Extract HlsPlaylistTracker interface

This allows injection of custom implementations and configuration of
DefaultHlsPlaylistTracker without modifying the HlsMediaSource interface.

Issue:#2844

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=198846607

RELEASENOTES.md

@@ -6,7 +6,9 @@
   extractor for this ([#4297](https://github.com/google/ExoPlayer/issues/4297)).
 * DASH: Fix playback getting stuck when playing representations that have both
   sidx atoms and non-zero presentationTimeOffset values.
-* HLS: Fix adaptation in live playlists with EXT-X-PROGRAM-DATE-TIME tags.
+* HLS:
+  * Allow injection of custom playlist trackers.
+  * Fix adaptation in live playlists with EXT-X-PROGRAM-DATE-TIME tags.
 * Mitigate memory leaks when `MediaSource` loads are slow to cancel
   ([#4249](https://github.com/google/ExoPlayer/issues/4249)).
 * Fix inconsistent `Player.EventListener` invocations for recursive player state

library/hls/src/main/java/com/google/android/exoplayer2/source/hls/HlsMediaSource.java

@@ -32,6 +32,7 @@ import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispat
 import com.google.android.exoplayer2.source.SequenceableLoader;
 import com.google.android.exoplayer2.source.SinglePeriodTimeline;
 import com.google.android.exoplayer2.source.ads.AdsMediaSource;
+import com.google.android.exoplayer2.source.hls.playlist.DefaultHlsPlaylistTracker;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist;
 import com.google.android.exoplayer2.source.hls.playlist.HlsPlaylist;
 import com.google.android.exoplayer2.source.hls.playlist.HlsPlaylistParser;
@@ -58,6 +59,7 @@ public final class HlsMediaSource extends BaseMediaSource
 
     private HlsExtractorFactory extractorFactory;
     private @Nullable ParsingLoadable.Parser<HlsPlaylist> playlistParser;
+    private @Nullable HlsPlaylistTracker playlistTracker;
     private CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory;
     private int minLoadableRetryCount;
     private boolean allowChunklessPreparation;
@@ -136,17 +138,38 @@ public final class HlsMediaSource extends BaseMediaSource
      * Sets the parser to parse HLS playlists. The default is an instance of {@link
      * HlsPlaylistParser}.
      *
+     * <p>Must not be called after calling {@link #setPlaylistTracker} on the same builder.
+     *
      * @param playlistParser A {@link ParsingLoadable.Parser} for HLS playlists.
      * @return This factory, for convenience.
      * @throws IllegalStateException If one of the {@code create} methods has already been called.
      */
     public Factory setPlaylistParser(ParsingLoadable.Parser<HlsPlaylist> playlistParser) {
       Assertions.checkState(!isCreateCalled);
+      Assertions.checkState(playlistTracker == null, "A playlist tracker has already been set.");
       this.playlistParser = Assertions.checkNotNull(playlistParser);
       return this;
     }
 
     /**
+     * Sets the HLS playlist tracker. The default is an instance of {@link
+     * DefaultHlsPlaylistTracker}. Playlist trackers must not be shared by {@link HlsMediaSource}
+     * instances.
+     *
+     * <p>Must not be called after calling {@link #setPlaylistParser} on the same builder.
+     *
+     * @param playlistTracker A tracker for HLS playlists.
+     * @return This factory, for convenience.
+     * @throws IllegalStateException If one of the {@code create} methods has already been called.
+     */
+    public Factory setPlaylistTracker(HlsPlaylistTracker playlistTracker) {
+      Assertions.checkState(!isCreateCalled);
+      Assertions.checkState(playlistParser == null, "A playlist parser has already been set.");
+      this.playlistTracker = Assertions.checkNotNull(playlistTracker);
+      return this;
+    }
+
+    /**
      * Sets the factory to create composite {@link SequenceableLoader}s for when this media source
      * loads data from multiple streams (video, audio etc...). The default is an instance of {@link
      * DefaultCompositeSequenceableLoaderFactory}.
@@ -187,8 +210,12 @@ public final class HlsMediaSource extends BaseMediaSource
     @Override
     public HlsMediaSource createMediaSource(Uri playlistUri) {
       isCreateCalled = true;
-      if (playlistParser == null) {
-        playlistParser = new HlsPlaylistParser();
+      if (playlistTracker == null) {
+        playlistTracker =
+            new DefaultHlsPlaylistTracker(
+                hlsDataSourceFactory,
+                minLoadableRetryCount,
+                playlistParser != null ? playlistParser : new HlsPlaylistParser());
       }
       return new HlsMediaSource(
           playlistUri,
@@ -196,7 +223,7 @@ public final class HlsMediaSource extends BaseMediaSource
           extractorFactory,
           compositeSequenceableLoaderFactory,
           minLoadableRetryCount,
-          playlistParser,
+          playlistTracker,
           allowChunklessPreparation,
           tag);
     }
@@ -233,12 +260,10 @@ public final class HlsMediaSource extends BaseMediaSource
   private final HlsDataSourceFactory dataSourceFactory;
   private final CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory;
   private final int minLoadableRetryCount;
-  private final ParsingLoadable.Parser<HlsPlaylist> playlistParser;
   private final boolean allowChunklessPreparation;
+  private final HlsPlaylistTracker playlistTracker;
   private final @Nullable Object tag;
 
