Merge "Fix a race condition in SeekBarVolumizer." into nyc-dev

am: 54f4a63

* commit '54f4a630dcb66f0b6d5ae5b1028dc88d7971c99e':
  Fix a race condition in SeekBarVolumizer.

core/java/android/preference/SeekBarVolumizer.java

@@ -38,6 +38,8 @@ import android.util.Log;
 import android.widget.SeekBar;
 import android.widget.SeekBar.OnSeekBarChangeListener;
 
+import com.android.internal.annotations.GuardedBy;
+
 /**
  * Turns a {@link SeekBar} into a volume control.
  * @hide
@@ -67,6 +69,10 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
     private Observer mVolumeObserver;
     private int mOriginalStreamVolume;
     private int mLastAudibleStreamVolume;
+    // When the old handler is destroyed and a new one is created, there could be a situation where
+    // this is accessed at the same time in different handlers. So, access to this field needs to be
+    // synchronized.
+    @GuardedBy("this")
     private Ringtone mRingtone;
     private int mLastProgress = -1;
     private boolean mMuted;
@@ -174,11 +180,13 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
     }
 
     private void onInitSample() {
+        synchronized (this) {
             mRingtone = RingtoneManager.getRingtone(mContext, mDefaultUri);
             if (mRingtone != null) {
                 mRingtone.setStreamType(mStreamType);
             }
         }
+    }
 
     private void postStartSample() {
         if (mHandler == null) return;
@@ -192,6 +200,8 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
             if (mCallback != null) {
                 mCallback.onSampleStarting(this);
             }
+
+            synchronized (this) {
                 if (mRingtone != null) {
                     try {
                         mRingtone.setAudioAttributes(new AudioAttributes.Builder(mRingtone
@@ -206,6 +216,7 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
                 }
             }
         }
+    }
 
     private void postStopSample() {
         if (mHandler == null) return;
@@ -216,10 +227,12 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
     }
 
     private void onStopSample() {
+        synchronized (this) {
             if (mRingtone != null) {
                 mRingtone.stop();
             }
         }
+    }
 
     public void stop() {
         if (mHandler == null) return;  // already stopped
@@ -274,8 +287,10 @@ public class SeekBarVolumizer implements OnSeekBarChangeListener, Handler.Callba
     }
 
     public boolean isSamplePlaying() {
+        synchronized (this) {
             return mRingtone != null && mRingtone.isPlaying();
         }
+    }
 
     public void startSample() {
         postStartSample();