Initialization of audio manager for Android is now done on the audio thread

media/audio/android/audio_manager_android.cc

 // Copyright (c) 2012 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 "media/audio/android/audio_manager_android.h"
 
 #include "base/android/build_info.h"
 #include "base/android/jni_array.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/logging.h"
+#include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "jni/AudioManagerAndroid_jni.h"
 #include "media/audio/android/audio_record_input.h"
 #include "media/audio/android/opensles_input.h"
 #include "media/audio/android/opensles_output.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_parameters.h"
 #include "media/audio/fake_audio_input_stream.h"
 #include "media/base/channel_layout.h"
 
@@ skipping 18 matching lines @@
 static const int kDefaultInputBufferSize = 1024;
 static const int kDefaultOutputBufferSize = 2048;
 
 AudioManager* CreateAudioManager(AudioLogFactory* audio_log_factory) {
   return new AudioManagerAndroid(audio_log_factory);
 }
 
 AudioManagerAndroid::AudioManagerAndroid(AudioLogFactory* audio_log_factory)
     : AudioManagerBase(audio_log_factory) {
   SetMaxOutputStreamsAllowed(kMaxOutputStreams);
-
-  j_audio_manager_.Reset(
-      Java_AudioManagerAndroid_createAudioManagerAndroid(
-          base::android::AttachCurrentThread(),
-          base::android::GetApplicationContext(),
-          reinterpret_cast<intptr_t>(this)));
-  Init();
 }
 
 AudioManagerAndroid::~AudioManagerAndroid() {
-  Close();
   Shutdown();
+  // Verify that WillDestroyCurrentMessageLoop() has been called.
+  DCHECK(j_audio_manager_.is_null());
 }
 
 bool AudioManagerAndroid::HasAudioOutputDevices() {
   return true;
 }
 
 bool AudioManagerAndroid::HasAudioInputDevices() {
   return true;
 }
 
 void AudioManagerAndroid::GetAudioInputDeviceNames(

[DaleCurtis, 2014/02/03 19:09:16]

Is there no way to move this call on to the audio thread?  Is this just for
unittests?  Apologies if I've missed previous discussion on this.

[henrika (OOO until Aug 14), 2014/02/03 19:23:42]

It is called on a so called device thread in the audio input device manager and
I did not feel confident in changing that since I know that thread was added for
a reason. I moved it to the audio thread here to simplify the threading model in
Java (to reduce the number of threads calling in).

[DaleCurtis, 2014/02/03 19:33:15]

Actually we can remove that thread now that we have the concept of a worker
thread.  Here's the CL that reverted the change previously:

https://codereview.chromium.org/18325021

It was reverted because the "audio thread" on OSX is the UI thread and
enumeration can block for seconds.  At the time we didn't have the concept of a
worker thread, but we do now.  That CL can now be relanded using
GetWorkerTaskRunner().

Want to take care of making that change?

[henrika (OOO until Aug 14), 2014/02/04 10:09:36]

I would very much appreciate if you could close the loop on that part Dale. You
know the whole background and I could fix this unit test once that thread has
been removed, but in a separate CL. Took a quick lock at it and can still see
some questions regarding UMA and method names that are still indicated that the
device thread exists. 

[DaleCurtis, 2014/02/04 19:14:11]

