33 Concurrency support library [thread]

33.6 Mutual exclusion [thread.mutex]

33.6.5 Locks [thread.lock]

33.6.5.5 Class template shared_lock [thread.lock.shared]

33.6.5.5.2 Constructors, destructor, and assignment [thread.lock.shared.cons]

shared_lock() noexcept;
Postconditions: pm == nullptr and owns == false.
explicit shared_lock(mutex_type& m);
Effects: Calls m.lock_shared().
Postconditions: pm == addressof(m) and owns == true.
shared_lock(mutex_type& m, defer_lock_t) noexcept;
Postconditions: pm == addressof(m) and owns == false.
shared_lock(mutex_type& m, try_to_lock_t);
Effects: Calls m.try_lock_shared().
Postconditions: pm == addressof(m) and owns == res where res is the value returned by the call to m.try_lock_shared().
shared_lock(mutex_type& m, adopt_lock_t);
Preconditions: The calling thread holds a shared lock on m.
Postconditions: pm == addressof(m) and owns == true.
template<class Clock, class Duration> shared_lock(mutex_type& m, const chrono::time_point<Clock, Duration>& abs_time);
Preconditions: Mutex meets the Cpp17SharedTimedLockable requirements ([thread.req.lockable.shared.timed]).
Effects: Calls m.try_lock_shared_until(abs_time).
Postconditions: pm == addressof(m) and owns == res where res is the value returned by the call to m.try_lock_shared_until(abs_time).
template<class Rep, class Period> shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
Preconditions: Mutex meets the Cpp17SharedTimedLockable requirements ([thread.req.lockable.shared.timed]).
Effects: Calls m.try_lock_shared_for(rel_time).
Postconditions: pm == addressof(m) and owns == res where res is the value returned by the call to m.try_lock_shared_for(rel_time).
~shared_lock();
Effects: If owns calls pm->unlock_shared().
shared_lock(shared_lock&& sl) noexcept;
Postconditions: pm == sl_p.pm and owns == sl_p.owns (where sl_p is the state of sl just prior to this construction), sl.pm == nullptr and sl.owns == false.
shared_lock& operator=(shared_lock&& sl) noexcept;
Effects: If owns calls pm->unlock_shared().
Postconditions: pm == sl_p.pm and owns == sl_p.owns (where sl_p is the state of sl just prior to this assignment), sl.pm == nullptr and sl.owns == false.