tmp/tmpdisjdmxq/{from.md → to.md}
RENAMED
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| 1 |
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##### General <a id="thread.lock.shared.general">[[thread.lock.shared.general]]</a>
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``` cpp
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namespace std {
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template<class Mutex>
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class shared_lock {
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public:
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using mutex_type = Mutex;
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// [thread.lock.shared.cons], construct/copy/destroy
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shared_lock() noexcept;
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explicit shared_lock(mutex_type& m); // blocking
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shared_lock(mutex_type& m, defer_lock_t) noexcept;
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shared_lock(mutex_type& m, try_to_lock_t);
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shared_lock(mutex_type& m, adopt_lock_t);
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template<class Clock, class Duration>
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shared_lock(mutex_type& m, const chrono::time_point<Clock, Duration>& abs_time);
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template<class Rep, class Period>
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shared_lock(mutex_type& m, const chrono::duration<Rep, Period>& rel_time);
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~shared_lock();
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shared_lock(const shared_lock&) = delete;
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shared_lock& operator=(const shared_lock&) = delete;
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shared_lock(shared_lock&& u) noexcept;
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shared_lock& operator=(shared_lock&& u) noexcept;
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// [thread.lock.shared.locking], locking
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void lock(); // blocking
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bool try_lock();
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template<class Rep, class Period>
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bool try_lock_for(const chrono::duration<Rep, Period>& rel_time);
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template<class Clock, class Duration>
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bool try_lock_until(const chrono::time_point<Clock, Duration>& abs_time);
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void unlock();
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// [thread.lock.shared.mod], modifiers
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void swap(shared_lock& u) noexcept;
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mutex_type* release() noexcept;
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// [thread.lock.shared.obs], observers
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bool owns_lock() const noexcept;
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explicit operator bool () const noexcept;
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mutex_type* mutex() const noexcept;
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private:
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mutex_type* pm; // exposition only
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bool owns; // exposition only
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};
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}
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```
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An object of type `shared_lock` controls the shared ownership of a
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lockable object within a scope. Shared ownership of the lockable object
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| 55 |
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may be acquired at construction or after construction, and may be
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transferred, after acquisition, to another `shared_lock` object. Objects
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of type `shared_lock` are not copyable but are movable. The behavior of
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a program is undefined if the contained pointer `pm` is not null and the
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lockable object pointed to by `pm` does not exist for the entire
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remaining lifetime [[basic.life]] of the `shared_lock` object. The
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supplied `Mutex` type shall meet the *Cpp17SharedLockable* requirements
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[[thread.req.lockable.shared]].
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[*Note 1*: `shared_lock<Mutex>` meets the *Cpp17Lockable* requirements
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[[thread.req.lockable.req]]. If `Mutex` meets the
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*Cpp17SharedTimedLockable* requirements
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[[thread.req.lockable.shared.timed]], `shared_lock<Mutex>` also meets
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the *Cpp17TimedLockable* requirements
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[[thread.req.lockable.timed]]. — *end note*]
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