https://codereview.chromium.org/154143002/

     AudioDeviceNames* device_names) {
-  // Always add default device parameters as first element.
-  DCHECK(device_names->empty());
-  AddDefaultDevice(device_names);
-
-  JNIEnv* env = AttachCurrentThread();
-  ScopedJavaLocalRef<jobjectArray> j_device_array =
-      Java_AudioManagerAndroid_getAudioInputDeviceNames(
-          env, j_audio_manager_.obj());
-  jsize len = env->GetArrayLength(j_device_array.obj());
-  AudioDeviceName device;
-  for (jsize i = 0; i < len; ++i) {
-    ScopedJavaLocalRef<jobject> j_device(
-        env, env->GetObjectArrayElement(j_device_array.obj(), i));
-    ScopedJavaLocalRef<jstring> j_device_name =
-        Java_AudioDeviceName_name(env, j_device.obj());
-    ConvertJavaStringToUTF8(env, j_device_name.obj(), &device.device_name);
-    ScopedJavaLocalRef<jstring> j_device_id =
-        Java_AudioDeviceName_id(env, j_device.obj());
-    ConvertJavaStringToUTF8(env, j_device_id.obj(), &device.unique_id);
-    device_names->push_back(device);
+  // Get list of available audio devices and use the audio thread to reduce
+  // the number of calling threads to the Java layer. Also, ensure that the
+  // calling thread sees this function call as synchronous.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner(GetTaskRunner());
+  if (task_runner->BelongsToCurrentThread()) {
+    GetAudioInputDeviceNamesOnAudioThread(NULL, device_names);
+  } else {
+    base::WaitableEvent event(false, false);
+    task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(
+            &AudioManagerAndroid::GetAudioInputDeviceNamesOnAudioThread,
+            base::Unretained(this),
+            &event,
+            device_names));
+    event.Wait();
   }
 }
 
 void AudioManagerAndroid::GetAudioOutputDeviceNames(
     AudioDeviceNames* device_names) {
   // TODO(henrika): enumerate using GetAudioInputDeviceNames().
   AddDefaultDevice(device_names);
 }
 
 AudioParameters AudioManagerAndroid::GetInputStreamParameters(
     const std::string& device_id) {
+  CreateAndInit();

[DaleCurtis, 2014/02/03 19:09:16]

I think you need to always post this task during construction, similar to how we
handle on audio thread initialization on OSX/Win.  You can then avoid any
waitable events for that call.

[henrika (OOO until Aug 14), 2014/02/03 19:23:42]

I recall your recent CL on Windows doing this but off-line discussions with
Tommi resulted in this solution instead. I would like to wait for comments from
Tommi as well.

My main goal here is to make construction of Chrome on Android as light as
possible and only touch audio components when needed. 

+
   JNIEnv* env = AttachCurrentThread();
+  CHECK(env);
+
   // Use mono as preferred number of input channels on Android to save
   // resources. Using mono also avoids a driver issue seen on Samsung
   // Galaxy S3 and S4 devices. See http://crbug.com/256851 for details.
   ChannelLayout channel_layout = CHANNEL_LAYOUT_MONO;
   int buffer_size = Java_AudioManagerAndroid_getMinInputFrameSize(
       env, GetNativeOutputSampleRate(),
       ChannelLayoutToChannelCount(channel_layout));
   int effects = AudioParameters::NO_EFFECTS;
   effects |= Java_AudioManagerAndroid_shouldUseAcousticEchoCanceler(env) ?
       AudioParameters::ECHO_CANCELLER : AudioParameters::NO_EFFECTS;
@@ skipping 23 matching lines @@
   {
     base::AutoLock lock(streams_lock_);
     streams_.insert(static_cast<OpenSLESOutputStream*>(stream));
   }
 
   return stream;
 }
 
 AudioInputStream* AudioManagerAndroid::MakeAudioInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   bool had_no_streams = HadNoAudioStreams();
   AudioInputStream* stream =
       AudioManagerBase::MakeAudioInputStream(params, device_id);
 
   // The audio manager for Android creates streams intended for real-time
   // VoIP sessions and therefore sets the audio mode to MODE_IN_COMMUNICATION.
   // If a Bluetooth headset is used, the audio stream will use the SCO
   // channel and therefore have a limited bandwidth (8kHz).
   if (stream && had_no_streams)
     SetCommunicationAudioModeOn(true);
@@ skipping 40 matching lines @@
   // TODO(henrika): add support for device selection if/when any client
   // needs it.
   DLOG_IF(ERROR, !device_id.empty()) << "Not implemented!";
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
   return new OpenSLESInputStream(this, params);
 }
 
