Clean up enabled renderers + processing of resets.

- Made enabledRenderers an array to avoid loads of method calls.
- Made if so that enabled renderers are always called in a consistent
  order, rather than their order changing if they're enabled/disabled
  over time. This is likely to make performance more predictable.
- Split out reading of resets into a separate method. This method is
  now called directly after seeking on the source, so as to ensure
  instant propagation of the new position from source->renderers in
  the common case.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=117225639

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

@@ -36,7 +36,12 @@ public final class DummyTrackRenderer extends TrackRenderer {
   }
 
   @Override
-  protected void doSomeWork(long positionUs, long elapsedRealtimeUs) {
+  protected void checkForReset() throws ExoPlaybackException {
+    throw new IllegalStateException();
+  }
+
+  @Override
+  protected void render(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
     throw new IllegalStateException();
   }
 

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

@@ -32,9 +32,7 @@ import android.util.Log;
 import android.util.Pair;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.List;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
@@ -73,7 +71,6 @@ import java.util.concurrent.atomic.AtomicInteger;
   private final StandaloneMediaClock standaloneMediaClock;
   private final long minBufferUs;
   private final long minRebufferUs;
-  private final List<TrackRenderer> enabledRenderers;
   private final TrackSelection[] trackSelections;
   private final Handler handler;
   private final HandlerThread internalPlaybackThread;
@@ -81,6 +78,7 @@ import java.util.concurrent.atomic.AtomicInteger;
   private final AtomicInteger pendingSeekCount;
 
   private SampleSource source;
+  private TrackRenderer[] enabledRenderers;
   private boolean released;
   private boolean playWhenReady;
   private boolean rebuffering;
@@ -123,8 +121,8 @@ import java.util.concurrent.atomic.AtomicInteger;
 
     standaloneMediaClock = new StandaloneMediaClock();
     pendingSeekCount = new AtomicInteger();
-    enabledRenderers = new ArrayList<>(renderers.length);
     trackSelections = new TrackSelection[renderers.length];
+    enabledRenderers = new TrackRenderer[0];
 
     trackSelector.init(this);
 
@@ -361,21 +359,21 @@ import java.util.concurrent.atomic.AtomicInteger;
   private void startRenderers() throws ExoPlaybackException {
     rebuffering = false;
     standaloneMediaClock.start();
-    for (int i = 0; i < enabledRenderers.size(); i++) {
+    for (TrackRenderer renderer : enabledRenderers) {
-      enabledRenderers.get(i).start();
+      renderer.start();
     }
   }
 
   private void stopRenderers() throws ExoPlaybackException {
     standaloneMediaClock.stop();
-    for (int i = 0; i < enabledRenderers.size(); i++) {
+    for (TrackRenderer renderer : enabledRenderers) {
-      ensureStopped(enabledRenderers.get(i));
+      ensureStopped(renderer);
     }
   }
 
   private void updatePositionUs() {
-    if (rendererMediaClock != null && enabledRenderers.contains(rendererMediaClockSource)
+    if (rendererMediaClock != null
-        && !rendererMediaClockSource.isEnded()) {
+        && rendererMediaClockSource.getState() != TrackRenderer.STATE_DISABLED) {
       positionUs = rendererMediaClock.getPositionUs();
       standaloneMediaClock.setPositionUs(positionUs);
     } else {
@@ -387,18 +385,23 @@ import java.util.concurrent.atomic.AtomicInteger;
   private void doSomeWork() throws ExoPlaybackException, IOException {
     TraceUtil.beginSection("doSomeWork");
     long operationStartTimeMs = SystemClock.elapsedRealtime();
+
+    // Process resets.
+    for (TrackRenderer renderer : enabledRenderers) {
+      renderer.checkForReset();
+    }
+
     updatePositionUs();
     bufferedPositionUs = source.getBufferedPositionUs();
     source.continueBuffering(positionUs);
 
