Add DownloadManager.getApplicationLooper

This is equivalent to the method ExoPlayer provides. It's nice for consistency,
and for retrieving the looper from test code.

PiperOrigin-RevId: 308830288

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerFactory.java

@@ -153,14 +153,14 @@ public final class ExoPlayerFactory {
       RenderersFactory renderersFactory,
       TrackSelector trackSelector,
       LoadControl loadControl,
-      Looper looper) {
+      Looper applicationLooper) {
     return newSimpleInstance(
         context,
         renderersFactory,
         trackSelector,
         loadControl,
         new AnalyticsCollector(Clock.DEFAULT),
-        looper);
+        applicationLooper);
   }
 
   /** @deprecated Use {@link SimpleExoPlayer.Builder} instead. */
@@ -172,7 +172,7 @@ public final class ExoPlayerFactory {
       TrackSelector trackSelector,
       LoadControl loadControl,
       AnalyticsCollector analyticsCollector,
-      Looper looper) {
+      Looper applicationLooper) {
     return newSimpleInstance(
         context,
         renderersFactory,
@@ -180,7 +180,7 @@ public final class ExoPlayerFactory {
         loadControl,
         DefaultBandwidthMeter.getSingletonInstance(context),
         analyticsCollector,
-        looper);
+        applicationLooper);
   }
 
   /** @deprecated Use {@link SimpleExoPlayer.Builder} instead. */
@@ -193,7 +193,7 @@ public final class ExoPlayerFactory {
       LoadControl loadControl,
       BandwidthMeter bandwidthMeter,
       AnalyticsCollector analyticsCollector,
-      Looper looper) {
+      Looper applicationLooper) {
     return new SimpleExoPlayer(
         context,
         renderersFactory,
@@ -204,7 +204,7 @@ public final class ExoPlayerFactory {
         analyticsCollector,
         /* useLazyPreparation= */ true,
         Clock.DEFAULT,
-        looper);
+        applicationLooper);
   }
 
   /** @deprecated Use {@link ExoPlayer.Builder} instead. */
@@ -231,14 +231,14 @@ public final class ExoPlayerFactory {
       Renderer[] renderers,
       TrackSelector trackSelector,
       LoadControl loadControl,
-      Looper looper) {
+      Looper applicationLooper) {
     return newInstance(
         context,
         renderers,
         trackSelector,
         loadControl,
         DefaultBandwidthMeter.getSingletonInstance(context),
-        looper);
+        applicationLooper);
   }
 
   /** @deprecated Use {@link ExoPlayer.Builder} instead. */
@@ -249,7 +249,7 @@ public final class ExoPlayerFactory {
       TrackSelector trackSelector,
       LoadControl loadControl,
       BandwidthMeter bandwidthMeter,
-      Looper looper) {
+      Looper applicationLooper) {
     return new ExoPlayerImpl(
         renderers,
         trackSelector,
@@ -259,6 +259,6 @@ public final class ExoPlayerFactory {
         /* analyticsCollector= */ null,
         /* useLazyPreparation= */ true,
         Clock.DEFAULT,
-        looper);
+        applicationLooper);
   }
 }

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImpl.java

@@ -65,7 +65,7 @@ import java.util.concurrent.TimeoutException;
 
   private final Renderer[] renderers;
   private final TrackSelector trackSelector;
-  private final Handler eventHandler;
+  private final Handler applicationHandler;
   private final ExoPlayerImplInternal internalPlayer;
   private final Handler internalPlayerHandler;
   private final CopyOnWriteArrayList<ListenerHolder> listeners;
@@ -110,8 +110,8 @@ import java.util.concurrent.TimeoutException;
    *     loads and other initial preparation steps happen immediately. If true, these initial
    *     preparations are triggered only when the player starts buffering the media.
    * @param clock The {@link Clock}.
-   * @param looper The {@link Looper} which must be used for all calls to the player and which is
-   *     used to call listeners on.
+   * @param applicationLooper The {@link Looper} that must be used for all calls to the player and
+   *     which is used to call listeners on.
    */
   @SuppressLint("HandlerLeak")
   public ExoPlayerImpl(
@@ -123,7 +123,7 @@ import java.util.concurrent.TimeoutException;
       @Nullable AnalyticsCollector analyticsCollector,
       boolean useLazyPreparation,
       Clock clock,
-      Looper looper) {
+      Looper applicationLooper) {
     Log.i(TAG, "Init " + Integer.toHexString(System.identityHashCode(this)) + " ["
         + ExoPlayerLibraryInfo.VERSION_SLASHY + "] [" + Util.DEVICE_DEBUG_INFO + "]");
     Assertions.checkState(renderers.length > 0);
@@ -144,8 +144,8 @@ import java.util.concurrent.TimeoutException;
     playbackSpeed = Player.DEFAULT_PLAYBACK_SPEED;
     seekParameters = SeekParameters.DEFAULT;
     maskingWindowIndex = C.INDEX_UNSET;
-    eventHandler =
-        new Handler(looper) {
+    applicationHandler =
+        new Handler(applicationLooper) {
           @Override
           public void handleMessage(Message msg) {
             ExoPlayerImpl.this.handleEvent(msg);
@@ -166,7 +166,7 @@ import java.util.concurrent.TimeoutException;
             repeatMode,
             shuffleModeEnabled,
             analyticsCollector,
-            eventHandler,
+            applicationHandler,
             clock);
     internalPlayerHandler = new Handler(internalPlayer.getPlaybackLooper());
   }
@@ -232,7 +232,7 @@ import java.util.concurrent.TimeoutException;
 
