std::jthread::request_stop

 

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bool request_stop() noexcept;		(since C++20)

Issues a stop request to the internal stop-state, if it has not yet already had stop requested.

The determination is made atomically, and if stop was requested, the stop-state is atomically updated to avoid race conditions, such that:

• stop_requested() and stop_possible() can be concurrently invoked on other std::stop_tokens and std::stop_sources of the same shared stop-state
• request_stop() can be concurrently invoked from multiple threads on the same jthread object or on other std::stop_source objects associated with the same stop-state, and only one will actually perform the stop request

However, see the Notes section.

Parameters

(none)

Return value

true if this invocation made a stop request, otherwise false

Postconditions

For a std::stop_token retrieved by get_stop_token() or a std::stop_source retrieved by get_stop_source(), stop_requested() is true.

Notes

If the request_stop() does issue a stop request (i.e., returns true), then any std::stop_callbacks registered for the same associated stop-state will be invoked synchronously, on the same thread request_stop() is issued on. If an invocation of a callback exits via an exception, std::terminate is called.

If a stop request has already been made, this function returns false. However there is no guarantee that another thread or std::stop_source object which has just (successfully) requested stop for the same stop-state is not still in the middle of invoking a std::stop_callback function.

If the request_stop() does issue a stop request (i.e., returns true), then all condition variables of base type std::condition_variable_any registered with an interruptible wait for std::stop_tokens associated with the jthread's internal stop-state will be awoken.