-  private HlsPlaylistTracker playlistTracker;
-
   /**
    * @param manifestUri The {@link Uri} of the HLS manifest.
    * @param dataSourceFactory An {@link HlsDataSourceFactory} for {@link DataSource}s for manifests,
@@ -276,8 +301,13 @@ public final class HlsMediaSource extends BaseMediaSource
       int minLoadableRetryCount,
       Handler eventHandler,
       MediaSourceEventListener eventListener) {
-    this(manifestUri, new DefaultHlsDataSourceFactory(dataSourceFactory),
-        HlsExtractorFactory.DEFAULT, minLoadableRetryCount, eventHandler, eventListener,
+    this(
+        manifestUri,
+        new DefaultHlsDataSourceFactory(dataSourceFactory),
+        HlsExtractorFactory.DEFAULT,
+        minLoadableRetryCount,
+        eventHandler,
+        eventListener,
         new HlsPlaylistParser());
   }
 
@@ -309,7 +339,8 @@ public final class HlsMediaSource extends BaseMediaSource
         extractorFactory,
         new DefaultCompositeSequenceableLoaderFactory(),
         minLoadableRetryCount,
-        playlistParser,
+        new DefaultHlsPlaylistTracker(
+            dataSourceFactory, minLoadableRetryCount, new HlsPlaylistParser()),
         /* allowChunklessPreparation= */ false,
         /* tag= */ null);
     if (eventHandler != null && eventListener != null) {
@@ -323,7 +354,7 @@ public final class HlsMediaSource extends BaseMediaSource
       HlsExtractorFactory extractorFactory,
       CompositeSequenceableLoaderFactory compositeSequenceableLoaderFactory,
       int minLoadableRetryCount,
-      ParsingLoadable.Parser<HlsPlaylist> playlistParser,
+      HlsPlaylistTracker playlistTracker,
       boolean allowChunklessPreparation,
       @Nullable Object tag) {
     this.manifestUri = manifestUri;
@@ -331,7 +362,7 @@ public final class HlsMediaSource extends BaseMediaSource
     this.extractorFactory = extractorFactory;
     this.compositeSequenceableLoaderFactory = compositeSequenceableLoaderFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
-    this.playlistParser = playlistParser;
+    this.playlistTracker = playlistTracker;
     this.allowChunklessPreparation = allowChunklessPreparation;
     this.tag = tag;
   }
@@ -339,9 +370,7 @@ public final class HlsMediaSource extends BaseMediaSource
   @Override
   public void prepareSourceInternal(ExoPlayer player, boolean isTopLevelSource) {
     EventDispatcher eventDispatcher = createEventDispatcher(/* mediaPeriodId= */ null);
-    playlistTracker = new HlsPlaylistTracker(manifestUri, dataSourceFactory, eventDispatcher,
-        minLoadableRetryCount, this, playlistParser);
-    playlistTracker.start();
+    playlistTracker.start(manifestUri, eventDispatcher, /* listener= */ this);
   }
 
   @Override
@@ -373,7 +402,6 @@ public final class HlsMediaSource extends BaseMediaSource
   public void releaseSourceInternal() {
     if (playlistTracker != null) {
       playlistTracker.release();
-      playlistTracker = null;
     }
   }