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

media/audio/android/audio_manager_android.cc

Index: media/audio/android/audio_manager_android.cc
diff --git a/media/audio/android/audio_manager_android.cc b/media/audio/android/audio_manager_android.cc
index a8d81c7e829af4ffa2697427db608c73ecfdbbdf..d800c31c694fd7ef0f70c495e5cc460408306ad6 100644
--- a/media/audio/android/audio_manager_android.cc
+++ b/media/audio/android/audio_manager_android.cc
@@ -9,6 +9,7 @@
 #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"
@@ -48,16 +49,22 @@ 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();
+  // WARNING: This is executed on the UI loop, do not add any code here which
+  // loads libraries or attempts to call out into the OS.  Instead add such code
+  // to the InitializeOnAudioThread() method below.
+
+  // Task must be posted last to avoid races from handing out "this" to the
+  // audio thread.
+  GetTaskRunner()->PostTask(FROM_HERE, base::Bind(
+      &AudioManagerAndroid::InitializeOnAudioThread,
+      base::Unretained(this)));
 }
 
 AudioManagerAndroid::~AudioManagerAndroid() {
-  Close();
+  // It's safe to post a task here since Shutdown() will wait for all tasks to
+  // complete before returning.
+  GetTaskRunner()->PostTask(FROM_HERE, base::Bind(

[DaleCurtis, 2014/02/19 19:10:16]

I'm not sure if this is a problem or not, but note that
AudioManagerBase::ShutdownOnAudioThread() will run after this, so you need to
ensure that method (which just closes dispatchers really), doesn't do anything
which might invoke the Java side code after this point.

For perspective, you might be interested in this CL
https://codereview.chromium.org/148373004/ where I try to early abort methods
which execute on the audio thread after this point (which does happen
regularly).

[henrika (OOO until Aug 14), 2014/02/21 11:46:16]

I am unable to see that it should be a problem but thanks for pointing it out.
Might have to revisit if we see issues related to closing down on Android.

+      &AudioManagerAndroid::ShutdownOnAudioThread, base::Unretained(this)));
   Shutdown();
 }
 
@@ -71,10 +78,12 @@ bool AudioManagerAndroid::HasAudioInputDevices() {
 
 void AudioManagerAndroid::GetAudioInputDeviceNames(
     AudioDeviceNames* device_names) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   // Always add default device parameters as first element.
   DCHECK(device_names->empty());
   AddDefaultDevice(device_names);
 
+  // Get list of available audio devices.
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobjectArray> j_device_array =
       Java_AudioManagerAndroid_getAudioInputDeviceNames(
@@ -102,10 +111,12 @@ void AudioManagerAndroid::GetAudioOutputDeviceNames(
 
 AudioParameters AudioManagerAndroid::GetInputStreamParameters(
     const std::string& device_id) {
-  JNIEnv* env = AttachCurrentThread();
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   // 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.
+  JNIEnv* env = AttachCurrentThread();

[DaleCurtis, 2014/02/19 19:10:16]

Check can probably be removed since you're ensuring you're on the audio thread
(here and elsewhere). Up to you though.

[henrika (OOO until Aug 14), 2014/02/21 11:46:16]

Done.

+  CHECK(env);
   ChannelLayout channel_layout = CHANNEL_LAYOUT_MONO;
   int buffer_size = Java_AudioManagerAndroid_getMinInputFrameSize(
       env, GetNativeOutputSampleRate(),
@@ -123,28 +134,27 @@ AudioParameters AudioManagerAndroid::GetInputStreamParameters(
 AudioOutputStream* AudioManagerAndroid::MakeAudioOutputStream(
     const AudioParameters& params,
     const std::string& device_id) {
-  bool had_no_streams = HadNoAudioStreams();
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  bool has_no_streams = HasNoAudioStreams();
   AudioOutputStream* stream =
       AudioManagerBase::MakeAudioOutputStream(params, std::string());
 
   // 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
+  // If a Bluetooth headset is selected, the audio stream will use the SCO
   // channel and therefore have a limited bandwidth (8-16kHz).
-  if (stream && had_no_streams)
+  if (stream && has_no_streams)
     SetCommunicationAudioModeOn(true);
 
-  {
-    base::AutoLock lock(streams_lock_);
-    streams_.insert(static_cast<OpenSLESOutputStream*>(stream));
-  }
+  streams_.insert(static_cast<OpenSLESOutputStream*>(stream));
 
   return stream;
 }
 
 AudioInputStream* AudioManagerAndroid::MakeAudioInputStream(
     const AudioParameters& params, const std::string& device_id) {
-  bool had_no_streams = HadNoAudioStreams();
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  bool has_no_streams = HasNoAudioStreams();
   AudioInputStream* stream =
       AudioManagerBase::MakeAudioInputStream(params, device_id);
 
@@ -152,34 +162,38 @@ AudioInputStream* AudioManagerAndroid::MakeAudioInputStream(
   // 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)
+  if (stream && has_no_streams)
     SetCommunicationAudioModeOn(true);
   return stream;
 }
 
 void AudioManagerAndroid::ReleaseOutputStream(AudioOutputStream* stream) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   AudioManagerBase::ReleaseOutputStream(stream);
 
