When a child process terminates on Windows, the QWinEventNotifier
emits the activated signal it its event handler. Before this
happens, we need to call setEnabled(false) to unregister the
wait object from the Windows thread pool. setEnabled(false)
also causes us to wait for any outstanding callbacks to complete
and then prevents QWinEventNotifier from trying to use the closed
handle.
This seems to follow the pattern from Qt where the destructor also
calls setEnabled(false) before destruction.
This commit splits out synchronization primitives from LibThreading into
LibSync. This is because LibThreading depends on LibCore, while LibCore
needs the synchronization primitives from LibThreading. This worked
while they were header only, but when I tried to add an implementation
file it ran into the circular dependency. To abstract away the pthread
implementation using cpp files is necessary so the synchronization
primitives were moved to a separate library.
Qt does not use IOCP's in their underlying Windows event loop
implementation; however, QWinEventNotifier allows us to register a wait
on a process handle that has SYNCHRONIZE access rights. This means an
event will be signalled when that process terminates which emits the
QWinEventNotifier::activated signal.
Co-authored-by: Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
Add a thread-safe deferred_invoke() API on WeakEventLoopReference that
queues work onto the owning thread's event queue and wakes that thread
via EventLoopManager hooks. This avoids calling wake() from foreign
threads during teardown.
Implement current_thread_handle()/wake_thread() in each backend and
track per-thread data so handles are validated before waking:
- Unix: wake via per-thread wake pipe
- Windows: wake via thread wake event
- macOS: wake via stored CFRunLoopRef
- Qt: wake via event target or QEventLoop::wakeUp()
- Android: wake via stored ALooper
Once upon a time, we needed the UI-specific event loops outside of the
UI process. This is no longer the case. Let's move the event loops back
to the UI folder to remove the awkward interface library we were left
with.
We currently compile the Qt event loop files multiple times, for every
target which wants to use them. This patch moves these to LibWebView as
a central location to avoid this.
