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;
@@ -136,16 +138,37 @@ 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
@@ -187,8 +210,12 @@ public final class HlsMediaSource extends BaseMediaSource
     @Override
     public HlsMediaSource createMediaSource(Uri playlistUri) {
       isCreateCalled = true;
-      if (playlistParser == null) {
+      if (playlistTracker == null) {
-        playlistParser = new HlsPlaylistParser();
+        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),
+    this(
-        HlsExtractorFactory.DEFAULT, minLoadableRetryCount, eventHandler, eventListener,
+        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,
+    playlistTracker.start(manifestUri, eventDispatcher, /* listener= */ this);
-        minLoadableRetryCount, this, playlistParser);
-    playlistTracker.start();
   }
 
   @Override
@@ -373,7 +402,6 @@ public final class HlsMediaSource extends BaseMediaSource
   public void releaseSourceInternal() {
     if (playlistTracker != null) {
       playlistTracker.release();
-      playlistTracker = null;
     }
   }
 

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

@@ -0,0 +1,566 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.source.hls.playlist;
+
+import android.net.Uri;
+import android.os.Handler;
+import android.os.SystemClock;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
+import com.google.android.exoplayer2.source.chunk.ChunkedTrackBlacklistUtil;
+import com.google.android.exoplayer2.source.hls.HlsDataSourceFactory;
+import com.google.android.exoplayer2.source.hls.playlist.HlsMasterPlaylist.HlsUrl;
+import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist.Segment;
+import com.google.android.exoplayer2.upstream.DataSource;
+import com.google.android.exoplayer2.upstream.Loader;
+import com.google.android.exoplayer2.upstream.ParsingLoadable;
+import com.google.android.exoplayer2.util.UriUtil;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.IdentityHashMap;
+import java.util.List;
+
+/** Default implementation for {@link HlsPlaylistTracker}. */
+public final class DefaultHlsPlaylistTracker
+    implements HlsPlaylistTracker, Loader.Callback<ParsingLoadable<HlsPlaylist>> {
+
+  /**
+   * Coefficient applied on the target duration of a playlist to determine the amount of time after
+   * which an unchanging playlist is considered stuck.
+   */
+  private static final double PLAYLIST_STUCK_TARGET_DURATION_COEFFICIENT = 3.5;
+
+  private final HlsDataSourceFactory dataSourceFactory;
+  private final ParsingLoadable.Parser<HlsPlaylist> playlistParser;
+  private final int minRetryCount;
+  private final IdentityHashMap<HlsUrl, MediaPlaylistBundle> playlistBundles;
+  private final List<PlaylistEventListener> listeners;
+  private final Loader initialPlaylistLoader;
+
+  private Handler playlistRefreshHandler;
+  private EventDispatcher eventDispatcher;
+  private PrimaryPlaylistListener primaryPlaylistListener;
+  private HlsMasterPlaylist masterPlaylist;
+  private HlsUrl primaryHlsUrl;
+  private HlsMediaPlaylist primaryUrlSnapshot;
+  private boolean isLive;
+  private long initialStartTimeUs;
+
+  /**
+   * @param dataSourceFactory A factory for {@link DataSource} instances.
+   * @param minRetryCount The minimum number of times loads must be retried before {@link
+   *     #maybeThrowPlaylistRefreshError(HlsUrl)} and {@link
+   *     #maybeThrowPrimaryPlaylistRefreshError()} propagate any loading errors.
+   * @param playlistParser A {@link ParsingLoadable.Parser} for HLS playlists.
+   */
+  public DefaultHlsPlaylistTracker(
+      HlsDataSourceFactory dataSourceFactory,
+      int minRetryCount,
+      ParsingLoadable.Parser<HlsPlaylist> playlistParser) {
+    this.dataSourceFactory = dataSourceFactory;
+    this.minRetryCount = minRetryCount;
+    this.playlistParser = playlistParser;
+    listeners = new ArrayList<>();
+    initialPlaylistLoader = new Loader("DefaultHlsPlaylistTracker:MasterPlaylist");
+    playlistBundles = new IdentityHashMap<>();
+    initialStartTimeUs = C.TIME_UNSET;
+  }
+
+  // HlsPlaylistTracker implementation.
+
+  @Override
+  public void start(
+      Uri initialPlaylistUri,
+      EventDispatcher eventDispatcher,
+      PrimaryPlaylistListener primaryPlaylistListener) {
+    this.playlistRefreshHandler = new Handler();
+    this.eventDispatcher = eventDispatcher;
+    this.primaryPlaylistListener = primaryPlaylistListener;
+    ParsingLoadable<HlsPlaylist> masterPlaylistLoadable =
+        new ParsingLoadable<>(
+            dataSourceFactory.createDataSource(C.DATA_TYPE_MANIFEST),
+            initialPlaylistUri,
+            C.DATA_TYPE_MANIFEST,
+            playlistParser);
+    initialPlaylistLoader.startLoading(masterPlaylistLoadable, this, minRetryCount);
+  }
+
+  @Override
+  public void release() {
+    initialPlaylistLoader.release();
+    for (MediaPlaylistBundle bundle : playlistBundles.values()) {
+      bundle.release();
+    }
+    playlistRefreshHandler.removeCallbacksAndMessages(null);
+    playlistBundles.clear();
+  }
+
+  @Override
+  public void addListener(PlaylistEventListener listener) {
+    listeners.add(listener);
+  }
+
+  @Override
+  public void removeListener(PlaylistEventListener listener) {
+    listeners.remove(listener);
+  }
+
+  @Override
+  public HlsMasterPlaylist getMasterPlaylist() {
+    return masterPlaylist;
+  }
+
+  @Override
+  public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url) {
+    HlsMediaPlaylist snapshot = playlistBundles.get(url).getPlaylistSnapshot();
+    if (snapshot != null) {
+      maybeSetPrimaryUrl(url);
+    }
+    return snapshot;
+  }
+
+  @Override
+  public long getInitialStartTimeUs() {
+    return initialStartTimeUs;
+  }
+
+  @Override
+  public boolean isSnapshotValid(HlsUrl url) {
+    return playlistBundles.get(url).isSnapshotValid();
+  }
+
+  @Override
+  public void maybeThrowPrimaryPlaylistRefreshError() throws IOException {
+    initialPlaylistLoader.maybeThrowError();
+    if (primaryHlsUrl != null) {
+      maybeThrowPlaylistRefreshError(primaryHlsUrl);
+    }
+  }
+
+  @Override
+  public void maybeThrowPlaylistRefreshError(HlsUrl url) throws IOException {
+    playlistBundles.get(url).maybeThrowPlaylistRefreshError();
+  }
+
+  @Override
+  public void refreshPlaylist(HlsUrl url) {
+    playlistBundles.get(url).loadPlaylist();
+  }
+
+  @Override
+  public boolean isLive() {
+    return isLive;
+  }
+
+  // Loader.Callback implementation.
+
+  @Override
+  public void onLoadCompleted(
+      ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs, long loadDurationMs) {
+    HlsPlaylist result = loadable.getResult();
+    HlsMasterPlaylist masterPlaylist;
+    boolean isMediaPlaylist = result instanceof HlsMediaPlaylist;
+    if (isMediaPlaylist) {
+      masterPlaylist = HlsMasterPlaylist.createSingleVariantMasterPlaylist(result.baseUri);
+    } else /* result instanceof HlsMasterPlaylist */ {
+      masterPlaylist = (HlsMasterPlaylist) result;
+    }
+    this.masterPlaylist = masterPlaylist;
+    primaryHlsUrl = masterPlaylist.variants.get(0);
+    ArrayList<HlsUrl> urls = new ArrayList<>();
+    urls.addAll(masterPlaylist.variants);
+    urls.addAll(masterPlaylist.audios);
+    urls.addAll(masterPlaylist.subtitles);
+    createBundles(urls);
