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Commit 95bd2329 authored by Glenn Kasten's avatar Glenn Kasten
Browse files

Simplify AudioTrack event handling and fix a race 

Fixed race where mEventHandlerDelegate was accessed multiple times with
an assumption that all values read were the same.

If setPlaybackPositionUpdateListener was called with a null listener,
it did not update the delegate.

Inner classes can access final local variables of the enclosing method.
Use this to remove fields mPositionListener, mPositionListenerLock, mListener.

Change-Id: Ibf5cae61a1a9d21b745b90d4b74f9be14b66e37b
parent 3251d363

media/java/android/media/AudioTrack.java

+17 −30
Original line number Diff line number Diff line
@@ -156,16 +156,6 @@ public class AudioTrack 
     * Lock to make sure mPlayState updates are reflecting the actual state of the object.

     */

    private final Object mPlayStateLock = new Object();

    /**

     * The listener the AudioTrack notifies when the playback position reaches a marker

     * or for periodic updates during the progression of the playback head.

     *  @see #setPlaybackPositionUpdateListener(OnPlaybackPositionUpdateListener)

     */

    private OnPlaybackPositionUpdateListener mPositionListener = null;

    /**

     * Lock to protect event listener updates against event notifications.

     */

    private final Object mPositionListenerLock = new Object();

    /**

     * Size of the native audio buffer.

     */
@@ -173,7 +163,7 @@ public class AudioTrack 
    /**

     * Handler for marker events coming from the native code.

     */

    private NativeEventHandlerDelegate mEventHandlerDelegate = null;

    private NativeEventHandlerDelegate mEventHandlerDelegate;

    /**

     * Looper associated with the thread that creates the AudioTrack instance.

     */
@@ -733,13 +723,11 @@ public class AudioTrack 
     */

    public void setPlaybackPositionUpdateListener(OnPlaybackPositionUpdateListener listener,

                                                    Handler handler) {

        synchronized (mPositionListenerLock) {

            mPositionListener = listener;

        }

        if (listener != null) {

            mEventHandlerDelegate = new NativeEventHandlerDelegate(this, handler);

            mEventHandlerDelegate = new NativeEventHandlerDelegate(this, listener, handler);

        } else {

            mEventHandlerDelegate = null;

        }



    }
@@ -1131,11 +1119,11 @@ public class AudioTrack 
     * (potentially) handled in a different thread

     */

    private class NativeEventHandlerDelegate {

        private final AudioTrack mAudioTrack;

        private final Handler mHandler;



        NativeEventHandlerDelegate(AudioTrack track, Handler handler) {

            mAudioTrack = track;

        NativeEventHandlerDelegate(final AudioTrack track,

                                   final OnPlaybackPositionUpdateListener listener,

                                   Handler handler) {

            // find the looper for our new event handler

            Looper looper;

            if (handler != null) {
@@ -1151,22 +1139,18 @@ public class AudioTrack 
                mHandler = new Handler(looper) {

                    @Override

                    public void handleMessage(Message msg) {

                        if (mAudioTrack == null) {

                        if (track == null) {

                            return;

                        }

                        OnPlaybackPositionUpdateListener listener = null;

                        synchronized (mPositionListenerLock) {

                            listener = mAudioTrack.mPositionListener;

                        }

                        switch(msg.what) {

                        case NATIVE_EVENT_MARKER:

                            if (listener != null) {

                                listener.onMarkerReached(mAudioTrack);

                                listener.onMarkerReached(track);

                            }

                            break;

                        case NATIVE_EVENT_NEW_POS:

                            if (listener != null) {

                                listener.onPeriodicNotification(mAudioTrack);

                                listener.onPeriodicNotification(track);

                            }

                            break;

                        default:
@@ -1199,10 +1183,13 @@ public class AudioTrack 
            return;

        }



        if (track.mEventHandlerDelegate != null) {

            Message m =

                track.mEventHandlerDelegate.getHandler().obtainMessage(what, arg1, arg2, obj);

            track.mEventHandlerDelegate.getHandler().sendMessage(m);

        NativeEventHandlerDelegate delegate = track.mEventHandlerDelegate;

        if (delegate != null) {

            Handler handler = delegate.getHandler();

            if (handler != null) {

                Message m = handler.obtainMessage(what, arg1, arg2, obj);

                handler.sendMessage(m);

            }

        }



    }