AudioFlinger: offload playback, non-blocking write

- Added specialized playback thread class for offload playback,
derived from directoutput thread.
This thread type handles specific state transitions for offloaded
tracks and offloading commands (pause/resume/drain/flush..) to audio HAL.
As opposed to other threads, does not go to standby if the track is paused.

- Added support for asynchronous write and drain operations at audio HAL.
Use a thread to handle async callback events from HAL: this avoids locking
playback thread mutex when executing the callback and cause deadlocks when
calling audio HAL functions with the playback thread mutex locked.

- Better accouting for track activity: call start/stop and release Output
methods in audio policy manager when tracks are actually added and removed
from the active tracks list.
Added a command thread in audio policy service to handle stop/release commands
asynchronously and avoid deadlocks with playback thread.

- Track terminated status is not a state anymore. This condition is othogonal
to state to permitted state transitions while terminated.

Change-Id: Id157f4b3277620568d8eace7535d9186602564de

1 files changed, 28 insertions, 2 deletions

diff --git a/services/audioflinger/AudioPolicyService.h b/services/audioflinger/AudioPolicyService.h
index e723c47..ae053a9 100644
--- a/services/audioflinger/AudioPolicyService.h
+++ b/services/audioflinger/AudioPolicyService.h
@@ -139,6 +139,11 @@ public:
     virtual status_t setVoiceVolume(float volume, int delayMs = 0);
     virtual bool isOffloadSupported(const audio_offload_info_t &config);
 
+            status_t doStopOutput(audio_io_handle_t output,
+                                  audio_stream_type_t stream,
+                                  int session = 0);
+            void doReleaseOutput(audio_io_handle_t output);
+
 private:
                         AudioPolicyService() ANDROID_API;
     virtual             ~AudioPolicyService();
@@ -161,10 +166,12 @@ private:
             STOP_TONE,
             SET_VOLUME,
             SET_PARAMETERS,
-            SET_VOICE_VOLUME
+            SET_VOICE_VOLUME,
+            STOP_OUTPUT,
+            RELEASE_OUTPUT
         };
 
-        AudioCommandThread (String8 name);
+        AudioCommandThread (String8 name, const wp<AudioPolicyService>& service);
         virtual             ~AudioCommandThread();
 
                     status_t    dump(int fd);
@@ -182,6 +189,11 @@ private:
                     status_t    parametersCommand(audio_io_handle_t ioHandle,
                                             const char *keyValuePairs, int delayMs = 0);
                     status_t    voiceVolumeCommand(float volume, int delayMs = 0);
+                    void        stopOutputCommand(audio_io_handle_t output,
+                                                  audio_stream_type_t stream,
+                                                  int session);
+                    void        releaseOutputCommand(audio_io_handle_t output);
+
                     void        insertCommand_l(AudioCommand *command, int delayMs = 0);
 
     private:
@@ -226,12 +238,25 @@ private:
             float mVolume;
         };
 
+        class StopOutputData {
+        public:
+            audio_io_handle_t mIO;
+            audio_stream_type_t mStream;
+            int mSession;
+        };
+
+        class ReleaseOutputData {
+        public:
+            audio_io_handle_t mIO;
+        };
+
         Mutex   mLock;
         Condition mWaitWorkCV;
         Vector <AudioCommand *> mAudioCommands; // list of pending commands
         ToneGenerator *mpToneGenerator;     // the tone generator
         AudioCommand mLastCommand;          // last processed command (used by dump)
         String8 mName;                      // string used by wake lock fo delayed commands
+        wp<AudioPolicyService> mService;
     };
 
     class EffectDesc {
@@ -316,6 +341,7 @@ private:
                             // device connection state  or routing
     sp<AudioCommandThread> mAudioCommandThread;     // audio commands thread
     sp<AudioCommandThread> mTonePlaybackThread;     // tone playback thread
+    sp<AudioCommandThread> mOutputCommandThread;    // process stop and release output
     struct audio_policy_device *mpAudioPolicyDev;
     struct audio_policy *mpAudioPolicy;
     KeyedVector< audio_source_t, InputSourceDesc* > mInputSources;