+    MediaPlaylistBundle primaryBundle = playlistBundles.get(primaryHlsUrl);
+    if (isMediaPlaylist) {
+      // We don't need to load the playlist again. We can use the same result.
+      primaryBundle.processLoadedPlaylist((HlsMediaPlaylist) result);
+    } else {
+      primaryBundle.loadPlaylist();
+    }
+    eventDispatcher.loadCompleted(
+        loadable.dataSpec,
+        C.DATA_TYPE_MANIFEST,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        loadable.bytesLoaded());
+  }
+
+  @Override
+  public void onLoadCanceled(
+      ParsingLoadable<HlsPlaylist> loadable,
+      long elapsedRealtimeMs,
+      long loadDurationMs,
+      boolean released) {
+    eventDispatcher.loadCanceled(
+        loadable.dataSpec,
+        C.DATA_TYPE_MANIFEST,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        loadable.bytesLoaded());
+  }
+
+  @Override
+  public @Loader.RetryAction int onLoadError(
+      ParsingLoadable<HlsPlaylist> loadable,
+      long elapsedRealtimeMs,
+      long loadDurationMs,
+      IOException error) {
+    boolean isFatal = error instanceof ParserException;
+    eventDispatcher.loadError(
+        loadable.dataSpec,
+        C.DATA_TYPE_MANIFEST,
+        elapsedRealtimeMs,
+        loadDurationMs,
+        loadable.bytesLoaded(),
+        error,
+        isFatal);
+    return isFatal ? Loader.DONT_RETRY_FATAL : Loader.RETRY;
+  }
+
+  // Internal methods.
+
+  private boolean maybeSelectNewPrimaryUrl() {
+    List<HlsUrl> variants = masterPlaylist.variants;
+    int variantsSize = variants.size();
+    long currentTimeMs = SystemClock.elapsedRealtime();
+    for (int i = 0; i < variantsSize; i++) {
+      MediaPlaylistBundle bundle = playlistBundles.get(variants.get(i));
+      if (currentTimeMs > bundle.blacklistUntilMs) {
+        primaryHlsUrl = bundle.playlistUrl;
+        bundle.loadPlaylist();
+        return true;
+      }
+    }
+    return false;
+  }
+
+  private void maybeSetPrimaryUrl(HlsUrl url) {
+    if (url == primaryHlsUrl
+        || !masterPlaylist.variants.contains(url)
+        || (primaryUrlSnapshot != null && primaryUrlSnapshot.hasEndTag)) {
+      // Ignore if the primary url is unchanged, if the url is not a variant url, or if the last
+      // primary snapshot contains an end tag.
+      return;
+    }
+    primaryHlsUrl = url;
+    playlistBundles.get(primaryHlsUrl).loadPlaylist();
+  }
+
+  private void createBundles(List<HlsUrl> urls) {
+    int listSize = urls.size();
+    for (int i = 0; i < listSize; i++) {
+      HlsUrl url = urls.get(i);
+      MediaPlaylistBundle bundle = new MediaPlaylistBundle(url);
+      playlistBundles.put(url, bundle);
+    }
+  }
+
+  /**
+   * Called by the bundles when a snapshot changes.
+   *
+   * @param url The url of the playlist.
+   * @param newSnapshot The new snapshot.
+   */
+  private void onPlaylistUpdated(HlsUrl url, HlsMediaPlaylist newSnapshot) {
+    if (url == primaryHlsUrl) {
+      if (primaryUrlSnapshot == null) {
+        // This is the first primary url snapshot.
+        isLive = !newSnapshot.hasEndTag;
+        initialStartTimeUs = newSnapshot.startTimeUs;
+      }
+      primaryUrlSnapshot = newSnapshot;
+      primaryPlaylistListener.onPrimaryPlaylistRefreshed(newSnapshot);
+    }
+    int listenersSize = listeners.size();
+    for (int i = 0; i < listenersSize; i++) {
+      listeners.get(i).onPlaylistChanged();
+    }
+  }
+
+  private boolean notifyPlaylistError(HlsUrl playlistUrl, boolean shouldBlacklist) {
+    int listenersSize = listeners.size();
+    boolean anyBlacklistingFailed = false;
+    for (int i = 0; i < listenersSize; i++) {
+      anyBlacklistingFailed |= !listeners.get(i).onPlaylistError(playlistUrl, shouldBlacklist);
+    }
+    return anyBlacklistingFailed;
+  }
+
+  private HlsMediaPlaylist getLatestPlaylistSnapshot(
+      HlsMediaPlaylist oldPlaylist, HlsMediaPlaylist loadedPlaylist) {
+    if (!loadedPlaylist.isNewerThan(oldPlaylist)) {
+      if (loadedPlaylist.hasEndTag) {
+        // If the loaded playlist has an end tag but is not newer than the old playlist then we have
+        // an inconsistent state. This is typically caused by the server incorrectly resetting the
+        // media sequence when appending the end tag. We resolve this case as best we can by
+        // returning the old playlist with the end tag appended.
+        return oldPlaylist.copyWithEndTag();
+      } else {
+        return oldPlaylist;
+      }
+    }
+    long startTimeUs = getLoadedPlaylistStartTimeUs(oldPlaylist, loadedPlaylist);
+    int discontinuitySequence = getLoadedPlaylistDiscontinuitySequence(oldPlaylist, loadedPlaylist);
+    return loadedPlaylist.copyWith(startTimeUs, discontinuitySequence);
+  }
+
+  private long getLoadedPlaylistStartTimeUs(
+      HlsMediaPlaylist oldPlaylist, HlsMediaPlaylist loadedPlaylist) {
+    if (loadedPlaylist.hasProgramDateTime) {
+      return loadedPlaylist.startTimeUs;
+    }
+    long primarySnapshotStartTimeUs =
+        primaryUrlSnapshot != null ? primaryUrlSnapshot.startTimeUs : 0;
+    if (oldPlaylist == null) {
+      return primarySnapshotStartTimeUs;
+    }
+    int oldPlaylistSize = oldPlaylist.segments.size();
+    Segment firstOldOverlappingSegment = getFirstOldOverlappingSegment(oldPlaylist, loadedPlaylist);
+    if (firstOldOverlappingSegment != null) {
+      return oldPlaylist.startTimeUs + firstOldOverlappingSegment.relativeStartTimeUs;
+    } else if (oldPlaylistSize == loadedPlaylist.mediaSequence - oldPlaylist.mediaSequence) {
+      return oldPlaylist.getEndTimeUs();
+    } else {
+      // No segments overlap, we assume the new playlist start coincides with the primary playlist.
+      return primarySnapshotStartTimeUs;
+    }
+  }
+
+  private int getLoadedPlaylistDiscontinuitySequence(
+      HlsMediaPlaylist oldPlaylist, HlsMediaPlaylist loadedPlaylist) {
+    if (loadedPlaylist.hasDiscontinuitySequence) {
+      return loadedPlaylist.discontinuitySequence;
+    }
+    // TODO: Improve cross-playlist discontinuity adjustment.
+    int primaryUrlDiscontinuitySequence =
+        primaryUrlSnapshot != null ? primaryUrlSnapshot.discontinuitySequence : 0;
+    if (oldPlaylist == null) {
+      return primaryUrlDiscontinuitySequence;
+    }
+    Segment firstOldOverlappingSegment = getFirstOldOverlappingSegment(oldPlaylist, loadedPlaylist);
+    if (firstOldOverlappingSegment != null) {
+      return oldPlaylist.discontinuitySequence
+          + firstOldOverlappingSegment.relativeDiscontinuitySequence
+          - loadedPlaylist.segments.get(0).relativeDiscontinuitySequence;
+    }
+    return primaryUrlDiscontinuitySequence;
+  }
+
+  private static Segment getFirstOldOverlappingSegment(
+      HlsMediaPlaylist oldPlaylist, HlsMediaPlaylist loadedPlaylist) {
+    int mediaSequenceOffset = (int) (loadedPlaylist.mediaSequence - oldPlaylist.mediaSequence);
+    List<Segment> oldSegments = oldPlaylist.segments;
+    return mediaSequenceOffset < oldSegments.size() ? oldSegments.get(mediaSequenceOffset) : null;
+  }
+
+  /** Holds all information related to a specific Media Playlist. */
+  private final class MediaPlaylistBundle
+      implements Loader.Callback<ParsingLoadable<HlsPlaylist>>, Runnable {
+
+    private final HlsUrl playlistUrl;
