Fix an issue with seeking that can lead to STATE_END not delivered.

GitHub: #1897

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=174841175

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

@@ -63,7 +63,11 @@ public final class CompositeSequenceableLoader implements SequenceableLoader {
         break;
       }
       for (SequenceableLoader loader : loaders) {
-        if (loader.getNextLoadPositionUs() == nextLoadPositionUs) {
+        long loaderNextLoadPositionUs = loader.getNextLoadPositionUs();
+        boolean isLoaderBehind =
+            loaderNextLoadPositionUs != C.TIME_END_OF_SOURCE
+                && loaderNextLoadPositionUs <= positionUs;
+        if (loaderNextLoadPositionUs == nextLoadPositionUs || isLoaderBehind) {
           madeProgressThisIteration |= loader.continueLoading(positionUs);
         }
       }

library/core/src/test/java/com/google/android/exoplayer2/source/CompositeSequenceableLoaderTest.java

@@ -0,0 +1,274 @@
+/*
+ * Copyright (C) 2017 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.exoplayer2.source;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.android.exoplayer2.C;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+/**
+ * Unit test for {@link CompositeSequenceableLoader}.
+ */
+@RunWith(RobolectricTestRunner.class)
+@Config(sdk = Config.TARGET_SDK, manifest = Config.NONE)
+public final class CompositeSequenceableLoaderTest {
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns minimum buffered
+   * position among all sub-loaders.
+   */
+  @Test
+  public void testGetBufferedPositionUsReturnsMinimumLoaderBufferedPosition() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(1000);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns minimum buffered
+   * position that is not {@link C#TIME_END_OF_SOURCE} among all sub-loaders.
+   */
+  @Test
+  public void testGetBufferedPositionUsReturnsMinimumNonEndOfSourceLoaderBufferedPosition() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader3 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
+            /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2, loader3});
+    assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(1000);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getBufferedPositionUs()} returns
+   * {@link C#TIME_END_OF_SOURCE} when all sub-loaders have buffered till end-of-source.
+   */
+  @Test
+  public void testGetBufferedPositionUsReturnsEndOfSourceWhenAllLoaderBufferedTillEndOfSource() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
+            /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ C.TIME_END_OF_SOURCE,
+            /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    assertThat(compositeSequenceableLoader.getBufferedPositionUs()).isEqualTo(C.TIME_END_OF_SOURCE);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns minimum next
+   * load position among all sub-loaders.
+   */
+  @Test
+  public void testGetNextLoadPositionUsReturnMinimumLoaderNextLoadPositionUs() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2001);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2000);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(2000);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns minimum next
+   * load position that is not {@link C#TIME_END_OF_SOURCE} among all sub-loaders.
+   */
+  @Test
+  public void testGetNextLoadPositionUsReturnMinimumNonEndOfSourceLoaderNextLoadPositionUs() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    FakeSequenceableLoader loader3 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2, loader3});
+    assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(2000);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#getNextLoadPositionUs()} returns
+   * {@link C#TIME_END_OF_SOURCE} when all sub-loaders have next load position at end-of-source.
+   */
+  @Test
+  public void testGetNextLoadPositionUsReturnsEndOfSourceWhenAllLoaderLoadingLastChunk() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    assertThat(compositeSequenceableLoader.getNextLoadPositionUs()).isEqualTo(C.TIME_END_OF_SOURCE);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} only allows the loader
+   * with minimum next load position to continue loading if next load positions are not behind
+   * current playback position.
+   */
+  @Test
+  public void testContinueLoadingOnlyAllowFurthestBehindLoaderToLoadIfNotBehindPlaybackPosition() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    compositeSequenceableLoader.continueLoading(100);
+
+    assertThat(loader1.numInvocations).isEqualTo(1);
+    assertThat(loader2.numInvocations).isEqualTo(0);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} allows all loaders
+   * with next load position behind current playback position to continue loading.
+   */
+  @Test
+  public void testContinueLoadingReturnAllowAllLoadersBehindPlaybackPositionToLoad() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    FakeSequenceableLoader loader3 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1002, /* nextLoadPositionUs */ 2002);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2, loader3});
+    compositeSequenceableLoader.continueLoading(3000);
+
+    assertThat(loader1.numInvocations).isEqualTo(1);
+    assertThat(loader2.numInvocations).isEqualTo(1);
+    assertThat(loader3.numInvocations).isEqualTo(1);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} does not allow loader
+   * with next load position at end-of-source to continue loading.
+   */
+  @Test
+  public void testContinueLoadingOnlyNotAllowEndOfSourceLoaderToLoad() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(
+            /* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ C.TIME_END_OF_SOURCE);
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+    compositeSequenceableLoader.continueLoading(3000);
+
+    assertThat(loader1.numInvocations).isEqualTo(0);
+    assertThat(loader2.numInvocations).isEqualTo(0);
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} returns true if the loader
+   * with minimum next load position can make progress if next load positions are not behind
+   * current playback position.
+   */
+  @Test
+  public void testContinueLoadingReturnTrueIfFurthestBehindLoaderCanMakeProgress() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    loader1.setNextChunkDurationUs(1000);
+
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+
+    assertThat(compositeSequenceableLoader.continueLoading(100)).isTrue();
+  }
+
+  /**
+   * Tests that {@link CompositeSequenceableLoader#continueLoading(long)} returns true if any loader
+   * that are behind current playback position can make progress, even if it is not the one with
+   * minimum next load position.
+   */
+  @Test
+  public void testContinueLoadingReturnTrueIfLoaderBehindPlaybackPositionCanMakeProgress() {
+    FakeSequenceableLoader loader1 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1000, /* nextLoadPositionUs */ 2000);
+    FakeSequenceableLoader loader2 =
+        new FakeSequenceableLoader(/* bufferedPositionUs */ 1001, /* nextLoadPositionUs */ 2001);
+    // loader2 is not the furthest behind, but it can make progress if allowed.
+    loader2.setNextChunkDurationUs(1000);
+
+    CompositeSequenceableLoader compositeSequenceableLoader = new CompositeSequenceableLoader(
+        new SequenceableLoader[] {loader1, loader2});
+
+    assertThat(compositeSequenceableLoader.continueLoading(3000)).isTrue();
+  }
+
+  private static class FakeSequenceableLoader implements SequenceableLoader {
+
+    private long bufferedPositionUs;
+    private long nextLoadPositionUs;
+    private int numInvocations;
+    private int nextChunkDurationUs;
+
+    private FakeSequenceableLoader(long bufferedPositionUs, long nextLoadPositionUs) {
+      this.bufferedPositionUs = bufferedPositionUs;
+      this.nextLoadPositionUs = nextLoadPositionUs;
+    }
+
+    @Override
+    public long getBufferedPositionUs() {
+      return bufferedPositionUs;
+    }
+
+    @Override
+    public long getNextLoadPositionUs() {
+      return nextLoadPositionUs;
+    }
+
+    @Override
+    public boolean continueLoading(long positionUs) {
+      numInvocations++;
+      boolean loaded = nextChunkDurationUs != 0;
+      // The current chunk has been loaded, advance to next chunk.
+      bufferedPositionUs = nextLoadPositionUs;
+      nextLoadPositionUs += nextChunkDurationUs;
+      nextChunkDurationUs = 0;
+      return loaded;
+    }
+
+    private void setNextChunkDurationUs(int nextChunkDurationUs) {
+      this.nextChunkDurationUs = nextChunkDurationUs;
+    }
+
+  }
+
+}