Inform DefaultPreloadManager when player uses PreloadMediaSource

Add a new method `onUsedByPlayer(PreloadMediaSource)` for `PreloadMediaSource.PreloadControl`, which will be invoked when the player starts to use the `PreloadMediaSource`, or calling `PreloadMediaSource.preload` while the player is already using that source. `DefaultPreloadManager` will immediately preload the next source when receiving `onUsedByPlayer` event.

PiperOrigin-RevId: 616789121

demos/shortform/src/main/java/androidx/media3/demo/shortform/MediaSourceManager.kt

@@ -26,7 +26,6 @@ import androidx.media3.common.util.UnstableApi
 import androidx.media3.common.util.Util
 import androidx.media3.exoplayer.RendererCapabilities
 import androidx.media3.exoplayer.RenderersFactory
-import androidx.media3.exoplayer.analytics.PlayerId
 import androidx.media3.exoplayer.audio.AudioRendererEventListener
 import androidx.media3.exoplayer.source.MediaSource
 import androidx.media3.exoplayer.source.preload.PreloadMediaSource
@@ -61,7 +60,7 @@ class MediaSourceManager(
         bandwidthMeter,
         getRendererCapabilities(renderersFactory = renderersFactory),
         allocator,
-        preloadLooper
+        preloadLooper,
       )
   }
 
@@ -104,7 +103,7 @@ class MediaSourceManager(
         Util.createHandlerForCurrentOrMainLooper(),
         object : VideoRendererEventListener {},
         object : AudioRendererEventListener {},
-        { _: CueGroup? -> }
+        { _: CueGroup? -> },
       ) { _: Metadata ->
       }
     val capabilities = ArrayList<RendererCapabilities>()
@@ -131,9 +130,14 @@ class MediaSourceManager(
 
     override fun onContinueLoadingRequested(
       mediaSource: PreloadMediaSource,
-      bufferedPositionUs: Long
+      bufferedPositionUs: Long,
     ): Boolean {
       return bufferedPositionUs < targetPreloadPositionUs
     }
+
+    override fun onUsedByPlayer(mediaSource: PreloadMediaSource) {
+      // Implementation is no-op until the whole class is removed with the adoption of
+      // DefaultPreloadManager.
+    }
   }
 }

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManager.java

@@ -171,10 +171,6 @@ public final class DefaultPreloadManager extends BasePreloadManager<Integer> {
   protected void preloadSourceInternal(MediaSource mediaSource, long startPositionsUs) {
     checkArgument(mediaSource instanceof PreloadMediaSource);
     PreloadMediaSource preloadMediaSource = (PreloadMediaSource) mediaSource;
-    if (preloadMediaSource.isUsedByPlayer()) {
-      onPreloadCompleted(preloadMediaSource);
-      return;
-    }
     preloadMediaSource.preload(startPositionsUs);
   }
 
@@ -227,6 +223,11 @@ public final class DefaultPreloadManager extends BasePreloadManager<Integer> {
                   && status.getValue() > Util.usToMs(bufferedPositionUs)));
     }
 
+    @Override
+    public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+      onPreloadCompleted(mediaSource);
+    }
+
     private boolean continueOrCompletePreloading(
         MediaSource mediaSource, Predicate<Status> continueLoadingPredicate) {
       @Nullable

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java

@@ -86,6 +86,13 @@ public final class PreloadMediaSource extends WrappingMediaSource {
      *     data is buffered, or {@link C#TIME_END_OF_SOURCE} if the track is fully buffered.
      */
     boolean onContinueLoadingRequested(PreloadMediaSource mediaSource, long bufferedPositionUs);
+
+    /**
+     * Called from {@link PreloadMediaSource} when the player starts using this source.
+     *
+     * @param mediaSource The {@link PreloadMediaSource} that the player starts using.
+     */
+    void onUsedByPlayer(PreloadMediaSource mediaSource);
   }
 