+    private final Loader mediaPlaylistLoader;
+    private final ParsingLoadable<HlsPlaylist> mediaPlaylistLoadable;
+
+    private HlsMediaPlaylist playlistSnapshot;
+    private long lastSnapshotLoadMs;
+    private long lastSnapshotChangeMs;
+    private long earliestNextLoadTimeMs;
+    private long blacklistUntilMs;
+    private boolean loadPending;
+    private IOException playlistError;
+
+    public MediaPlaylistBundle(HlsUrl playlistUrl) {
+      this.playlistUrl = playlistUrl;
+      mediaPlaylistLoader = new Loader("DefaultHlsPlaylistTracker:MediaPlaylist");
+      mediaPlaylistLoadable =
+          new ParsingLoadable<>(
+              dataSourceFactory.createDataSource(C.DATA_TYPE_MANIFEST),
+              UriUtil.resolveToUri(masterPlaylist.baseUri, playlistUrl.url),
+              C.DATA_TYPE_MANIFEST,
+              playlistParser);
+    }
+
+    public HlsMediaPlaylist getPlaylistSnapshot() {
+      return playlistSnapshot;
+    }
+
+    public boolean isSnapshotValid() {
+      if (playlistSnapshot == null) {
+        return false;
+      }
+      long currentTimeMs = SystemClock.elapsedRealtime();
+      long snapshotValidityDurationMs = Math.max(30000, C.usToMs(playlistSnapshot.durationUs));
+      return playlistSnapshot.hasEndTag
+          || playlistSnapshot.playlistType == HlsMediaPlaylist.PLAYLIST_TYPE_EVENT
+          || playlistSnapshot.playlistType == HlsMediaPlaylist.PLAYLIST_TYPE_VOD
+          || lastSnapshotLoadMs + snapshotValidityDurationMs > currentTimeMs;
+    }
+
+    public void release() {
+      mediaPlaylistLoader.release();
+    }
+
+    public void loadPlaylist() {
+      blacklistUntilMs = 0;
+      if (loadPending || mediaPlaylistLoader.isLoading()) {
+        // Load already pending or in progress. Do nothing.
+        return;
+      }
+      long currentTimeMs = SystemClock.elapsedRealtime();
+      if (currentTimeMs < earliestNextLoadTimeMs) {
+        loadPending = true;
+        playlistRefreshHandler.postDelayed(this, earliestNextLoadTimeMs - currentTimeMs);
+      } else {
+        loadPlaylistImmediately();
+      }
+    }
+
+    public void maybeThrowPlaylistRefreshError() throws IOException {
+      mediaPlaylistLoader.maybeThrowError();
+      if (playlistError != null) {
+        throw playlistError;
+      }
+    }
+
+    // Loader.Callback implementation.
+
+    @Override
+    public void onLoadCompleted(
+        ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs, long loadDurationMs) {
+      HlsPlaylist result = loadable.getResult();
+      if (result instanceof HlsMediaPlaylist) {
+        processLoadedPlaylist((HlsMediaPlaylist) result);
+        eventDispatcher.loadCompleted(
+            loadable.dataSpec,
+            C.DATA_TYPE_MANIFEST,
+            elapsedRealtimeMs,
+            loadDurationMs,
+            loadable.bytesLoaded());
+      } else {
+        playlistError = new ParserException("Loaded playlist has unexpected type.");
+      }
+    }
+
+    @Override
+    public void onLoadCanceled(
+        ParsingLoadable<HlsPlaylist> loadable,
+        long elapsedRealtimeMs,
+        long loadDurationMs,
+        boolean released) {
+      eventDispatcher.loadCanceled(
+          loadable.dataSpec,
+          C.DATA_TYPE_MANIFEST,
+          elapsedRealtimeMs,
+          loadDurationMs,
+          loadable.bytesLoaded());
+    }
+
+    @Override
+    public @Loader.RetryAction int onLoadError(
+        ParsingLoadable<HlsPlaylist> loadable,
+        long elapsedRealtimeMs,
+        long loadDurationMs,
+        IOException error) {
+      boolean isFatal = error instanceof ParserException;
+      eventDispatcher.loadError(
+          loadable.dataSpec,
+          C.DATA_TYPE_MANIFEST,
+          elapsedRealtimeMs,
+          loadDurationMs,
+          loadable.bytesLoaded(),
+          error,
+          isFatal);
+      boolean shouldBlacklist = ChunkedTrackBlacklistUtil.shouldBlacklist(error);
+      boolean shouldRetryIfNotFatal =
+          notifyPlaylistError(playlistUrl, shouldBlacklist) || !shouldBlacklist;
+      if (isFatal) {
+        return Loader.DONT_RETRY_FATAL;
+      }
+      if (shouldBlacklist) {
+        shouldRetryIfNotFatal |= blacklistPlaylist();
+      }
+      return shouldRetryIfNotFatal ? Loader.RETRY : Loader.DONT_RETRY;
+    }
+
+    // Runnable implementation.
+
+    @Override
+    public void run() {
+      loadPending = false;
+      loadPlaylistImmediately();
+    }
+
+    // Internal methods.
+
+    private void loadPlaylistImmediately() {
+      mediaPlaylistLoader.startLoading(mediaPlaylistLoadable, this, minRetryCount);
+    }
+
+    private void processLoadedPlaylist(HlsMediaPlaylist loadedPlaylist) {
+      HlsMediaPlaylist oldPlaylist = playlistSnapshot;
+      long currentTimeMs = SystemClock.elapsedRealtime();
+      lastSnapshotLoadMs = currentTimeMs;
+      playlistSnapshot = getLatestPlaylistSnapshot(oldPlaylist, loadedPlaylist);
+      if (playlistSnapshot != oldPlaylist) {
+        playlistError = null;
+        lastSnapshotChangeMs = currentTimeMs;
+        onPlaylistUpdated(playlistUrl, playlistSnapshot);
+      } else if (!playlistSnapshot.hasEndTag) {
+        if (loadedPlaylist.mediaSequence + loadedPlaylist.segments.size()
+            < playlistSnapshot.mediaSequence) {
+          // The media sequence jumped backwards. The server has probably reset.
+          playlistError = new PlaylistResetException(playlistUrl.url);
+          notifyPlaylistError(playlistUrl, false);
+        } else if (currentTimeMs - lastSnapshotChangeMs
+            > C.usToMs(playlistSnapshot.targetDurationUs)
+                * PLAYLIST_STUCK_TARGET_DURATION_COEFFICIENT) {
+          // The playlist seems to be stuck. Blacklist it.
+          playlistError = new PlaylistStuckException(playlistUrl.url);
+          notifyPlaylistError(playlistUrl, true);
+          blacklistPlaylist();
+        }
+      }
+      // Do not allow the playlist to load again within the target duration if we obtained a new
+      // snapshot, or half the target duration otherwise.
+      earliestNextLoadTimeMs =
+          currentTimeMs
+              + C.usToMs(
+                  playlistSnapshot != oldPlaylist
+                      ? playlistSnapshot.targetDurationUs
+                      : (playlistSnapshot.targetDurationUs / 2));
+      // Schedule a load if this is the primary playlist and it doesn't have an end tag. Else the
+      // next load will be scheduled when refreshPlaylist is called, or when this playlist becomes
+      // the primary.
+      if (playlistUrl == primaryHlsUrl && !playlistSnapshot.hasEndTag) {
+        loadPlaylist();
+      }
+    }
+
+    /**
+     * Blacklists the playlist.
+     *
+     * @return Whether the playlist is the primary, despite being blacklisted.
+     */
+    private boolean blacklistPlaylist() {
+      blacklistUntilMs =
+          SystemClock.elapsedRealtime() + ChunkedTrackBlacklistUtil.DEFAULT_TRACK_BLACKLIST_MS;
+      return primaryHlsUrl == playlistUrl && !maybeSelectNewPrimaryUrl();
+    }
+  }
+}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 The Android Open Source Project
+ * Copyright (C) 2018 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,66 +16,28 @@
 package com.google.android.exoplayer2.source.hls.playlist;
 
