Fix unnecessary media playlist requests when playing live streams

Issue: #5059
PiperOrigin-RevId: 222803511

RELEASENOTES.md

@@ -2,6 +2,8 @@
 
 ### dev-v2 (not yet released) ###
 
+* HLS: Fix issue causing unnecessary media playlist requests when playing live
+  streams ([#5059](https://github.com/google/ExoPlayer/issues/5059)).
 * MP4: Support Opus and FLAC in the MP4 container, and in DASH
   ([#4883](https://github.com/google/ExoPlayer/issues/4883)).
 * DASH: Fix detecting the end of live events

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

@@ -262,7 +262,8 @@ public void getNextChunk(
       // Retry when playlist is refreshed.
       return;
     }
-    HlsMediaPlaylist mediaPlaylist = playlistTracker.getPlaylistSnapshot(selectedUrl);
+    HlsMediaPlaylist mediaPlaylist =
+        playlistTracker.getPlaylistSnapshot(selectedUrl, /* isForPlayback= */ true);
     independentSegments = mediaPlaylist.hasIndependentSegments;
 
     updateLiveEdgeTimeUs(mediaPlaylist);
@@ -279,7 +280,7 @@ public void getNextChunk(
         // behind the live window.
         selectedVariantIndex = oldVariantIndex;
         selectedUrl = variants[selectedVariantIndex];
-        mediaPlaylist = playlistTracker.getPlaylistSnapshot(selectedUrl);
+        mediaPlaylist = playlistTracker.getPlaylistSnapshot(selectedUrl, /* isForPlayback= */ true);
         startOfPlaylistInPeriodUs =
             mediaPlaylist.startTimeUs - playlistTracker.getInitialStartTimeUs();
         chunkMediaSequence = previous.getNextChunkIndex();
@@ -435,7 +436,8 @@ public MediaChunkIterator[] createMediaChunkIterators(
         chunkIterators[i] = MediaChunkIterator.EMPTY;
         continue;
       }
-      HlsMediaPlaylist playlist = playlistTracker.getPlaylistSnapshot(variantUrl);
+      HlsMediaPlaylist playlist =
+          playlistTracker.getPlaylistSnapshot(variantUrl, /* isForPlayback= */ false);
       long startOfPlaylistInPeriodUs =
           playlist.startTimeUs - playlistTracker.getInitialStartTimeUs();
       boolean switchingVariant = variantIndex != oldVariantIndex;

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

@@ -162,9 +162,9 @@ public void removeListener(PlaylistEventListener listener) {
   }
 
   @Override
-  public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url) {
+  public HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url, boolean isForPlayback) {
     HlsMediaPlaylist snapshot = playlistBundles.get(url).getPlaylistSnapshot();
-    if (snapshot != null) {
+    if (snapshot != null && isForPlayback) {
       maybeSetPrimaryUrl(url);
     }
     return snapshot;

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

@@ -167,11 +167,13 @@ void start(
    * HlsUrl}.
    *
    * @param url The {@link HlsUrl} corresponding to the requested media playlist.
+   * @param isForPlayback Whether the caller might use the snapshot to request media segments for
+   *     playback. If true, the primary playlist may be updated to the one requested.
    * @return The most recent snapshot of the playlist referenced by the provided {@link HlsUrl}. May
    *     be null if no snapshot has been loaded yet.
    */
   @Nullable
-  HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url);
+  HlsMediaPlaylist getPlaylistSnapshot(HlsUrl url, boolean isForPlayback);
 
   /**
    * Returns the start time of the first loaded primary playlist, or {@link C#TIME_UNSET} if no