Implement tail processing for AudioNodes

third_party/WebKit/Source/modules/webaudio/AudioNode.cpp

Index: third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
index 64cc1d575fa39161d2f8b3260d2c130396d932dd..1debbd08aab14746a0eab08410784ad308644af3 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
@@ -90,8 +90,6 @@ void AudioHandler::Uninitialize() {
   is_initialized_ = false;
 }
 
-void AudioHandler::ClearInternalStateWhenDisabled() {}
-
 void AudioHandler::Dispose() {
   DCHECK(IsMainThread());
   DCHECK(Context()->IsGraphOwner());
@@ -325,12 +323,6 @@ void AudioHandler::ProcessIfNecessary(size_t frames_to_process) {
     PullInputs(frames_to_process);
 
     bool silent_inputs = InputsAreSilent();
-    if (!silent_inputs) {
-      last_non_silent_time_ =
-          (Context()->CurrentSampleFrame() + frames_to_process) /
-          static_cast<double>(Context()->sampleRate());
-    }
-
     if (silent_inputs && PropagatesSilence()) {
       SilenceOutputs();
       // AudioParams still need to be processed so that the value can be updated
@@ -345,6 +337,15 @@ void AudioHandler::ProcessIfNecessary(size_t frames_to_process) {
       UnsilenceOutputs();
       Process(frames_to_process);
     }
+
+    if (!silent_inputs) {
+      // Update last_non_silent_time AFTER processing this block.
+      // Doing it before causes PropagateSilence to be one render
+      // quantum longer than necessary.
+      last_non_silent_time_ =
+          (Context()->CurrentSampleFrame() + frames_to_process) /
+          static_cast<double>(Context()->sampleRate());
+    }
   }
 }
 
@@ -402,6 +403,10 @@ void AudioHandler::EnableOutputsIfNecessary() {
 }
 
 void AudioHandler::DisableOutputsIfNecessary() {
+  // This function calls other functions that require graph ownership,
+  // so assert that this needs graph ownership too.
+  DCHECK(Context()->IsGraphOwner());
+
   // Disable outputs if appropriate. We do this if the number of connections is
   // 0 or 1. The case of 0 is from deref() where there are no connections left.
   // The case of 1 is from AudioNodeInput::disable() where we want to disable
@@ -418,36 +423,35 @@ void AudioHandler::DisableOutputsIfNecessary() {
     // they're connected to.  disable() can recursively deref connections (and
     // call disable()) down a whole chain of connected nodes.
 
-    // TODO(rtoy,hongchan): we need special cases the convolver, delay, biquad,
-    // and IIR since they have a significant tail-time and shouldn't be
-    // disconnected simply because they no longer have any input connections.
-    // This needs to be handled more generally where AudioNodes have a tailTime
-    // attribute. Then the AudioNode only needs to remain "active" for tailTime
-    // seconds after there are no longer any active connections.
-    //
-    // The analyser node also requires special handling because we
-    // need the internal state to be updated for the time and FFT data
-    // even if it has no connections.
-    if (GetNodeType() != kNodeTypeConvolver &&
-        GetNodeType() != kNodeTypeDelay &&
-        GetNodeType() != kNodeTypeBiquadFilter &&
-        GetNodeType() != kNodeTypeIIRFilter &&
-        GetNodeType() != kNodeTypeAnalyser) {
-      is_disabled_ = true;
-      ClearInternalStateWhenDisabled();
-      for (auto& output : outputs_)
-        output->Disable();
+    // If a node requires tail processing, we defer the disabling of
+    // the outputs so that the tail for the node can be output.
+    // Otherwise, we can disable the outputs right away.
+    if (RequiresTailProcessing()) {
+      if (Context()->ContextState() !=
+          BaseAudioContext::AudioContextState::kClosed) {
+        Context()->GetDeferredTaskHandler().AddTailProcessingNode(this);
+      }
+    } else {
+      ReallyDisableOutputs();
     }
   }
 }
 
+void AudioHandler::ReallyDisableOutputs() {
+  is_disabled_ = true;
+  for (auto& output : outputs_)
+    output->Disable();
+}
+
 void AudioHandler::MakeConnection() {
   AtomicIncrement(&connection_ref_count_);
 
+  Context()->GetDeferredTaskHandler().RemoveTailProcessingNode(this);
+
 #if DEBUG_AUDIONODE_REFERENCES
-  fprintf(stderr, "[%16p]: %16p: %2d: AudioHandler::ref   %3d [%3d]\n",
+  fprintf(stderr, "[%16p]: %16p: %2d: AudioHandler::ref   %3d [%3d] @%.15g\n",
           Context(), this, GetNodeType(), connection_ref_count_,
-          node_count_[GetNodeType()]);
+          node_count_[GetNodeType()], Context()->currentTime());
 #endif
   // See the disabling code in disableOutputsIfNecessary(). This handles
   // the case where a node is being re-connected after being used at least
@@ -483,9 +487,9 @@ void AudioHandler::BreakConnectionWithLock() {
   AtomicDecrement(&connection_ref_count_);
 
 #if DEBUG_AUDIONODE_REFERENCES
-  fprintf(stderr, "[%16p]: %16p: %2d: AudioHandler::deref %3d [%3d]\n",
+  fprintf(stderr, "[%16p]: %16p: %2d: AudioHandler::deref %3d [%3d] @%.15g\n",
           Context(), this, GetNodeType(), connection_ref_count_,
-          node_count_[GetNodeType()]);
+          node_count_[GetNodeType()], Context()->currentTime());
 #endif
 
   if (!connection_ref_count_)
@@ -511,6 +515,31 @@ void AudioHandler::PrintNodeCounts() {
 
 #endif  // DEBUG_AUDIONODE_REFERENCES
 
+#if DEBUG_AUDIONODE_REFERENCES > 1
+void AudioHandler::TailProcessingDebug(const char* note) {
+  fprintf(stderr, "[%16p]: %16p: %2d: %s %d @%.15g", Context(), this,
+          GetNodeType(), note, connection_ref_count_, Context()->currentTime());
+
+  // If we're on the audio thread, we can print out the tail and
+  // latency times (because these methods can only be called from the
+  // audio thread.)
+  if (Context()->IsAudioThread()) {
+    fprintf(stderr, ", tail=%.15g + %.15g, last=%.15g\n", TailTime(),
+            LatencyTime(), last_non_silent_time_);
+  }
+
+  fprintf(stderr, "\n");
+}
+
+void AudioHandler::AddTailProcessingDebug() {
+  TailProcessingDebug("addTail");
+}
+
+void AudioHandler::RemoveTailProcessingDebug() {
+  TailProcessingDebug("remTail");
+}
+#endif  // DEBUG_AUDIONODE_REFERENCES > 1
+
 void AudioHandler::UpdateChannelCountMode() {
   channel_count_mode_ = new_channel_count_mode_;
   UpdateChannelsForInputs();