Method WaitForIO

library/cpp/coroutine/engine/impl.cpp:164–204

}

void TContExecutor::WaitForIO() {
    while (Ready_.Empty() && !WaitQueue_.Empty()) {
        const auto now = Now();

        // Waking a coroutine puts it into ReadyNext_ list
        const auto next = WaitQueue_.WakeTimedout(now);

        if (!UserEvents_.Empty()) {
            TIntrusiveList<IUserEvent> userEvents;
            userEvents.Swap(UserEvents_);
            do {
                userEvents.PopFront()->Execute();
            } while (!userEvents.Empty());
        }

        // Polling will return as soon as there is an event to process or a timeout.
        // If there are woken coroutines we do not want to sleep in the poller
        //      yet still we want to check for new io
        //      to prevent ourselves from locking out of io by constantly waking coroutines.

        if (ReadyNext_.Empty()) {
            if (EnterPollerCallback_) {
                EnterPollerCallback_->OnEnterPoller();
            }
            Poll(next);
            if (EnterPollerCallback_) {
                EnterPollerCallback_->OnExitPoller();
            }
        } else if (LastPoll_ + TDuration::MilliSeconds(5) < now) {
            if (EnterPollerCallback_) {
                EnterPollerCallback_->OnEnterPoller();
            }
            Poll(now);
            if (EnterPollerCallback_) {
                EnterPollerCallback_->OnExitPoller();
            }
        }

        Ready_.Append(ReadyNext_);
    }
}

void TContExecutor::Poll(TInstant deadline) {
    Poller_.Wait(PollerEvents_, deadline);