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session: fix a deadlock due to onPlayRequested() #2256

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1ca8dff
Add failing unit test
nift4 Jul 25, 2025
92e1f62
session: fix a deadlock due to onPlayRequested()
nift4 Mar 22, 2025
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190 changes: 106 additions & 84 deletions libraries/session/src/main/java/androidx/media3/session/MediaSessionImpl.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1100,20 +1100,23 @@ protected MediaSessionServiceLegacyStub getLegacyBrowserService() {
});
}

/* package */ boolean onPlayRequested() {
/* package */ ListenableFuture<Boolean> onPlayRequested() {
if (Looper.myLooper() != Looper.getMainLooper()) {
SettableFuture<Boolean> playRequested = SettableFuture.create();
mainHandler.post(() -> playRequested.set(onPlayRequested()));
try {
return playRequested.get();
} catch (InterruptedException | ExecutionException e) {
throw new IllegalStateException(e);
}
mainHandler.post(
() -> {
try {
playRequested.set(onPlayRequested().get());
} catch (ExecutionException | InterruptedException e) {
playRequested.setException(new IllegalStateException(e));
}
});
return playRequested;
}
if (this.mediaSessionListener != null) {
return this.mediaSessionListener.onPlayRequested(instance);
return Futures.immediateFuture(this.mediaSessionListener.onPlayRequested(instance));
}
return true;
return Futures.immediateFuture(true);
}

/**
Expand All @@ -1124,84 +1127,103 @@ protected MediaSessionServiceLegacyStub getLegacyBrowserService() {
*
* @param controller The controller requesting to play.
*/
/* package */ void handleMediaControllerPlayRequest(
/* package */ ListenableFuture<SessionResult> handleMediaControllerPlayRequest(
ControllerInfo controller, boolean callOnPlayerInteractionFinished) {
if (!onPlayRequested()) {
// Request denied, e.g. due to missing foreground service abilities.
return;
}
boolean hasCurrentMediaItem =
playerWrapper.isCommandAvailable(Player.COMMAND_GET_CURRENT_MEDIA_ITEM)
&& playerWrapper.getCurrentMediaItem() != null;
boolean canAddMediaItems =
playerWrapper.isCommandAvailable(COMMAND_SET_MEDIA_ITEM)
|| playerWrapper.isCommandAvailable(COMMAND_CHANGE_MEDIA_ITEMS);
ControllerInfo controllerForRequest = resolveControllerInfoForCallback(controller);
Player.Commands playCommand =
new Player.Commands.Builder().add(Player.COMMAND_PLAY_PAUSE).build();
if (hasCurrentMediaItem || !canAddMediaItems) {
// No playback resumption needed or possible.
if (!hasCurrentMediaItem) {
Log.w(
TAG,
"Play requested without current MediaItem, but playback resumption prevented by"
+ " missing available commands");
}
Util.handlePlayButtonAction(playerWrapper);
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(controllerForRequest, playCommand);
}
} else {
@Nullable
ListenableFuture<MediaItemsWithStartPosition> future =
checkNotNull(
callback.onPlaybackResumption(
instance, controllerForRequest, /* isForPlayback= */ true),
"Callback.onPlaybackResumption must return a non-null future");
Futures.addCallback(
future,
new FutureCallback<MediaItemsWithStartPosition>() {
@Override
public void onSuccess(MediaItemsWithStartPosition mediaItemsWithStartPosition) {
callWithControllerForCurrentRequestSet(
controllerForRequest,
() -> {
MediaUtils.setMediaItemsWithStartIndexAndPosition(
playerWrapper, mediaItemsWithStartPosition);
Util.handlePlayButtonAction(playerWrapper);
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(controllerForRequest, playCommand);
}
})
.run();
SettableFuture<SessionResult> sessionFuture = SettableFuture.create();
ListenableFuture<Boolean> playRequestedFuture = onPlayRequested();
playRequestedFuture.addListener(
() -> {
boolean playRequested;
try {
playRequested = playRequestedFuture.get();
} catch (ExecutionException | InterruptedException e) {
sessionFuture.setException(new IllegalStateException(e));
return;
}
if (!playRequested) {
// Request denied, e.g. due to missing foreground service abilities.
sessionFuture.set(new SessionResult(SessionResult.RESULT_ERROR_UNKNOWN));
return;
}
boolean hasCurrentMediaItem =
playerWrapper.isCommandAvailable(Player.COMMAND_GET_CURRENT_MEDIA_ITEM)
&& playerWrapper.getCurrentMediaItem() != null;
boolean canAddMediaItems =
playerWrapper.isCommandAvailable(COMMAND_SET_MEDIA_ITEM)
|| playerWrapper.isCommandAvailable(COMMAND_CHANGE_MEDIA_ITEMS);
ControllerInfo controllerForRequest = resolveControllerInfoForCallback(controller);
Player.Commands playCommand =
new Player.Commands.Builder().add(Player.COMMAND_PLAY_PAUSE).build();
if (hasCurrentMediaItem || !canAddMediaItems) {
// No playback resumption needed or possible.
if (!hasCurrentMediaItem) {
Log.w(
TAG,
"Play requested without current MediaItem, but playback resumption prevented by"
+ " missing available commands");
}

