Remove child data holder helper from AbstractConcatenatedTimeline.

This helper class required a scratch instance to write on. Such a scratch
instance may violate the immuatability of the timelines if used by multiple
threads simultaneously.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=163992458

library/core/src/main/java/com/google/android/exoplayer2/source/AbstractConcatenatedTimeline.java

@@ -25,68 +25,25 @@ import com.google.android.exoplayer2.Timeline;
  */
 /* package */ abstract class AbstractConcatenatedTimeline extends Timeline {
 
-  /**
-   * Meta data of a child timeline.
-   */
-  protected static final class ChildDataHolder {
+  private final int childCount;
 
-    /**
-     * Child timeline.
-     */
-    public Timeline timeline;
-
-    /**
-     * First period index belonging to the child timeline.
-     */
-    public int firstPeriodIndexInChild;
-
-    /**
-     * First window index belonging to the child timeline.
-     */
-    public int firstWindowIndexInChild;
-
-    /**
-     * UID of child timeline.
-     */
-    public Object uid;
-
-    /**
-     * Set child holder data.
-     *
-     * @param timeline Child timeline.
-     * @param firstPeriodIndexInChild First period index belonging to the child timeline.
-     * @param firstWindowIndexInChild First window index belonging to the child timeline.
-     * @param uid UID of child timeline.
-     */
-    public void setData(Timeline timeline, int firstPeriodIndexInChild, int firstWindowIndexInChild,
-        Object uid) {
-      this.timeline = timeline;
-      this.firstPeriodIndexInChild = firstPeriodIndexInChild;
-      this.firstWindowIndexInChild = firstWindowIndexInChild;
-      this.uid = uid;
-    }
-
-  }
-
-  private final ChildDataHolder childDataHolder;
-
-  public AbstractConcatenatedTimeline() {
-    childDataHolder = new ChildDataHolder();
+  public AbstractConcatenatedTimeline(int childCount) {
+    this.childCount = childCount;
   }
 
   @Override
   public int getNextWindowIndex(int windowIndex, @Player.RepeatMode int repeatMode) {
-    getChildDataByWindowIndex(windowIndex, childDataHolder);
-    int firstWindowIndexInChild = childDataHolder.firstWindowIndexInChild;
-    int nextWindowIndexInChild = childDataHolder.timeline.getNextWindowIndex(
+    int childIndex = getChildIndexByWindowIndex(windowIndex);
+    int firstWindowIndexInChild = getFirstWindowIndexByChildIndex(childIndex);
+    int nextWindowIndexInChild = getTimelineByChildIndex(childIndex).getNextWindowIndex(
         windowIndex - firstWindowIndexInChild,
         repeatMode == Player.REPEAT_MODE_ALL ? Player.REPEAT_MODE_OFF : repeatMode);
     if (nextWindowIndexInChild != C.INDEX_UNSET) {
       return firstWindowIndexInChild + nextWindowIndexInChild;
     } else {
-      firstWindowIndexInChild += childDataHolder.timeline.getWindowCount();
-      if (firstWindowIndexInChild < getWindowCount()) {
-        return firstWindowIndexInChild;
+      int nextChildIndex = childIndex + 1;
+      if (nextChildIndex < childCount) {
+        return getFirstWindowIndexByChildIndex(nextChildIndex);
       } else if (repeatMode == Player.REPEAT_MODE_ALL) {
         return 0;
       } else {
@@ -97,9 +54,9 @@ import com.google.android.exoplayer2.Timeline;
 