 import android.net.Uri;
-import android.os.Handler;
+import android.support.annotation.Nullable;
-import android.os.SystemClock;
 import com.google.android.exoplayer2.C;
-import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.source.MediaSourceEventListener.EventDispatcher;
-import com.google.android.exoplayer2.source.chunk.ChunkedTrackBlacklistUtil;
-import com.google.android.exoplayer2.source.hls.HlsDataSourceFactory;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMasterPlaylist.HlsUrl;
-import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist.Segment;
-import com.google.android.exoplayer2.upstream.DataSource;
-import com.google.android.exoplayer2.upstream.Loader;
-import com.google.android.exoplayer2.upstream.ParsingLoadable;
-import com.google.android.exoplayer2.util.UriUtil;
 import java.io.IOException;
-import java.util.ArrayList;
-import java.util.IdentityHashMap;
-import java.util.List;
 
 /**
- * Tracks playlists linked to a provided playlist url. The provided url might reference an HLS
+ * Tracks playlists associated to an HLS stream and provides snapshots.
- * master playlist or a media playlist.
+ *
+ * <p>The playlist tracker is responsible for exposing the seeking window, which is defined by the
+ * segments that one of the playlists exposes. This playlist is called primary and needs to be
+ * periodically refreshed in the case of live streams. Note that the primary playlist is one of the
+ * media playlists while the master playlist is an optional kind of playlist defined by the HLS
+ * specification (RFC 8216).
+ *
+ * <p>Playlist loads might encounter errors. The tracker may choose to blacklist them to ensure a
+ * primary playlist is always available.
  */
-public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable<HlsPlaylist>> {
+public interface HlsPlaylistTracker {
 
-  /**
+  /** Listener for primary playlist changes. */
-   * Thrown when a playlist is considered to be stuck due to a server side error.
+  interface PrimaryPlaylistListener {
-   */
-  public static final class PlaylistStuckException extends IOException {
-
-    /**
-     * The url of the stuck playlist.
-     */
-    public final String url;
-
-    private PlaylistStuckException(String url) {
-      this.url = url;
-    }
-
-  }
-
-  /**
-   * Thrown when the media sequence of a new snapshot indicates the server has reset.
-   */
-  public static final class PlaylistResetException extends IOException {
-
-    /**
-     * The url of the reset playlist.
-     */
-    public final String url;
-
-    private PlaylistResetException(String url) {
-      this.url = url;
-    }
-
-  }
-
-  /**
-   * Listener for primary playlist changes.
-   */
-  public interface PrimaryPlaylistListener {
 