     boolean allRenderersEnded = true;
     boolean allRenderersReadyOrEnded = true;
-    for (int i = 0; i < enabledRenderers.size(); i++) {
+    for (TrackRenderer renderer : enabledRenderers) {
-      TrackRenderer renderer = enabledRenderers.get(i);
       // TODO: Each renderer should return the maximum delay before which it wishes to be
       // invoked again. The minimum of these values should then be used as the delay before the next
       // invocation of this method.
-      renderer.doSomeWork(positionUs, elapsedRealtimeUs);
+      renderer.render(positionUs, elapsedRealtimeUs);
       allRenderersEnded = allRenderersEnded && renderer.isEnded();
       // Determine whether the renderer is ready (or ended). If it's not, throw an error that's
       // preventing the renderer from making progress, if such an error exists.
@@ -427,7 +430,7 @@ import java.util.concurrent.atomic.AtomicInteger;
     handler.removeMessages(MSG_DO_SOME_WORK);
     if ((playWhenReady && state == ExoPlayer.STATE_READY) || state == ExoPlayer.STATE_BUFFERING) {
       scheduleNextOperation(MSG_DO_SOME_WORK, operationStartTimeMs, RENDERING_INTERVAL_MS);
-    } else if (!enabledRenderers.isEmpty()) {
+    } else if (enabledRenderers.length != 0) {
       scheduleNextOperation(MSG_DO_SOME_WORK, operationStartTimeMs, IDLE_INTERVAL_MS);
     }
 
@@ -459,12 +462,16 @@ import java.util.concurrent.atomic.AtomicInteger;
       if (state == ExoPlayer.STATE_IDLE || state == ExoPlayer.STATE_PREPARING) {
         return;
       }
-      for (int i = 0; i < enabledRenderers.size(); i++) {
+
-        TrackRenderer renderer = enabledRenderers.get(i);
+      for (TrackRenderer renderer : enabledRenderers) {
         ensureStopped(renderer);
       }
       setState(ExoPlayer.STATE_BUFFERING);
       source.seekToUs(positionUs);
+      for (TrackRenderer renderer : enabledRenderers) {
+        renderer.checkForReset();
+      }
+
       handler.sendEmptyMessage(MSG_DO_SOME_WORK);
     } finally {
       pendingSeekCount.decrementAndGet();
@@ -493,10 +500,10 @@ import java.util.concurrent.atomic.AtomicInteger;
     if (renderers == null) {
       return;
     }
-    for (int i = 0; i < renderers.length; i++) {
+    for (TrackRenderer renderer : renderers) {
-      resetRendererInternal(renderers[i]);
+      resetRendererInternal(renderer);
     }
-    enabledRenderers.clear();
+    enabledRenderers = new TrackRenderer[0];
     Arrays.fill(trackSelections, null);
     source = null;
   }
@@ -547,16 +554,19 @@ import java.util.concurrent.atomic.AtomicInteger;
 
     // Disable renderers whose track selections have changed.
     boolean[] rendererWasEnabledFlags = new boolean[renderers.length];
+    int enabledRendererCount = 0;
     for (int i = 0; i < renderers.length; i++) {
       TrackRenderer renderer = renderers[i];
       TrackSelection previousTrackSelection = trackSelections[i];
       trackSelections[i] = newTrackSelections.get(i);
+      if (trackSelections[i] != null) {
+        enabledRendererCount++;
+      }
+      rendererWasEnabledFlags[i] = renderer.getState() != TrackRenderer.STATE_DISABLED;
       if (!Util.areEqual(previousTrackSelection, trackSelections[i])) {
         // The track selection has changed for this renderer.
-        int rendererState = renderer.getState();
+        if (rendererWasEnabledFlags[i]) {
-        boolean isEnabled = rendererState == TrackRenderer.STATE_ENABLED
+          // We need to disable the renderer so that we can enable it with its new selection.
-            || rendererState == TrackRenderer.STATE_STARTED;
-        if (isEnabled) {
           if (trackSelections[i] == null && renderer == rendererMediaClockSource) {
             // We've been using rendererMediaClockSource to advance the current position, but it's
             // being disabled and won't be re-enabled. Sync standaloneMediaClock so that it can take
@@ -564,21 +574,21 @@ import java.util.concurrent.atomic.AtomicInteger;
             standaloneMediaClock.setPositionUs(rendererMediaClock.getPositionUs());
           }
           ensureStopped(renderer);
-          enabledRenderers.remove(renderer);
           renderer.disable();
         }
-        rendererWasEnabledFlags[i] = isEnabled;
       }
     }
 