   // Restore the audio mode which was used before the first communication-
   // mode stream was created.
-  if (HadNoAudioStreams())
+  if (HasNoAudioStreams())
     SetCommunicationAudioModeOn(false);
-  base::AutoLock lock(streams_lock_);
+
   streams_.erase(static_cast<OpenSLESOutputStream*>(stream));
 }
 
 void AudioManagerAndroid::ReleaseInputStream(AudioInputStream* stream) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  DCHECK(!j_audio_manager_.is_null());
   AudioManagerBase::ReleaseInputStream(stream);
 
   // Restore the audio mode which was used before the first communication-
   // mode stream was created.
-  if (HadNoAudioStreams())
+  if (HasNoAudioStreams())
     SetCommunicationAudioModeOn(false);
 }
 
 AudioOutputStream* AudioManagerAndroid::MakeLinearOutputStream(
     const AudioParameters& params) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LINEAR, params.format());
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   return new OpenSLESOutputStream(this, params);
 }
 
@@ -202,8 +216,10 @@ AudioInputStream* AudioManagerAndroid::MakeLinearInputStream(
 
 AudioInputStream* AudioManagerAndroid::MakeLowLatencyInputStream(
     const AudioParameters& params, const std::string& device_id) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
   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.
@@ -229,22 +245,25 @@ AudioInputStream* AudioManagerAndroid::MakeLowLatencyInputStream(
   return new OpenSLESInputStream(this, params);
 }
 
-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));
-  }
+// static
+bool AudioManagerAndroid::RegisterAudioManager(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+void AudioManagerAndroid::SetMute(JNIEnv* env, jobject obj, jboolean muted) {
+  GetTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &AudioManagerAndroid::DoSetMuteOnAudioThread,
+          base::Unretained(this),
+          muted));
 }
 
 AudioParameters AudioManagerAndroid::GetPreferredOutputStreamParameters(
     const std::string& output_device_id,
     const AudioParameters& input_params) {
   // TODO(tommi): Support |output_device_id|.
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
   DLOG_IF(ERROR, !output_device_id.empty()) << "Not implemented!";
   ChannelLayout channel_layout = CHANNEL_LAYOUT_STEREO;
   int sample_rate = GetNativeOutputSampleRate();
@@ -270,42 +289,38 @@ AudioParameters AudioManagerAndroid::GetPreferredOutputStreamParameters(
       sample_rate, bits_per_sample, buffer_size, AudioParameters::NO_EFFECTS);
 }
 
-bool AudioManagerAndroid::HadNoAudioStreams() {
-  return output_stream_count() == 0 && input_stream_count() == 0;
-}
+void AudioManagerAndroid::InitializeOnAudioThread() {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
 
-// static
-bool AudioManagerAndroid::RegisterAudioManager(JNIEnv* env) {
-  return RegisterNativesImpl(env);
-}
+  JNIEnv* env = base::android::AttachCurrentThread();
+  CHECK(env);
+
+  // Create the Android audio manager on the audio thread.
+  DVLOG(2) << "Creating Java part of the audio manager";
+  j_audio_manager_.Reset(
+      Java_AudioManagerAndroid_createAudioManagerAndroid(
+          env,
+          base::android::GetApplicationContext(),
+          reinterpret_cast<intptr_t>(this)));
 
-void AudioManagerAndroid::Init() {
+  // Prepare the list of audio devices and register receivers for device
+  // notifications.
   Java_AudioManagerAndroid_init(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
 }
 
-void AudioManagerAndroid::Close() {
+void AudioManagerAndroid::ShutdownOnAudioThread() {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  DVLOG(2) << "Destroying Java part of the audio manager";
   Java_AudioManagerAndroid_close(
       base::android::AttachCurrentThread(),
       j_audio_manager_.obj());
+  j_audio_manager_.Reset();
 }
 
-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);
-  }
+bool AudioManagerAndroid::HasNoAudioStreams() {
+  return output_stream_count() == 0 && input_stream_count() == 0;
 }
 
 void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
@@ -315,11 +330,13 @@ void AudioManagerAndroid::SetCommunicationAudioModeOn(bool on) {
 }
 
 bool AudioManagerAndroid::SetAudioDevice(const std::string& device_id) {
-  JNIEnv* env = AttachCurrentThread();
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
 
   // 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();
+  CHECK(env);
   ScopedJavaLocalRef<jstring> j_device_id = ConvertUTF8ToJavaString(
       env,
       device_id == AudioManagerBase::kDefaultDeviceId ?
@@ -346,4 +363,24 @@ int AudioManagerAndroid::GetAudioLowLatencyOutputFrameSize() {
       j_audio_manager_.obj());
 }
 
+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));
+  }
+}
+
+void AudioManagerAndroid::DoSetMuteOnAudioThread(bool muted) {
+  DCHECK(GetTaskRunner()->BelongsToCurrentThread());
+  for (OutputStreams::iterator it = streams_.begin();
+       it != streams_.end(); ++it) {
+    (*it)->SetMute(muted);
+  }
+}
+
 }  // namespace media