Guard timeline access in ImaSSAIMS against empty timelines

All methods check if the player is currently handling the ad source
by calling isCurrentAdPlaying(). This method was missing a check
for empty timelines that throws an exception when trying to access
a non-existent period.

Also add this check to two methods that assume the current item
is the ads source, but didn't check it yet.

PiperOrigin-RevId: 653963557

RELEASENOTES.md

@@ -61,6 +61,9 @@
 *   Effect:
 *   Muxers:
 *   IMA extension:
+    *   Fix bug where clearing the playlist may cause an
+        `ArrayIndexOutOfBoundsException` in
+        `ImaServerSideAdInsertionMediaSource`.
 *   Session:
     *   Add `MediaButtonReceiver.shouldStartForegroundService(Intent)` to allow
         apps to suppress a play command coming in for playback resumption by

libraries/exoplayer_ima/build.gradle

@@ -39,6 +39,7 @@ dependencies {
     androidTestImplementation 'androidx.test:runner:' + androidxTestRunnerVersion
     androidTestCompileOnly 'org.checkerframework:checker-qual:' + checkerframeworkVersion
     testImplementation project(modulePrefix + 'test-utils')
+    testImplementation project(modulePrefix + 'test-utils-robolectric')
     testImplementation 'org.robolectric:robolectric:' + robolectricVersion
 }
 

libraries/exoplayer_ima/src/main/java/androidx/media3/exoplayer/ima/ImaServerSideAdInsertionMediaSource.java

@@ -1021,7 +1021,7 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
 
     @Override
     public void onMetadata(Metadata metadata) {
-      if (!isCurrentAdPlaying(player, getMediaItem(), adsId)) {
+      if (!isCurrentlyPlayingMediaPeriodFromThisSource(player, getMediaItem(), adsId)) {
         return;
       }
       for (int i = 0; i < metadata.length(); i++) {
@@ -1041,14 +1041,15 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
 
     @Override
     public void onPlaybackStateChanged(@Player.State int state) {
-      if (state == Player.STATE_ENDED && isCurrentAdPlaying(player, getMediaItem(), adsId)) {
+      if (state == Player.STATE_ENDED
+          && isCurrentlyPlayingMediaPeriodFromThisSource(player, getMediaItem(), adsId)) {
         streamPlayer.onContentCompleted();
       }
     }
 
     @Override
     public void onVolumeChanged(float volume) {
-      if (!isCurrentAdPlaying(player, getMediaItem(), adsId)) {
+      if (!isCurrentlyPlayingMediaPeriodFromThisSource(player, getMediaItem(), adsId)) {
         return;
       }
       int volumePct = (int) Math.floor(volume * 100);
@@ -1312,7 +1313,7 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
 
     @Override
     public VideoProgressUpdate getContentProgress() {
-      if (!isCurrentAdPlaying(player, mediaItem, adsId)) {
+      if (!isCurrentlyPlayingMediaPeriodFromThisSource(player, mediaItem, adsId)) {
         return VideoProgressUpdate.VIDEO_TIME_NOT_READY;
       } else if (adPlaybackStates.isEmpty()) {
         return new VideoProgressUpdate(/* currentTimeMs= */ 0, /* durationMs= */ C.TIME_UNSET);
@@ -1428,9 +1429,9 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
     }
   }
 
-  private static boolean isCurrentAdPlaying(
+  private static boolean isCurrentlyPlayingMediaPeriodFromThisSource(
       Player player, MediaItem mediaItem, @Nullable Object adsId) {
-    if (player.getPlaybackState() == Player.STATE_IDLE) {
+    if (player.getPlaybackState() == Player.STATE_IDLE || player.getMediaItemCount() == 0) {
       return false;
     }
     Timeline.Period period = new Timeline.Period();
@@ -1510,7 +1511,8 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
   private class SinglePeriodLiveAdEventListener implements AdEventListener {
     @Override
     public void onAdEvent(AdEvent event) {
-      if (!Objects.equals(event.getType(), LOADED)) {
+      if (!Objects.equals(event.getType(), LOADED)
+          || !isCurrentlyPlayingMediaPeriodFromThisSource(player, getMediaItem(), adsId)) {
         return;
       }
       AdPlaybackState newAdPlaybackState = adPlaybackState;
@@ -1541,7 +1543,8 @@ public final class ImaServerSideAdInsertionMediaSource extends CompositeMediaSou
   private class MultiPeriodLiveAdEventListener implements AdEventListener {
     @Override
     public void onAdEvent(AdEvent event) {
-      if (!Objects.equals(event.getType(), LOADED)) {
+      if (!Objects.equals(event.getType(), LOADED)
+          || !isCurrentlyPlayingMediaPeriodFromThisSource(player, getMediaItem(), adsId)) {
         return;
       }
       AdPodInfo adPodInfo = event.getAd().getAdPodInfo();

libraries/exoplayer_ima/src/test/java/androidx/media3/exoplayer/ima/ImaServerSideAdInsertionMediaSourceTest.java

@@ -15,12 +15,21 @@
  */
 package androidx.media3.exoplayer.ima;
 
+import static androidx.media3.test.utils.robolectric.TestPlayerRunHelper.run;
 import static com.google.common.truth.Truth.assertThat;
 
+import android.content.Context;
+import android.widget.LinearLayout;
 import androidx.media3.common.AdPlaybackState;
 import androidx.media3.common.C;
+import androidx.media3.common.MediaItem;
+import androidx.media3.exoplayer.ExoPlayer;
 import androidx.media3.exoplayer.ima.ImaServerSideAdInsertionMediaSource.AdsLoader.State;
+import androidx.media3.exoplayer.source.DefaultMediaSourceFactory;
+import androidx.media3.exoplayer.source.MediaSource;
 import androidx.media3.exoplayer.source.ads.ServerSideAdInsertionUtil;
+import androidx.media3.test.utils.TestExoPlayerBuilder;
+import androidx.test.core.app.ApplicationProvider;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 import com.google.common.collect.ImmutableMap;
 import org.junit.Test;
@@ -70,4 +79,30 @@ public class ImaServerSideAdInsertionMediaSourceTest {
 
     assertThat(State.fromBundle(state.toBundle())).isEqualTo(state);
   }
+
+  @Test
+  public void clearPlaylist_withAdsSource_handlesCleanupWithoutThrowing() throws Exception {
+    Context context = ApplicationProvider.getApplicationContext();
+    ExoPlayer player = new TestExoPlayerBuilder(context).build();
+    ImaServerSideAdInsertionMediaSource.AdsLoader adsLoader =
+        new ImaServerSideAdInsertionMediaSource.AdsLoader.Builder(
+                context, /* adViewProvider= */ () -> new LinearLayout(context))
+            .build();
+    adsLoader.setPlayer(player);
+    MediaSource mediaSource =
+        new ImaServerSideAdInsertionMediaSource.Factory(
+                adsLoader, new DefaultMediaSourceFactory(context))
+            .createMediaSource(
+                MediaItem.fromUri("ssai://dai.google.com/?assetKey=ABC&format=0&adsId=2"));
+    player.setMediaSource(mediaSource);
+    player.prepare();
+    run(player).untilPendingCommandsAreFullyHandled();
+
+    // Clearing the playlist will cause internal state of the ads source to be invalid and
+    // potentially accessing empty timelines. See b/354026260. The test simply ensures that clearing
+    // the playlist will not throw any exceptions.
+    player.clearMediaItems();
+    run(player).untilPendingCommandsAreFullyHandled();
+    player.release();
+  }
 }