mfmediaengine: Don't send event notify when engine is shutdown.

I've also tried saving a cancel cookie from `BeginCreateObject*` and using it to cancel the operation in engine shutdown. However there are 2 problems: 1. Callback might still get called after `CancelObjectCreation`. Microsoft's [own documentation](https://learn.microsoft.com/en-us/windows/win32/api/mfidl/nf-mfidl-imfsourceresolver-cancelobjectcreation) says as much: > Because these methods are asynchronous, however, they might be completed before the > operation can be canceled. Therefore, your callback might still be invoked after you > call this method. 2. Our implementations of `BeginCreateObject*` are not cancellable. They call either `MFPutWorkItem` or `IMFByteStream_BeginRead`, neight of which provides cancellation. (and our `CancelObjectCreation` doesn't actually work. AsyncResult objects aren't added to `handler->results` list until they are completed, which means any attempts to cancel an yet-to-be-completed object creation will always fail with `MF_E_UNEXPECTED`)

mfmediaengine: Don't send event notify when engine is shutdown.
e8943a64 · Yuxuan Shui · Alexandre Julliard · d0400e56 · e8943a64
Commit e8943a64 authored Oct 17, 2023 by Yuxuan Shui Committed by Alexandre Julliard Oct 27, 2023
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main.c dlls/mfmediaengine/main.c +6 -0

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--- a/dlls/mfmediaengine/main.c
+++ b/dlls/mfmediaengine/main.c
@@ -1356,6 +1356,12 @@ static HRESULT WINAPI media_engine_load_handler_Invoke(IMFAsyncCallback *iface, 

    EnterCriticalSection(&engine->cs);

+    if (engine->flags & FLAGS_ENGINE_SHUT_DOWN)
+    {
+        LeaveCriticalSection(&engine->cs);
+        return S_OK;
+    }
+
    engine->network_state = MF_MEDIA_ENGINE_NETWORK_LOADING;
    IMFMediaEngineNotify_EventNotify(engine->callback, MF_MEDIA_ENGINE_EVENT_LOADSTART, 0, 0);