   @Override
   public int getPreviousWindowIndex(int windowIndex, @Player.RepeatMode int repeatMode) {
-    getChildDataByWindowIndex(windowIndex, childDataHolder);
-    int firstWindowIndexInChild = childDataHolder.firstWindowIndexInChild;
-    int previousWindowIndexInChild = childDataHolder.timeline.getPreviousWindowIndex(
+    int childIndex = getChildIndexByWindowIndex(windowIndex);
+    int firstWindowIndexInChild = getFirstWindowIndexByChildIndex(childIndex);
+    int previousWindowIndexInChild = getTimelineByChildIndex(childIndex).getPreviousWindowIndex(
         windowIndex - firstWindowIndexInChild,
         repeatMode == Player.REPEAT_MODE_ALL ? Player.REPEAT_MODE_OFF : repeatMode);
     if (previousWindowIndexInChild != C.INDEX_UNSET) {
@@ -118,11 +75,11 @@ import com.google.android.exoplayer2.Timeline;
   @Override
   public final Window getWindow(int windowIndex, Window window, boolean setIds,
       long defaultPositionProjectionUs) {
-    getChildDataByWindowIndex(windowIndex, childDataHolder);
-    int firstWindowIndexInChild = childDataHolder.firstWindowIndexInChild;
-    int firstPeriodIndexInChild = childDataHolder.firstPeriodIndexInChild;
-    childDataHolder.timeline.getWindow(windowIndex - firstWindowIndexInChild, window, setIds,
-        defaultPositionProjectionUs);
+    int childIndex = getChildIndexByWindowIndex(windowIndex);
+    int firstWindowIndexInChild = getFirstWindowIndexByChildIndex(childIndex);
+    int firstPeriodIndexInChild = getFirstPeriodIndexByChildIndex(childIndex);
+    getTimelineByChildIndex(childIndex).getWindow(windowIndex - firstWindowIndexInChild, window,
+        setIds, defaultPositionProjectionUs);
     window.firstPeriodIndex += firstPeriodIndexInChild;
     window.lastPeriodIndex += firstPeriodIndexInChild;
     return window;
@@ -130,13 +87,14 @@ import com.google.android.exoplayer2.Timeline;
 
   @Override
   public final Period getPeriod(int periodIndex, Period period, boolean setIds) {
-    getChildDataByPeriodIndex(periodIndex, childDataHolder);
-    int firstWindowIndexInChild = childDataHolder.firstWindowIndexInChild;
-    int firstPeriodIndexInChild = childDataHolder.firstPeriodIndexInChild;
-    childDataHolder.timeline.getPeriod(periodIndex - firstPeriodIndexInChild, period, setIds);
+    int childIndex = getChildIndexByPeriodIndex(periodIndex);
+    int firstWindowIndexInChild = getFirstWindowIndexByChildIndex(childIndex);
+    int firstPeriodIndexInChild = getFirstPeriodIndexByChildIndex(childIndex);
+    getTimelineByChildIndex(childIndex).getPeriod(periodIndex - firstPeriodIndexInChild, period,
+        setIds);
     period.windowIndex += firstWindowIndexInChild;
     if (setIds) {
-      period.uid = Pair.create(childDataHolder.uid, period.uid);
+      period.uid = Pair.create(getChildUidByChildIndex(childIndex), period.uid);
     }
     return period;
   }
@@ -149,37 +107,64 @@ import com.google.android.exoplayer2.Timeline;
     Pair<?, ?> childUidAndPeriodUid = (Pair<?, ?>) uid;
     Object childUid = childUidAndPeriodUid.first;
     Object periodUid = childUidAndPeriodUid.second;
-    if (!getChildDataByChildUid(childUid, childDataHolder)) {
+    int childIndex = getChildIndexByChildUid(childUid);
+    if (childIndex == C.INDEX_UNSET) {
       return C.INDEX_UNSET;
     }
-    int periodIndexInChild = childDataHolder.timeline.getIndexOfPeriod(periodUid);
+    int periodIndexInChild = getTimelineByChildIndex(childIndex).getIndexOfPeriod(periodUid);
     return periodIndexInChild == C.INDEX_UNSET ? C.INDEX_UNSET
-        : childDataHolder.firstPeriodIndexInChild + periodIndexInChild;
+        : getFirstPeriodIndexByChildIndex(childIndex) + periodIndexInChild;
   }
 
   /**
-   * Populates {@link ChildDataHolder} for the child timeline containing the given period index.
+   * Returns the index of the child timeline containing the given period index.
    *
    * @param periodIndex A valid period index within the bounds of the timeline.
-   * @param childData A data holder to be populated.
    */
-  protected abstract void getChildDataByPeriodIndex(int periodIndex, ChildDataHolder childData);
+  protected abstract int getChildIndexByPeriodIndex(int periodIndex);
 