+    enabledRenderers = new TrackRenderer[enabledRendererCount];
+    enabledRendererCount = 0;
+
     // Enable renderers with their new track selections.
     for (int i = 0; i < renderers.length; i++) {
       TrackRenderer renderer = renderers[i];
       TrackSelection trackSelection = trackSelections[i];
-      int rendererState = renderer.getState();
+      if (trackSelection != null) {
-      boolean isEnabled = rendererState == TrackRenderer.STATE_ENABLED
+        enabledRenderers[enabledRendererCount++] = renderer;
-          || rendererState == TrackRenderer.STATE_STARTED;
+        if (renderer.getState() == TrackRenderer.STATE_DISABLED) {
-      if (!isEnabled && trackSelection != null) {
           // The renderer needs enabling with its new track selection.
           boolean playing = playWhenReady && state == ExoPlayer.STATE_READY;
           // Consider as joining only if the renderer was previously disabled.
@@ -592,12 +602,12 @@ import java.util.concurrent.atomic.AtomicInteger;
           }
           // Enable the renderer.
           renderer.enable(formats, trackStream, positionUs, joining);
-        enabledRenderers.add(renderer);
           if (playing) {
             renderer.start();
           }
         }
       }
+    }
 
     // The new selections have been activated.
     trackSelector.onSelectionActivated(result.second);

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

@@ -319,8 +319,8 @@ public class MediaCodecAudioTrackRenderer extends MediaCodecTrackRenderer implem
   }
 
   @Override
-  protected void onReset(long positionUs) throws ExoPlaybackException {
+  protected void reset(long positionUs) throws ExoPlaybackException {
-    super.onReset(positionUs);
+    super.reset(positionUs);
     audioTrack.reset();
     currentPositionUs = positionUs;
     allowPositionDiscontinuity = true;

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

@@ -461,7 +461,7 @@ public abstract class MediaCodecTrackRenderer extends SampleSourceTrackRenderer
   }
 
   @Override
-  protected void onReset(long positionUs) throws ExoPlaybackException {
+  protected void reset(long positionUs) throws ExoPlaybackException {
     sourceState = SOURCE_STATE_NOT_READY;
     inputStreamEnded = false;
     outputStreamEnded = false;
@@ -481,7 +481,7 @@ public abstract class MediaCodecTrackRenderer extends SampleSourceTrackRenderer
   }
 
   @Override
-  protected void doSomeWork(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
+  protected void render(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
       throws ExoPlaybackException {
     sourceState = sourceIsReady
         ? (sourceState == SOURCE_STATE_NOT_READY ? SOURCE_STATE_READY : sourceState)
@@ -537,7 +537,7 @@ public abstract class MediaCodecTrackRenderer extends SampleSourceTrackRenderer
 
   /**
    * @param firstFeed True if this is the first call to this method from the current invocation of
-   *     {@link #doSomeWork(long, long)}. False otherwise.
+   *     {@link #render(long, long)}. False otherwise.
    * @return True if it may be possible to feed more input data. False otherwise.
    * @throws ExoPlaybackException If an error occurs feeding the input buffer.
    */

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

@@ -284,8 +284,8 @@ public class MediaCodecVideoTrackRenderer extends MediaCodecTrackRenderer {
   }
 
   @Override
-  protected void onReset(long positionUs) throws ExoPlaybackException {
+  protected void reset(long positionUs) throws ExoPlaybackException {
-    super.onReset(positionUs);
+    super.reset(positionUs);
     renderedFirstFrame = false;
     consecutiveDroppedFrameCount = 0;
     joiningDeadlineUs = -1;
@@ -293,8 +293,8 @@ public class MediaCodecVideoTrackRenderer extends MediaCodecTrackRenderer {
 
   @Override
   protected boolean isReady() {
-    if (super.isReady() && (renderedFirstFrame || !codecInitialized()
+    if (super.isReady()
-        || getSourceState() == SOURCE_STATE_READY_READ_MAY_FAIL)) {
+        && (renderedFirstFrame || getSourceState() == SOURCE_STATE_READY_READ_MAY_FAIL)) {
       // Ready. If we were joining then we've now joined, so clear the joining deadline.
       joiningDeadlineUs = -1;
       return true;

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

@@ -31,23 +31,26 @@ public abstract class SampleSourceTrackRenderer extends TrackRenderer {
   protected void onEnabled(Format[] formats, TrackStream trackStream, long positionUs,
       boolean joining) throws ExoPlaybackException {
     this.trackStream = Assertions.checkNotNull(trackStream);
-    onReset(positionUs);
+    reset(positionUs);
   }
 
