Concurrency support library
(C++11)(deprecated in C++20)
(C++11)(deprecated in C++20)
(C++11)(deprecated in C++26)
(C++11)(C++11)(C++11)(C++11)
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std::shared_lock
Member functions
Shared locking
Modifiers
Observers
Non-member functions
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
constructs a
shared_lock, optionally locking the supplied mutex
(public member function) [edit]
unlocks the associated mutex
(public member function) [edit]
unlocks the mutex, if owned, and acquires ownership of another
(public member function) [edit]
Shared locking
locks the associated mutex
(public member function) [edit]
tries to lock the associated mutex
(public member function) [edit]
tries to lock the associated mutex, for the specified duration
(public member function) [edit]
tries to lock the associated mutex, until a specified time point
(public member function) [edit]
unlocks the associated mutex
(public member function) [edit]
Modifiers
swaps the data members with another
shared_lock (public member function) [edit]
disassociates the mutex without unlocking
(public member function) [edit]
Observers
returns a pointer to the associated mutex
(public member function) [edit]
tests whether the lock owns its associated mutex
(public member function) [edit]
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.
| DR
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Applied to
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Behavior as published
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Correct behavior
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| LWG 2981
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C++17
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redundant deduction guide from shared_lock<Mutex> was provided
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removed
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