   /**
-   * Populates {@link ChildDataHolder} for the child timeline containing the given window index.
+   * Returns the index of the child timeline containing the given window index.
    *
    * @param windowIndex A valid window index within the bounds of the timeline.
-   * @param childData A data holder to be populated.
    */
-  protected abstract void getChildDataByWindowIndex(int windowIndex, ChildDataHolder childData);
+  protected abstract int getChildIndexByWindowIndex(int windowIndex);
 
   /**
-   * Populates {@link ChildDataHolder} for the child timeline with the given UID.
+   * Returns the index of the child timeline with the given UID or {@link C#INDEX_UNSET} if not
+   * found.
    *
    * @param childUid A child UID.
-   * @param childData A data holder to be populated.
-   * @return Whether a child with the given UID was found.
+   * @return Index of child timeline or {@link C#INDEX_UNSET} if UID was not found.
    */
-  protected abstract boolean getChildDataByChildUid(Object childUid, ChildDataHolder childData);
+  protected abstract int getChildIndexByChildUid(Object childUid);
+
+  /**
+   * Returns the child timeline for the child with the given index.
+   *
+   * @param childIndex A valid child index within the bounds of the timeline.
+   */
+  protected abstract Timeline getTimelineByChildIndex(int childIndex);
+
+  /**
+   * Returns the first period index belonging to the child timeline with the given index.
+   *
+   * @param childIndex A valid child index within the bounds of the timeline.
+   */
+  protected abstract int getFirstPeriodIndexByChildIndex(int childIndex);
+
+  /**
+   * Returns the first window index belonging to the child timeline with the given index.
+   *
+   * @param childIndex A valid child index within the bounds of the timeline.
+   */
+  protected abstract int getFirstWindowIndexByChildIndex(int childIndex);
+
+  /**
+   * Returns the UID of the child timeline with the given index.
+   *
+   * @param childIndex A valid child index within the bounds of the timeline.
+   */
+  protected abstract Object getChildUidByChildIndex(int childIndex);
 
 }

library/core/src/main/java/com/google/android/exoplayer2/source/ConcatenatingMediaSource.java

@@ -15,6 +15,7 @@
  */
 package com.google.android.exoplayer2.source;
 
+import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.ExoPlayer;
 import com.google.android.exoplayer2.Player;
 import com.google.android.exoplayer2.Timeline;
@@ -97,7 +98,7 @@ public final class ConcatenatingMediaSource implements MediaSource {
   public MediaPeriod createPeriod(MediaPeriodId id, Allocator allocator) {
     int sourceIndex = timeline.getChildIndexByPeriodIndex(id.periodIndex);
     MediaPeriodId periodIdInSource =
-        new MediaPeriodId(id.periodIndex - timeline.getFirstPeriodIndexInChild(sourceIndex));
+        new MediaPeriodId(id.periodIndex - timeline.getFirstPeriodIndexByChildIndex(sourceIndex));
     MediaPeriod mediaPeriod = mediaSources[sourceIndex].createPeriod(periodIdInSource, allocator);
     sourceIndexByMediaPeriod.put(mediaPeriod, sourceIndex);
     return mediaPeriod;
@@ -166,6 +167,7 @@ public final class ConcatenatingMediaSource implements MediaSource {
     private final boolean isRepeatOneAtomic;
 
     public ConcatenatedTimeline(Timeline[] timelines, boolean isRepeatOneAtomic) {
+      super(timelines.length);
       int[] sourcePeriodOffsets = new int[timelines.length];
       int[] sourceWindowOffsets = new int[timelines.length];
       long periodCount = 0;
@@ -212,44 +214,43 @@ public final class ConcatenatingMediaSource implements MediaSource {
     }
 