@Override
public void onFailure(Throwable t) {
if (t instanceof UnsupportedOperationException) {
Log.w(
TAG,
"UnsupportedOperationException: Make sure to implement"
+ " MediaSession.Callback.onPlaybackResumption() if you add a"
+ " media button receiver to your manifest or if you implement the recent"
+ " media item contract with your MediaLibraryService.",
t);
} else {
Log.e(
TAG,
"Failure calling MediaSession.Callback.onPlaybackResumption(): "
+ t.getMessage(),
t);
}
// Play as requested even if playback resumption fails.
Util.handlePlayButtonAction(playerWrapper);
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(controllerForRequest, playCommand);
}
Util.handlePlayButtonAction(playerWrapper);
sessionFuture.set(new SessionResult(SessionResult.RESULT_SUCCESS));
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(controllerForRequest, playCommand);
}
},
this::postOrRunOnApplicationHandler);
}
} else {
@Nullable
ListenableFuture<MediaItemsWithStartPosition> future =
checkNotNull(
callback.onPlaybackResumption(
instance, controllerForRequest, /* isForPlayback= */ true),
"Callback.onPlaybackResumption must return a non-null future");
Futures.addCallback(
future,
new FutureCallback<MediaItemsWithStartPosition>() {
@Override
public void onSuccess(MediaItemsWithStartPosition mediaItemsWithStartPosition) {
callWithControllerForCurrentRequestSet(
controllerForRequest,
() -> {
MediaUtils.setMediaItemsWithStartIndexAndPosition(
playerWrapper, mediaItemsWithStartPosition);
Util.handlePlayButtonAction(playerWrapper);
sessionFuture.set(new SessionResult(SessionResult.RESULT_SUCCESS));
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(
controllerForRequest, playCommand);
}
})
.run();
}

@Override
public void onFailure(Throwable t) {
if (t instanceof UnsupportedOperationException) {
Log.w(
TAG,
"UnsupportedOperationException: Make sure to implement"
+ " MediaSession.Callback.onPlaybackResumption() if you add a media"
+ " button receiver to your manifest or if you implement the recent"
+ " media item contract with your MediaLibraryService.",
t);
} else {
Log.e(
TAG,
"Failure calling MediaSession.Callback.onPlaybackResumption(): "
+ t.getMessage(),
t);
}
// Play as requested even if playback resumption fails.
Util.handlePlayButtonAction(playerWrapper);
sessionFuture.set(new SessionResult(SessionResult.RESULT_SUCCESS));
if (callOnPlayerInteractionFinished) {
onPlayerInteractionFinishedOnHandler(controllerForRequest, playCommand);
}
}
},
this::postOrRunOnApplicationHandler);
}
},
this::postOrRunOnApplicationHandler);
return sessionFuture;
}

/* package */ void triggerPlayerInfoUpdate() {
Expand Down
24 changes: 21 additions & 3 deletions libraries/session/src/main/java/androidx/media3/session/MediaSessionLegacyStub.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -607,9 +607,27 @@ public void onPrepareFromUri(@Nullable Uri mediaUri, @Nullable Bundle extras) {
public void onPlay() {
dispatchSessionTaskWithPlayerCommand(
COMMAND_PLAY_PAUSE,
controller ->
sessionImpl.handleMediaControllerPlayRequest(
controller, /* callOnPlayerInteractionFinished= */ true),
controller -> {
ListenableFuture<SessionResult> resultFuture =
sessionImpl.handleMediaControllerPlayRequest(
controller, /* callOnPlayerInteractionFinished= */ true);
Futures.addCallback(
resultFuture,
new FutureCallback<SessionResult>() {
@Override
public void onSuccess(SessionResult result) {
if (result.resultCode != RESULT_SUCCESS) {
Log.w(TAG, "onPlay() failed: " + result + " (from: " + controller + ")");
}
}

