std::shared_lock - cppreference.com (original) (raw)

| | | | | -------------------------------------------- | | ------------- | | template< class Mutex > class shared_lock; | | (since C++14) |

The class shared_lock is a general-purpose shared mutex ownership wrapper allowing deferred locking, timed locking and transfer of lock ownership. Locking a shared_lock locks the associated shared mutex in shared mode (to lock it in exclusive mode, std::unique_lock can be used).

The shared_lock class is movable, but not copyable – it meets the requirements of MoveConstructible and MoveAssignable but not of CopyConstructible or CopyAssignable.

shared_lock meets the Lockable requirements. If Mutex meets the SharedTimedLockable requirements, shared_lock also meets TimedLockable requirements.

In order to wait in a shared mutex in shared ownership mode, std::condition_variable_any can be used (std::condition_variable requires std::unique_lock and so can only wait in unique ownership mode).

[edit] Template parameters

Mutex	-	the type of the shared mutex to lock. The type must meet the SharedLockable requirements

[edit] Member types

Type	Definition
mutex_type	Mutex

[edit] Member functions

(constructor)	constructs a shared_lock, optionally locking the supplied mutex (public member function) [edit]
(destructor)	unlocks the associated mutex (public member function) [edit]
operator=	unlocks the mutex, if owned, and acquires ownership of another (public member function) [edit]
Shared locking
lock	locks the associated mutex (public member function) [edit]
try_lock	tries to lock the associated mutex (public member function) [edit]
try_lock_for	tries to lock the associated mutex, for the specified duration (public member function) [edit]
try_lock_until	tries to lock the associated mutex, until a specified time point (public member function) [edit]
unlock	unlocks the associated mutex (public member function) [edit]
Modifiers
swap	swaps the data members with another shared_lock (public member function) [edit]
release	disassociates the mutex without unlocking (public member function) [edit]
Observers
mutex	returns a pointer to the associated mutex (public member function) [edit]
owns_lock	tests whether the lock owns its associated mutex (public member function) [edit]
operator bool	tests whether the lock owns its associated mutex (public member function) [edit]

[edit] Non-member functions

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.