std::shared_lock

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Concurrency support library

Threads

thread

(C++11)

jthread

(C++20)

hardware_destructive_interference_sizehardware_constructive_interference_size

(C++17)(C++17)

this_thread namespace

get_id (C++11)
yield (C++11)

sleep_for (C++11)
sleep_until (C++11)

Cooperative cancellation

stop_token (C++20)
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stoppable_token (C++26)
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stoppable-source (C++26)
stoppable-callback-for (C++26)

Mutual exclusion

mutex (C++11)
recursive_mutex (C++11)
shared_mutex (C++17)

timed_mutex (C++11)
recursive_timed_mutex (C++11)
shared_timed_mutex (C++14)

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lock (C++11)
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shared_lock (C++14)
once_flag (C++11)
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try_lock (C++11)
defer_locktry_to_lockadopt_lockdefer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11)(C++11)(C++11)(C++11)

Condition variables

condition_variable

(C++11)

condition_variable_any

(C++11)

notify_all_at_thread_exit

(C++11)

cv_status

(C++11)

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(C++20)(C++20)

(C++20)

(C++20)

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rcu_obj_base (C++26)
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rcu_synchronize (C++26)
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hazard_pointer_obj_base

(C++26)

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(C++26)

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atomic_storeatomic_store_explicit (C++11)(C++11)
atomic_loadatomic_load_explicit (C++11)(C++11)
atomic_exchangeatomic_exchange_explicit (C++11)(C++11)
atomic_compare_exchange_weakatomic_compare_exchange_weak_explicitatomic_compare_exchange_strongatomic_compare_exchange_strong_explicit (C++11)(C++11)(C++11)(C++11)
atomic_fetch_addatomic_fetch_add_explicit (C++11)(C++11)
atomic_fetch_subatomic_fetch_sub_explicit (C++11)(C++11)
atomic_fetch_andatomic_fetch_and_explicit (C++11)(C++11)
atomic_fetch_oratomic_fetch_or_explicit (C++11)(C++11)
atomic_fetch_xoratomic_fetch_xor_explicit (C++11)(C++11)
atomic_fetch_maxatomic_fetch_max_explicit (C++26)(C++26)
atomic_fetch_minatomic_fetch_min_explicit (C++26)(C++26)
atomic_is_lock_free (C++11)
atomic_waitatomic_wait_explicit (C++20)(C++20)
atomic_notify_one (C++20)
atomic_notify_all (C++20)
Free functions for atomic flags
atomic_flag_test_and_setatomic_flag_test_and_set_explicit (C++11)(C++11)
atomic_flag_clearatomic_flag_clear_explicit (C++11)(C++11)
atomic_flag_testatomic_flag_test_explicit (C++20)(C++20)
atomic_flag_waitatomic_flag_wait_explicit (C++20)(C++20)
atomic_flag_notify_one (C++20)
atomic_flag_notify_all (C++20)

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std::shared_lock

Member functions
shared_lock::shared_lock
shared_lock::~shared_lock
shared_lock::operator=
Shared locking
shared_lock::lock
shared_lock::try_lock
shared_lock::try_lock_for
shared_lock::try_lock_until
shared_lock::unlock
Modifiers
shared_lock::swap
shared_lock::release
Observers
shared_lock::mutex
shared_lock::owns_lock
shared_lock::operator bool
Non-member functions
swap(std::shared_lock)

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Defined in header`<shared_mutex>`
template<class Mutex> class shared_lock;		(since C++14)

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

Theshared_lock class is movable, but not copyable – it meets the requirements ofMoveConstructible andMoveAssignable but not ofCopyConstructible orCopyAssignable.

shared_lock meets theLockable requirements. IfMutex meets theSharedTimedLockable requirements,shared_lock also meetsTimedLockable requirements.

In order to wait in a shared mutex in shared ownership mode,std::condition_variable_any can be used (std::condition_variable requiresstd::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 theSharedLockable 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]