Android: Get rid of OpenSLESStream's global state

Not sure if we're ever going to want to have more than one of these at
the same time, but these global variables are a code smell nonetheless.

I'm also deleting the existing member variables because they were
unused.

Source/Core/AudioCommon/OpenSLESStream.cpp

@@ -14,34 +14,19 @@
 #include "Common/Logging/Log.h"
 #include "Core/ConfigManager.h"
 
-// engine interfaces
-static SLObjectItf engineObject;
-static SLEngineItf engineEngine;
-static SLObjectItf outputMixObject;
-
-// buffer queue player interfaces
-static SLObjectItf bqPlayerObject = nullptr;
-static SLPlayItf bqPlayerPlay;
-static SLAndroidSimpleBufferQueueItf bqPlayerBufferQueue;
-static SLVolumeItf bqPlayerVolume;
-static Mixer* g_mixer;
-#define BUFFER_SIZE 512
-#define BUFFER_SIZE_IN_SAMPLES (BUFFER_SIZE / 2)
-
-// Double buffering.
-static short buffer[2][BUFFER_SIZE];
-static int curBuffer = 0;
-
-static void bqPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void* context)
+void OpenSLESStream::BQPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void* context)
 {
-  ASSERT(bq == bqPlayerBufferQueue);
-  ASSERT(nullptr == context);
+  reinterpret_cast<OpenSLESStream*>(context)->PushSamples(bq);
+}
+
+void OpenSLESStream::PushSamples(SLAndroidSimpleBufferQueueItf bq)
+{
+  ASSERT(bq == m_bq_player_buffer_queue);
 
   // Render to the fresh buffer
-  g_mixer->Mix(reinterpret_cast<short*>(buffer[curBuffer]), BUFFER_SIZE_IN_SAMPLES);
-  SLresult result =
-      (*bqPlayerBufferQueue)->Enqueue(bqPlayerBufferQueue, buffer[curBuffer], sizeof(buffer[0]));
-  curBuffer ^= 1;  // Switch buffer
+  m_mixer->Mix(reinterpret_cast<short*>(m_buffer[m_current_buffer]), BUFFER_SIZE_IN_SAMPLES);
+  SLresult result = (*bq)->Enqueue(bq, m_buffer[m_current_buffer], sizeof(m_buffer[0]));
+  m_current_buffer ^= 1;  // Switch buffer
 
   // Comment from sample code:
   // the most likely other result is SL_RESULT_BUFFER_INSUFFICIENT,
@@ -53,15 +38,15 @@ bool OpenSLESStream::Init()
 {
   SLresult result;
   // create engine
-  result = slCreateEngine(&engineObject, 0, nullptr, 0, nullptr, nullptr);
+  result = slCreateEngine(&m_engine_object, 0, nullptr, 0, nullptr, nullptr);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*engineObject)->Realize(engineObject, SL_BOOLEAN_FALSE);
+  result = (*m_engine_object)->Realize(m_engine_object, SL_BOOLEAN_FALSE);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*engineObject)->GetInterface(engineObject, SL_IID_ENGINE, &engineEngine);
+  result = (*m_engine_object)->GetInterface(m_engine_object, SL_IID_ENGINE, &m_engine_engine);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*engineEngine)->CreateOutputMix(engineEngine, &outputMixObject, 0, 0, 0);
+  result = (*m_engine_engine)->CreateOutputMix(m_engine_engine, &m_output_mix_object, 0, 0, 0);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*outputMixObject)->Realize(outputMixObject, SL_BOOLEAN_FALSE);
+  result = (*m_output_mix_object)->Realize(m_output_mix_object, SL_BOOLEAN_FALSE);
   ASSERT(SL_RESULT_SUCCESS == result);
 
   SLDataLocator_AndroidSimpleBufferQueue loc_bufq = {SL_DATALOCATOR_ANDROIDSIMPLEBUFFERQUEUE, 2};
@@ -76,36 +61,38 @@ bool OpenSLESStream::Init()
   SLDataSource audioSrc = {&loc_bufq, &format_pcm};
 
   // configure audio sink
-  SLDataLocator_OutputMix loc_outmix = {SL_DATALOCATOR_OUTPUTMIX, outputMixObject};
+  SLDataLocator_OutputMix loc_outmix = {SL_DATALOCATOR_OUTPUTMIX, m_output_mix_object};
   SLDataSink audioSnk = {&loc_outmix, nullptr};
 
   // create audio player
   const SLInterfaceID ids[2] = {SL_IID_BUFFERQUEUE, SL_IID_VOLUME};
   const SLboolean req[2] = {SL_BOOLEAN_TRUE, SL_BOOLEAN_TRUE};
-  result =
-      (*engineEngine)
-          ->CreateAudioPlayer(engineEngine, &bqPlayerObject, &audioSrc, &audioSnk, 2, ids, req);
+  result = (*m_engine_engine)
+               ->CreateAudioPlayer(m_engine_engine, &m_bq_player_object, &audioSrc, &audioSnk, 2,
+                                   ids, req);
   ASSERT(SL_RESULT_SUCCESS == result);
 
