Move AudioDriver ownership to AudioMixer

src/engine/audio/audio_driver.h

@@ -1,12 +1,8 @@
 #ifndef ENGINE_AUDIO_AUDIO_DRIVER_H
 #define ENGINE_AUDIO_AUDIO_DRIVER_H
 
-#include "engine/audio/audio_driver.h"
-
 namespace eng {
 
-class AudioDriverDelegate;
-
 // Models an audio sink sending mixed audio to the audio driver. Audio data from
 // the mixer source is delivered on a pull model using AudioDriverDelegate.
 class AudioDriver {
@@ -14,12 +10,8 @@ class AudioDriver {
   AudioDriver() = default;
   virtual ~AudioDriver() = default;
 
-  virtual void SetDelegate(AudioDriverDelegate* delegate) = 0;
-
   virtual bool Initialize() = 0;
 
-  virtual void Shutdown() = 0;
-
   virtual void Suspend() = 0;
   virtual void Resume() = 0;
 

src/engine/audio/audio_driver_alsa.cc

@@ -11,17 +11,19 @@ using namespace base;
 
 namespace eng {
 
-AudioDriverAlsa::AudioDriverAlsa() = default;
+AudioDriverAlsa::AudioDriverAlsa(AudioDriverDelegate* delegate)
+    : delegate_(delegate) {}
 
-AudioDriverAlsa::~AudioDriverAlsa() = default;
+AudioDriverAlsa::~AudioDriverAlsa() {
+  LOG << "Shutting down audio.";
 
-void AudioDriverAlsa::SetDelegate(AudioDriverDelegate* delegate) {
-  delegate_ = delegate;
-  Resume();
+  TerminateAudioThread();
+  snd_pcm_drop(device_);
+  snd_pcm_close(device_);
 }
 
 bool AudioDriverAlsa::Initialize() {
-  LOG << "Initializing audio system.";
+  LOG << "Initializing audio.";
 
   int err;
 
@@ -142,13 +144,6 @@ bool AudioDriverAlsa::Initialize() {
   return false;
 }
 
-void AudioDriverAlsa::Shutdown() {
-  LOG << "Shutting down audio system.";
-  TerminateAudioThread();
-  snd_pcm_drop(device_);
-  snd_pcm_close(device_);
-}
-
 void AudioDriverAlsa::Suspend() {
   suspend_audio_thread_.store(true, std::memory_order_relaxed);
 }
@@ -162,15 +157,16 @@ int AudioDriverAlsa::GetHardwareSampleRate() {
 }
 
 void AudioDriverAlsa::StartAudioThread() {
+  DCHECK(!audio_thread_.joinable());
+
   LOG << "Starting audio thread.";
   terminate_audio_thread_.store(false, std::memory_order_relaxed);
-  suspend_audio_thread_.store(delegate_ ? false : true,
-                              std::memory_order_relaxed);
+  suspend_audio_thread_.store(false, std::memory_order_relaxed);
   audio_thread_ = std::thread(&AudioDriverAlsa::AudioThreadMain, this);
 }
 
 void AudioDriverAlsa::TerminateAudioThread() {
-  if (terminate_audio_thread_.load(std::memory_order_relaxed))
+  if (!audio_thread_.joinable())
     return;
 
   LOG << "Terminating audio thread";
@@ -180,6 +176,8 @@ void AudioDriverAlsa::TerminateAudioThread() {
 }
 
 void AudioDriverAlsa::AudioThreadMain() {
+  DCHECK(delegate_);
+
   size_t num_frames = period_size_ / (num_channels_ * sizeof(float));
   auto buffer = std::make_unique<float[]>(num_frames * 2);
 

src/engine/audio/audio_driver_alsa.h

@@ -10,17 +10,15 @@ typedef struct _snd_pcm snd_pcm_t;
 
 namespace eng {
 
+class AudioDriverDelegate;
+
 class AudioDriverAlsa final : public AudioDriver {
  public:
-  AudioDriverAlsa();
+  AudioDriverAlsa(AudioDriverDelegate* delegate);
   ~AudioDriverAlsa() final;
 