 AudioInputStream* AudioManagerAndroid::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DLOG_IF(ERROR, device_id.empty()) << "Invalid device ID!";
   // Use the device ID to select the correct input device.
   // Note that the input device is always associated with a certain output
   // device, i.e., this selection does also switch the output device.
   // All input and output streams will be affected by the device selection.
   if (!SetAudioDevice(device_id)) {
     LOG(ERROR) << "Unable to select audio device!";
     return NULL;
   }
 
   if (params.effects() != AudioParameters::NO_EFFECTS) {
     // Platform effects can only be enabled through the AudioRecord path.
     // An effect should only have been requested here if recommended by
     // AudioManagerAndroid.shouldUse<Effect>.
     //
     // Creating this class requires Jelly Bean, which is already guaranteed by
     // shouldUse<Effect>. Only DCHECK on that condition to allow tests to use
     // the effect settings as a way to select the input path.
     DCHECK_GE(base::android::BuildInfo::GetInstance()->sdk_int(), 16);
     DVLOG(1) << "Creating AudioRecordInputStream";
     return new AudioRecordInputStream(this, params);
   }
   DVLOG(1) << "Creating OpenSLESInputStream";
   return new OpenSLESInputStream(this, params);
 }
 
+void AudioManagerAndroid::WillDestroyCurrentMessageLoop() {
+  CloseOnAudioThread();
+}
+
 int AudioManagerAndroid::GetOptimalOutputFrameSize(int sample_rate,
                                                    int channels) {
   if (IsAudioLowLatencySupported()) {
     return GetAudioLowLatencyOutputFrameSize();
   } else {
     return std::max(kDefaultOutputBufferSize,
                     Java_AudioManagerAndroid_getMinOutputFrameSize(
                         base::android::AttachCurrentThread(),
                         sample_rate, channels));
   }
@@ skipping 30 matching lines @@
 
 bool AudioManagerAndroid::HadNoAudioStreams() {
   return output_stream_count() == 0 && input_stream_count() == 0;
 }
 
 // static
 bool AudioManagerAndroid::RegisterAudioManager(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
+void AudioManagerAndroid::CreateAndInit() {
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner(GetTaskRunner());
+  if (task_runner->BelongsToCurrentThread()) {
+    CreateAndInitOnAudioThread(NULL);
+  } else {
+    base::WaitableEvent event(false, false);
+    task_runner->PostTask(
+        FROM_HERE,
+        base::Bind(
+            &AudioManagerAndroid::CreateAndInitOnAudioThread,
+            base::Unretained(this),
+            &event));
+    event.Wait();
+  }
+}
+
+void AudioManagerAndroid::CreateAndInitOnAudioThread(
+    base::WaitableEvent* event) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  if (!j_audio_manager_.is_null())
+    return;
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  CHECK(env);
+
+  // Create the Android audio manager on the audio thread.
+  j_audio_manager_.Reset(
+    Java_AudioManagerAndroid_createAudioManagerAndroid(
+        env,
+        base::android::GetApplicationContext(),
+        reinterpret_cast<intptr_t>(this)));
+
+  // Prepare the list of audio devices and register receivers for device
+  // notifications.
+  Init();
+
+  // Ensure that we are notified when the audio thread dies.
+  base::MessageLoop::current()->AddDestructionObserver(this);
+
+  if (event)
+    event->Signal();
+}
+
 void AudioManagerAndroid::Init() {
   Java_AudioManagerAndroid_init(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 void AudioManagerAndroid::Close() {
   Java_AudioManagerAndroid_close(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 void AudioManagerAndroid::SetMute(JNIEnv* env, jobject obj, jboolean muted) {
   GetTaskRunner()->PostTask(
       FROM_HERE,
       base::Bind(
           &AudioManagerAndroid::DoSetMuteOnAudioThread,
           base::Unretained(this),
           muted));
 }
 