-  result = (*bqPlayerObject)->Realize(bqPlayerObject, SL_BOOLEAN_FALSE);
+  result = (*m_bq_player_object)->Realize(m_bq_player_object, SL_BOOLEAN_FALSE);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_PLAY, &bqPlayerPlay);
+  result = (*m_bq_player_object)->GetInterface(m_bq_player_object, SL_IID_PLAY, &m_bq_player_play);
+  ASSERT(SL_RESULT_SUCCESS == result);
+  result = (*m_bq_player_object)
+               ->GetInterface(m_bq_player_object, SL_IID_BUFFERQUEUE, &m_bq_player_buffer_queue);
   ASSERT(SL_RESULT_SUCCESS == result);
   result =
-      (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_BUFFERQUEUE, &bqPlayerBufferQueue);
+      (*m_bq_player_object)->GetInterface(m_bq_player_object, SL_IID_VOLUME, &m_bq_player_volume);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*bqPlayerObject)->GetInterface(bqPlayerObject, SL_IID_VOLUME, &bqPlayerVolume);
+  result = (*m_bq_player_buffer_queue)
+               ->RegisterCallback(m_bq_player_buffer_queue, BQPlayerCallback, this);
   ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*bqPlayerBufferQueue)->RegisterCallback(bqPlayerBufferQueue, bqPlayerCallback, nullptr);
-  ASSERT(SL_RESULT_SUCCESS == result);
-  result = (*bqPlayerPlay)->SetPlayState(bqPlayerPlay, SL_PLAYSTATE_PLAYING);
+  result = (*m_bq_player_play)->SetPlayState(m_bq_player_play, SL_PLAYSTATE_PLAYING);
   ASSERT(SL_RESULT_SUCCESS == result);
 
   // Render and enqueue a first buffer.
-  curBuffer ^= 1;
-  g_mixer = m_mixer.get();
+  m_current_buffer ^= 1;
 
-  result = (*bqPlayerBufferQueue)->Enqueue(bqPlayerBufferQueue, buffer[0], sizeof(buffer[0]));
+  result = (*m_bq_player_buffer_queue)
+               ->Enqueue(m_bq_player_buffer_queue, m_buffer[0], sizeof(m_buffer[0]));
   if (SL_RESULT_SUCCESS != result)
     return false;
 
@@ -114,39 +101,39 @@ bool OpenSLESStream::Init()
 
 OpenSLESStream::~OpenSLESStream()
 {
-  if (bqPlayerObject != nullptr)
+  if (m_bq_player_object != nullptr)
   {
-    (*bqPlayerObject)->Destroy(bqPlayerObject);
-    bqPlayerObject = nullptr;
-    bqPlayerPlay = nullptr;
-    bqPlayerBufferQueue = nullptr;
-    bqPlayerVolume = nullptr;
+    (*m_bq_player_object)->Destroy(m_bq_player_object);
+    m_bq_player_object = nullptr;
+    m_bq_player_play = nullptr;
+    m_bq_player_buffer_queue = nullptr;
+    m_bq_player_volume = nullptr;
   }
 
-  if (outputMixObject != nullptr)
+  if (m_output_mix_object != nullptr)
   {
-    (*outputMixObject)->Destroy(outputMixObject);
-    outputMixObject = nullptr;
+    (*m_output_mix_object)->Destroy(m_output_mix_object);
+    m_output_mix_object = nullptr;
   }
 
-  if (engineObject != nullptr)
+  if (m_engine_object != nullptr)
   {
-    (*engineObject)->Destroy(engineObject);
-    engineObject = nullptr;
-    engineEngine = nullptr;
+    (*m_engine_object)->Destroy(m_engine_object);
+    m_engine_object = nullptr;
+    m_engine_engine = nullptr;
   }
 }
 
 bool OpenSLESStream::SetRunning(bool running)
 {
   SLuint32 new_state = running ? SL_PLAYSTATE_PLAYING : SL_PLAYSTATE_PAUSED;
-  return (*bqPlayerPlay)->SetPlayState(bqPlayerPlay, new_state) == SL_RESULT_SUCCESS;
+  return (*m_bq_player_play)->SetPlayState(m_bq_player_play, new_state) == SL_RESULT_SUCCESS;
 }
 
 void OpenSLESStream::SetVolume(int volume)
 {
   const SLmillibel attenuation =
       volume <= 0 ? SL_MILLIBEL_MIN : static_cast<SLmillibel>(2000 * std::log10(volume / 100.0f));
-  (*bqPlayerVolume)->SetVolumeLevel(bqPlayerVolume, attenuation);
+  (*m_bq_player_volume)->SetVolumeLevel(m_bq_player_volume, attenuation);
 }
 #endif  // HAVE_OPENSL_ES

Source/Core/AudioCommon/OpenSLESStream.h

@@ -3,10 +3,12 @@
 
 #pragma once
 
-#include <thread>
+#ifdef HAVE_OPENSL_ES
+#include <SLES/OpenSLES.h>
+#include <SLES/OpenSLES_Android.h>
+#endif  // HAVE_OPENSL_ES
 
 #include "AudioCommon/SoundStream.h"
-#include "Common/Event.h"
 
 class OpenSLESStream final : public SoundStream
 {
@@ -19,7 +21,25 @@ public:
   static bool IsValid() { return true; }
 
 private:
-  std::thread thread;
-  Common::Event soundSyncEvent;
+  static void BQPlayerCallback(SLAndroidSimpleBufferQueueItf bq, void* context);
+  void PushSamples(SLAndroidSimpleBufferQueueItf bq);
+
+  // engine interfaces
+  SLObjectItf m_engine_object;
+  SLEngineItf m_engine_engine;
+  SLObjectItf m_output_mix_object;
+
+  // buffer queue player interfaces
+  SLObjectItf m_bq_player_object = nullptr;
+  SLPlayItf m_bq_player_play;
+  SLAndroidSimpleBufferQueueItf m_bq_player_buffer_queue;
+  SLVolumeItf m_bq_player_volume;
+
+  static constexpr int BUFFER_SIZE = 512;
+  static constexpr int BUFFER_SIZE_IN_SAMPLES = BUFFER_SIZE / 2;
+
+  // Double buffering.
+  short m_buffer[2][BUFFER_SIZE];
+  int m_current_buffer = 0;
 #endif  // HAVE_OPENSL_ES
 };