In 11b8bbe one thing that was claimed was that we now properly set the
Notifier's actual fd on the NotifierActivationEvent. It turns out that
claim was false because a crucial step was forgotten: actually set the
m_notifier_fd when registering. Despite that mistake, it ultimately was
irrelevant as the methods on NotifierActivationEvent are currently
unused code. We were posting the event to the correct Notifier receiver
so the on_activation was still getting invoked.
Given they are unused, NotifierActivationEvent can be defined the same
way as TimerEvent is, where we just pass the event type enum to the
Event base class. Additionally, NotificationType can be moved to
the Notifier header as this enum is now always used in the context of
creating or using a Notifier instance.
This commit changes the event loop to use IOCPs instead of
WaitForMultipleObjects to wait on events. This is done through the Nt
kernel api NtAssociateWaitCompletionPacket which associates an event
with a completion packet. Each completion packet notifies only once, as
they are normally used to signal completion of an operation so to use
them for notifiers they are associated again after each time they are
triggered.
There are more optimizations that can be done, such as reusing the
EventLoopNotifier and EventLoopTimer structures to reduce the number of
allocations and context switches for timer and notifier registration.
If a file descriptor is being closed, we need to permanently disable
any Notifier and remove it from the event loop. This method removes
the notifier and disables it so that the EventLoop does not use a
invalid file descriptor.