-  void SetDelegate(AudioDriverDelegate* delegate) final;
-
   bool Initialize() final;
 
-  void Shutdown() final;
-
   void Suspend() final;
   void Resume() final;
 

src/engine/audio/audio_driver_delegate.h

@@ -10,6 +10,8 @@ class AudioDriverDelegate {
   AudioDriverDelegate() = default;
   virtual ~AudioDriverDelegate() = default;
 
+  virtual int GetChannelCount() = 0;
+
   virtual void RenderAudio(float* output_buffer, size_t num_frames) = 0;
 };
 

src/engine/audio/audio_driver_oboe.cc

@@ -8,28 +8,19 @@ using namespace base;
 
 namespace eng {
 
-AudioDriverOboe::AudioDriverOboe()
-    : callback_(std::make_unique<StreamCallback>(this)) {}
+AudioDriverOboe::AudioDriverOboe(AudioDriverDelegate* delegate)
+    : callback_(std::make_unique<StreamCallback>(this)), delegate_(delegate) {}
 
-AudioDriverOboe::~AudioDriverOboe() = default;
-
-void AudioDriverOboe::SetDelegate(AudioDriverDelegate* delegate) {
-  delegate_ = delegate;
-  stream_->start();
+AudioDriverOboe::~AudioDriverOboe() {
+  LOG << "Shutting down audio.";
+  stream_->stop();
 }
 
 bool AudioDriverOboe::Initialize() {
-  LOG << "Initializing audio system.";
-
+  LOG << "Initializing audio.";
   return RestartStream();
 }
 
-void AudioDriverOboe::Shutdown() {
-  LOG << "Shutting down audio system.";
-
-  stream_->stop();
-}
-
 void AudioDriverOboe::Suspend() {
   stream_->pause();
 }
@@ -70,7 +61,7 @@ bool AudioDriverOboe::RestartStream() {
       builder.setSharingMode(oboe::SharingMode::Exclusive)
           ->setPerformanceMode(oboe::PerformanceMode::LowLatency)
           ->setFormat(oboe::AudioFormat::Float)
-          ->setChannelCount(kChannelCount)
+          ->setChannelCount(delegate_->GetChannelCount())
           ->setDirection(oboe::Direction::Output)
           ->setUsage(oboe::Usage::Game)
           ->setCallback(callback_.get())
@@ -88,8 +79,7 @@ bool AudioDriverOboe::RestartStream() {
     return false;
   }
 
-  if (delegate_)
-    stream_->start();
+  stream_->start();
   return true;
 }
 

src/engine/audio/audio_driver_oboe.h

@@ -10,25 +10,21 @@
 
 namespace eng {
 
+class AudioDriverDelegate;
+
 class AudioDriverOboe final : public AudioDriver {
  public:
-  AudioDriverOboe();
+  AudioDriverOboe(AudioDriverDelegate* delegate);
   ~AudioDriverOboe() final;
 
-  void SetDelegate(AudioDriverDelegate* delegate) final;
-
   bool Initialize() final;
 
-  void Shutdown() final;
-
   void Suspend() final;
   void Resume() final;
 
   int GetHardwareSampleRate() final;
 
  private:
-  static constexpr int kChannelCount = 2;
-
   class StreamCallback final : public oboe::AudioStreamCallback {
    public:
     StreamCallback(AudioDriverOboe* audio);

src/engine/audio/audio_mixer.cc

@@ -7,12 +7,26 @@
 #include "base/thread_pool.h"
 #include "engine/sound.h"
 