     /**
      * Called when the primary playlist changes.
@@ -85,10 +47,8 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
     void onPrimaryPlaylistRefreshed(HlsMediaPlaylist mediaPlaylist);
   }
 
-  /**
+  /** Called on playlist loading events. */
-   * Called on playlist loading events.
+  interface PlaylistEventListener {
-   */
-  public interface PlaylistEventListener {
 
     /**
      * Called a playlist changes.
@@ -105,141 +65,107 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
     boolean onPlaylistError(HlsUrl url, boolean shouldBlacklist);
   }
 
-  /**
+  /** Thrown when a playlist is considered to be stuck due to a server side error. */
-   * Coefficient applied on the target duration of a playlist to determine the amount of time after
+  final class PlaylistStuckException extends IOException {
-   * which an unchanging playlist is considered stuck.
-   */
-  private static final double PLAYLIST_STUCK_TARGET_DURATION_COEFFICIENT = 3.5;
 
-  private final Uri initialPlaylistUri;
+    /** The url of the stuck playlist. */
-  private final HlsDataSourceFactory dataSourceFactory;
+    public final String url;
-  private final ParsingLoadable.Parser<HlsPlaylist> playlistParser;
-  private final int minRetryCount;
-  private final IdentityHashMap<HlsUrl, MediaPlaylistBundle> playlistBundles;
-  private final Handler playlistRefreshHandler;
-  private final PrimaryPlaylistListener primaryPlaylistListener;
-  private final List<PlaylistEventListener> listeners;
-  private final Loader initialPlaylistLoader;
-  private final EventDispatcher eventDispatcher;
 
-  private HlsMasterPlaylist masterPlaylist;
+    /**
-  private HlsUrl primaryHlsUrl;
+     * Creates an instance.
-  private HlsMediaPlaylist primaryUrlSnapshot;
+     *
-  private boolean isLive;
+     * @param url See {@link #url}.
-  private long initialStartTimeUs;
+     */
-
+    public PlaylistStuckException(String url) {
-  /**
+      this.url = url;
-   * @param initialPlaylistUri Uri for the initial playlist of the stream. Can refer a media
+    }
-   *     playlist or a master playlist.
-   * @param dataSourceFactory A factory for {@link DataSource} instances.
-   * @param eventDispatcher A dispatcher to notify of events.
-   * @param minRetryCount The minimum number of times loads must be retried before
-   *     {@link #maybeThrowPlaylistRefreshError(HlsUrl)} and
-   *     {@link #maybeThrowPrimaryPlaylistRefreshError()} propagate any loading errors.
-   * @param primaryPlaylistListener A callback for the primary playlist change events.
-   */
-  public HlsPlaylistTracker(Uri initialPlaylistUri, HlsDataSourceFactory dataSourceFactory,
-      EventDispatcher eventDispatcher, int minRetryCount,
-      PrimaryPlaylistListener primaryPlaylistListener,
-      ParsingLoadable.Parser<HlsPlaylist> playlistParser) {
-    this.initialPlaylistUri = initialPlaylistUri;
-    this.dataSourceFactory = dataSourceFactory;
-    this.eventDispatcher = eventDispatcher;
-    this.minRetryCount = minRetryCount;
-    this.primaryPlaylistListener = primaryPlaylistListener;
-    this.playlistParser = playlistParser;
-    listeners = new ArrayList<>();
-    initialPlaylistLoader = new Loader("HlsPlaylistTracker:MasterPlaylist");
-    playlistBundles = new IdentityHashMap<>();
-    playlistRefreshHandler = new Handler();
-    initialStartTimeUs = C.TIME_UNSET;
   }
 
+  /** Thrown when the media sequence of a new snapshot indicates the server has reset. */
+  final class PlaylistResetException extends IOException {
+
+    /** The url of the reset playlist. */
+    public final String url;
+
+    /**
+     * Creates an instance.
+     *
+     * @param url See {@link #url}.
+     */
+    public PlaylistResetException(String url) {
+      this.url = url;
+    }
+  }
+
+  /**
+   * Starts the playlist tracker.
+   *
+   * <p>Must be called from the playback thread. A tracker may be restarted after a {@link
+   * #release()} call.
+   *
+   * @param initialPlaylistUri Uri of the HLS stream. Can point to a media playlist or a master
+   *     playlist.
+   * @param eventDispatcher A dispatcher to notify of events.
+   * @param listener A callback for the primary playlist change events.
+   */
+  void start(
+      Uri initialPlaylistUri, EventDispatcher eventDispatcher, PrimaryPlaylistListener listener);
+
+  /** Releases all acquired resources. Must be called once per {@link #start} call. */
+  void release();
+
   /**
    * Registers a listener to receive events from the playlist tracker.
    *
    * @param listener The listener.
    */
-  public void addListener(PlaylistEventListener listener) {
+  void addListener(PlaylistEventListener listener);
-    listeners.add(listener);
-  }
 
   /**
    * Unregisters a listener.
    *
    * @param listener The listener to unregister.
    */
-  public void removeListener(PlaylistEventListener listener) {
+  void removeListener(PlaylistEventListener listener);
-    listeners.remove(listener);
-  }
-
-  /**
-   * Starts tracking all the playlists related to the provided Uri.
-   */
-  public void start() {
-    ParsingLoadable<HlsPlaylist> masterPlaylistLoadable = new ParsingLoadable<>(
-        dataSourceFactory.createDataSource(C.DATA_TYPE_MANIFEST), initialPlaylistUri,
-        C.DATA_TYPE_MANIFEST, playlistParser);
-    initialPlaylistLoader.startLoading(masterPlaylistLoadable, this, minRetryCount);
-  }
 
   /**
    * Returns the master playlist.
    *
+   * <p>If the uri passed to {@link #start} points to a media playlist, an {@link HlsMasterPlaylist}
+   * with a single variant for said media playlist is returned.
+   *
    * @return The master playlist. Null if the initial playlist has yet to be loaded.
    */
-  public HlsMasterPlaylist getMasterPlaylist() {
+  @Nullable
-    return masterPlaylist;
+  HlsMasterPlaylist getMasterPlaylist();
-  }
 
   /**
-   * Returns the most recent snapshot available of the playlist referenced by the provided
+   * Returns the most recent snapshot available of the playlist referenced by the provided {@link
-   * {@link HlsUrl}.
+   * HlsUrl}.
    *
    * @param url The {@link HlsUrl} corresponding to the requested media playlist.
    * @return The most recent snapshot of the playlist referenced by the provided {@link HlsUrl}. May
    *     be null if no snapshot has been loaded yet.
    */
-  public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url) {
+  @Nullable
-    HlsMediaPlaylist snapshot = playlistBundles.get(url).getPlaylistSnapshot();
+  HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url);
-    if (snapshot != null) {
-      maybeSetPrimaryUrl(url);
-    }
-    return snapshot;
-  }
 
