std::shared_lock
| Defined in header <shared_mutex>
|
||
| 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.
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)
Template parameters
| Mutex | - | the type of the shared mutex to lock. The type must meet the SharedMutex requirements |
Member types
| Type | Definition |
mutex_type
|
Mutex |
Member functions
constructs a shared_lock, optionally locking the supplied mutex (public member function) | |
| unlocks the associated mutex (public member function) | |
| unlocks the mutex, if owned, and acquires ownership of another (public member function) | |
| | |
| locks the associated mutex (public member function) | |
| tries to lock the associated mutex (public member function) | |
| tries to lock the associated mutex, for the specified duration (public member function) | |
| tries to lock the associated mutex, until a specified time point (public member function) | |
| unlocks the associated mutex (public member function) | |
Modifiers | |
| swaps the data members with another shared_lock (public member function) | |
| disassociates the mutex without unlocking (public member function) | |
Observers | |
| returns a pointer to the associated mutex (public member function) | |
| tests whether the lock owns its associated mutex (public member function) | |
| tests whether the lock owns its associated mutex (public member function) | |
Non-member functions
specialization of std::swap for shared_lock (function template) |
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2981 | C++17 | redundant deduction guide from shared_lock<Mutex> was provided
|
removed |