   /** Factory for {@link PreloadMediaSource}. */
@@ -197,6 +204,7 @@ public final class PreloadMediaSource extends WrappingMediaSource {
   @Nullable private Timeline timeline;
   @Nullable private Pair<PreloadMediaPeriod, MediaPeriodKey> preloadingMediaPeriodAndKey;
   @Nullable private Pair<PreloadMediaPeriod, MediaPeriodId> playingPreloadedMediaPeriodAndId;
+  private boolean onUsedByPlayerNotified;
 
   private PreloadMediaSource(
       MediaSource mediaSource,
@@ -230,7 +238,9 @@ public final class PreloadMediaSource extends WrappingMediaSource {
         () -> {
           preloadCalled = true;
           this.startPositionUs = startPositionUs;
-          if (!isUsedByPlayer()) {
+          if (isUsedByPlayer()) {
+            notifyOnUsedByPlayer();
+          } else {
             setPlayerId(PlayerId.UNSET); // Set to PlayerId.UNSET as there is no ongoing playback.
             prepareSourceInternal(bandwidthMeter.getTransferListener());
           }
@@ -239,6 +249,9 @@ public final class PreloadMediaSource extends WrappingMediaSource {
 
   @Override
   protected void prepareSourceInternal() {
+    if (isUsedByPlayer() && !onUsedByPlayerNotified) {
+      notifyOnUsedByPlayer();
+    }
     if (timeline != null) {
       onChildSourceInfoRefreshed(timeline);
     } else if (!prepareChildSourceCalled) {
@@ -318,10 +331,13 @@ public final class PreloadMediaSource extends WrappingMediaSource {
 
   @Override
   protected void releaseSourceInternal() {
-    if (!preloadCalled && !isUsedByPlayer()) {
+    if (!isUsedByPlayer()) {
-      timeline = null;
+      onUsedByPlayerNotified = false;
-      prepareChildSourceCalled = false;
+      if (!preloadCalled) {
-      super.releaseSourceInternal();
+        timeline = null;
+        prepareChildSourceCalled = false;
+        super.releaseSourceInternal();
+      }
     }
   }
 
@@ -355,6 +371,9 @@ public final class PreloadMediaSource extends WrappingMediaSource {
 
     @Override
     public void onPrepared(MediaPeriod mediaPeriod) {
+      if (isUsedByPlayer()) {
+        return;
+      }
       prepared = true;
       PreloadMediaPeriod preloadMediaPeriod = (PreloadMediaPeriod) mediaPeriod;
       TrackGroupArray trackGroups = preloadMediaPeriod.getTrackGroups();
@@ -379,6 +398,9 @@ public final class PreloadMediaSource extends WrappingMediaSource {
 
     @Override
     public void onContinueLoadingRequested(MediaPeriod mediaPeriod) {
+      if (isUsedByPlayer()) {
+        return;
+      }
       PreloadMediaPeriod preloadMediaPeriod = (PreloadMediaPeriod) mediaPeriod;
       if (!prepared
           || preloadControl.onContinueLoadingRequested(
@@ -389,10 +411,15 @@ public final class PreloadMediaSource extends WrappingMediaSource {
     }
   }
 
-  /* package */ boolean isUsedByPlayer() {
+  private boolean isUsedByPlayer() {
     return prepareSourceCalled();
   }
 
+  private void notifyOnUsedByPlayer() {
+    preloadControl.onUsedByPlayer(this);
+    onUsedByPlayerNotified = true;
+  }
+
   private static boolean mediaPeriodIdEqualsWithoutWindowSequenceNumber(
       MediaPeriodId firstPeriodId, MediaPeriodId secondPeriodId) {
     return firstPeriodId.periodUid.equals(secondPeriodId.periodUid)

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManagerTest.java

@@ -246,11 +246,10 @@ public class DefaultPreloadManagerTest {
     FakeMediaSource wrappedMediaSource2 = fakeMediaSourceFactory.getLastCreatedSource();
     wrappedMediaSource2.setAllowPreparation(false);
 
-    MediaSource.MediaSourceCaller externalCaller = (source, timeline) -> {};
     PreloadMediaSource preloadMediaSource2 =
         (PreloadMediaSource) preloadManager.getMediaSource(mediaItem2);
     preloadMediaSource2.prepareSource(
-        externalCaller, bandwidthMeter.getTransferListener(), PlayerId.UNSET);
+        (source, timeline) -> {}, bandwidthMeter.getTransferListener(), PlayerId.UNSET);
     preloadManager.setCurrentPlayingIndex(2);
     preloadManager.invalidate();
     shadowOf(Looper.getMainLooper()).idle();
@@ -261,6 +260,51 @@ public class DefaultPreloadManagerTest {
     assertThat(targetPreloadStatusControlCallReference).containsExactly(2, 1, 0).inOrder();
   }
 