   @Override
-  protected final void doSomeWork(long positionUs, long elapsedRealtimeUs)
+  protected final void checkForReset() throws ExoPlaybackException {
-      throws ExoPlaybackException {
-    // TODO[REFACTOR]: Consider splitting reading of resets into a separate method?
     long resetPositionUs = trackStream.readReset();
     if (resetPositionUs != TrackStream.NO_RESET) {
-      onReset(resetPositionUs);
+      reset(resetPositionUs);
       return;
     }
-    doSomeWork(positionUs, elapsedRealtimeUs, trackStream.isReady());
   }
 
   @Override
-  protected void maybeThrowError() throws IOException {
+  protected final void render(long positionUs, long elapsedRealtimeUs)
+      throws ExoPlaybackException {
+    render(positionUs, elapsedRealtimeUs, trackStream.isReady());
+  }
+
+  @Override
+  protected final void maybeThrowError() throws IOException {
     trackStream.maybeThrowError();
   }
 
@@ -77,15 +80,15 @@ public abstract class SampleSourceTrackRenderer extends TrackRenderer {
   // Abstract methods.
 
   /**
-   * Invoked when a reset is encountered. Also invoked when the renderer is enabled.
+   * Invoked when a reset is encountered, and also when the renderer is enabled.
    *
    * @param positionUs The playback position in microseconds.
    * @throws ExoPlaybackException If an error occurs handling the reset.
    */
-  protected abstract void onReset(long positionUs) throws ExoPlaybackException;
+  protected abstract void reset(long positionUs) throws ExoPlaybackException;
 
   /**
-   * Called by {@link #doSomeWork(long, long)}.
+   * Called by {@link #render(long, long)}.
    *
    * @param positionUs The current media time in microseconds, measured at the start of the
    *     current iteration of the rendering loop.
@@ -93,9 +96,8 @@ public abstract class SampleSourceTrackRenderer extends TrackRenderer {
    *     measured at the start of the current iteration of the rendering loop.
    * @param sourceIsReady The result of the most recent call to  {@link TrackStream#isReady()}.
    * @throws ExoPlaybackException If an error occurs.
-   * @throws ExoPlaybackException
    */
-  protected abstract void doSomeWork(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
+  protected abstract void render(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
       throws ExoPlaybackException;
 
 }

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

@@ -92,19 +92,16 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
   public static final int ADAPTIVE_NOT_SUPPORTED = 0b0000;
 
   /**
-   * The renderer is idle.
+   * The renderer is disabled.
    */
-  protected static final int STATE_IDLE = 0;
+  protected static final int STATE_DISABLED = 0;
   /**
-   * The renderer is enabled. It should either be ready to be started, or be actively working
+   * The renderer is enabled but not started. A renderer in this state will typically hold any
-   * towards this state (e.g. a renderer in this state will typically hold any resources that it
+   * resources that it requires for rendering (e.g. media decoders).
-   * requires, such as media decoders, and will have buffered or be buffering any media data that
-   * is required to start playback).
    */
   protected static final int STATE_ENABLED = 1;
   /**
-   * The renderer is started. Calls to {@link #doSomeWork(long, long)} should cause the media to be
+   * The renderer is started. Calls to {@link #render(long, long)} will cause media to be rendered.
-   * rendered.
    */
   protected static final int STATE_STARTED = 2;
 
@@ -195,7 +192,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    */
   /* package */ final void enable(Format[] formats, TrackStream trackStream, long positionUs,
       boolean joining) throws ExoPlaybackException {
-    Assertions.checkState(state == STATE_IDLE);
+    Assertions.checkState(state == STATE_DISABLED);
     state = STATE_ENABLED;
     onEnabled(formats, trackStream, positionUs, joining);
   }
@@ -217,8 +214,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
   }
 
   /**
-   * Starts the renderer, meaning that calls to {@link #doSomeWork(long, long)} will cause the
+   * Starts the renderer, meaning that calls to {@link #render(long, long)} will cause media to be
-   * track to be rendered.
+   * rendered.
    *
    * @throws ExoPlaybackException If an error occurs.
    */
@@ -268,7 +265,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    */
   /* package */ final void disable() throws ExoPlaybackException {
     Assertions.checkState(state == STATE_ENABLED);
-    state = STATE_IDLE;
+    state = STATE_DISABLED;
     onDisabled();
   }
 
