Introduce TrackGroupArray.

This change replaces TrackGroup[] with TrackGroupArray. This is
to allow equality based hashCode and equals implementations.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=115563146

library/src/main/java/com/google/android/exoplayer/ExoPlayerImplInternal.java

@@ -299,13 +299,13 @@ import java.util.concurrent.atomic.AtomicInteger;
 
     durationUs = source.getDurationUs();
     bufferedPositionUs = source.getBufferedPositionUs();
-    TrackGroup[] trackGroups = source.getTrackGroups();
+    TrackGroupArray trackGroups = source.getTrackGroups();
 
     // The maximum number of tracks that one renderer can support is the total number of tracks in
     // all groups, plus possibly one adaptive track per group.
     int maxTrackCount = trackGroups.length;
     for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
-      maxTrackCount += trackGroups[groupIndex].length;
+      maxTrackCount += trackGroups.get(groupIndex).length;
     }
     // Construct tracks for each renderer.
     Format[][] externalTrackFormats = new Format[renderers.length][];
@@ -316,7 +316,7 @@ import java.util.concurrent.atomic.AtomicInteger;
       TrackSelection[] rendererTrackSelections = new TrackSelection[maxTrackCount];
       Format[][] rendererTrackFormats = new Format[maxTrackCount][];
       for (int groupIndex = 0; groupIndex < trackGroups.length; groupIndex++) {
-        TrackGroup trackGroup = trackGroups[groupIndex];
+        TrackGroup trackGroup = trackGroups.get(groupIndex);
         // TODO[REFACTOR]: This should check that the renderer is capable of adaptive playback, in
         // addition to checking that the group is adaptive.
         if (trackGroup.adaptive) {

library/src/main/java/com/google/android/exoplayer/Format.java

@@ -143,7 +143,7 @@ public final class Format {
    */
   public final String language;
 
-  // Lazy-initialized hashcode and framework media format.
+  // Lazily initialized hashcode and framework media format.
 
   private int hashCode;
   private MediaFormat frameworkMediaFormat;

library/src/main/java/com/google/android/exoplayer/FrameworkSampleSource.java

@@ -75,7 +75,7 @@ public final class FrameworkSampleSource implements SampleSource {
   private boolean prepared;
   private long durationUs;
   private MediaExtractor extractor;
-  private TrackGroup[] tracks;
+  private TrackGroupArray tracks;
   private int[] trackStates;
   private boolean[] pendingResets;
 
@@ -133,7 +133,7 @@ public final class FrameworkSampleSource implements SampleSource {
     durationUs = C.UNKNOWN_TIME_US;
     trackStates = new int[extractor.getTrackCount()];
     pendingResets = new boolean[trackStates.length];
-    tracks = new TrackGroup[trackStates.length];
+    TrackGroup[] tracks = new TrackGroup[trackStates.length];
     for (int i = 0; i < trackStates.length; i++) {
       MediaFormat format = extractor.getTrackFormat(i);
       if (format.containsKey(MediaFormat.KEY_DURATION)) {
@@ -141,6 +141,7 @@ public final class FrameworkSampleSource implements SampleSource {
       }
       tracks[i] = new TrackGroup(createFormat(i, format));
     }
+    this.tracks = new TrackGroupArray(tracks);
     prepared = true;
     return true;
   }
@@ -156,7 +157,7 @@ public final class FrameworkSampleSource implements SampleSource {
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
     return tracks;
   }
 
@@ -194,7 +195,7 @@ public final class FrameworkSampleSource implements SampleSource {
       return TrackStream.NOTHING_READ;
     }
     if (trackStates[track] != TRACK_STATE_FORMAT_SENT) {
-      formatHolder.format = tracks[track].getFormat(0);
+      formatHolder.format = tracks.get(track).getFormat(0);
       formatHolder.drmInitData = Util.SDK_INT >= 18 ? getDrmInitDataV18() : null;
       trackStates[track] = TRACK_STATE_FORMAT_SENT;
       return TrackStream.FORMAT_READ;

library/src/main/java/com/google/android/exoplayer/MultiSampleSource.java

@@ -28,7 +28,7 @@ public class MultiSampleSource implements SampleSource {
 
   private boolean prepared;
   private long durationUs;
-  private TrackGroup[] tracks;
+  private TrackGroupArray trackGroups;
 
   public MultiSampleSource(SampleSource... sources) {
     this.sources = sources;
@@ -53,14 +53,15 @@ public class MultiSampleSource implements SampleSource {
           durationUs = sources[i].getDurationUs();
         }
       }
-      tracks = new TrackGroup[totalTrackGroupCount];
+      TrackGroup[] trackGroups = new TrackGroup[totalTrackGroupCount];
       int trackGroupIndex = 0;
       for (int i = 0; i < sources.length; i++) {
         int sourceTrackGroupCount = sources[i].getTrackGroups().length;
         for (int j = 0; j < sourceTrackGroupCount; j++) {
-          tracks[trackGroupIndex++] = sources[i].getTrackGroups()[j];
+          trackGroups[trackGroupIndex++] = sources[i].getTrackGroups().get(j);
         }
       }
+      this.trackGroups = new TrackGroupArray(trackGroups);
     }
     return prepared;
   }
@@ -71,8 +72,8 @@ public class MultiSampleSource implements SampleSource {
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
-    return tracks;
+    return trackGroups;
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer/SampleSource.java