     @Override
-    protected void getChildDataByPeriodIndex(int periodIndex, ChildDataHolder childData) {
-      int childIndex = getChildIndexByPeriodIndex(periodIndex);
-      getChildDataByChildIndex(childIndex, childData);
-    }
-
-    @Override
-    protected void getChildDataByWindowIndex(int windowIndex, ChildDataHolder childData) {
-      int childIndex = Util.binarySearchFloor(sourceWindowOffsets, windowIndex, true, false) + 1;
-      getChildDataByChildIndex(childIndex, childData);
-    }
-
-    @Override
-    protected boolean getChildDataByChildUid(Object childUid, ChildDataHolder childData) {
-      if (!(childUid instanceof Integer)) {
-        return false;
-      }
-      int childIndex = (Integer) childUid;
-      getChildDataByChildIndex(childIndex, childData);
-      return true;
-    }
-
-    private void getChildDataByChildIndex(int childIndex, ChildDataHolder childData) {
-      childData.setData(timelines[childIndex], getFirstPeriodIndexInChild(childIndex),
-          getFirstWindowIndexInChild(childIndex), childIndex);
-    }
-
-    private int getChildIndexByPeriodIndex(int periodIndex) {
+    protected int getChildIndexByPeriodIndex(int periodIndex) {
       return Util.binarySearchFloor(sourcePeriodOffsets, periodIndex, true, false) + 1;
     }
 
-    private int getFirstPeriodIndexInChild(int childIndex) {
+    @Override
+    protected int getChildIndexByWindowIndex(int windowIndex) {
+      return Util.binarySearchFloor(sourceWindowOffsets, windowIndex, true, false) + 1;
+    }
+
+    @Override
+    protected int getChildIndexByChildUid(Object childUid) {
+      if (!(childUid instanceof Integer)) {
+        return C.INDEX_UNSET;
+      }
+      return (Integer) childUid;
+    }
+
+    @Override
+    protected Timeline getTimelineByChildIndex(int childIndex) {
+      return timelines[childIndex];
+    }
+
+    @Override
+    protected int getFirstPeriodIndexByChildIndex(int childIndex) {
       return childIndex == 0 ? 0 : sourcePeriodOffsets[childIndex - 1];
     }
 
-    private int getFirstWindowIndexInChild(int childIndex) {
+    @Override
+    protected int getFirstWindowIndexByChildIndex(int childIndex) {
       return childIndex == 0 ? 0 : sourceWindowOffsets[childIndex - 1];
     }
 
+    @Override
+    protected Object getChildUidByChildIndex(int childIndex) {
+      return childIndex;
+    }
+
   }
 
 }

library/core/src/main/java/com/google/android/exoplayer2/source/DynamicConcatenatingMediaSource.java

@@ -397,6 +397,7 @@ public final class DynamicConcatenatingMediaSource implements MediaSource, ExoPl
 
     public ConcatenatedTimeline(Collection<MediaSourceHolder> mediaSourceHolders, int windowCount,
         int periodCount) {
+      super(mediaSourceHolders.size());
       this.windowCount = windowCount;
       this.periodCount = periodCount;
       int childCount = mediaSourceHolders.size();
@@ -416,28 +417,42 @@ public final class DynamicConcatenatingMediaSource implements MediaSource, ExoPl
     }
 
     @Override
-    protected void getChildDataByPeriodIndex(int periodIndex, ChildDataHolder childDataHolder) {
-      int index = Util.binarySearchFloor(firstPeriodInChildIndices, periodIndex, true, false);
-      setChildData(index, childDataHolder);
+    protected int getChildIndexByPeriodIndex(int periodIndex) {
+      return Util.binarySearchFloor(firstPeriodInChildIndices, periodIndex, true, false);
     }
 
     @Override
-    protected void getChildDataByWindowIndex(int windowIndex, ChildDataHolder childDataHolder) {
-      int index = Util.binarySearchFloor(firstWindowInChildIndices, windowIndex, true, false);
-      setChildData(index, childDataHolder);
+    protected int getChildIndexByWindowIndex(int windowIndex) {
+      return Util.binarySearchFloor(firstWindowInChildIndices, windowIndex, true, false);
     }
 
