Out-of-order command execution in MediaController if Android 12(L) workaround has to kick in

Version

Media3 main branch

More version details

cb5ee435c1efe4d7101a677c9bc1b69ec66c832d

Devices that reproduce the issue

SDK 31/32 emulator

Devices that do not reproduce the issue

Only Android 12 / 12L are affected, so it can't be reproduced on SDK 33 emulator for example

Reproducible in the demo app?

Yes

Reproduction steps

Apply the following diff and run the MediaSessionServiceWithNonMainApplicationThreadTest.play_playCalledOnAppThread() test, it will fail.

diff --git a/libraries/test_session_current/src/androidTest/java/androidx/media3/session/MediaSessionServiceWithNonMainApplicationThreadTest.java b/libraries/test_session_current/src/androidTest/java/androidx/media3/session/MediaSessionServiceWithNonMainApplicationThreadTest.java
index 855e44ef0b..a30702d014 100644
--- a/libraries/test_session_current/src/androidTest/java/androidx/media3/session/MediaSessionServiceWithNonMainApplicationThreadTest.java
+++ b/libraries/test_session_current/src/androidTest/java/androidx/media3/session/MediaSessionServiceWithNonMainApplicationThreadTest.java
@@ -25,6 +25,7 @@ import android.app.ForegroundServiceStartNotAllowedException;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
+import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.Looper;
 import androidx.media3.common.C;
@@ -94,6 +95,7 @@ public class MediaSessionServiceWithNonMainApplicationThreadTest {
     Looper appLooper = appThread.getLooper();
 
     SettableFuture<Looper> playFuture = SettableFuture.create();
+    SettableFuture<Void> setVolumeWasCalled = SettableFuture.create();
     testServiceRegistry.setOnGetSessionHandler(
         controllerInfo -> {
           ExoPlayer exoPlayer =
@@ -107,6 +109,17 @@ public class MediaSessionServiceWithNonMainApplicationThreadTest {
                 public void play() {
                   playFuture.set(Looper.myLooper());
                 }
+
+                @Override
+                public void setVolume(float volume) {
+                  // Must be already done as setVolume() is called after play() on the controller.
+                  try {
+                    assertThat(playFuture.get(0, MILLISECONDS)).isNotNull();
+                  } catch (Exception e) {
+                    throw new RuntimeException(e);
+                  }
+                  setVolumeWasCalled.set(null);
+                }
               };
           return new MediaSession.Builder(context, player)
               .setCallback(
@@ -133,9 +146,13 @@ public class MediaSessionServiceWithNonMainApplicationThreadTest {
     RemoteMediaController controller = controllerTestRule.createRemoteController(token);
 
     controller.play();
+    // Send a command after play to assert they are processed in the correct order even if play
+    // takes a moment. See setVolume above.
+    controller.setVolume(0.5f);
 
     // Verify that playback starts on the application looper.
     assertThat(playFuture.get(TIMEOUT_MS, MILLISECONDS)).isEqualTo(appLooper);
+    assertThat(setVolumeWasCalled.get(TIMEOUT_MS, MILLISECONDS)).isEqualTo(null);
     appThread.quitSafely();
   }

Expected result

MediaController forwards commands to Player in the order it recieves them

Actual result

setVolume is called before play

Media

N/A

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.