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std::shared_lock

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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.

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).

Contents

[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

(C++14)
 specializes the std::swap algorithm
(function template) [edit]

[edit] 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
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