Bug 1993981 - Implement nsIDirectTaskDispatcher for MediaTrackGraphImpl. r=karlt

Differential Revision: https://phabricator.services.mozilla.com/D277174

Author: Pehrsons

dom/media/MediaTrackGraph.cpp

@@ -183,6 +183,9 @@ MediaTrackGraphImpl::~MediaTrackGraphImpl() {
   MOZ_ASSERT(mTracks.IsEmpty() && mSuspendedTracks.IsEmpty(),
              "All tracks should have been destroyed by messages from the main "
              "thread");
+  MOZ_ASSERT(
+      mDirectMessages.IsEmpty(),
+      "All direct tasks should have been drained in the final iteration");
   LOG(LogLevel::Debug, ("MediaTrackGraph {} destroyed", fmt::ptr(this)));
   LOG(LogLevel::Debug, ("MediaTrackGraphImpl::~MediaTrackGraphImpl"));
 }
@@ -1251,14 +1254,7 @@ void MediaTrackGraphImpl::ProduceDataForTracksBlockByBlock(
 void MediaTrackGraphImpl::RunMessageAfterProcessing(
     already_AddRefed<nsIRunnable> aMessage) {
   MOZ_ASSERT(OnGraphThread());
-
-  if (mFrontMessageQueue.IsEmpty()) {
-    mFrontMessageQueue.AppendElement();
-  }
-
-  // Only one block is used for messages from the graph thread.
-  MOZ_ASSERT(mFrontMessageQueue.Length() == 1);
-  mFrontMessageQueue[0].mMessages.AppendElement(std::move(aMessage));
+  DispatchDirectTask(std::move(aMessage));
 }
 
 void MediaTrackGraphImpl::RunMessagesInQueue() {
@@ -1632,9 +1628,7 @@ auto MediaTrackGraphImpl::OneIterationImpl(
 
   ProcessChunkMetadata(oldProcessedTime);
 
-  // Process graph messages queued from RunMessageAfterProcessing() on this
-  // thread during the iteration.
-  RunMessagesInQueue();
+  DrainDirectTasks();
 
   if (!UpdateMainThreadState()) {
     if (Switching()) {
@@ -3597,8 +3591,9 @@ void MediaTrackGraph::ForceShutDown() {
   graph->ForceShutDown();
 }
 
-NS_IMPL_ISUPPORTS(MediaTrackGraphImpl, nsIMemoryReporter, nsIObserver,
-                  nsIThreadObserver, nsITimerCallback, nsINamed)
+NS_IMPL_ISUPPORTS(MediaTrackGraphImpl, nsIDirectTaskDispatcher,
+                  nsIMemoryReporter, nsIObserver, nsIThreadObserver,
+                  nsITimerCallback, nsINamed)
 
 NS_IMETHODIMP
 MediaTrackGraphImpl::CollectReports(nsIHandleReportCallback* aHandleReport,
@@ -4377,6 +4372,42 @@ NS_IMETHODIMP
 MediaTrackGraphImpl::AfterProcessNextEvent(nsIThreadInternal*, bool) {
   return NS_OK;
 }
+
+// nsIDirectTaskDispatcher methods
+
+NS_IMETHODIMP
+MediaTrackGraphImpl::DispatchDirectTask(already_AddRefed<nsIRunnable> aTask) {
+  MOZ_ASSERT(OnGraphThread());
+  nsCOMPtr task = aTask;
+  PROFILER_MARKER("MediaTrackGraphImpl::DispatchDirectTask", OTHER,
+                  {MarkerStack::Capture()}, FlowMarker,
+                  Flow::FromPointer(task.get()));
+  mDirectMessages.AppendElement(task.forget());
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MediaTrackGraphImpl::DrainDirectTasks() {
+  MOZ_ASSERT(OnGraphThread());
+  // Run all tasks in mDirectMessages. This continues even if one direct task
+  // adds another.
+  for (size_t i = 0; i < mDirectMessages.Length(); ++i) {
+    nsCOMPtr<nsIRunnable> message = std::move(mDirectMessages[i]);
+    AUTO_PROFILE_FOLLOWING_RUNNABLE(message);
+    message->Run();
+  }
+  mDirectMessages.ClearAndRetainStorage();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+MediaTrackGraphImpl::HaveDirectTasks(bool* aResult) {
+  if (!OnGraphThread()) {
+    return NS_ERROR_FAILURE;
+  }
+  *aResult = !mDirectMessages.IsEmpty();
+  return NS_OK;
+}
 }  // namespace mozilla
 
 #undef LOG

dom/media/MediaTrackGraphImpl.h

@@ -7,7 +7,6 @@
 
 #include <atomic>
 
-#include "AsyncLogger.h"
 #include "AudioMixer.h"
 #include "DeviceInputTrack.h"
 #include "GraphDriver.h"
@@ -17,7 +16,7 @@
 #include "mozilla/Monitor.h"
 #include "mozilla/TimeStamp.h"
 #include "mozilla/UniquePtr.h"
-#include "nsClassHashtable.h"
+#include "nsIDirectTaskDispatcher.h"
 #include "nsIMemoryReporter.h"
 #include "nsINamed.h"
 #include "nsIRunnable.h"
@@ -106,6 +105,7 @@ class MessageBlock {
  */
 class MediaTrackGraphImpl : public MediaTrackGraph,
                             public GraphInterface,
+                            public nsIDirectTaskDispatcher,
                             public nsIMemoryReporter,
                             public nsIObserver,
                             public nsIThreadObserver,
@@ -116,6 +116,7 @@ class MediaTrackGraphImpl : public MediaTrackGraph,
   using ControlMessageWrapper = MediaTrack::ControlMessageWrapper;
 
   NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIDIRECTTASKDISPATCHER
   NS_DECL_NSIMEMORYREPORTER
   NS_DECL_NSIOBSERVER
   NS_DECL_NSITHREADOBSERVER
@@ -869,6 +870,12 @@ class MediaTrackGraphImpl : public MediaTrackGraph,
    * A list of batches of messages to process. Each batch is processed
    * as an atomic unit.
    */
+  /*
+   * Queue of direct messages added by the currently processed MessageBlock.
+   * Processed by the MTG thread at the end of an iteration.
+   * Accessed on graph thread only.
+   */
+  nsTArray<nsCOMPtr<nsIRunnable>> mDirectMessages;
   /*
    * Message queue processed by the MTG thread during an iteration.
    * Accessed on graph thread only.