@@ -289,7 +286,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    * returned by all of its {@link TrackRenderer}s.
    * <p>
    * This method may be called when the renderer is in the following states:
-   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}
+   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}.
    *
    * @return Whether the renderer is ready for the player to transition to the ended state.
    */
@@ -306,26 +303,30 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    * renderer is ready for playback to be started. Returning false indicates that it is not.
    * <p>
    * This method may be called when the renderer is in the following states:
-   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}
+   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}.
    *
    * @return True if the renderer is ready to render media. False otherwise.
    */
   protected abstract boolean isReady();
 
   /**
-   * Invoked to make progress when the renderer is in the {@link #STATE_ENABLED} or
+   * Attempts to read and process a pending reset from the {@link TrackStream}.
-   * {@link #STATE_STARTED} states.
-   * <p>
-   * If the renderer's state is {@link #STATE_STARTED}, then repeated calls to this method should
-   * cause the media track to be rendered. If the state is {@link #STATE_ENABLED}, then repeated
-   * calls should make progress towards getting the renderer into a position where it is ready to
-   * render the track.
-   * <p>
-   * This method should return quickly, and should not block if the renderer is currently unable to
-   * make any useful progress.
    * <p>
    * This method may be called when the renderer is in the following states:
-   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}
+   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}.
+   *
+   * @throws ExoPlaybackException If an error occurs.
+   */
+  protected abstract void checkForReset() throws ExoPlaybackException;
+
+  /**
+   * Incrementally renders the {@link TrackStream}.
+   * <p>
+   * This method should return quickly, and should not block if the renderer is unable to make
+   * useful progress.
+   * <p>
+   * This method may be called when the renderer is in the following states:
+   * {@link #STATE_ENABLED}, {@link #STATE_STARTED}.
    *
    * @param positionUs The current media time in microseconds, measured at the start of the
    *     current iteration of the rendering loop.
@@ -333,7 +334,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    *     measured at the start of the current iteration of the rendering loop.
    * @throws ExoPlaybackException If an error occurs.
    */
-  protected abstract void doSomeWork(long positionUs, long elapsedRealtimeUs)
+  protected abstract void render(long positionUs, long elapsedRealtimeUs)
       throws ExoPlaybackException;
 
   /**
@@ -341,7 +342,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    * this point in time.
    * <p>
    * This method may be called when the renderer is in the following states:
-   * {@link #STATE_ENABLED}
+   * {@link #STATE_ENABLED}.
    *
    * @throws IOException An error that's preventing the renderer from making progress or buffering
    *     more data.

library/src/main/java/com/google/android/exoplayer/metadata/MetadataTrackRenderer.java

@@ -92,13 +92,13 @@ public final class MetadataTrackRenderer<T> extends SampleSourceTrackRenderer im
   }
 
   @Override
-  protected void onReset(long positionUs) {
+  protected void reset(long positionUs) {
     pendingMetadata = null;
     inputStreamEnded = false;
   }
 
   @Override
-  protected void doSomeWork(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
+  protected void render(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
       throws ExoPlaybackException {
     if (!inputStreamEnded && pendingMetadata == null) {
       sampleHolder.clearData();

library/src/main/java/com/google/android/exoplayer/text/TextTrackRenderer.java

@@ -173,7 +173,7 @@ public final class TextTrackRenderer extends SampleSourceTrackRenderer implement
   }
 
   @Override
-  protected void onReset(long positionUs) {
+  protected void reset(long positionUs) {
     inputStreamEnded = false;
     subtitle = null;
     nextSubtitle = null;
@@ -184,7 +184,7 @@ public final class TextTrackRenderer extends SampleSourceTrackRenderer implement
   }
 
   @Override
-  protected void doSomeWork(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
+  protected void render(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
       throws ExoPlaybackException {
     if (nextSubtitle == null) {
       try {

library/src/main/java/com/google/android/exoplayer/text/eia608/Eia608TrackRenderer.java

@@ -93,7 +93,7 @@ public final class Eia608TrackRenderer extends SampleSourceTrackRenderer impleme
   }
 
   @Override
-  protected void onReset(long positionUs) {
+  protected void reset(long positionUs) {
     inputStreamEnded = false;
     repeatableControl = null;
     pendingCaptionLists.clear();
@@ -104,7 +104,7 @@ public final class Eia608TrackRenderer extends SampleSourceTrackRenderer impleme
   }
 
   @Override
-  protected void doSomeWork(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
+  protected void render(long positionUs, long elapsedRealtimeUs, boolean sourceIsReady)
       throws ExoPlaybackException {
     if (isSamplePending()) {
       maybeParsePendingSample(positionUs);