33 Concurrency support library [thread]

33.3 Stop tokens [thread.stoptoken]

33.3.5 Class template stop_callback [stopcallback]

33.3.5.2 Constructors and destructor [stopcallback.cons]

template<class C>
explicit stop_callback(const stop_token& st, C&& cb)
  noexcept(is_nothrow_constructible_v<Callback, C>);
template<class C>
explicit stop_callback(stop_token&& st, C&& cb)
  noexcept(is_nothrow_constructible_v<Callback, C>);

Constraints: Callback and C satisfy constructible_from<Callback, C>.

Preconditions: Callback and C model constructible_from<Callback, C>.

Effects: Initializes callback with std::forward<C>(cb).

If st.stop_requested() is true, then std::forward<Callback>(callback)() is evaluated in the current thread before the constructor returns.

Otherwise, if st has ownership of a stop state, acquires shared ownership of that stop state and registers the callback with that stop state such that std::forward<Callback>(callback)() is evaluated by the first call to request_stop() on an associated stop_source.

Throws: Any exception thrown by the initialization of callback.

Remarks: If evaluating std::forward<Callback>(callback)() exits via an exception, then terminate is invoked ([except.terminate]).

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~stop_callback();

Effects: Unregisters the callback from the owned stop state, if any.

The destructor does not block waiting for the execution of another callback registered by an associated stop_callback.

If callback is concurrently executing on another thread, then the return from the invocation of callback strongly happens before ([intro.races]) callback is destroyed.

If callback is executing on the current thread, then the destructor does not block ([defns.block]) waiting for the return from the invocation of callback.

Releases ownership of the stop state, if any.