1 files changed, 143 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/trackselection/RandomTrackSelection.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/trackselection/RandomTrackSelection.java
new file mode 100644
index 0000000000..75b7fc21f1
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/trackselection/RandomTrackSelection.java
@@ -0,0 +1,143 @@
+/*
+ * 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 org.mozilla.thirdparty.com.google.android.exoplayer2.trackselection;
+
+import android.os.SystemClock;
+import androidx.annotation.Nullable;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.TrackGroup;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.chunk.MediaChunk;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.source.chunk.MediaChunkIterator;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.upstream.BandwidthMeter;
+import java.util.List;
+import java.util.Random;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
+
+/**
+ * A {@link TrackSelection} whose selected track is updated randomly.
+ */
+public final class RandomTrackSelection extends BaseTrackSelection {
+
+  /**
+   * Factory for {@link RandomTrackSelection} instances.
+   */
+  public static final class Factory implements TrackSelection.Factory {
+
+    private final Random random;
+
+    public Factory() {
+      random = new Random();
+    }
+
+    /**
+     * @param seed A seed for the {@link Random} instance used by the factory.
+     */
+    public Factory(int seed) {
+      random = new Random(seed);
+    }
+
+    @Override
+    public @NullableType TrackSelection[] createTrackSelections(
+        @NullableType Definition[] definitions, BandwidthMeter bandwidthMeter) {
+      return TrackSelectionUtil.createTrackSelectionsForDefinitions(
+          definitions,
+          definition -> new RandomTrackSelection(definition.group, definition.tracks, random));
+    }
+  }
+
+  private final Random random;
+
+  private int selectedIndex;
+
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   */
+  public RandomTrackSelection(TrackGroup group, int... tracks) {
+    super(group, tracks);
+    random = new Random();
+    selectedIndex = random.nextInt(length);
+  }
+
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   * @param seed A seed for the {@link Random} instance used to update the selected track.
+   */
+  public RandomTrackSelection(TrackGroup group, int[] tracks, long seed) {
+    this(group, tracks, new Random(seed));
+  }
+
+  /**
+   * @param group The {@link TrackGroup}. Must not be null.
+   * @param tracks The indices of the selected tracks within the {@link TrackGroup}. Must not be
+   *     null or empty. May be in any order.
+   * @param random A source of random numbers.
+   */
+  public RandomTrackSelection(TrackGroup group, int[] tracks, Random random) {
+    super(group, tracks);
+    this.random = random;
+    selectedIndex = random.nextInt(length);
+  }
+
+  @Override
+  public void updateSelectedTrack(
+      long playbackPositionUs,
+      long bufferedDurationUs,
+      long availableDurationUs,
+      List<? extends MediaChunk> queue,
+      MediaChunkIterator[] mediaChunkIterators) {
+    // Count the number of non-blacklisted formats.
+    long nowMs = SystemClock.elapsedRealtime();
+    int nonBlacklistedFormatCount = 0;
+    for (int i = 0; i < length; i++) {
+      if (!isBlacklisted(i, nowMs)) {
+        nonBlacklistedFormatCount++;
+      }
+    }
+
+    selectedIndex = random.nextInt(nonBlacklistedFormatCount);
+    if (nonBlacklistedFormatCount != length) {
+      // Adjust the format index to account for blacklisted formats.
+      nonBlacklistedFormatCount = 0;
+      for (int i = 0; i < length; i++) {
+        if (!isBlacklisted(i, nowMs) && selectedIndex == nonBlacklistedFormatCount++) {
+          selectedIndex = i;
+          return;
+        }
+      }
+    }
+  }
+
+  @Override
+  public int getSelectedIndex() {
+    return selectedIndex;
+  }
+
+  @Override
+  public int getSelectionReason() {
+    return C.SELECTION_REASON_ADAPTIVE;
+  }
+
+  @Override
+  @Nullable
+  public Object getSelectionData() {
+    return null;
+  }
+
+}