+  @Test
+  public void invalidate_sourceHandedOverToPlayerDuringPreloading_continuesPreloadingNextSource() {
+    ArrayList<Integer> targetPreloadStatusControlCallReference = new ArrayList<>();
+    TargetPreloadStatusControl<Integer> targetPreloadStatusControl =
+        rankingData -> {
+          targetPreloadStatusControlCallReference.add(rankingData);
+          return new DefaultPreloadManager.Status(
+              DefaultPreloadManager.Status.STAGE_TIMELINE_REFRESHED);
+        };
+    FakeMediaSourceFactory fakeMediaSourceFactory = new FakeMediaSourceFactory();
+    DefaultPreloadManager preloadManager =
+        new DefaultPreloadManager(
+            targetPreloadStatusControl,
+            fakeMediaSourceFactory,
+            trackSelector,
+            bandwidthMeter,
+            rendererCapabilitiesListFactory,
+            allocator,
+            Util.getCurrentOrMainLooper());
+    MediaItem.Builder mediaItemBuilder = new MediaItem.Builder();
+    MediaItem mediaItem0 =
+        mediaItemBuilder.setMediaId("mediaId0").setUri("http://exoplayer.dev/video0").build();
+    MediaItem mediaItem1 =
+        mediaItemBuilder.setMediaId("mediaId1").setUri("http://exoplayer.dev/video1").build();
+
+    preloadManager.add(mediaItem0, /* rankingData= */ 0);
+    FakeMediaSource wrappedMediaSource0 = fakeMediaSourceFactory.getLastCreatedSource();
+    wrappedMediaSource0.setAllowPreparation(false);
+    preloadManager.add(mediaItem1, /* rankingData= */ 1);
+    FakeMediaSource wrappedMediaSource1 = fakeMediaSourceFactory.getLastCreatedSource();
+    wrappedMediaSource1.setAllowPreparation(false);
+    preloadManager.invalidate();
+    assertThat(targetPreloadStatusControlCallReference).containsExactly(0);
+
+    PreloadMediaSource preloadMediaSource0 =
+        (PreloadMediaSource) preloadManager.getMediaSource(mediaItem0);
+    preloadMediaSource0.prepareSource(
+        (source, timeline) -> {}, bandwidthMeter.getTransferListener(), PlayerId.UNSET);
+    shadowOf(Looper.getMainLooper()).idle();
+
+    // The preload of mediaItem0 should complete and the preload manager continues to preload
+    // mediaItem1, even when the preloadMediaSource0 hasn't finished preparation.
+    assertThat(targetPreloadStatusControlCallReference).containsExactly(0, 1).inOrder();
+  }
+
   @Test
   public void invalidate_beforePreloadCompletedForLastInvalidate_preloadRespectsToLatestOrder() {
     ArrayList<Integer> targetPreloadStatusControlCallReference = new ArrayList<>();

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/PreloadAndPlaybackCoordinationTest.java

@@ -70,6 +70,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
   private final AtomicInteger preloadControlOnSourceInfoRefreshedCalledCounter;
   private final AtomicInteger preloadControlOnPreparedCalledCounter;
+  private final AtomicInteger preloadControlOnUsedByPlayerCounter;
   private final AtomicBoolean playbackSourceCallerOnSourceInfoRefreshedCalled;
   private final AtomicBoolean playbackPeriodCallbackOnPreparedCalled;
   private final AtomicReference<MediaPeriod> preloadMediaPeriodReference;
@@ -94,6 +95,7 @@ public class PreloadAndPlaybackCoordinationTest {
             };
     preloadControlOnSourceInfoRefreshedCalledCounter = new AtomicInteger();
     preloadControlOnPreparedCalledCounter = new AtomicInteger();
+    preloadControlOnUsedByPlayerCounter = new AtomicInteger();
     playbackSourceCallerOnSourceInfoRefreshedCalled = new AtomicBoolean();
     playbackPeriodCallbackOnPreparedCalled = new AtomicBoolean();
     preloadMediaPeriodReference = new AtomicReference<>();
@@ -117,6 +119,11 @@ public class PreloadAndPlaybackCoordinationTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            preloadControlOnUsedByPlayerCounter.addAndGet(1);
+          }
         };
     PreloadMediaSource.Factory preloadMediaSourceFactory =
         new PreloadMediaSource.Factory(
@@ -168,6 +175,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(0);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(0);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
     assertThat(playbackSourceCallerOnSourceInfoRefreshedCalled.get()).isTrue();
     assertThat(playbackPeriodCallbackOnPreparedCalled.get()).isTrue();
     assertThat(preloadMediaPeriodReference.get()).isNotNull();
@@ -181,6 +189,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(1);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(1);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
   }
 