-void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
-  base::AutoLock lock(streams_lock_);
-  for (OutputStreams::iterator it = streams_.begin();
-       it != streams_.end(); ++it) {
-    (*it)->SetMute(muted);
+void AudioManagerAndroid::GetAudioInputDeviceNamesOnAudioThread(
+    base::WaitableEvent* event, AudioDeviceNames* device_names) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+
+  // Set up the initial list of available audio devices and register for
+  // broadcasted notifications about any changes of availability.
+  // This method is only executed when called for the first time and it can
+  // also be called from SetAudioDeviceOnAudioThread().
+  // InitializeOnAudioThread();
+
+  // Always add default device parameters as first element.
+  DCHECK(device_names->empty());
+  AddDefaultDevice(device_names);
+
+  JNIEnv* env = AttachCurrentThread();
+  ScopedJavaLocalRef<jobjectArray> j_device_array =
+      Java_AudioManagerAndroid_getAudioInputDeviceNames(
+          env, j_audio_manager_.obj());
+  jsize len = env->GetArrayLength(j_device_array.obj());
+  AudioDeviceName device;
+  for (jsize i = 0; i < len; ++i) {
+    ScopedJavaLocalRef<jobject> j_device(
+        env, env->GetObjectArrayElement(j_device_array.obj(), i));
+    ScopedJavaLocalRef<jstring> j_device_name =
+        Java_AudioDeviceName_name(env, j_device.obj());
+    ConvertJavaStringToUTF8(env, j_device_name.obj(), &device.device_name);
+    ScopedJavaLocalRef<jstring> j_device_id =
+        Java_AudioDeviceName_id(env, j_device.obj());
+    ConvertJavaStringToUTF8(env, j_device_id.obj(), &device.unique_id);
+    device_names->push_back(device);
   }
+
+  if (event)
+    event->Signal();
 }
 
-void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
-  Java_AudioManagerAndroid_setCommunicationAudioModeOn(
-      base::android::AttachCurrentThread(),
-      j_audio_manager_.obj(), on);
+void AudioManagerAndroid::CloseOnAudioThread() {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  if (j_audio_manager_.is_null())
+    return;
+  Close();
+  j_audio_manager_.Reset();
 }
 
 bool AudioManagerAndroid::SetAudioDevice(const std::string& device_id) {
-  JNIEnv* env = AttachCurrentThread();
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  // Set up the initial list of available audio devices and register for
+  // broadcasted notifications about any changes of availability.
+  // This method is only executed when called for the first time and it can
+  // also be called from GetAudioInputDeviceNamesOnAudioThread().
+  // InitializeOnAudioThread();
 
   // Send the unique device ID to the Java audio manager and make the
   // device switch. Provide an empty string to the Java audio manager
   // if the default device is selected.
+  JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jstring> j_device_id = ConvertUTF8ToJavaString(
       env,
       device_id == AudioManagerBase::kDefaultDeviceId ?
           std::string() : device_id);
   return Java_AudioManagerAndroid_setDevice(
       env, j_audio_manager_.obj(), j_device_id.obj());
 }
 
+void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  base::AutoLock lock(streams_lock_);
+  for (OutputStreams::iterator it = streams_.begin();
+       it != streams_.end(); ++it) {
+    (*it)->SetMute(muted);
+  }
+}
+
+void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
+  Java_AudioManagerAndroid_setCommunicationAudioModeOn(
+      base::android::AttachCurrentThread(),
+      j_audio_manager_.obj(), on);
+}
+
 int AudioManagerAndroid::GetNativeOutputSampleRate() {
   return Java_AudioManagerAndroid_getNativeOutputSampleRate(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 bool AudioManagerAndroid::IsAudioLowLatencySupported() {
   return Java_AudioManagerAndroid_isAudioLowLatencySupported(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 int AudioManagerAndroid::GetAudioLowLatencyOutputFrameSize() {
   return Java_AudioManagerAndroid_getAudioLowLatencyOutputFrameSize(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
 }  // namespace media