Add WebThread in AudioDestination to support AudioWorkletThread

third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/audio/PushPullFIFO.h"
 
 #include <memory>
 #include "platform/audio/AudioUtilities.h"
 #include "platform/wtf/PtrUtil.h"
 
 namespace blink {
 
 namespace {
 
 // Suppress the warning log if over/underflow happens more than 100 times.
 const unsigned kMaxMessagesToLog = 100;
 }
 
 const size_t PushPullFIFO::kMaxFIFOLength = 65536;
 
 PushPullFIFO::PushPullFIFO(unsigned number_of_channels, size_t fifo_length)
-    : fifo_length_(fifo_length),
-      frames_available_(0),
-      index_read_(0),
-      index_write_(0),
-      overflow_count_(0),
-      underflow_count_(0) {
+    : fifo_length_(fifo_length) {
   CHECK_LE(fifo_length_, kMaxFIFOLength);
   fifo_bus_ = AudioBus::Create(number_of_channels, fifo_length_);
 }
 
 PushPullFIFO::~PushPullFIFO() {}
 
-// Push the data from |inputBus| to FIFO. The size of push is determined by
-// the length of |inputBus|.
+// Push the data from |input_bus| to FIFO. The size of push is determined by
+// the length of |input_bus|.
 void PushPullFIFO::Push(const AudioBus* input_bus) {
+  MutexLocker locker(lock_);
+
   CHECK(input_bus);
   CHECK_EQ(input_bus->length(), AudioUtilities::kRenderQuantumFrames);
   SECURITY_CHECK(input_bus->length() <= fifo_length_);
   SECURITY_CHECK(index_write_ < fifo_length_);
 
   const size_t input_bus_length = input_bus->length();
   const size_t remainder = fifo_length_ - index_write_;
 
   for (unsigned i = 0; i < fifo_bus_->NumberOfChannels(); ++i) {
     float* fifo_bus_channel = fifo_bus_->Channel(i)->MutableData();
     const float* input_bus_channel = input_bus->Channel(i)->Data();
     if (remainder >= input_bus_length) {
       // The remainder is big enough for the input data.
       memcpy(fifo_bus_channel + index_write_, input_bus_channel,
              input_bus_length * sizeof(*fifo_bus_channel));
     } else {
       // The input data overflows the remainder size. Wrap around the index.
       memcpy(fifo_bus_channel + index_write_, input_bus_channel,
              remainder * sizeof(*fifo_bus_channel));
       memcpy(fifo_bus_channel, input_bus_channel + remainder,
              (input_bus_length - remainder) * sizeof(*fifo_bus_channel));
     }
   }
 
   // Update the write index; wrap it around if necessary.
   index_write_ = (index_write_ + input_bus_length) % fifo_length_;
 
-  // In case of overflow, move the |indexRead| to the updated |indexWrite| to
-  // avoid reading overwritten frames by the next pull.
+  // In case of overflow, move the |index_read_| to the updated |index_write_|
+  // to avoid reading overwritten frames by the next pull.
   if (input_bus_length > fifo_length_ - frames_available_) {
     index_read_ = index_write_;
     if (++overflow_count_ < kMaxMessagesToLog) {
       LOG(WARNING) << "PushPullFIFO: overflow while pushing ("
                    << "overflowCount=" << overflow_count_
                    << ", availableFrames=" << frames_available_
                    << ", inputFrames=" << input_bus_length
                    << ", fifoLength=" << fifo_length_ << ")";
     }
   }
 
   // Update the number of frames available in FIFO.
   frames_available_ =
       std::min(frames_available_ + input_bus_length, fifo_length_);
   DCHECK_EQ((index_read_ + frames_available_) % fifo_length_, index_write_);
 }
 
-// Pull the data out of FIFO to |outputBus|. If remaining frame in the FIFO
+// Pull the data out of FIFO to |output_bus|. If remaining frame in the FIFO
 // is less than the frames to pull, provides remaining frame plus the silence.
-void PushPullFIFO::Pull(AudioBus* output_bus, size_t frames_requested) {
+size_t PushPullFIFO::Pull(AudioBus* output_bus, size_t frames_requested) {
+  MutexLocker locker(lock_);
+
 #if OS(ANDROID)
   if (!output_bus) {
     // Log when outputBus or FIFO object is invalid. (crbug.com/692423)
     LOG(WARNING) << "[WebAudio/PushPullFIFO::pull <" << static_cast<void*>(this)
                  << ">] |outputBus| is invalid.";
     // Silently return to avoid crash.
-    return;
+    return 0;
   }
 
   // The following checks are in place to catch the inexplicable crash.
   // (crbug.com/692423)
   if (frames_requested > output_bus->length()) {
     LOG(WARNING) << "[WebAudio/PushPullFIFO::pull <" << static_cast<void*>(this)
                  << ">] framesRequested > outputBus->length() ("
                  << frames_requested << " > " << output_bus->length() << ")";
   }
   if (frames_requested > fifo_length_) {
     LOG(WARNING) << "[WebAudio/PushPullFIFO::pull <" << static_cast<void*>(this)
                  << ">] framesRequested > m_fifoLength (" << frames_requested
                  << " > " << fifo_length_ << ")";
   }
   if (index_read_ >= fifo_length_) {
     LOG(WARNING) << "[WebAudio/PushPullFIFO::pull <" << static_cast<void*>(this)
                  << ">] m_indexRead >= m_fifoLength (" << index_read_
                  << " >= " << fifo_length_ << ")";
   }
 #endif
+
   CHECK(output_bus);
   SECURITY_CHECK(frames_requested <= output_bus->length());
   SECURITY_CHECK(frames_requested <= fifo_length_);
   SECURITY_CHECK(index_read_ < fifo_length_);
 
   const size_t remainder = fifo_length_ - index_read_;
   const size_t frames_to_fill = std::min(frames_available_, frames_requested);
 
   for (unsigned i = 0; i < fifo_bus_->NumberOfChannels(); ++i) {
     const float* fifo_bus_channel = fifo_bus_->Channel(i)->Data();
@@ skipping 32 matching lines @@
                    << "underflowCount=" << underflow_count_
                    << ", availableFrames=" << frames_available_
                    << ", requestedFrames=" << frames_requested
                    << ", fifoLength=" << fifo_length_ << ")";
     }
   }
 
   // Update the number of frames in FIFO.
   frames_available_ -= frames_to_fill;
   DCHECK_EQ((index_read_ + frames_available_) % fifo_length_, index_write_);
+
+  // |frames_requested > frames_available_| means the frames in FIFO is not
+  // enough to fulfill the requested frames from the audio device.
+  return frames_requested > frames_available_
+      ? frames_requested - frames_available_
+      : 0;
 }
 
 const PushPullFIFOStateForTest PushPullFIFO::GetStateForTest() const {
-  return {length(),     NumberOfChannels(), FramesAvailable(), index_read_,
+  return {length(),     NumberOfChannels(), frames_available_, index_read_,
           index_write_, overflow_count_,    underflow_count_};
 }
 
 }  // namespace blink