@@ -58,7 +58,7 @@ public interface SampleSource {
    *
    * @return The {@link TrackGroup}s.
    */
-  public TrackGroup[] getTrackGroups();
+  public TrackGroupArray getTrackGroups();
 
   /**
    * Indicates to the source that it should continue buffering data for its enabled tracks.

library/src/main/java/com/google/android/exoplayer/SingleSampleSource.java

@@ -52,7 +52,7 @@ public final class SingleSampleSource implements SampleSource, TrackStream, Load
   private final Format format;
   private final long durationUs;
   private final int minLoadableRetryCount;
-  private final TrackGroup[] trackGroups;
+  private final TrackGroupArray tracks;
 
   private int state;
   private byte[] sampleData;
@@ -75,7 +75,7 @@ public final class SingleSampleSource implements SampleSource, TrackStream, Load
     this.format = format;
     this.durationUs = durationUs;
     this.minLoadableRetryCount = minLoadableRetryCount;
-    trackGroups = new TrackGroup[] {new TrackGroup(format)};
+    tracks = new TrackGroupArray(new TrackGroup(format));
     sampleData = new byte[INITIAL_SAMPLE_SIZE];
   }
 
@@ -105,8 +105,8 @@ public final class SingleSampleSource implements SampleSource, TrackStream, Load
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
-    return trackGroups;
+    return tracks;
   }
 
   @Override

library/src/main/java/com/google/android/exoplayer/TrackGroup.java

@@ -15,6 +15,10 @@
  */
 package com.google.android.exoplayer;
 
+import com.google.android.exoplayer.util.Assertions;
+
+import java.util.Arrays;
+
 /**
  * Defines a group of tracks exposed by a {@link SampleSource}.
  * <p>
@@ -26,7 +30,7 @@ package com.google.android.exoplayer;
 public final class TrackGroup {
 
   /**
-   * The number of tracks in the group.
+   * The number of tracks in the group. Always greater than zero.
    */
   public final int length;
   /**
@@ -36,18 +40,22 @@ public final class TrackGroup {
 
   private final Format[] formats;
 
+  // Lazily initialized hashcode.
+  private int hashCode;
+
   /**
    * @param format The format of the single track.
    */
   public TrackGroup(Format format) {
-    this(false, format);
+    this(false, Assertions.checkNotNull(format));
   }
 
   /**
    * @param adaptive Whether it's possible to adapt between multiple tracks in the group.
-   * @param formats The track formats.
+   * @param formats The track formats. Must not be null or empty. Must not contain null elements.
    */
   public TrackGroup(boolean adaptive, Format... formats) {
+    Assertions.checkState(formats.length > 0);
     this.adaptive = adaptive;
     this.formats = formats;
     length = formats.length;
@@ -63,4 +71,29 @@ public final class TrackGroup {
     return formats[index];
   }
 
+  @Override
+  public int hashCode() {
+    if (hashCode == 0) {
+      int result = 17;
+      result = 31 * result + (adaptive ? 1231 : 1237);
+      result = 31 * result + Arrays.hashCode(formats);
+      result = 31 * result + length;
+      hashCode = result;
+    }
+    return hashCode;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    TrackGroup other = (TrackGroup) obj;
+    return adaptive == other.adaptive && length == other.length
+        && Arrays.equals(formats, other.formats);
+  }
+
 }

