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.
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).
| Mutex | - | the type of the shared mutex to lock. The type must meet the SharedLockable requirements |
| Type | Definition |
|---|---|
mutex_type | Mutex |
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) |
|
Shared locking |
|
| 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) |
|
|
(C++14) | specialization of std::swap for shared_lock (function template) |
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 |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/thread/shared_lock