32 Thread support library [thread]

32.5 Mutual exclusion [thread.mutex]

32.5.5 Locks [thread.lock]

32.5.5.4 Class template unique_­lock [thread.lock.unique]

32.5.5.4.2 Constructors, destructor, and assignment [thread.lock.unique.cons]

unique_lock() noexcept;
Postconditions: pm == 0 and owns == false.
explicit unique_lock(mutex_type& m);
Effects: Calls m.lock().
Postconditions: pm == addressof(m) and owns == true.
unique_lock(mutex_type& m, defer_lock_t) noexcept;
Postconditions: pm == addressof(m) and owns == false.
unique_lock(mutex_type& m, try_to_lock_t);
Preconditions: The supplied Mutex type meets the Cpp17Lockable requirements ([thread.req.lockable.req]).
Effects: Calls m.try_­lock().
Postconditions: pm == addressof(m) and owns == res, where res is the value returned by the call to m.try_­lock().
unique_lock(mutex_type& m, adopt_lock_t);
Preconditions: The calling thread holds a non-shared lock on m.
Postconditions: pm == addressof(m) and owns == true.
Throws: Nothing.
template<class Clock, class Duration> unique_lock(mutex_type& m, const chrono::time_point<Clock, Duration>& abs_time);
Preconditions: The supplied Mutex type meets the Cpp17TimedLockable requirements ([thread.req.lockable.timed]).
Effects: Calls m.try_­lock_­until(abs_­time).
Postconditions: pm == addressof(m) and owns == res, where res is the value returned by the call to m.try_­lock_­until(abs_­time).
template<class Rep, class Period> unique_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
Preconditions: The supplied Mutex type meets the Cpp17TimedLockable requirements ([thread.req.lockable.timed]).
Effects: Calls m.try_­lock_­for(rel_­time).
Postconditions: pm == addressof(m) and owns == res, where res is the value returned by the call to m.try_­lock_­for(rel_­time).
unique_lock(unique_lock&& u) noexcept;
Postconditions: pm == u_­p.pm and owns == u_­p.owns (where u_­p is the state of u just prior to this construction), u.pm == 0 and u.owns == false.
unique_lock& operator=(unique_lock&& u);
Effects: If owns calls pm->unlock().
Postconditions: pm == u_­p.pm and owns == u_­p.owns (where u_­p is the state of u just prior to this construction), u.pm == 0 and u.owns == false.
[Note 1:
With a recursive mutex it is possible for both *this and u to own the same mutex before the assignment.
In this case, *this will own the mutex after the assignment and u will not.
— end note]
Throws: Nothing.
~unique_lock();
Effects: If owns calls pm->unlock().