutex.

Effects: The function attempts to obtain shared ownership of the mutex.

Ifabs_time has already passed, the function attempts to obtain shared ownership without blocking (as if by calling try_lock_shared()).

The function returns before the absolute timeout ([thread.req.timing]) specified by abs_time only if it has obtained shared ownership of the mutex object.

[Note 3:

As with try_lock(), there is no guarantee that ownership will be obtained if the lock is available, but implementations are expected to make a strong effort to do so.

— _end note_]

If an exception is thrown then a shared lock has not been acquired for the current thread.

Synchronization: If try_lock_shared_until() returns true, priorunlock() operations on the same object synchronize with ([intro.multithread]) this operation.

Returns: true if the shared lock was acquired, otherwise false.

32.6.4.5.2 Class shared_timed_mutex [thread.sharedtimedmutex.class]

namespace std { class shared_timed_mutex { public: shared_timed_mutex();~shared_timed_mutex(); shared_timed_mutex(const shared_timed_mutex&) = delete; shared_timed_mutex& operator=(const shared_timed_mutex&) = delete;void lock(); bool try_lock();template<class Rep, class Period> bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);template<class Clock, class Duration> bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);void unlock();void lock_shared(); bool try_lock_shared();template<class Rep, class Period> bool try_lock_shared_for(const chrono::duration<Rep, Period>& rel_time);template<class Clock, class Duration> bool try_lock_shared_until(const chrono::time_point<Clock, Duration>& abs_time);void unlock_shared();};}