Add TrackSelector.release()

The TrackSelector is released when the player is released. The
TrackSelector can be reused if TrackSelector.init() is called again.

PiperOrigin-RevId: 446439717

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/ExoPlayerImpl.java

@@ -980,6 +980,7 @@ import java.util.concurrent.TimeoutException;
     playbackInfo.bufferedPositionUs = playbackInfo.positionUs;
     playbackInfo.totalBufferedDurationUs = 0;
     analyticsCollector.release();
+    trackSelector.release();
     removeSurfaceCallbacks();
     if (ownedSurface != null) {
       ownedSurface.release();

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/offline/DownloadHelper.java

@@ -516,6 +516,7 @@ public final class DownloadHelper {
     if (mediaPreparer != null) {
       mediaPreparer.release();
     }
+    trackSelector.release();
   }
 
   /**

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/trackselection/TrackSelector.java

@@ -15,10 +15,12 @@
  */
 package androidx.media3.exoplayer.trackselection;
 
+import static androidx.media3.common.util.Assertions.checkStateNotNull;
+
 import androidx.annotation.Nullable;
+import androidx.media3.common.Player;
 import androidx.media3.common.Timeline;
 import androidx.media3.common.TrackSelectionParameters;
-import androidx.media3.common.util.Assertions;
 import androidx.media3.common.util.UnstableApi;
 import androidx.media3.exoplayer.ExoPlaybackException;
 import androidx.media3.exoplayer.ExoPlayer;
@@ -65,6 +67,8 @@ import androidx.media3.exoplayer.upstream.BandwidthMeter;
  *       track selection for the currently playing period differs from the one that was invalidated.
  *       Implementing subclasses can trigger invalidation by calling {@link #invalidate()}, which
  *       will call {@link InvalidationListener#onTrackSelectionsInvalidated()}.
+ *   <li>When the player is {@linkplain Player#release() released}, it will release the track
+ *       selector by calling {@link #release()}.
  * </ul>
  *
  * <h2>Renderer configuration</h2>
@@ -113,6 +117,15 @@ public abstract class TrackSelector {
     this.bandwidthMeter = bandwidthMeter;
   }
 
+  /**
+   * Called by the player to release the selector. The selector cannot be used until {@link
+   * #init(InvalidationListener, BandwidthMeter)} is called again.
+   */
+  public final void release() {
+    this.listener = null;
+    this.bandwidthMeter = null;
+  }
+
   /**
    * Called by the player to perform a track selection.
    *
@@ -177,9 +190,10 @@ public abstract class TrackSelector {
 
   /**
    * Returns a bandwidth meter which can be used by track selections to select tracks. Must only be
-   * called after {@link #init(InvalidationListener, BandwidthMeter)} has been called.
+   * called when the track selector is {@linkplain #init(InvalidationListener, BandwidthMeter)
+   * initialized}.
    */
   protected final BandwidthMeter getBandwidthMeter() {
-    return Assertions.checkNotNull(bandwidthMeter);
+    return checkStateNotNull(bandwidthMeter);
   }
 }

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/DefaultTrackSelectorTest.java

@@ -62,6 +62,7 @@ import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import java.util.HashMap;
 import java.util.Map;
+import org.junit.After;
 import org.junit.Before;
 import org.junit.BeforeClass;
 import org.junit.Test;
@@ -146,6 +147,11 @@ public final class DefaultTrackSelectorTest {
     trackSelector.init(invalidationListener, bandwidthMeter);
   }
 
+  @After
+  public void tearDown() {
+    trackSelector.release();
+  }
+
   @Test
   public void parameters_buildUponThenBuild_isEqual() {
     Parameters parameters = buildParametersForEqualsTest();

libraries/exoplayer/src/test/java/androidx/media3/exoplayer/trackselection/TrackSelectorTest.java

@@ -16,7 +16,7 @@
 package androidx.media3.exoplayer.trackselection;
 
 import static com.google.common.truth.Truth.assertThat;
-import static org.junit.Assert.fail;
+import static org.junit.Assert.assertThrows;
 
 import androidx.annotation.Nullable;
 import androidx.media3.common.Timeline;
@@ -59,12 +59,7 @@ public class TrackSelectorTest {
 
   @Test
   public void getBandwidthMeter_beforeInitialization_throwsException() {
-    try {
-      trackSelector.getBandwidthMeter();
-      fail();
-    } catch (Exception e) {
-      // Expected.
-    }
+    assertThrows(IllegalStateException.class, () -> trackSelector.getBandwidthMeter());
   }
 
   @Test
@@ -73,6 +68,30 @@ public class TrackSelectorTest {
     BandwidthMeter bandwidthMeter = Mockito.mock(BandwidthMeter.class);
     trackSelector.init(invalidationListener, bandwidthMeter);
 
-    assertThat(trackSelector.getBandwidthMeter()).isEqualTo(bandwidthMeter);
+    assertThat(trackSelector.getBandwidthMeter()).isSameInstanceAs(bandwidthMeter);
+  }
+
+  @Test
+  public void getBandwidthMeter_afterRelease_throwsException() {
+    InvalidationListener invalidationListener = Mockito.mock(InvalidationListener.class);
+    BandwidthMeter bandwidthMeter = Mockito.mock(BandwidthMeter.class);
+    trackSelector.init(invalidationListener, bandwidthMeter);
+
+    trackSelector.release();
+
+    assertThrows(IllegalStateException.class, () -> trackSelector.getBandwidthMeter());
+  }
+
+  @Test
+  public void initialize_afterRelease() {
+    InvalidationListener invalidationListener = Mockito.mock(InvalidationListener.class);
+    BandwidthMeter bandwidthMeter = Mockito.mock(BandwidthMeter.class);
+    trackSelector.init(invalidationListener, bandwidthMeter);
+
+    trackSelector.release();
+    BandwidthMeter anotherBandwidthMeter = Mockito.mock(BandwidthMeter.class);
+    trackSelector.init(invalidationListener, anotherBandwidthMeter);
+
+    assertThat(trackSelector.getBandwidthMeter()).isSameInstanceAs(anotherBandwidthMeter);
   }
 }