NAME¶

std::stop_source::request_stop - std::stop_source::request_stop

Synopsis¶

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

Issues a stop request to the stop-state, if the stop_source object has a stop-state
and 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
stop_tokens and stop_sources of the same stop-state;
* request_stop() can be concurrently invoked on other stop_source objects, and
only one will actually perform the stop request.

However, see the Notes section.

Parameters¶

(none)

Return value¶

true if the stop_source object has a stop-state and this invocation made a stop
request, otherwise false.

Postconditions¶

stop_possible() is false or stop_requested() is true.

Notes¶

If the request_stop() does issue a stop request (i.e., returns true), then any
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 the stop_source object has a stop-state but a stop request has already been made,
this function returns false. However there is no guarantee that another stop_source
object which has just (successfully) requested stop is not still in the middle of
invoking a 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 stop_tokens associated with the stop_source's stop-state will
be notified.

Example¶

This section is incomplete
Reason: no example