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

[Alexandre Julliard]

Module: wine
Branch: master
Commit: e8943a64635a330ad23a3ce4957e7c6dcee8e6df
URL:    https://gitlab.winehq.org/wine/wine/-/commit/e8943a64635a330ad23a3ce4957e7c6...

Author: Yuxuan Shui 
Date:   Tue Oct 17 20:40:44 2023 +0100

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-imfsource...)
     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`)

---

dlls/mfmediaengine/main.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/dlls/mfmediaengine/main.c b/dlls/mfmediaengine/main.c
index 0d553a40a7e..d8694cf6011 100644
--- 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);