webaudio: Use std::atomic for atomic operations in AudioDestinationHandler and ReverbInputBuffer.

Bug: 736037
Change-Id: I88d3a6a314fbbf83ca90dd0293b9370f8453ad22
Reviewed-on: https://chromium-review.googlesource.com/c/1348956Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611424}

third_party/blink/renderer/modules/webaudio/audio_destination_node.cc

@@ -30,7 +30,7 @@
 namespace blink {
 
 AudioDestinationHandler::AudioDestinationHandler(AudioNode& node)
-    : AudioHandler(kNodeTypeDestination, node, 0), current_sample_frame_(0) {
+    : AudioHandler(kNodeTypeDestination, node, 0) {
   AddInput();
 }
 

third_party/blink/renderer/modules/webaudio/audio_destination_node.h

@@ -26,8 +26,8 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_DESTINATION_NODE_H_
 #define THIRD_PARTY_BLINK_RENDERER_MODULES_WEBAUDIO_AUDIO_DESTINATION_NODE_H_
 
+#include <atomic>
 #include "third_party/blink/renderer/modules/webaudio/audio_node.h"
-#include "third_party/blink/renderer/platform/wtf/atomics.h"
 
 namespace blink {
 
@@ -54,7 +54,7 @@ class AudioDestinationHandler : public AudioHandler {
   virtual void RestartRendering() = 0;
 
   size_t CurrentSampleFrame() const {
-    return AcquireLoad(&current_sample_frame_);
+    return current_sample_frame_.load(std::memory_order_acquire);
   }
 
   double CurrentTime() const {
@@ -70,10 +70,15 @@ class AudioDestinationHandler : public AudioHandler {
   }
 
  protected:
-  // The number of sample frames processed by the destination so far.
-  size_t current_sample_frame_;
+  void AdvanceCurrentSampleFrame(size_t number_of_frames) {
+    current_sample_frame_.fetch_add(number_of_frames,
+                                    std::memory_order_release);
+  }
 
  private:
+  // The number of sample frames processed by the destination so far.
+  std::atomic_size_t current_sample_frame_{0};
+
   // True if the execution context is being destroyed.  If this is true, the
   // destination ndoe must avoid checking for or accessing the execution
   // context.

third_party/blink/renderer/modules/webaudio/default_audio_destination_node.cc

@@ -35,7 +35,6 @@
 #include "third_party/blink/renderer/platform/audio/audio_utilities.h"
 #include "third_party/blink/renderer/platform/audio/denormal_disabler.h"
 #include "third_party/blink/renderer/platform/instrumentation/tracing/trace_event.h"
-#include "third_party/blink/renderer/platform/wtf/atomics.h"
 
 namespace blink {
 
@@ -198,8 +197,7 @@ void DefaultAudioDestinationHandler::Render(
   Context()->HandlePostRenderTasks(destination_bus);
 
   // Advances the current sample-frame.
-  size_t new_sample_frame = current_sample_frame_ + number_of_frames;
-  ReleaseStore(&current_sample_frame_, new_sample_frame);
+  AdvanceCurrentSampleFrame(number_of_frames);
 
   Context()->UpdateWorkletGlobalScopeOnRenderingThread();
 }

third_party/blink/renderer/modules/webaudio/offline_audio_destination_node.cc

@@ -340,8 +340,7 @@ bool OfflineAudioDestinationHandler::RenderIfNotSuspended(
   Context()->HandlePostOfflineRenderTasks();
 
   // Advance current sample-frame.
-  size_t new_sample_frame = current_sample_frame_ + number_of_frames;
-  ReleaseStore(&current_sample_frame_, new_sample_frame);
+  AdvanceCurrentSampleFrame(number_of_frames);
 
   Context()->UpdateWorkletGlobalScopeOnRenderingThread();
 

third_party/blink/renderer/platform/audio/reverb_input_buffer.h

@@ -29,10 +29,10 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_INPUT_BUFFER_H_
 #define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_REVERB_INPUT_BUFFER_H_
 
+#include <atomic>
 #include "third_party/blink/renderer/platform/audio/audio_array.h"
 #include "third_party/blink/renderer/platform/platform_export.h"
 #include "third_party/blink/renderer/platform/wtf/allocator.h"
-#include "third_party/blink/renderer/platform/wtf/atomics.h"
 #include "third_party/blink/renderer/platform/wtf/noncopyable.h"
 
 namespace blink {
@@ -53,9 +53,8 @@ class PLATFORM_EXPORT ReverbInputBuffer {
   void Write(const float* source_p, size_t number_of_frames);
 
   // Background threads can call this to check if there's anything to read...
-  size_t WriteIndex() const { return AcquireLoad(&write_index_); }
-  void SetWriteIndex(size_t new_index) {
-    ReleaseStore(&write_index_, new_index);
+  size_t WriteIndex() const {
+    return write_index_.load(std::memory_order_acquire);
   }
 
   // The individual background threads read here (and hope that they can keep up
@@ -69,12 +68,16 @@ class PLATFORM_EXPORT ReverbInputBuffer {
   void Reset();
 
  private:
+  void SetWriteIndex(size_t new_index) {
+    write_index_.store(new_index, std::memory_order_release);
+  }
+
   AudioFloatArray buffer_;
 
   // |write_index_| can be accessed from several threads.  Only use
   // the getter and setter to access it atomically.  Don't access
   // directly!
-  size_t write_index_;
+  std::atomic_size_t write_index_;
 };
 
 }  // namespace blink