@Override
public void onFailure(Throwable t) {
Log.e(TAG, "Unexpected exception in onPlay() of " + controller, t);
}
},
MoreExecutors.directExecutor());
},
sessionCompat.getCurrentControllerInfo(),
/* callOnPlayerInteractionFinished= */ false);
}
Expand Down
13 changes: 4 additions & 9 deletions libraries/session/src/main/java/androidx/media3/session/MediaSessionStub.java
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -749,15 +749,10 @@ public void playForControllerInfo(ControllerInfo controller, int sequenceNumber)
controller,
sequenceNumber,
COMMAND_PLAY_PAUSE,
sendSessionResultSuccess(
player -> {
@Nullable MediaSessionImpl impl = sessionImpl.get();
if (impl == null || impl.isReleased()) {
return;
}
impl.handleMediaControllerPlayRequest(
controller, /* callOnPlayerInteractionFinished= */ false);
}));
sendSessionResultWhenReady(
(session, theController, sequenceId) ->
session.handleMediaControllerPlayRequest(
theController, /* callOnPlayerInteractionFinished= */ false)));
}

@Override
Expand Down
69 changes: 69 additions & 0 deletions ...session_current/src/androidTest/java/androidx/media3/session/MediaSessionServiceTest.java
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -26,12 +26,15 @@
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.HandlerThread;
import android.os.Looper;
import android.support.v4.media.session.MediaControllerCompat;
import android.support.v4.media.session.MediaSessionCompat;
import android.support.v4.media.session.PlaybackStateCompat;
import androidx.core.content.ContextCompat;
import androidx.media3.common.ForwardingPlayer;
import androidx.media3.common.MediaItem;
import androidx.media3.common.PlaybackParameters;
import androidx.media3.common.Player;
import androidx.media3.common.util.ConditionVariable;
import androidx.media3.exoplayer.ExoPlayer;
Expand All @@ -47,6 +50,8 @@
import androidx.test.filters.MediumTest;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.FutureCallback;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import java.util.ArrayList;
Expand Down Expand Up @@ -242,6 +247,70 @@ public ListenableFuture<List<MediaItem>> onAddMediaItems(
service.blockUntilAllControllersUnbind(TIMEOUT_MS);
}

@Test
public void onPlayRequested_doesNotCauseDeadlock_ifPlaybackThreadIsNotMain() throws Exception {
HandlerThread ht = new HandlerThread("MSSTest:PlaybackThread");
ht.start();
TestServiceRegistry testServiceRegistry = TestServiceRegistry.getInstance();
ConditionVariable playerToldToSpeedUp = new ConditionVariable();
AtomicReference<MediaController> mediaController = new AtomicReference<>();
AtomicReference<MediaSession> mediaSession = new AtomicReference<>();
testServiceRegistry.setOnGetSessionHandler(
controllerInfo -> {
MockMediaSessionService service =
(MockMediaSessionService) testServiceRegistry.getServiceInstance();
Player player = new ExoPlayer.Builder(service).setLooper(ht.getLooper()).build();
player.addListener(
new Player.Listener() {
@Override
public void onPlaybackParametersChanged(PlaybackParameters playbackParameters) {
if (playbackParameters.speed == 2f) {
playerToldToSpeedUp.open();
}
}
});
mediaSession.set(new MediaSession.Builder(service, player).build());
return mediaSession.get();
});
TestHandler handler = new TestHandler(Looper.getMainLooper());
TestHandler bgHandler = new TestHandler(ht.getLooper());
handler.post(
() -> {
ListenableFuture<MediaController> controllerFuture =
new MediaController.Builder(context, token).buildAsync();
Futures.addCallback(
controllerFuture,
new FutureCallback<MediaController>() {
@Override
public void onSuccess(MediaController controller) {
controller.addMediaItem(new MediaItem.Builder().setMediaId("media_id").build());
controller.play();
bgHandler.post(
() ->
handler.post(
() -> {
controller.setPlaybackSpeed(2f);
mediaController.set(controller);
}));
}

@Override
public void onFailure(Throwable t) {
throw new RuntimeException(t);
}
},
ContextCompat.getMainExecutor(context));
});
playerToldToSpeedUp.block(TIMEOUT_MS);
if (!playerToldToSpeedUp.isOpen()) {
ht.interrupt(); // avoid deadlocking the test forever.
}
assertThat(playerToldToSpeedUp.isOpen()).isTrue();
handler.postAndSync(() -> mediaController.get().release());
mediaSession.get().release();
ht.quitSafely();
}

@Test
public void onCreate_withCustomLayout_correctSessionStateFromOnConnect() throws Exception {
SessionCommand command1 = new SessionCommand("command1", Bundle.EMPTY);
Expand Down