Prevent old playlist snapshots from being used on live HLS streams

This aims to replace InvalidCodeResponse's with BLWE's caused by trying to load chunks that have been removed from the server. Issue:#2344 ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=145679171
google · Jan 30, 2017 · c49d142 · c49d142
1 parent 25c18ca
commit c49d142
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Showing 2 changed files with 43 additions and 12 deletions.
diff --git a/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java b/library/src/main/java/com/google/android/exoplayer2/source/hls/HlsChunkSource.java
@@ -194,15 +194,16 @@ public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChu
 
     // Select the variant.
     trackSelection.updateSelectedTrack(bufferedDurationUs);
-    int newVariantIndex = trackSelection.getSelectedIndexInTrackGroup();
+    int selectedVariantIndex = trackSelection.getSelectedIndexInTrackGroup();
 
-    boolean switchingVariant = oldVariantIndex != newVariantIndex;
-    HlsMediaPlaylist mediaPlaylist = playlistTracker.getPlaylistSnapshot(variants[newVariantIndex]);
-    if (mediaPlaylist == null) {
-      out.playlist = variants[newVariantIndex];
+    boolean switchingVariant = oldVariantIndex != selectedVariantIndex;
+    HlsUrl selectedUrl = variants[selectedVariantIndex];
+    if (!playlistTracker.isSnapshotValid(selectedUrl)) {
+      out.playlist = selectedUrl;
       // Retry when playlist is refreshed.
       return;
     }
+    HlsMediaPlaylist mediaPlaylist = playlistTracker.getPlaylistSnapshot(selectedUrl);
 
     // Select the chunk.
     int chunkMediaSequence;
@@ -218,8 +219,9 @@ public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChu
         if (chunkMediaSequence < mediaPlaylist.mediaSequence && previous != null) {
           // We try getting the next chunk without adapting in case that's the reason for falling
           // behind the live window.
-          newVariantIndex = oldVariantIndex;
-          mediaPlaylist = playlistTracker.getPlaylistSnapshot(variants[newVariantIndex]);
+          selectedVariantIndex = oldVariantIndex;
+          selectedUrl = variants[selectedVariantIndex];
+          mediaPlaylist = playlistTracker.getPlaylistSnapshot(selectedUrl);
           chunkMediaSequence = previous.getNextChunkIndex();
         }
       }
@@ -236,7 +238,7 @@ public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChu
       if (mediaPlaylist.hasEndTag) {
         out.endOfStream = true;
       } else /* Live */ {
-        out.playlist = variants[newVariantIndex];
+        out.playlist = selectedUrl;
       }
       return;
     }
@@ -249,7 +251,7 @@ public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChu
       Uri keyUri = UriUtil.resolveToUri(mediaPlaylist.baseUri, segment.encryptionKeyUri);
       if (!keyUri.equals(encryptionKeyUri)) {
         // Encryption is specified and the key has changed.
-        out.chunk = newEncryptionKeyChunk(keyUri, segment.encryptionIV, newVariantIndex,
+        out.chunk = newEncryptionKeyChunk(keyUri, segment.encryptionIV, selectedVariantIndex,
             trackSelection.getSelectionReason(), trackSelection.getSelectionData());
         return;
       }
@@ -279,7 +281,7 @@ public void getNextChunk(HlsMediaChunk previous, long playbackPositionUs, HlsChu
     Uri chunkUri = UriUtil.resolveToUri(mediaPlaylist.baseUri, segment.url);
     DataSpec dataSpec = new DataSpec(chunkUri, segment.byterangeOffset, segment.byterangeLength,
         null);
-    out.chunk = new HlsMediaChunk(dataSource, dataSpec, initDataSpec, variants[newVariantIndex],
+    out.chunk = new HlsMediaChunk(dataSource, dataSpec, initDataSpec, selectedUrl,
         trackSelection.getSelectionReason(), trackSelection.getSelectionData(),
         startTimeUs, startTimeUs + segment.durationUs, chunkMediaSequence, discontinuitySequence,
         isTimestampMaster, timestampAdjuster, previous, encryptionKey, encryptionIv);

diff --git a/...y/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java b/...y/src/main/java/com/google/android/exoplayer2/source/hls/playlist/HlsPlaylistTracker.java
@@ -166,8 +166,24 @@ public HlsMasterPlaylist getMasterPlaylist() {
    *     be null if no snapshot has been loaded yet.
    */
   public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url) {
-    maybeSetPrimaryUrl(url);
-    return playlistBundles.get(url).getPlaylistSnapshot();
+    HlsMediaPlaylist snapshot = playlistBundles.get(url).getPlaylistSnapshot();
+    if (snapshot != null) {
+      maybeSetPrimaryUrl(url);
+    }
+    return snapshot;
+  }
+
+  /**
+   * 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) {
+    return playlistBundles.get(url).isSnapshotValid();
   }
 
   /**
@@ -412,6 +428,7 @@ private final class MediaPlaylistBundle implements Loader.Callback<ParsingLoadab
     private final ParsingLoadable<HlsPlaylist> mediaPlaylistLoadable;
 
     private HlsMediaPlaylist playlistSnapshot;
+    private long lastSnapshotLoadMs;
     private long lastSnapshotAccessTimeMs;
     private long blacklistUntilMs;
 
@@ -429,6 +446,17 @@ public HlsMediaPlaylist getPlaylistSnapshot() {
       return playlistSnapshot;
     }
 
+    public boolean isSnapshotValid() {
+      if (playlistSnapshot == null) {
+        return false;
+      }
+      // TODO: Return true for event playlists once playlist types are supported.
+      long currentTimeMs = SystemClock.elapsedRealtime();
+      long snapshotValidityDurationMs = Math.max(30000, C.usToMs(playlistSnapshot.durationUs));
+      return playlistSnapshot.hasEndTag
+          || lastSnapshotLoadMs + snapshotValidityDurationMs > currentTimeMs;
+    }
+
     public void release() {
       mediaPlaylistLoader.release();
     }
@@ -488,6 +516,7 @@ public void run() {
 
     private void processLoadedPlaylist(HlsMediaPlaylist loadedPlaylist) {
       HlsMediaPlaylist oldPlaylist = playlistSnapshot;
+      lastSnapshotLoadMs = SystemClock.elapsedRealtime();
       playlistSnapshot = getLatestPlaylistSnapshot(oldPlaylist, loadedPlaylist);
       long refreshDelayUs = C.TIME_UNSET;
       if (playlistSnapshot != oldPlaylist) {