   @Test
@@ -192,6 +201,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(0);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(0);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(2);
     assertThat(playbackSourceCallerOnSourceInfoRefreshedCalled.get()).isTrue();
     assertThat(playbackPeriodCallbackOnPreparedCalled.get()).isTrue();
     assertThat(preloadMediaPeriodReference.get()).isNotNull();
@@ -205,6 +215,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(1);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(1);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(2);
   }
 
   @Test
@@ -220,6 +231,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(0);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(0);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
     assertThat(playbackSourceCallerOnSourceInfoRefreshedCalled.get()).isTrue();
     assertThat(playbackPeriodCallbackOnPreparedCalled.get()).isTrue();
     assertThat(preloadMediaPeriodReference.get()).isNotNull();
@@ -233,6 +245,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(1);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(1);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
   }
 
   @Test
@@ -251,6 +264,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(1);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(0);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
     assertThat(playbackSourceCallerOnSourceInfoRefreshedCalled.get()).isTrue();
     assertThat(playbackPeriodCallbackOnPreparedCalled.get()).isTrue();
     assertThat(preloadMediaPeriodReference.get()).isNotNull();
@@ -265,6 +279,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(2);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(1);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
   }
 
   @Test
@@ -277,6 +292,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(1);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(1);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
     assertThat(playbackSourceCallerOnSourceInfoRefreshedCalled.get()).isTrue();
     assertThat(playbackPeriodCallbackOnPreparedCalled.get()).isTrue();
     assertThat(preloadMediaPeriodReference.get()).isNotNull();
@@ -290,6 +306,7 @@ public class PreloadAndPlaybackCoordinationTest {
 
     assertThat(preloadControlOnSourceInfoRefreshedCalledCounter.get()).isEqualTo(2);
     assertThat(preloadControlOnPreparedCalledCounter.get()).isEqualTo(2);
+    assertThat(preloadControlOnUsedByPlayerCounter.get()).isEqualTo(1);
   }
 
   private static RendererCapabilities[] getRendererCapabilities(RenderersFactory renderersFactory) {

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/PreloadMediaSourceTest.java

@@ -104,6 +104,7 @@ public final class PreloadMediaSourceTest {
     AtomicBoolean onPreparedCalled = new AtomicBoolean();
     AtomicBoolean onContinueLoadingStopped = new AtomicBoolean();
     AtomicReference<PreloadMediaSource> preloadMediaSourceReference = new AtomicReference<>();
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -128,6 +129,11 @@ public final class PreloadMediaSourceTest {
             }
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     ProgressiveMediaSource.Factory mediaSourceFactory =
         new ProgressiveMediaSource.Factory(
@@ -156,6 +162,7 @@ public final class PreloadMediaSourceTest {
 
     assertThat(onTimelineRefreshedCalled.get()).isTrue();
     assertThat(onPreparedCalled.get()).isTrue();
+    assertThat(onUsedByPlayerCalled.get()).isFalse();
     assertThat(preloadMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
   }
 
@@ -165,6 +172,7 @@ public final class PreloadMediaSourceTest {
     AtomicBoolean onPreparedCalled = new AtomicBoolean();
     AtomicReference<PreloadMediaSource> preloadMediaSourceReference = new AtomicReference<>();
     AtomicBoolean onContinueLoadingRequestedCalled = new AtomicBoolean();
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -186,6 +194,11 @@ public final class PreloadMediaSourceTest {
             onContinueLoadingRequestedCalled.set(true);
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     ProgressiveMediaSource.Factory mediaSourceFactory =
         new ProgressiveMediaSource.Factory(
@@ -215,6 +228,7 @@ public final class PreloadMediaSourceTest {
     assertThat(onTimelineRefreshedCalled.get()).isTrue();
     assertThat(preloadMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
     assertThat(onContinueLoadingRequestedCalled.get()).isFalse();
+    assertThat(onUsedByPlayerCalled.get()).isFalse();
   }
 