+#if defined(__ANDROID__)
+#include "engine/audio/audio_driver_oboe.h"
+#elif defined(__linux__)
+#include "engine/audio/audio_driver_alsa.h"
+#endif
+
 using namespace base;
 
 namespace eng {
 
 AudioMixer::AudioMixer()
-    : main_thread_task_runner_(TaskRunner::GetThreadLocalTaskRunner()) {}
+    : main_thread_task_runner_(TaskRunner::GetThreadLocalTaskRunner()),
+#if defined(__ANDROID__)
+      audio_driver_{std::make_unique<AudioDriverOboe>(this)} {
+#elif defined(__linux__)
+      audio_driver_{std::make_unique<AudioDriverAlsa>(this)} {
+#endif
+  bool res = audio_driver_->Initialize();
+  CHECK(res) << "Failed to initialize audio driver.";
+}
 
 AudioMixer::~AudioMixer() = default;
 
@@ -139,6 +153,18 @@ void AudioMixer::SetEndCallback(uint64_t resource_id, base::Closure cb) {
   it->second->end_cb = std::move(cb);
 }
 
+void AudioMixer::Suspend() {
+  audio_driver_->Suspend();
+}
+
+void AudioMixer::Resume() {
+  audio_driver_->Resume();
+}
+
+int AudioMixer::GetHardwareSampleRate() {
+  return audio_driver_->GetHardwareSampleRate();
+}
+
 void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
   {
     std::unique_lock<std::mutex> scoped_lock(lock_, std::try_to_lock);

src/engine/audio/audio_mixer.h

@@ -16,10 +16,11 @@ class TaskRunner;
 
 namespace eng {
 
+class AudioDriver;
 class Sound;
 
 // Mix and render audio with low overhead. A platform specific AudioDriver
-// implementation is expected to periodically call Render() in a background
+// implementation is expected to periodically call RenderAudio() in a background
 // thread.
 class AudioMixer : public AudioDriverDelegate {
  public:
@@ -44,6 +45,11 @@ class AudioMixer : public AudioDriverDelegate {
 
   void SetEnableAudio(bool enable) { audio_enabled_ = enable; }
 
+  void Suspend();
+  void Resume();
+
+  int GetHardwareSampleRate();
+
  private:
   enum SampleFlags { kLoop = 1, kStopped = 2, kSimulateStereo = 4 };
   static constexpr int kChannelCount = 2;
@@ -80,9 +86,12 @@ class AudioMixer : public AudioDriverDelegate {
 
   base::TaskRunner* main_thread_task_runner_;
 
+  std::unique_ptr<AudioDriver> audio_driver_;
+
   bool audio_enabled_ = true;
 
   // AudioDriverDelegate implementation
+  int GetChannelCount() final { return kChannelCount; }
   void RenderAudio(float* output_buffer, size_t num_frames) final;
 
   void DoStream(std::shared_ptr<Resource> sample, bool loop);

src/engine/engine.cc

@@ -2,7 +2,6 @@
 
 #include "base/log.h"
 #include "engine/animator.h"
-#include "engine/audio/audio_driver.h"
 #include "engine/audio/audio_mixer.h"
 #include "engine/drawable.h"
 #include "engine/font.h"
@@ -26,17 +25,13 @@ namespace eng {
 
 Engine* Engine::singleton = nullptr;
 
-Engine::Engine(Platform* platform,
-               Renderer* renderer,
-               AudioDriver* audio_driver)
+Engine::Engine(Platform* platform, Renderer* renderer)
     : platform_(platform),
       renderer_(renderer),
-      audio_driver_(audio_driver),
       audio_mixer_{std::make_unique<AudioMixer>()} {
   DCHECK(!singleton);
   singleton = this;
 