   /**
    * Returns the start time of the first loaded primary playlist, or {@link C#TIME_UNSET} if no
    * media playlist has been loaded.
    */
-  public long getInitialStartTimeUs() {
+  long getInitialStartTimeUs();
-    return initialStartTimeUs;
-  }
 
   /**
    * Returns whether the snapshot of the playlist referenced by the provided {@link HlsUrl} is
    * valid, meaning all the segments referenced by the playlist are expected to be available. If the
    * playlist is not valid then some of the segments may no longer be available.
-
+   *
    * @param url The {@link HlsUrl}.
    * @return Whether the snapshot of the playlist referenced by the provided {@link HlsUrl} is
    *     valid.
    */
-  public boolean isSnapshotValid(HlsUrl url) {
+  boolean isSnapshotValid(HlsUrl url);
-    return playlistBundles.get(url).isSnapshotValid();
-  }
-
-  /**
-   * Releases the playlist tracker.
-   */
-  public void release() {
-    initialPlaylistLoader.release();
-    for (MediaPlaylistBundle bundle : playlistBundles.values()) {
-      bundle.release();
-    }
-    playlistRefreshHandler.removeCallbacksAndMessages(null);
-    playlistBundles.clear();
-  }
 
   /**
    * If the tracker is having trouble refreshing the master playlist or the primary playlist, this
@@ -247,401 +173,31 @@ public final class HlsPlaylistTracker implements Loader.Callback<ParsingLoadable
    *
    * @throws IOException The underlying error.
    */
-  public void maybeThrowPrimaryPlaylistRefreshError() throws IOException {
+  void maybeThrowPrimaryPlaylistRefreshError() throws IOException;
-    initialPlaylistLoader.maybeThrowError();
-    if (primaryHlsUrl != null) {
-      maybeThrowPlaylistRefreshError(primaryHlsUrl);
-    }
-  }
 
   /**
-   * If the playlist is having trouble refreshing the playlist referenced by the given
+   * If the playlist is having trouble refreshing the playlist referenced by the given {@link
-   * {@link HlsUrl}, this method throws the underlying error.
+   * HlsUrl}, this method throws the underlying error.
    *
    * @param url The {@link HlsUrl}.
    * @throws IOException The underyling error.
    */
-  public void maybeThrowPlaylistRefreshError(HlsUrl url) throws IOException {
+  void maybeThrowPlaylistRefreshError(HlsUrl url) throws IOException;
-    playlistBundles.get(url).maybeThrowPlaylistRefreshError();
-  }
 
   /**
-   * Triggers a playlist refresh and whitelists it.
+   * Requests a playlist refresh and whitelists it.
+   *
+   * <p>The playlist tracker may choose the delay the playlist refresh. The request is discarded if
+   * a refresh was already pending.
    *
    * @param url The {@link HlsUrl} of the playlist to be refreshed.
    */
-  public void refreshPlaylist(HlsUrl url) {
+  void refreshPlaylist(HlsUrl url);
-    playlistBundles.get(url).loadPlaylist();
-  }
 
