Release internal components on preload thread in DefaultPreloadManager

The `RendererCapabilities` and `TrackSelector` objects are accessed on the preload thread during the preloading, when releasing them, they need to be released on the same thread. Otherwise, it is possible that they have already released on the application thread, while the PreloadMediaSource still tries to access them on the preload thread before the source is released.

#cherrypick

PiperOrigin-RevId: 694173131

Author: tianyif

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

@@ -22,6 +22,7 @@
 import static java.lang.annotation.ElementType.TYPE_USE;
 
 import android.content.Context;
+import android.os.Handler;
 import android.os.Looper;
 import android.os.Process;
 import androidx.annotation.IntDef;
@@ -327,6 +328,7 @@ public long getValue() {
   private final TrackSelector trackSelector;
   private final PlaybackLooperProvider preloadLooperProvider;
   private final PreloadMediaSource.Factory preloadMediaSourceFactory;
+  private final Handler preloadHandler;
   private final boolean deprecatedConstructorCalled;
 
   private DefaultPreloadManager(Builder builder) {
@@ -341,6 +343,7 @@ private DefaultPreloadManager(Builder builder) {
     trackSelector = builder.trackSelectorFactory.createTrackSelector(builder.context);
     BandwidthMeter bandwidthMeter = builder.bandwidthMeterSupplier.get();
     trackSelector.init(() -> {}, bandwidthMeter);
+    Looper preloadLooper = preloadLooperProvider.obtainLooper();
     preloadMediaSourceFactory =
         new PreloadMediaSource.Factory(
             builder.mediaSourceFactorySupplier.get(),
@@ -349,7 +352,8 @@ private DefaultPreloadManager(Builder builder) {
             bandwidthMeter,
             rendererCapabilitiesList.getRendererCapabilities(),
             builder.loadControlSupplier.get().getAllocator(),
-            preloadLooperProvider.obtainLooper());
+            preloadLooper);
+    preloadHandler = Util.createHandler(preloadLooper, /* callback= */ null);
     deprecatedConstructorCalled = false;
   }
 
@@ -370,6 +374,7 @@ public DefaultPreloadManager(
         rendererCapabilitiesListFactory.createRendererCapabilitiesList();
     this.preloadLooperProvider = new PlaybackLooperProvider(preloadLooper);
     this.trackSelector = trackSelector;
+    Looper obtainedPreloadLooper = preloadLooperProvider.obtainLooper();
     preloadMediaSourceFactory =
         new PreloadMediaSource.Factory(
             mediaSourceFactory,
@@ -378,7 +383,8 @@ public DefaultPreloadManager(
             bandwidthMeter,
             rendererCapabilitiesList.getRendererCapabilities(),
             allocator,
-            preloadLooperProvider.obtainLooper());
+            obtainedPreloadLooper);
+    preloadHandler = Util.createHandler(obtainedPreloadLooper, /* callback= */ null);
     deprecatedConstructorCalled = true;
   }
 
@@ -418,13 +424,16 @@ protected void releaseSourceInternal(MediaSource mediaSource) {
 
   @Override
   protected void releaseInternal() {
-    rendererCapabilitiesList.release();
-    preloadLooperProvider.releaseLooper();
-    if (!deprecatedConstructorCalled) {
-      // TODO: Remove the property deprecatedConstructorCalled and release the TrackSelector anyway
-      // after the deprecated constructor is removed.
-      trackSelector.release();
-    }
+    preloadHandler.post(
+        () -> {
+          rendererCapabilitiesList.release();
+          if (!deprecatedConstructorCalled) {
+            // TODO: Remove the property deprecatedConstructorCalled and release the TrackSelector
+            // anyway after the deprecated constructor is removed.
+            trackSelector.release();
+          }
+          preloadLooperProvider.releaseLooper();
+        });
   }
 
   private static final class RankingDataComparator implements Comparator<Integer> {

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

@@ -830,7 +830,8 @@ protected void releaseSourceInternal() {
   }
 
   @Test
-  public void release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased() {
+  public void release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased()
+      throws Exception {
     TargetPreloadStatusControl<Integer> targetPreloadStatusControl =
         rankingData -> new DefaultPreloadManager.Status(STAGE_SOURCE_PREPARED);
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);
@@ -853,11 +854,13 @@ public void release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased()
           underlyingRenderers.add(fakeAudioRenderer);
           return underlyingRenderers.toArray(new Renderer[2]);
         };
+    HandlerThread preloadThread = new HandlerThread("preload");
+    preloadThread.start();
     DefaultPreloadManager preloadManager =
         new DefaultPreloadManager.Builder(context, targetPreloadStatusControl)
             .setMediaSourceFactory(mockMediaSourceFactory)
             .setRenderersFactory(renderersFactory)
-            .setPreloadLooper(Util.getCurrentOrMainLooper())
+            .setPreloadLooper(preloadThread.getLooper())
             .build();
     MediaItem.Builder mediaItemBuilder = new MediaItem.Builder();
     MediaItem mediaItem1 =
@@ -885,16 +888,19 @@ protected void releaseSourceInternal() {
     preloadManager.add(mediaItem1, /* rankingData= */ 1);
     preloadManager.add(mediaItem2, /* rankingData= */ 2);
     preloadManager.invalidate();
+    shadowOf(preloadThread.getLooper()).idle();
     shadowOf(Looper.getMainLooper()).idle();
 
     preloadManager.release();
-    shadowOf(Looper.getMainLooper()).idle();
+    shadowOf(preloadThread.getLooper()).idle();
 
     assertThat(preloadManager.getSourceCount()).isEqualTo(0);
     assertThat(internalSourceToReleaseReferenceByMediaId).containsExactly("mediaId1", "mediaId2");
     for (FakeRenderer renderer : underlyingRenderers) {
       assertThat(renderer.isReleased).isTrue();
     }
+
+    preloadThread.quit();
   }
 
   private static class TestPreloadManagerListener implements BasePreloadManager.Listener {