Add live media playlist refresh requests when live edge is reached

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=131931868

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

@@ -29,7 +29,6 @@ import com.google.android.exoplayer2.extractor.ts.TsExtractor;
 import com.google.android.exoplayer2.source.BehindLiveWindowException;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.chunk.Chunk;
-import com.google.android.exoplayer2.source.chunk.ChunkHolder;
 import com.google.android.exoplayer2.source.chunk.ChunkedTrackBlacklistUtil;
 import com.google.android.exoplayer2.source.chunk.DataChunk;
 import com.google.android.exoplayer2.source.hls.playlist.HlsMediaPlaylist;
@@ -49,9 +48,44 @@ import java.util.Arrays;
 import java.util.Locale;
 
 /**
- * A temporary test source of HLS chunks.
+ * Source of Hls(possibly adaptive) chunks.
  */
-public class HlsChunkSource {
+/* package */ class HlsChunkSource {
+
+  /**
+   * Chunk holder that allows the scheduling of retries.
+   */
+  public static final class HlsChunkHolder {
+
+    public HlsChunkHolder() {
+      clear();
+    }
+
+    /**
+     * The chunk.
+     */
+    public Chunk chunk;
+
+    /**
+     * Indicates that the end of the stream has been reached.
+     */
+    public boolean endOfStream;
+
+    /**
+     * Milliseconds to wait before retrying.
+     */
+    public long retryInMs;
+
+    /**
+     * Clears the holder.
+     */
+    public void clear() {
+      chunk = null;
+      endOfStream = false;
+      retryInMs = C.TIME_UNSET;
+    }
+
+  }
 
   /**
    * The default time for which a media playlist should be blacklisted.
@@ -173,9 +207,10 @@ public class HlsChunkSource {
   /**
    * Returns the next chunk to load.
    * <p>
-   * If a chunk is available then {@link ChunkHolder#chunk} is set. If the end of the stream has
+   * If a chunk is available then {@link HlsChunkHolder#chunk} is set. If the end of the stream has
-   * been reached then {@link ChunkHolder#endOfStream} is set. If a chunk is not available but the
+   * been reached then {@link HlsChunkHolder#endOfStream} is set. If a chunk is not available but
-   * end of the stream has not been reached, the {@link ChunkHolder} is not modified.
+   * the end of the stream has not been reached, {@link HlsChunkHolder#retryInMs} is set to contain
+   * the amount of milliseconds to wait before retrying.
    *
    * @param previous The most recently loaded media chunk.
    * @param playbackPositionUs The current playback position. If {@code previous} is null then this
@@ -183,7 +218,7 @@ public class HlsChunkSource {
    *     should be interpreted as a seek position.
    * @param out A holder to populate.
    */
-  public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, ChunkHolder out) {
+  public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChunkHolder out) {
     int oldVariantIndex = previous == null ? C.INDEX_UNSET
         : trackGroup.indexOf(previous.trackFormat);
 
@@ -206,8 +241,13 @@ public class HlsChunkSource {
     int chunkMediaSequence;
     if (live) {
       if (previous == null) {
-        chunkMediaSequence = Util.binarySearchFloor(mediaPlaylist.segments, playbackPositionUs,
+        // When playling a live stream, the starting chunk will be the third counting from the live
-            true, true) + mediaPlaylist.mediaSequence;
+        // edge.
+        chunkMediaSequence = Math.max(0, mediaPlaylist.segments.size() - 3)
+            + mediaPlaylist.mediaSequence;
+        // TODO: Bring this back for live window seeking.
+        // chunkMediaSequence = Util.binarySearchFloor(mediaPlaylist.segments, playbackPositionUs,
+        //     true, true) + mediaPlaylist.mediaSequence;
       } else {
         chunkMediaSequence = getLiveNextChunkSequenceNumber(previous.chunkIndex, oldVariantIndex,
             newVariantIndex);
@@ -233,9 +273,16 @@ public class HlsChunkSource {
     if (chunkIndex >= mediaPlaylist.segments.size()) {
       if (!mediaPlaylist.live) {
         out.endOfStream = true;
-      } else if (shouldRerequestLiveMediaPlaylist(newVariantIndex)) {
+      } else /* Live */ {
-        out.chunk = newMediaPlaylistChunk(newVariantIndex,
+        long msToRerequestLiveMediaPlaylist = msToRerequestLiveMediaPlaylist(newVariantIndex);
-            trackSelection.getSelectionReason(), trackSelection.getSelectionData());
+        if (msToRerequestLiveMediaPlaylist <= 0) {
+          out.chunk = newMediaPlaylistChunk(newVariantIndex,
+              trackSelection.getSelectionReason(), trackSelection.getSelectionData());
+        } else {
+          // 10 milliseconds are added to the wait to make sure the playlist is refreshed when
+          // getNextChunk() is called.
+          out.retryInMs = msToRerequestLiveMediaPlaylist + 10;
+        }
       }
       return;
     }
@@ -417,12 +464,12 @@ public class HlsChunkSource {
 
   // Private methods.
 