   /**
-   * Returns whether this is live content.
+   * Returns whether the tracked playlists describe a live stream.
    *
    * @return True if the content is live. False otherwise.
    */
-  public boolean isLive() {
+  boolean isLive();
-    return isLive;
-  }
-
-  // Loader.Callback implementation.
-
-  @Override
-  public void onLoadCompleted(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
-      long loadDurationMs) {
-    HlsPlaylist result = loadable.getResult();
-    HlsMasterPlaylist masterPlaylist;
-    boolean isMediaPlaylist = result instanceof HlsMediaPlaylist;
-    if (isMediaPlaylist) {
-      masterPlaylist = HlsMasterPlaylist.createSingleVariantMasterPlaylist(result.baseUri);
-    } else /* result instanceof HlsMasterPlaylist */ {
-      masterPlaylist = (HlsMasterPlaylist) result;
-    }
-    this.masterPlaylist = masterPlaylist;
-    primaryHlsUrl = masterPlaylist.variants.get(0);
-    ArrayList<HlsUrl> urls = new ArrayList<>();
-    urls.addAll(masterPlaylist.variants);
-    urls.addAll(masterPlaylist.audios);
-    urls.addAll(masterPlaylist.subtitles);
-    createBundles(urls);
-    MediaPlaylistBundle primaryBundle = playlistBundles.get(primaryHlsUrl);
-    if (isMediaPlaylist) {
-      // We don't need to load the playlist again. We can use the same result.
-      primaryBundle.processLoadedPlaylist((HlsMediaPlaylist) result);
-    } else {
-      primaryBundle.loadPlaylist();
-    }
-    eventDispatcher.loadCompleted(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-        loadDurationMs, loadable.bytesLoaded());
-  }
-
-  @Override
-  public void onLoadCanceled(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
-      long loadDurationMs, boolean released) {
-    eventDispatcher.loadCanceled(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-        loadDurationMs, loadable.bytesLoaded());
-  }
-
-  @Override
-  public @Loader.RetryAction int onLoadError(
-      ParsingLoadable<HlsPlaylist> loadable,
-      long elapsedRealtimeMs,
-      long loadDurationMs,
-      IOException error) {
-    boolean isFatal = error instanceof ParserException;
-    eventDispatcher.loadError(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-        loadDurationMs, loadable.bytesLoaded(), error, isFatal);
-    return isFatal ? Loader.DONT_RETRY_FATAL : Loader.RETRY;
-  }
-
-  // Internal methods.
-
-  private boolean maybeSelectNewPrimaryUrl() {
-    List<HlsUrl> variants = masterPlaylist.variants;
-    int variantsSize = variants.size();
-    long currentTimeMs = SystemClock.elapsedRealtime();
-    for (int i = 0; i < variantsSize; i++) {
-      MediaPlaylistBundle bundle = playlistBundles.get(variants.get(i));
-      if (currentTimeMs > bundle.blacklistUntilMs) {
-        primaryHlsUrl = bundle.playlistUrl;
-        bundle.loadPlaylist();
-        return true;
-      }
-    }
-    return false;
-  }
-
-  private void maybeSetPrimaryUrl(HlsUrl url) {
-    if (url == primaryHlsUrl
-        || !masterPlaylist.variants.contains(url)
-        || (primaryUrlSnapshot != null && primaryUrlSnapshot.hasEndTag)) {
-      // Ignore if the primary url is unchanged, if the url is not a variant url, or if the last
-      // primary snapshot contains an end tag.
-      return;
-    }
-    primaryHlsUrl = url;
-    playlistBundles.get(primaryHlsUrl).loadPlaylist();
-  }
-
-  private void createBundles(List<HlsUrl> urls) {
-    int listSize = urls.size();
-    for (int i = 0; i < listSize; i++) {
-      HlsUrl url = urls.get(i);
-      MediaPlaylistBundle bundle = new MediaPlaylistBundle(url);
-      playlistBundles.put(url, bundle);
-    }
-  }
-
-  /**
-   * Called by the bundles when a snapshot changes.
-   *
-   * @param url The url of the playlist.
-   * @param newSnapshot The new snapshot.
-   */
-  private void onPlaylistUpdated(HlsUrl url, HlsMediaPlaylist newSnapshot) {
-    if (url == primaryHlsUrl) {
-      if (primaryUrlSnapshot == null) {
-        // This is the first primary url snapshot.
-        isLive = !newSnapshot.hasEndTag;
-        initialStartTimeUs = newSnapshot.startTimeUs;
-      }
-      primaryUrlSnapshot = newSnapshot;
-      primaryPlaylistListener.onPrimaryPlaylistRefreshed(newSnapshot);
-    }
-    int listenersSize = listeners.size();
-    for (int i = 0; i < listenersSize; i++) {
-      listeners.get(i).onPlaylistChanged();
-    }
-  }
-
-  private boolean notifyPlaylistError(HlsUrl playlistUrl, boolean shouldBlacklist) {
-    int listenersSize = listeners.size();
-    boolean anyBlacklistingFailed = false;
-    for (int i = 0; i < listenersSize; i++) {
-      anyBlacklistingFailed |= !listeners.get(i).onPlaylistError(playlistUrl, shouldBlacklist);
-    }
-    return anyBlacklistingFailed;
-  }
-
-  private HlsMediaPlaylist getLatestPlaylistSnapshot(HlsMediaPlaylist oldPlaylist,
-      HlsMediaPlaylist loadedPlaylist) {
-    if (!loadedPlaylist.isNewerThan(oldPlaylist)) {
-      if (loadedPlaylist.hasEndTag) {
-        // If the loaded playlist has an end tag but is not newer than the old playlist then we have
-        // an inconsistent state. This is typically caused by the server incorrectly resetting the
-        // media sequence when appending the end tag. We resolve this case as best we can by
-        // returning the old playlist with the end tag appended.
-        return oldPlaylist.copyWithEndTag();
-      } else {
-        return oldPlaylist;
-      }
-    }
-    long startTimeUs = getLoadedPlaylistStartTimeUs(oldPlaylist, loadedPlaylist);
-    int discontinuitySequence = getLoadedPlaylistDiscontinuitySequence(oldPlaylist, loadedPlaylist);
-    return loadedPlaylist.copyWith(startTimeUs, discontinuitySequence);
-  }
-
-  private long getLoadedPlaylistStartTimeUs(HlsMediaPlaylist oldPlaylist,
-      HlsMediaPlaylist loadedPlaylist) {
-    if (loadedPlaylist.hasProgramDateTime) {
-      return loadedPlaylist.startTimeUs;
-    }
-    long primarySnapshotStartTimeUs = primaryUrlSnapshot != null
-        ? primaryUrlSnapshot.startTimeUs : 0;
-    if (oldPlaylist == null) {
-      return primarySnapshotStartTimeUs;
-    }
-    int oldPlaylistSize = oldPlaylist.segments.size();
-    Segment firstOldOverlappingSegment = getFirstOldOverlappingSegment(oldPlaylist, loadedPlaylist);
-    if (firstOldOverlappingSegment != null) {
-      return oldPlaylist.startTimeUs + firstOldOverlappingSegment.relativeStartTimeUs;
-    } else if (oldPlaylistSize == loadedPlaylist.mediaSequence - oldPlaylist.mediaSequence) {
-      return oldPlaylist.getEndTimeUs();
-    } else {
-      // No segments overlap, we assume the new playlist start coincides with the primary playlist.
-      return primarySnapshotStartTimeUs;
-    }
-  }
-
-  private int getLoadedPlaylistDiscontinuitySequence(HlsMediaPlaylist oldPlaylist,
-      HlsMediaPlaylist loadedPlaylist) {
-    if (loadedPlaylist.hasDiscontinuitySequence) {
-      return loadedPlaylist.discontinuitySequence;
-    }
-    // TODO: Improve cross-playlist discontinuity adjustment.
-    int primaryUrlDiscontinuitySequence = primaryUrlSnapshot != null
-        ? primaryUrlSnapshot.discontinuitySequence : 0;
-    if (oldPlaylist == null) {
-      return primaryUrlDiscontinuitySequence;
-    }
-    Segment firstOldOverlappingSegment = getFirstOldOverlappingSegment(oldPlaylist, loadedPlaylist);
-    if (firstOldOverlappingSegment != null) {
-      return oldPlaylist.discontinuitySequence
-          + firstOldOverlappingSegment.relativeDiscontinuitySequence