library/src/main/java/com/google/android/exoplayer/TrackGroupArray.java

@@ -0,0 +1,76 @@
+/*
+ * 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.exoplayer;
+
+import java.util.Arrays;
+
+/**
+ * An array of {@link TrackGroup}s exposed by a {@link SampleSource}.
+ */
+public final class TrackGroupArray {
+
+  /**
+   * The number of groups in the list. Greater than or equal to zero.
+   */
+  public final int length;
+
+  private final TrackGroup[] trackGroups;
+
+  // Lazily initialized hashcode.
+  private int hashCode;
+
+  /**
+   * @param trackGroups The groups. Must not be null or contain null elements, but may be empty.
+   */
+  public TrackGroupArray(TrackGroup... trackGroups) {
+    this.trackGroups = trackGroups;
+    this.length = trackGroups.length;
+  }
+
+  /**
+   * Gets the group at a given index.
+   *
+   * @param index The index of the group.
+   * @return The group.
+   */
+  public TrackGroup get(int index) {
+    return trackGroups[index];
+  }
+
+  @Override
+  public int hashCode() {
+    if (hashCode == 0) {
+      int result = 17;
+      result = 31 * result + Arrays.hashCode(trackGroups);
+      result = 31 * result + length;
+      hashCode = result;
+    }
+    return hashCode;
+  }
+
+  @Override
+  public boolean equals(Object obj) {
+    if (this == obj) {
+      return true;
+    }
+    if (obj == null || getClass() != obj.getClass()) {
+      return false;
+    }
+    TrackGroupArray other = (TrackGroupArray) obj;
+    return length == other.length && Arrays.equals(trackGroups, other.trackGroups);
+  }
+
+}

library/src/main/java/com/google/android/exoplayer/chunk/ChunkSampleSource.java

@@ -22,6 +22,7 @@ import com.google.android.exoplayer.LoadControl;
 import com.google.android.exoplayer.SampleHolder;
 import com.google.android.exoplayer.SampleSource;
 import com.google.android.exoplayer.TrackGroup;
+import com.google.android.exoplayer.TrackGroupArray;
 import com.google.android.exoplayer.TrackSelection;
 import com.google.android.exoplayer.TrackStream;
 import com.google.android.exoplayer.extractor.DefaultTrackOutput;
@@ -78,7 +79,7 @@ public class ChunkSampleSource implements SampleSource, TrackStream, Loader.Call
   private long lastPerformedBufferOperation;
   private boolean pendingReset;
 
-  private TrackGroup[] trackGroups;
+  private TrackGroupArray trackGroups;
   private long durationUs;
   private Loader loader;
   private boolean loadingFinished;
@@ -156,11 +157,11 @@ public class ChunkSampleSource implements SampleSource, TrackStream, Loader.Call
     }
     durationUs = chunkSource.getDurationUs();
     TrackGroup trackGroup = chunkSource.getTracks();
-    if (trackGroup.length > 0) {
+    if (trackGroup != null) {
       loader = new Loader("Loader:" + trackGroup.getFormat(0).containerMimeType);
-      trackGroups = new TrackGroup[] {trackGroup};
+      trackGroups = new TrackGroupArray(trackGroup);
     } else {
-      trackGroups = new TrackGroup[0];
+      trackGroups = new TrackGroupArray();
     }
     state = STATE_PREPARED;
     return true;
@@ -177,7 +178,7 @@ public class ChunkSampleSource implements SampleSource, TrackStream, Loader.Call
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
     Assertions.checkState(state != STATE_IDLE);
     return trackGroups;
   }

library/src/main/java/com/google/android/exoplayer/dash/DashChunkSource.java

@@ -495,9 +495,10 @@ public class DashChunkSource implements ChunkSource {
     for (int i = 0; i < period.adaptationSets.size(); i++) {
       AdaptationSet adaptationSet = period.adaptationSets.get(i);
       if (adaptationSet.type == adaptationSetType) {
-        // We've found an adaptation set of the exposed type.
         adaptationSetIndex = i;
         List<Representation> representations = adaptationSet.representations;
+        if (!representations.isEmpty()) {
+          // We've found a non-empty adaptation set of the exposed type.
           Format[] trackFormats = new Format[representations.size()];
           for (int j = 0; j < trackFormats.length; j++) {
             trackFormats[j] = representations.get(j).format;
@@ -506,7 +507,8 @@ public class DashChunkSource implements ChunkSource {
           return;
         }
       }
-    trackGroup = new TrackGroup(adaptiveFormatEvaluator != null);
+    }
+    trackGroup = null;
   }
 
   // Visible for testing.

library/src/main/java/com/google/android/exoplayer/extractor/ExtractorSampleSource.java

@@ -21,6 +21,7 @@ import com.google.android.exoplayer.ParserException;
 import com.google.android.exoplayer.SampleHolder;
 import com.google.android.exoplayer.SampleSource;
 import com.google.android.exoplayer.TrackGroup;
+import com.google.android.exoplayer.TrackGroupArray;
 import com.google.android.exoplayer.TrackSelection;
 import com.google.android.exoplayer.TrackStream;
 import com.google.android.exoplayer.drm.DrmInitData;
@@ -176,7 +177,7 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
 
   private boolean prepared;
   private int enabledTrackCount;
-  private TrackGroup[] tracks;
+  private TrackGroupArray tracks;
   private long durationUs;
   private boolean[] pendingMediaFormat;
   private boolean[] pendingResets;
@@ -264,7 +265,7 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
 