-  audio_driver_->SetDelegate(audio_mixer_.get());
   renderer_->SetContextLostCB(std::bind(&Engine::ContextLost, this));
 
   quad_ = CreateRenderResource<Geometry>();
@@ -143,14 +138,14 @@ void Engine::Draw(float frame_frac) {
 }
 
 void Engine::LostFocus() {
-  audio_driver_->Suspend();
+  audio_mixer_->Suspend();
 
   if (game_)
     game_->LostFocus();
 }
 
 void Engine::GainedFocus(bool from_interstitial_ad) {
-  audio_driver_->Resume();
+  audio_mixer_->Resume();
 
   if (game_)
     game_->GainedFocus(from_interstitial_ad);
@@ -488,7 +483,7 @@ const std::string& Engine::GetSharedDataPath() const {
 }
 
 int Engine::GetAudioHardwareSampleRate() {
-  return audio_driver_->GetHardwareSampleRate();
+  return audio_mixer_->GetHardwareSampleRate();
 }
 
 bool Engine::IsMobile() const {

src/engine/engine.h

@@ -16,7 +16,6 @@ class TextureCompressor;
 namespace eng {
 
 class Animator;
-class AudioDriver;
 class AudioMixer;
 class Font;
 class Game;
@@ -34,7 +33,7 @@ class Engine {
  public:
   using CreateImageCB = std::function<std::unique_ptr<Image>()>;
 
-  Engine(Platform* platform, Renderer* renderer, AudioDriver* audio_driver);
+  Engine(Platform* platform, Renderer* renderer);
   ~Engine();
 
   static Engine& Get();
@@ -176,9 +175,9 @@ class Engine {
 
   Platform* platform_ = nullptr;
   Renderer* renderer_ = nullptr;
-  AudioDriver* audio_driver_ = nullptr;
 
   std::unique_ptr<AudioMixer> audio_mixer_;
+
   std::unique_ptr<Game> game_;
 
   std::unique_ptr<Geometry> quad_;

src/engine/platform/platform.cc

@@ -6,12 +6,6 @@
 #include "engine/renderer/opengl/renderer_opengl.h"
 #include "engine/renderer/vulkan/renderer_vulkan.h"
 
-#if defined(__ANDROID__)
-#include "engine/audio/audio_driver_oboe.h"
-#elif defined(__linux__)
-#include "engine/audio/audio_driver_alsa.h"
-#endif
-
 #define USE_VULKAN_RENDERER 1
 
 using namespace base;
@@ -47,14 +41,6 @@ void Platform::InitializeCommon() {
   thread_pool_.Initialize();
   TaskRunner::CreateThreadLocalTaskRunner();
 
-#if defined(__ANDROID__)
-  audio_driver_ = std::make_unique<AudioDriverOboe>();
-#elif defined(__linux__)
-  audio_driver_ = std::make_unique<AudioDriverAlsa>();
-#endif
-  bool res = audio_driver_->Initialize();
-  CHECK(res) << "Failed to initialize audio driver.";
-
 #if (USE_VULKAN_RENDERER == 1)
   renderer_ = std::make_unique<RendererVulkan>();
 #else
@@ -65,13 +51,12 @@ void Platform::InitializeCommon() {
 void Platform::ShutdownCommon() {
   LOG << "Shutting down platform.";
 
-  audio_driver_->Shutdown();
   renderer_->Shutdown();
 }
 
 void Platform::RunMainLoop() {
   engine_ =
-      std::make_unique<Engine>(this, renderer_.get(), audio_driver_.get());
+      std::make_unique<Engine>(this, renderer_.get());
   bool res = engine_->Initialize();
   CHECK(res) << "Failed to initialize the engine.";
 

src/engine/platform/platform.h

@@ -24,7 +24,6 @@ struct ANativeWindow;
 
 namespace eng {
 
-class AudioDriver;
 class Renderer;
 class Engine;
 
@@ -79,7 +78,6 @@ class Platform {
   bool has_focus_ = false;
   bool should_exit_ = false;
 
-  std::unique_ptr<AudioDriver> audio_driver_;
   std::unique_ptr<Renderer> renderer_;
   std::unique_ptr<Engine> engine_;