-  private boolean shouldRerequestLiveMediaPlaylist(int variantIndex) {
+  private long msToRerequestLiveMediaPlaylist(int variantIndex) {
     HlsMediaPlaylist mediaPlaylist = variantPlaylists[variantIndex];
     long timeSinceLastMediaPlaylistLoadMs =
         SystemClock.elapsedRealtime() - variantLastPlaylistLoadTimesMs[variantIndex];
     // Don't re-request media playlist more often than one-half of the target duration.
-    return timeSinceLastMediaPlaylistLoadMs >= (mediaPlaylist.targetDurationSecs * 1000) / 2;
+    return (mediaPlaylist.targetDurationSecs * 1000) / 2 - timeSinceLastMediaPlaylistLoadMs;
   }
 
   private MediaPlaylistChunk newMediaPlaylistChunk(int variantIndex, int trackSelectionReason,

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

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.source.hls;
 
 import android.net.Uri;
+import android.os.Handler;
 import android.text.TextUtils;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
@@ -60,6 +61,7 @@ import java.util.List;
   private final IdentityHashMap<SampleStream, Integer> streamWrapperIndices;
   private final PtsTimestampAdjusterProvider timestampAdjusterProvider;
   private final HlsPlaylistParser manifestParser;
+  private final Handler continueLoadingHandler;
   private final Loader manifestFetcher;
   private final long preparePositionUs;
 
@@ -72,10 +74,11 @@ import java.util.List;
   private HlsSampleStreamWrapper[] sampleStreamWrappers;
   private HlsSampleStreamWrapper[] enabledSampleStreamWrappers;
   private CompositeSequenceableLoader sequenceableLoader;
+  private Runnable continueLoadingRunnable;
 
   public HlsMediaPeriod(Uri manifestUri, DataSource.Factory dataSourceFactory,
       int minLoadableRetryCount, EventDispatcher eventDispatcher,
-      MediaSource.Listener sourceListener, Callback callback, Allocator allocator,
+      MediaSource.Listener sourceListener, final Callback callback, Allocator allocator,
       long positionUs) {
     this.dataSourceFactory = dataSourceFactory;
     this.minLoadableRetryCount = minLoadableRetryCount;
@@ -86,8 +89,15 @@ import java.util.List;
     streamWrapperIndices = new IdentityHashMap<>();
     timestampAdjusterProvider = new PtsTimestampAdjusterProvider();
     manifestParser = new HlsPlaylistParser();
+    continueLoadingHandler = new Handler();
     manifestFetcher = new Loader("Loader:ManifestFetcher");
     preparePositionUs = positionUs;
+    continueLoadingRunnable = new Runnable() {
+      @Override
+      public void run() {
+        callback.onContinueLoadingRequested(HlsMediaPeriod.this);
+      }
+    };
 
     ParsingLoadable<HlsPlaylist> loadable = new ParsingLoadable<>(
         dataSourceFactory.createDataSource(), manifestUri, C.DATA_TYPE_MANIFEST, manifestParser);
@@ -96,6 +106,7 @@ import java.util.List;
   }
 
   public void release() {
+    continueLoadingHandler.removeCallbacksAndMessages(null);
     manifestFetcher.release();
     for (HlsSampleStreamWrapper sampleStreamWrapper : sampleStreamWrappers) {
       sampleStreamWrapper.release();
@@ -286,6 +297,12 @@ import java.util.List;
     sourceListener.onSourceInfoRefreshed(timeline, playlist);
   }
 
+  @Override
+  public void onContinueLoadingRequiredInMs(final HlsSampleStreamWrapper sampleStreamWrapper,
+      long delayMs) {
+    continueLoadingHandler.postDelayed(continueLoadingRunnable, delayMs);
+  }
+
   @Override
   public void onContinueLoadingRequested(HlsSampleStreamWrapper sampleStreamWrapper) {
     if (trackGroups == null) {

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

@@ -30,7 +30,6 @@ import com.google.android.exoplayer2.source.SequenceableLoader;
 import com.google.android.exoplayer2.source.TrackGroup;
 import com.google.android.exoplayer2.source.TrackGroupArray;
 import com.google.android.exoplayer2.source.chunk.Chunk;
-import com.google.android.exoplayer2.source.chunk.ChunkHolder;
 import com.google.android.exoplayer2.trackselection.TrackSelection;
 import com.google.android.exoplayer2.upstream.Allocator;
 import com.google.android.exoplayer2.upstream.Loader;
@@ -56,6 +55,12 @@ import java.util.LinkedList;
      */
     void onPrepared();
 
+    /**
+     * Called to schedule a {@link #continueLoading(long)} call.
+     */
+    void onContinueLoadingRequiredInMs(HlsSampleStreamWrapper sampleStreamSource,
+        long delayMs);
+
   }
 
   private static final int PRIMARY_TYPE_NONE = 0;
@@ -72,7 +77,7 @@ import java.util.LinkedList;
   private final int minLoadableRetryCount;
   private final Loader loader;
   private final EventDispatcher eventDispatcher;
-  private final ChunkHolder nextChunkHolder;
+  private final HlsChunkSource.HlsChunkHolder nextChunkHolder;
   private final SparseArray<DefaultTrackOutput> sampleQueues;
   private final LinkedList<HlsMediaChunk> mediaChunks;
 
@@ -121,7 +126,7 @@ import java.util.LinkedList;
     this.minLoadableRetryCount = minLoadableRetryCount;
     this.eventDispatcher = eventDispatcher;
     loader = new Loader("Loader:HlsSampleStreamWrapper");
-    nextChunkHolder = new ChunkHolder();
+    nextChunkHolder = new HlsChunkSource.HlsChunkHolder();
     sampleQueues = new SparseArray<>();
     mediaChunks = new LinkedList<>();
     lastSeekPositionUs = positionUs;
@@ -310,6 +315,7 @@ import java.util.LinkedList;
         nextChunkHolder);
     boolean endOfStream = nextChunkHolder.endOfStream;
     Chunk loadable = nextChunkHolder.chunk;
+    long retryInMs = nextChunkHolder.retryInMs;
     nextChunkHolder.clear();
 
     if (endOfStream) {
@@ -318,6 +324,8 @@ import java.util.LinkedList;
     }
 
     if (loadable == null) {
+      Assertions.checkState(retryInMs != C.TIME_UNSET && chunkSource.isLive());
+      callback.onContinueLoadingRequiredInMs(this, retryInMs);
       return false;
     }