     @Override
-    protected boolean getChildDataByChildUid(Object childUid, ChildDataHolder childDataHolder) {
+    protected int getChildIndexByChildUid(Object childUid) {
       if (!(childUid instanceof Integer)) {
-        return false;
+        return C.INDEX_UNSET;
       }
       int index = childIndexByUid.get((int) childUid, -1);
-      if (index == -1) {
-        return false;
-      }
-      setChildData(index, childDataHolder);
-      return true;
+      return index == -1 ? C.INDEX_UNSET : index;
+    }
+
+    @Override
+    protected Timeline getTimelineByChildIndex(int childIndex) {
+      return timelines[childIndex];
+    }
+
+    @Override
+    protected int getFirstPeriodIndexByChildIndex(int childIndex) {
+      return firstPeriodInChildIndices[childIndex];
+    }
+
+    @Override
+    protected int getFirstWindowIndexByChildIndex(int childIndex) {
+      return firstWindowInChildIndices[childIndex];
+    }
+
+    @Override
+    protected Object getChildUidByChildIndex(int childIndex) {
+      return uids[childIndex];
     }
 
     @Override
@@ -450,10 +465,6 @@ public final class DynamicConcatenatingMediaSource implements MediaSource, ExoPl
       return periodCount;
     }
 
-    private void setChildData(int srcIndex, ChildDataHolder dest) {
-      dest.setData(timelines[srcIndex], firstPeriodInChildIndices[srcIndex],
-          firstWindowInChildIndices[srcIndex], uids[srcIndex]);
-    }
   }
 
   private static final class DeferredTimeline extends Timeline {

library/core/src/main/java/com/google/android/exoplayer2/source/LoopingMediaSource.java

@@ -101,6 +101,7 @@ public final class LoopingMediaSource implements MediaSource {
     private final int loopCount;
 
     public LoopingTimeline(Timeline childTimeline, int loopCount) {
+      super(loopCount);
       this.childTimeline = childTimeline;
       childPeriodCount = childTimeline.getPeriodCount();
       childWindowCount = childTimeline.getWindowCount();
@@ -120,30 +121,41 @@ public final class LoopingMediaSource implements MediaSource {
     }
 
     @Override
-    protected void getChildDataByPeriodIndex(int periodIndex, ChildDataHolder childData) {
-      int childIndex = periodIndex / childPeriodCount;
-      getChildDataByChildIndex(childIndex, childData);
+    protected int getChildIndexByPeriodIndex(int periodIndex) {
+      return periodIndex / childPeriodCount;
     }
 
     @Override
-    protected void getChildDataByWindowIndex(int windowIndex, ChildDataHolder childData) {
-      int childIndex = windowIndex / childWindowCount;
-      getChildDataByChildIndex(childIndex, childData);
+    protected int getChildIndexByWindowIndex(int windowIndex) {
+      return windowIndex / childWindowCount;
     }
 
     @Override
-    protected boolean getChildDataByChildUid(Object childUid, ChildDataHolder childData) {
+    protected int getChildIndexByChildUid(Object childUid) {
       if (!(childUid instanceof Integer)) {
-        return false;
+        return C.INDEX_UNSET;
       }
-      int childIndex = (Integer) childUid;
-      getChildDataByChildIndex(childIndex, childData);
-      return true;
+      return (Integer) childUid;
     }
 
-    private void getChildDataByChildIndex(int childIndex, ChildDataHolder childData) {
-      childData.setData(childTimeline, childIndex * childPeriodCount, childIndex * childWindowCount,
-          childIndex);
+    @Override
+    protected Timeline getTimelineByChildIndex(int childIndex) {
+      return childTimeline;
+    }
+
+    @Override
+    protected int getFirstPeriodIndexByChildIndex(int childIndex) {
+      return childIndex * childPeriodCount;
+    }
+
+    @Override
+    protected int getFirstWindowIndexByChildIndex(int childIndex) {
+      return childIndex * childWindowCount;
+    }
+
+    @Override
+    protected Object getChildUidByChildIndex(int childIndex) {
+      return childIndex;
     }
 
   }