     if (seekMap != null && tracksBuilt && haveFormatsForAllTracks()) {
       int trackCount = sampleQueues.size();
-      tracks = new TrackGroup[trackCount];
+      TrackGroup[] tracks = new TrackGroup[trackCount];
       trackEnabledStates = new boolean[trackCount];
       pendingResets = new boolean[trackCount];
       pendingMediaFormat = new boolean[trackCount];
@@ -272,6 +273,7 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
       for (int i = 0; i < trackCount; i++) {
         tracks[i] = new TrackGroup(sampleQueues.valueAt(i).getFormat());
       }
+      this.tracks = new TrackGroupArray(tracks);
       prepared = true;
       return true;
     }
@@ -290,7 +292,7 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
     return tracks;
   }
 

library/src/main/java/com/google/android/exoplayer/hls/HlsSampleSource.java

@@ -22,6 +22,7 @@ import com.google.android.exoplayer.LoadControl;
 import com.google.android.exoplayer.SampleHolder;
 import com.google.android.exoplayer.SampleSource;
 import com.google.android.exoplayer.TrackGroup;
+import com.google.android.exoplayer.TrackGroupArray;
 import com.google.android.exoplayer.TrackSelection;
 import com.google.android.exoplayer.TrackStream;
 import com.google.android.exoplayer.chunk.BaseChunkSampleSourceEventListener;
@@ -79,7 +80,7 @@ public final class HlsSampleSource implements SampleSource, Loader.Callback {
 
   // Tracks are complicated in HLS. See documentation of buildTracks for details.
   // Indexed by track (as exposed by this source).
-  private TrackGroup[] trackGroups;
+  private TrackGroupArray trackGroups;
   private int primaryTrackGroupIndex;
   private int[] primarySelectedTracks;
   // Indexed by group.
@@ -181,7 +182,7 @@ public final class HlsSampleSource implements SampleSource, Loader.Callback {
   }
 
   @Override
-  public TrackGroup[] getTrackGroups() {
+  public TrackGroupArray getTrackGroups() {
     Assertions.checkState(prepared);
     return trackGroups;
   }
@@ -506,12 +507,12 @@ public final class HlsSampleSource implements SampleSource, Loader.Callback {
 
     // Instantiate the necessary internal data-structures.
     primaryTrackGroupIndex = -1;
-    trackGroups = new TrackGroup[extractorTrackCount];
     groupEnabledStates = new boolean[extractorTrackCount];
     pendingResets = new boolean[extractorTrackCount];
     downstreamSampleFormats = new Format[extractorTrackCount];
 
     // Construct the set of exposed track groups.
+    TrackGroup[] trackGroups = new TrackGroup[extractorTrackCount];
     for (int i = 0; i < extractorTrackCount; i++) {
       Format sampleFormat = extractor.getSampleFormat(i);
       if (i == primaryExtractorTrackIndex) {
@@ -525,6 +526,7 @@ public final class HlsSampleSource implements SampleSource, Loader.Callback {
         trackGroups[i] = new TrackGroup(sampleFormat);
       }
     }
+    this.trackGroups = new TrackGroupArray(trackGroups);
   }
 
   /**

library/src/main/java/com/google/android/exoplayer/smoothstreaming/SmoothStreamingChunkSource.java

@@ -328,10 +328,10 @@ public class SmoothStreamingChunkSource implements ChunkSource {
   private void initForManifest(SmoothStreamingManifest manifest) {
     for (int i = 0; i < manifest.streamElements.length; i++) {
       if (manifest.streamElements[i].type == streamElementType) {
-        // We've found an element of the desired type.
-        elementIndex = i;
-        long timescale = manifest.streamElements[i].timescale;
         Format[] formats = manifest.streamElements[i].formats;
+        if (formats.length > 0) {
+          // We've found an element of the desired type.
+          long timescale = manifest.streamElements[i].timescale;
           extractorWrappers = new ChunkExtractorWrapper[formats.length];
           for (int j = 0; j < formats.length; j++) {
             int nalUnitLengthFieldLength = streamElementType == StreamElement.TYPE_VIDEO ? 4 : -1;
@@ -343,12 +343,14 @@ public class SmoothStreamingChunkSource implements ChunkSource {
             extractor.setTrack(track);
             extractorWrappers[j] = new ChunkExtractorWrapper(extractor);
           }
+          elementIndex = i;
           trackGroup = new TrackGroup(adaptiveFormatEvaluator != null, formats);
           return;
         }
       }
+    }
     extractorWrappers = null;
-    trackGroup = new TrackGroup(adaptiveFormatEvaluator != null);
+    trackGroup = null;
   }
 
   /**