   @Override
   public Looper getApplicationLooper() {
-    return eventHandler.getLooper();
+    return applicationHandler.getLooper();
   }
 
   @Override
@@ -568,7 +568,7 @@ import java.util.concurrent.TimeoutException;
       // general because the midroll ad preceding the seek destination must be played before the
       // content position can be played, if a different ad is playing at the moment.
       Log.w(TAG, "seekTo ignored because an ad is playing");
-      eventHandler
+      applicationHandler
           .obtainMessage(
               ExoPlayerImplInternal.MSG_PLAYBACK_INFO_CHANGED,
               /* operationAcks */ 1,
@@ -690,7 +690,7 @@ import java.util.concurrent.TimeoutException;
                   ExoPlaybackException.createForUnexpected(
                       new RuntimeException(new TimeoutException("Player release timed out.")))));
     }
-    eventHandler.removeCallbacksAndMessages(null);
+    applicationHandler.removeCallbacksAndMessages(null);
     playbackInfo =
         getResetPlaybackInfo(
             /* clearPlaylist= */ false,

library/core/src/main/java/com/google/android/exoplayer2/SimpleExoPlayer.java

@@ -343,7 +343,6 @@ public class SimpleExoPlayer extends BasePlayer
   protected final Renderer[] renderers;
 
   private final ExoPlayerImpl player;
-  private final Handler eventHandler;
   private final ComponentListener componentListener;
   private final CopyOnWriteArraySet<com.google.android.exoplayer2.video.VideoListener>
       videoListeners;
@@ -420,8 +419,8 @@ public class SimpleExoPlayer extends BasePlayer
    *     preparations are triggered only when the player starts buffering the media.
    * @param clock The {@link Clock} that will be used by the instance. Should always be {@link
    *     Clock#DEFAULT}, unless the player is being used from a test.
-   * @param looper The {@link Looper} which must be used for all calls to the player and which is
-   *     used to call listeners on.
+   * @param applicationLooper The {@link Looper} which must be used for all calls to the player and
+   *     which is used to call listeners on.
    */
   protected SimpleExoPlayer(
       Context context,
@@ -433,7 +432,7 @@ public class SimpleExoPlayer extends BasePlayer
       AnalyticsCollector analyticsCollector,
       boolean useLazyPreparation,
       Clock clock,
-      Looper looper) {
+      Looper applicationLooper) {
     this.bandwidthMeter = bandwidthMeter;
     this.analyticsCollector = analyticsCollector;
     componentListener = new ComponentListener();
@@ -444,7 +443,7 @@ public class SimpleExoPlayer extends BasePlayer
     deviceListeners = new CopyOnWriteArraySet<>();
     videoDebugListeners = new CopyOnWriteArraySet<>();
     audioDebugListeners = new CopyOnWriteArraySet<>();
-    eventHandler = new Handler(looper);
+    Handler eventHandler = new Handler(applicationLooper);
     renderers =
         renderersFactory.createRenderers(
             eventHandler,
@@ -471,7 +470,7 @@ public class SimpleExoPlayer extends BasePlayer
             analyticsCollector,
             useLazyPreparation,
             clock,
-            looper);
+            applicationLooper);
     analyticsCollector.setPlayer(player);
     player.addListener(analyticsCollector);
     player.addListener(componentListener);

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadManager.java

@@ -62,7 +62,9 @@ import java.util.concurrent.CopyOnWriteArraySet;
  *
  * <p>A download manager instance must be accessed only from the thread that created it, unless that
  * thread does not have a {@link Looper}. In that case, it must be accessed only from the
- * application's main thread. Registered listeners will be called on the same thread.
+ * application's main thread. Registered listeners will be called on the same thread. In all cases
+ * the `Looper` of the thread from which the manager must be accessed can be queried using {@link
+ * #getApplicationLooper()}.
  */
 public final class DownloadManager {
 
@@ -167,7 +169,7 @@ public final class DownloadManager {
 
   private final Context context;
   private final WritableDownloadIndex downloadIndex;
-  private final Handler mainHandler;
+  private final Handler applicationHandler;
   private final InternalHandler internalHandler;
   private final RequirementsWatcher.Listener requirementsListener;
   private final CopyOnWriteArraySet<Listener> listeners;
@@ -224,7 +226,7 @@ public final class DownloadManager {
 
     @SuppressWarnings("methodref.receiver.bound.invalid")
     Handler mainHandler = Util.createHandler(this::handleMainMessage);
-    this.mainHandler = mainHandler;
+    this.applicationHandler = mainHandler;
     HandlerThread internalThread = new HandlerThread("ExoPlayer:DownloadManager");
     internalThread.start();
     internalHandler =
@@ -250,6 +252,14 @@ public final class DownloadManager {
         .sendToTarget();
   }
 
+  /**
+   * Returns the {@link Looper} associated with the application thread that's used to access the
+   * manager, and on which the manager will call its {@link Listener Listeners}.
+   */
+  public Looper getApplicationLooper() {
+    return applicationHandler.getLooper();
+  }
+
   /** Returns whether the manager has completed initialization. */
   public boolean isInitialized() {
     return initialized;
@@ -488,7 +498,7 @@ public final class DownloadManager {
         // Restore the interrupted status.
         Thread.currentThread().interrupt();
       }
-      mainHandler.removeCallbacksAndMessages(/* token= */ null);
+      applicationHandler.removeCallbacksAndMessages(/* token= */ null);
       // Reset state.
       downloads = Collections.emptyList();
       pendingMessages = 0;