Audio focus: clean up FocusRequester early

For audio focus client death:
- call release on stack entry,
- fix logs messages.

Bug 28781809

Change-Id: I2d3e2b0635f7db2c52fcae0d6f5d6d3a773c6549

services/core/java/com/android/server/audio/FocusRequester.java

@@ -40,9 +40,9 @@ public class FocusRequester {
     private static final String TAG = "MediaFocusControl";
     private static final boolean DEBUG = false;
 
-    private AudioFocusDeathHandler mDeathHandler;
-    private final IAudioFocusDispatcher mFocusDispatcher; // may be null
-    private final IBinder mSourceRef;
+    private AudioFocusDeathHandler mDeathHandler; // may be null
+    private IAudioFocusDispatcher mFocusDispatcher; // may be null
+    private final IBinder mSourceRef; // may be null
     private final String mClientId;
     private final String mPackageName;
     private final int mCallingUid;
@@ -205,6 +205,7 @@ public class FocusRequester {
             if (mSourceRef != null && mDeathHandler != null) {
                 mSourceRef.unlinkToDeath(mDeathHandler, 0);
                 mDeathHandler = null;
+                mFocusDispatcher = null;
             }
         } catch (java.util.NoSuchElementException e) {
             Log.e(TAG, "FocusRequester.release() hit ", e);
@@ -275,12 +276,13 @@ public class FocusRequester {
             mFocusLossReceived = AudioManager.AUDIOFOCUS_NONE;
             mFocusController.notifyExtPolicyFocusGrant_syncAf(toAudioFocusInfo(),
                     AudioManager.AUDIOFOCUS_REQUEST_GRANTED);
-            if (mFocusDispatcher != null) {
+            final IAudioFocusDispatcher fd = mFocusDispatcher;
+            if (fd != null) {
                 if (DEBUG) {
                     Log.v(TAG, "dispatching " + focusChangeToString(focusGain) + " to "
                         + mClientId);
                 }
-                mFocusDispatcher.dispatchAudioFocusChange(focusGain, mClientId);
+                fd.dispatchAudioFocusChange(focusGain, mClientId);
             }
         } catch (android.os.RemoteException e) {
             Log.e(TAG, "Failure to signal gain of audio focus due to: ", e);
@@ -311,14 +313,15 @@ public class FocusRequester {
                             toAudioFocusInfo(), false /* wasDispatched */);
                     return;
                 }
-                if (mFocusDispatcher != null) {
+                final IAudioFocusDispatcher fd = mFocusDispatcher;
+                if (fd != null) {
                     if (DEBUG) {
                         Log.v(TAG, "dispatching " + focusChangeToString(mFocusLossReceived) + " to "
                             + mClientId);
                     }
                     mFocusController.notifyExtPolicyFocusLoss_syncAf(
                             toAudioFocusInfo(), true /* wasDispatched */);
-                    mFocusDispatcher.dispatchAudioFocusChange(mFocusLossReceived, mClientId);
+                    fd.dispatchAudioFocusChange(mFocusLossReceived, mClientId);
                 }
             }
         } catch (android.os.RemoteException e) {

services/core/java/com/android/server/audio/MediaFocusControl.java

@@ -160,6 +160,7 @@ public class MediaFocusControl {
                     Log.i(TAG, "AudioFocus  removeFocusStackEntry(): removing entry for "
                             + clientToRemove);
                     stackIterator.remove();
+                    // stack entry not used anymore, clear references
                     fr.release();
                 }
             }
@@ -171,7 +172,7 @@ public class MediaFocusControl {
      * Called synchronized on mAudioFocusLock
      * Remove focus listeners from the focus stack for a particular client when it has died.
      */
-    private void removeFocusStackEntryForClient(IBinder cb) {
+    private void removeFocusStackEntryOnDeath(IBinder cb) {
         // is the owner of the audio focus part of the client to remove?
         boolean isTopOfStackForClientToRemove = !mFocusStack.isEmpty() &&
                 mFocusStack.peek().hasSameBinder(cb);
@@ -181,9 +182,10 @@ public class MediaFocusControl {
         while(stackIterator.hasNext()) {
             FocusRequester fr = stackIterator.next();
             if(fr.hasSameBinder(cb)) {
-                Log.i(TAG, "AudioFocus  removeFocusStackEntry(): removing entry for " + cb);
+                Log.i(TAG, "AudioFocus  removeFocusStackEntryOnDeath(): removing entry for " + cb);
                 stackIterator.remove();
-                // the client just died, no need to unlink to its death
+                // stack entry not used anymore, clear references
+                fr.release();
             }
         }
         if (isTopOfStackForClientToRemove) {
@@ -257,14 +259,9 @@ public class MediaFocusControl {
 
         public void binderDied() {
             synchronized(mAudioFocusLock) {
-                Log.w(TAG, "  AudioFocus   audio focus client died");
-                removeFocusStackEntryForClient(mCb);
+                removeFocusStackEntryOnDeath(mCb);
             }
         }
-
-        public IBinder getBinder() {
-            return mCb;
-        }
     }
 
     /**
@@ -420,6 +417,7 @@ public class MediaFocusControl {
             // (premature death == death before abandoning focus)
             // Register for client death notification
             AudioFocusDeathHandler afdh = new AudioFocusDeathHandler(cb);
+
             try {
                 cb.linkToDeath(afdh, 0);
             } catch (RemoteException e) {