-          - loadedPlaylist.segments.get(0).relativeDiscontinuitySequence;
-    }
-    return primaryUrlDiscontinuitySequence;
-  }
-
-  private static Segment getFirstOldOverlappingSegment(HlsMediaPlaylist oldPlaylist,
-      HlsMediaPlaylist loadedPlaylist) {
-    int mediaSequenceOffset = (int) (loadedPlaylist.mediaSequence - oldPlaylist.mediaSequence);
-    List<Segment> oldSegments = oldPlaylist.segments;
-    return mediaSequenceOffset < oldSegments.size() ? oldSegments.get(mediaSequenceOffset) : null;
-  }
-
-  /**
-   * Holds all information related to a specific Media Playlist.
-   */
-  private final class MediaPlaylistBundle implements Loader.Callback<ParsingLoadable<HlsPlaylist>>,
-      Runnable {
-
-    private final HlsUrl playlistUrl;
-    private final Loader mediaPlaylistLoader;
-    private final ParsingLoadable<HlsPlaylist> mediaPlaylistLoadable;
-
-    private HlsMediaPlaylist playlistSnapshot;
-    private long lastSnapshotLoadMs;
-    private long lastSnapshotChangeMs;
-    private long earliestNextLoadTimeMs;
-    private long blacklistUntilMs;
-    private boolean loadPending;
-    private IOException playlistError;
-
-    public MediaPlaylistBundle(HlsUrl playlistUrl) {
-      this.playlistUrl = playlistUrl;
-      mediaPlaylistLoader = new Loader("HlsPlaylistTracker:MediaPlaylist");
-      mediaPlaylistLoadable = new ParsingLoadable<>(
-          dataSourceFactory.createDataSource(C.DATA_TYPE_MANIFEST),
-          UriUtil.resolveToUri(masterPlaylist.baseUri, playlistUrl.url), C.DATA_TYPE_MANIFEST,
-          playlistParser);
-    }
-
-    public HlsMediaPlaylist getPlaylistSnapshot() {
-      return playlistSnapshot;
-    }
-
-    public boolean isSnapshotValid() {
-      if (playlistSnapshot == null) {
-        return false;
-      }
-      long currentTimeMs = SystemClock.elapsedRealtime();
-      long snapshotValidityDurationMs = Math.max(30000, C.usToMs(playlistSnapshot.durationUs));
-      return playlistSnapshot.hasEndTag
-          || playlistSnapshot.playlistType == HlsMediaPlaylist.PLAYLIST_TYPE_EVENT
-          || playlistSnapshot.playlistType == HlsMediaPlaylist.PLAYLIST_TYPE_VOD
-          || lastSnapshotLoadMs + snapshotValidityDurationMs > currentTimeMs;
-    }
-
-    public void release() {
-      mediaPlaylistLoader.release();
-    }
-
-    public void loadPlaylist() {
-      blacklistUntilMs = 0;
-      if (loadPending || mediaPlaylistLoader.isLoading()) {
-        // Load already pending or in progress. Do nothing.
-        return;
-      }
-      long currentTimeMs = SystemClock.elapsedRealtime();
-      if (currentTimeMs < earliestNextLoadTimeMs) {
-        loadPending = true;
-        playlistRefreshHandler.postDelayed(this, earliestNextLoadTimeMs - currentTimeMs);
-      } else {
-        loadPlaylistImmediately();
-      }
-    }
-
-    public void maybeThrowPlaylistRefreshError() throws IOException {
-      mediaPlaylistLoader.maybeThrowError();
-      if (playlistError != null) {
-        throw playlistError;
-      }
-    }
-
-    // Loader.Callback implementation.
-
-    @Override
-    public void onLoadCompleted(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
-        long loadDurationMs) {
-      HlsPlaylist result = loadable.getResult();
-      if (result instanceof HlsMediaPlaylist) {
-        processLoadedPlaylist((HlsMediaPlaylist) result);
-        eventDispatcher.loadCompleted(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-            loadDurationMs, loadable.bytesLoaded());
-      } else {
-        playlistError = new ParserException("Loaded playlist has unexpected type.");
-      }
-    }
-
-    @Override
-    public void onLoadCanceled(ParsingLoadable<HlsPlaylist> loadable, long elapsedRealtimeMs,
-        long loadDurationMs, boolean released) {
-      eventDispatcher.loadCanceled(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-          loadDurationMs, loadable.bytesLoaded());
-    }
-
-    @Override
-    public @Loader.RetryAction int onLoadError(
-        ParsingLoadable<HlsPlaylist> loadable,
-        long elapsedRealtimeMs,
-        long loadDurationMs,
-        IOException error) {
-      boolean isFatal = error instanceof ParserException;
-      eventDispatcher.loadError(loadable.dataSpec, C.DATA_TYPE_MANIFEST, elapsedRealtimeMs,
-          loadDurationMs, loadable.bytesLoaded(), error, isFatal);
-      boolean shouldBlacklist = ChunkedTrackBlacklistUtil.shouldBlacklist(error);
-      boolean shouldRetryIfNotFatal =
-          notifyPlaylistError(playlistUrl, shouldBlacklist) || !shouldBlacklist;
-      if (isFatal) {
-        return Loader.DONT_RETRY_FATAL;
-      }
-      if (shouldBlacklist) {
-        shouldRetryIfNotFatal |= blacklistPlaylist();
-      }
-      return shouldRetryIfNotFatal ? Loader.RETRY : Loader.DONT_RETRY;
-    }
-
-    // Runnable implementation.
-
-    @Override
-    public void run() {
-      loadPending = false;
-      loadPlaylistImmediately();
-    }
-
-    // Internal methods.
-
-    private void loadPlaylistImmediately() {
-      mediaPlaylistLoader.startLoading(mediaPlaylistLoadable, this, minRetryCount);
-    }
-
-    private void processLoadedPlaylist(HlsMediaPlaylist loadedPlaylist) {
-      HlsMediaPlaylist oldPlaylist = playlistSnapshot;
-      long currentTimeMs = SystemClock.elapsedRealtime();
-      lastSnapshotLoadMs = currentTimeMs;
-      playlistSnapshot = getLatestPlaylistSnapshot(oldPlaylist, loadedPlaylist);
-      if (playlistSnapshot != oldPlaylist) {
-        playlistError = null;
-        lastSnapshotChangeMs = currentTimeMs;
-        onPlaylistUpdated(playlistUrl, playlistSnapshot);
-      } else if (!playlistSnapshot.hasEndTag) {
-        if (loadedPlaylist.mediaSequence + loadedPlaylist.segments.size()
-            < playlistSnapshot.mediaSequence) {
-          // The media sequence jumped backwards. The server has probably reset.
-          playlistError = new PlaylistResetException(playlistUrl.url);
-          notifyPlaylistError(playlistUrl, false);
-        } else if (currentTimeMs - lastSnapshotChangeMs
-            > C.usToMs(playlistSnapshot.targetDurationUs)
-                * PLAYLIST_STUCK_TARGET_DURATION_COEFFICIENT) {
-          // The playlist seems to be stuck. Blacklist it.
-          playlistError = new PlaylistStuckException(playlistUrl.url);
-          notifyPlaylistError(playlistUrl, true);
-          blacklistPlaylist();
-        }
-      }
-      // Do not allow the playlist to load again within the target duration if we obtained a new
-      // snapshot, or half the target duration otherwise.
-      earliestNextLoadTimeMs = currentTimeMs + C.usToMs(playlistSnapshot != oldPlaylist
-          ? playlistSnapshot.targetDurationUs : (playlistSnapshot.targetDurationUs / 2));
-      // Schedule a load if this is the primary playlist and it doesn't have an end tag. Else the
-      // next load will be scheduled when refreshPlaylist is called, or when this playlist becomes
-      // the primary.
-      if (playlistUrl == primaryHlsUrl && !playlistSnapshot.hasEndTag) {
-        loadPlaylist();
-      }
-    }
-
-    /**
-     * Blacklists the playlist.
-     *
-     * @return Whether the playlist is the primary, despite being blacklisted.
-     */
-    private boolean blacklistPlaylist() {
-      blacklistUntilMs = SystemClock.elapsedRealtime()
-          + ChunkedTrackBlacklistUtil.DEFAULT_TRACK_BLACKLIST_MS;
-      return primaryHlsUrl == playlistUrl && !maybeSelectNewPrimaryUrl();
-    }
-
-  }
-
 }