   @Test
@@ -223,6 +237,7 @@ public final class PreloadMediaSourceTest {
     AtomicReference<PreloadMediaSource> preloadMediaSourceReference = new AtomicReference<>();
     AtomicBoolean onPreparedCalled = new AtomicBoolean();
     AtomicBoolean onContinueLoadingRequestedCalled = new AtomicBoolean();
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -244,6 +259,11 @@ public final class PreloadMediaSourceTest {
             onContinueLoadingRequestedCalled.set(true);
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     ProgressiveMediaSource.Factory mediaSourceFactory =
         new ProgressiveMediaSource.Factory(
@@ -272,12 +292,14 @@ public final class PreloadMediaSourceTest {
     assertThat(preloadMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
     assertThat(onPreparedCalled.get()).isFalse();
     assertThat(onContinueLoadingRequestedCalled.get()).isFalse();
+    assertThat(onUsedByPlayerCalled.get()).isFalse();
   }
 
   @Test
   public void preload_whileSourceIsAccessedByExternalCaller_notProceedWithPreloading() {
     AtomicBoolean onTimelineRefreshedCalled = new AtomicBoolean(false);
     AtomicBoolean onPreparedCalled = new AtomicBoolean(false);
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -297,6 +319,11 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     TrackSelector trackSelector = new FakeTrackSelector();
     trackSelector.init(() -> {}, bandwidthMeter);
@@ -332,6 +359,7 @@ public final class PreloadMediaSourceTest {
     assertThat(externalCallerMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
     assertThat(onTimelineRefreshedCalled.get()).isFalse();
     assertThat(onPreparedCalled.get()).isFalse();
+    assertThat(onUsedByPlayerCalled.get()).isTrue();
   }
 
   @Test
@@ -339,6 +367,7 @@ public final class PreloadMediaSourceTest {
       prepareSource_beforeSourceInfoRefreshedForPreloading_onlyInvokeExternalCallerOnSourceInfoRefreshed() {
     AtomicBoolean onTimelineRefreshedCalled = new AtomicBoolean(false);
     AtomicBoolean onPreparedCalled = new AtomicBoolean(false);
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -358,6 +387,11 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     FakeMediaSourceFactory mediaSourceFactory = new FakeMediaSourceFactory();
     TrackSelector trackSelector = new FakeTrackSelector();
@@ -396,12 +430,14 @@ public final class PreloadMediaSourceTest {
     assertThat(externalCallerMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
     assertThat(onTimelineRefreshedCalled.get()).isFalse();
     assertThat(onPreparedCalled.get()).isFalse();
+    assertThat(onUsedByPlayerCalled.get()).isTrue();
   }
 
   @Test
   public void prepareSource_afterPreload_immediatelyInvokeExternalCallerOnSourceInfoRefreshed() {
     AtomicBoolean onTimelineRefreshedCalled = new AtomicBoolean(false);
     AtomicBoolean onPreparedCalled = new AtomicBoolean(false);
+    AtomicBoolean onUsedByPlayerCalled = new AtomicBoolean();
     PreloadMediaSource.PreloadControl preloadControl =
         new PreloadMediaSource.PreloadControl() {
           @Override
@@ -421,6 +457,11 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {
+            onUsedByPlayerCalled.set(true);
+          }
         };
     FakeMediaSourceFactory mediaSourceFactory = new FakeMediaSourceFactory();
     TrackSelector trackSelector = new FakeTrackSelector();
@@ -456,6 +497,7 @@ public final class PreloadMediaSourceTest {
     assertThat(onTimelineRefreshedCalled.get()).isTrue();
     assertThat(onPreparedCalled.get()).isTrue();
     assertThat(externalCallerMediaSourceReference.get()).isSameInstanceAs(preloadMediaSource);
+    assertThat(onUsedByPlayerCalled.get()).isTrue();
   }
 
   @Test
@@ -480,6 +522,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -587,6 +632,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -692,6 +740,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -769,6 +820,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return true;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -847,6 +901,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -935,6 +992,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -1004,6 +1064,9 @@ public final class PreloadMediaSourceTest {
               PreloadMediaSource mediaSource, long bufferedPositionUs) {
             return false;
           }
+
+          @Override
+          public void onUsedByPlayer(PreloadMediaSource mediaSource) {}
         };
     AtomicReference<MediaSource> internalSourceReference = new AtomicReference<>();
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);