[PATCH v3 5/9] mf: Handle media source EndGetEvent() failure due to shutdown.

[Conor McCarthy]

From: Conor McCarthy

Windows robustly handles asynchronous shutdown of a media source used in
a session.
---
 dlls/mf/session.c | 59 +++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/dlls/mf/session.c b/dlls/mf/session.c
index e24cc6376b4..67af5ade4ae 100644
--- a/dlls/mf/session.c
+++ b/dlls/mf/session.c
@@ -1001,6 +1001,54 @@ static void session_flush_nodes(struct media_session *session)
     }
 }

+static void session_purge_pending_commands(struct media_session *session)
+{
+    struct session_op *op, *op2;
+
+    /* Purge all commands which are no longer valid after a forced source shutdown.
+     * Calling Stop() in this case is not required in native Windows. */
+    LIST_FOR_EACH_ENTRY_SAFE(op, op2, &session->commands, struct session_op, entry)
+    {
+        if (op->command == SESSION_CMD_CLEAR_TOPOLOGIES || op->command == SESSION_CMD_SET_TOPOLOGY
+                || op->command == SESSION_CMD_CLOSE || op->command == SESSION_CMD_SHUTDOWN)
+            continue;
+        list_remove(&op->entry);
+        IUnknown_Release(&op->IUnknown_iface);
+    }
+}
+
+static void session_reset(struct media_session *session)
+{
+    /* Media sessions in native Windows are not consistently usable after a
+     * forced source shutdown, but we try to clean up as well as possible. */
+    session->state = SESSION_STATE_STOPPED;
+    session_clear_presentation(session);
+    session_purge_pending_commands(session);
+    session_command_complete(session);
+}
+
+static void session_handle_source_shutdown(struct media_session *session)
+{
+    EnterCriticalSection(&session->cs);
+
+    /* When stopping the session, MESessionStopped is sent without waiting
+     * for MESourceStopped, so we need do nothing in that case. */
+    switch (session->state)
+    {
+        case SESSION_STATE_STARTING_SOURCES:
+        case SESSION_STATE_RESTARTING_SOURCES:
+            IMFMediaEventQueue_QueueEventParamVar(session->event_queue, MESessionStarted, &GUID_NULL,
+                    MF_E_INVALIDREQUEST, NULL);
+            break;
+        default:
+            break;
+    }
+
+    session_reset(session);
+
+    LeaveCriticalSection(&session->cs);
+}
+
 static void session_start(struct media_session *session, const GUID *time_format, const PROPVARIANT *start_position)
 {
     struct media_source *source;
@@ -4050,8 +4098,15 @@ static HRESULT WINAPI session_events_callback_Invoke(IMFAsyncCallback *iface, IM

if (FAILED(hr = IMFMediaEventGenerator_EndGetEvent(event_source, result, &event)))
     {
-        WARN("Failed to get event from %p, hr %#lx.\n", event_source, hr);
-        IMFMediaEventQueue_QueueEventParamVar(session->event_queue, MEError, &GUID_NULL, hr, NULL);
+        if (hr == MF_E_SHUTDOWN)
+        {
+            session_handle_source_shutdown(session);
+        }
+        else
+        {
+            WARN("Failed to get event from %p, hr %#lx.\n", event_source, hr);
+            IMFMediaEventQueue_QueueEventParamVar(session->event_queue, MEError, &GUID_NULL, hr, NULL);
+        }
         IMFMediaEventGenerator_Release(event_source);
         return hr;
     }