Closes#22653
After some investigation, I found this bug is due to that sometimes
`foreground_task` is not dispatched to the main thread unless there is
user input. The current Windows implementation works as follows: when
the `WindowsDispatcher` receives a `foreground_task`, it adds the task
to a queue and uses `SetEvent(dispatch_event)` to notify the main
thread.
The main thread then listens for notifications using
`MsgWaitForMultipleObjects(&[dispatch_event])`.
Essentially, this is a synchronous method, but it is not robust. For
example, if 100 `foreground_task`s are sent, `dispatch_event` should
theoretically be triggered 100 times, and
`MsgWaitForMultipleObjects(&[dispatch_event])` should receive 100
notifications, causing the main thread to execute all 100 tasks.
However, in practice, some `foreground_task`s may not get a chance to
execute due to certain reasons.
As shown in the attached video, when I don't move the mouse, there are
about 20-30 `foreground_task`s waiting in the queue to be executed. When
I move the mouse, `run_foreground_tasks()` is called, which processes
the tasks in the queue.
https://github.com/user-attachments/assets/83cd09ca-4b17-4a1f-9a2a-5d1569b23483
To address this, this PR adopts an approach similar to `winit`. In
`winit`, an invisible window is created for message passing. In this PR,
we use `PostThreadMessage` to directly send messages to the main thread.
With this implementation, when 100 `foreground_task`s are sent, the
`WindowsDispatcher` uses `PostThreadMessageW(thread_id,
RUNNABLE_DISPATCHED)` to notify the main thread. This approach enqueues
100 `RUNNABLE_DISPATCHED` messages in the main thread's message queue,
ensuring that each `foreground_task` is executed as expected. The main
thread continuously processes these messages, guaranteeing that all 100
tasks are executed.
Release Notes:
- N/A
728a874b1e