Fix AudioEngine to allow re-initialization

Add AudioEngine::CompareAndSetEngine and change
VariableSpeed::initializeEngine to use this method so it only initializes
a new engine once rather than asserting on subsequent calls.

Change AudioEngine::DeleteEngine so it ignores repeated calls instead of
asserting. Add VariableSpeed::isReadyToPlay so callers can detect when
the audio library has been properly initialized.

Bug:11511992
Change-Id: I4517cb2ab4c186da43dffc7dbc2a9ad49000059f

6 files changed, 33 insertions, 9 deletions

diff --git a/variablespeed/jni/jni_entry.cc b/variablespeed/jni/jni_entry.cc
index 93c12ba..20bcf3c 100644
--- a/variablespeed/jni/jni_entry.cc
+++ b/variablespeed/jni/jni_entry.cc
@@ -81,9 +81,12 @@ JNI_METHOD(initializeEngine, void) (JNIEnv*, jclass,
     jfloat initialRate, jint decodeInitialSize, jint decodeMaxSize,
     jint startPositionMillis, jint audioStreamType) {
   MethodLog _("initializeEngine");
-  AudioEngine::SetEngine(new AudioEngine(targetFrames,
+  AudioEngine *engine = new AudioEngine(targetFrames,
       windowDuration, windowOverlapDuration, maxPlayBufferCount, initialRate,
-      decodeInitialSize, decodeMaxSize, startPositionMillis, audioStreamType));
+      decodeInitialSize, decodeMaxSize, startPositionMillis, audioStreamType);
+  if (!AudioEngine::CompareAndSetEngine(NULL, engine)) {
+    delete engine;
+  }
 }
 
 JNI_METHOD(shutdownEngine, void) (JNIEnv*, jclass) {
diff --git a/variablespeed/jni/variablespeed.cc b/variablespeed/jni/variablespeed.cc
index b5d9067..8e161fc 100644
--- a/variablespeed/jni/variablespeed.cc
+++ b/variablespeed/jni/variablespeed.cc
@@ -129,14 +129,21 @@ void AudioEngine::SetEngine(AudioEngine* engine) {
   audioEngine_ = engine;
 }
 
+bool AudioEngine::CompareAndSetEngine(AudioEngine* expect, AudioEngine* update) {
+  android::Mutex::Autolock autoLock(publishEngineLock_);
+  if (audioEngine_ == expect) {
+    DeleteEngine();
+    audioEngine_ = update;
+    return true;
+  }
+  return false;
+}
+
 void AudioEngine::DeleteEngine() {
-  if (audioEngine_ == NULL) {
-    LOGE("you haven't initialized the audio engine");
-    CHECK(false);
-    return;
+  if (audioEngine_ != NULL) {
+    delete audioEngine_;
+    audioEngine_ = NULL;
   }
-  delete audioEngine_;
-  audioEngine_ = NULL;
 }
 
 // ****************************************************************************
diff --git a/variablespeed/jni/variablespeed.h b/variablespeed/jni/variablespeed.h
index cf856da..74710e5 100644
--- a/variablespeed/jni/variablespeed.h
+++ b/variablespeed/jni/variablespeed.h
@@ -64,6 +64,7 @@ class AudioEngine {
 
   static AudioEngine* GetEngine();
   static void SetEngine(AudioEngine* engine);
+  static bool CompareAndSetEngine(AudioEngine* expect, AudioEngine* update);
   static void DeleteEngine();
 
  private:
diff --git a/variablespeed/src/com/android/ex/variablespeed/MediaPlayerProxy.java b/variablespeed/src/com/android/ex/variablespeed/MediaPlayerProxy.java
index 8489dc1..3b7b576 100644
--- a/variablespeed/src/com/android/ex/variablespeed/MediaPlayerProxy.java
+++ b/variablespeed/src/com/android/ex/variablespeed/MediaPlayerProxy.java
@@ -42,6 +42,7 @@ public interface MediaPlayerProxy {
     int getDuration();
     void seekTo(int startPosition);
     void start();
+    boolean isReadyToPlay();
     boolean isPlaying();
     int getCurrentPosition();
     void pause();
diff --git a/variablespeed/src/com/android/ex/variablespeed/SingleThreadedMediaPlayerProxy.java b/variablespeed/src/com/android/ex/variablespeed/SingleThreadedMediaPlayerProxy.java
index 17692f7..c9a9741 100644
--- a/variablespeed/src/com/android/ex/variablespeed/SingleThreadedMediaPlayerProxy.java
+++ b/variablespeed/src/com/android/ex/variablespeed/SingleThreadedMediaPlayerProxy.java
@@ -85,6 +85,11 @@ public class SingleThreadedMediaPlayerProxy implements MediaPlayerProxy {
     }
 
     @Override
+    public synchronized boolean isReadyToPlay() {
+        return mDelegate.isReadyToPlay();
+    }
+
+    @Override
     public synchronized boolean isPlaying() {
         return mDelegate.isPlaying();
     }
diff --git a/variablespeed/src/com/android/ex/variablespeed/VariableSpeed.java b/variablespeed/src/com/android/ex/variablespeed/VariableSpeed.java
index 5c93d26..e44a375 100644
--- a/variablespeed/src/com/android/ex/variablespeed/VariableSpeed.java
+++ b/variablespeed/src/com/android/ex/variablespeed/VariableSpeed.java
@@ -337,9 +337,16 @@ public class VariableSpeed implements MediaPlayerProxy {
     }
 
     @Override
+    public boolean isReadyToPlay() {
+        synchronized (lock) {
+            return !mHasBeenReleased && mHasDuration;
+        }
+    }
+
+    @Override
     public boolean isPlaying() {
         synchronized (lock) {
-            return mHasStartedPlayback && !hasPlaybackFinished();
+            return isReadyToPlay() && mHasStartedPlayback && !hasPlaybackFinished();
         }
     }