Improve error propagation

extensions/opus/src/main/java/com/google/android/exoplayer/ext/opus/LibopusAudioTrackRenderer.java

@@ -126,24 +126,19 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
   }
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
-
+    int trackCount = source.getTrackCount();
-    for (int i = 0; i < source.getTrackCount(); i++) {
+    for (int i = 0; i < trackCount; i++) {
       if (source.getTrackInfo(i).mimeType.equalsIgnoreCase(MimeTypes.AUDIO_OPUS)
           || source.getTrackInfo(i).mimeType.equalsIgnoreCase(MimeTypes.AUDIO_WEBM)) {
         trackIndex = i;
         return TrackRenderer.STATE_PREPARED;
       }
     }
-
     return TrackRenderer.STATE_IGNORE;
   }
 
@@ -152,42 +147,49 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
     if (outputStreamEnded) {
       return;
     }
-    try {
+    sourceIsReady = source.continueBuffering(trackIndex, positionUs);
-      sourceIsReady = source.continueBuffering(trackIndex, positionUs);
+    checkForDiscontinuity();
-      checkForDiscontinuity();
-      if (format == null) {
-        readFormat();
-      } else {
-        // Create the decoder.
-        if (decoder == null) {
-          // For opus, the format can contain upto 3 entries in initializationData in the following
-          // exact order:
-          // 1) Opus Header Information (required)
-          // 2) Codec Delay in nanoseconds (required if Seek Preroll is present)
-          // 3) Seek Preroll in nanoseconds (required if Codec Delay is present)
-          List<byte[]> initializationData = format.initializationData;
-          if (initializationData.size() < 1) {
-            throw new ExoPlaybackException("Missing initialization data");
-          }
-          long codecDelayNs = -1;
-          long seekPreRollNs = -1;
-          if (initializationData.size() == 3) {
-            if (initializationData.get(1).length != Long.SIZE
-                || initializationData.get(2).length != Long.SIZE) {
-              throw new ExoPlaybackException("Invalid Codec Delay or Seek Preroll");
-            }
-            codecDelayNs = ByteBuffer.wrap(initializationData.get(1)).getLong();
-            seekPreRollNs = ByteBuffer.wrap(initializationData.get(2)).getLong();
-          }
-          decoder =
-              new OpusDecoderWrapper(initializationData.get(0), codecDelayNs, seekPreRollNs);
-          decoder.start();
-        }
-        renderBuffer();
 
-        // Queue input buffers.
+    // Try and read a format if we don't have one already.
-        while (feedInputBuffer()) {}
+    if (format == null && !readFormat(positionUs)) {
+      // We can't make progress without one.
+      return;
+    }
+
+    // If we don't have a decoder yet, we need to instantiate one.
+    if (decoder == null) {
+      // For opus, the format can contain upto 3 entries in initializationData in the following
+      // exact order:
+      // 1) Opus Header Information (required)
+      // 2) Codec Delay in nanoseconds (required if Seek Preroll is present)
+      // 3) Seek Preroll in nanoseconds (required if Codec Delay is present)
+      List<byte[]> initializationData = format.initializationData;
+      if (initializationData.size() < 1) {
+        throw new ExoPlaybackException("Missing initialization data");
       }
+      long codecDelayNs = -1;
+      long seekPreRollNs = -1;
+      if (initializationData.size() == 3) {
+        if (initializationData.get(1).length != Long.SIZE
+            || initializationData.get(2).length != Long.SIZE) {
+          throw new ExoPlaybackException("Invalid Codec Delay or Seek Preroll");
+        }
+        codecDelayNs = ByteBuffer.wrap(initializationData.get(1)).getLong();
+        seekPreRollNs = ByteBuffer.wrap(initializationData.get(2)).getLong();
+      }
+      try {
+        decoder = new OpusDecoderWrapper(initializationData.get(0), codecDelayNs, seekPreRollNs);
+      } catch (OpusDecoderException e) {
+        notifyDecoderError(e);
+        throw new ExoPlaybackException(e);
+      }
+      decoder.start();
+    }
+
+    // Rendering loop.
+    try {
+      renderBuffer();
+      while (feedInputBuffer()) {}
     } catch (AudioTrack.InitializationException e) {
       notifyAudioTrackInitializationError(e);
       throw new ExoPlaybackException(e);
@@ -197,8 +199,6 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
     } catch (OpusDecoderException e) {
       notifyDecoderError(e);
       throw new ExoPlaybackException(e);
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
   }
 
@@ -249,7 +249,7 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
     }
   }
 
-  private boolean feedInputBuffer() throws IOException, OpusDecoderException {
+  private boolean feedInputBuffer() throws OpusDecoderException {
     if (inputStreamEnded) {
       return false;
     }
@@ -291,7 +291,7 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
     return true;
   }
 
-  private void checkForDiscontinuity() throws IOException {
+  private void checkForDiscontinuity() {
     if (decoder == null) {
       return;
     }
@@ -394,12 +394,23 @@ public class LibopusAudioTrackRenderer extends TrackRenderer implements MediaClo
     }
   }
 
-  private void readFormat() throws IOException {
+  @Override
-    int result = source.readData(trackIndex, currentPositionUs, formatHolder, null, false);
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
+  private boolean readFormat(long positionUs) {
+    int result = source.readData(trackIndex, positionUs, formatHolder, null, false);
     if (result == SampleSource.FORMAT_READ) {
       format = formatHolder.format;
       audioTrack.reconfigure(format.getFrameworkMediaFormatV16());
+      return true;
     }
+    return false;
   }
 
   @Override

extensions/vp9/src/main/java/com/google/android/exoplayer/ext/vp9/LibvpxVideoTrackRenderer.java

@@ -153,23 +153,18 @@ public class LibvpxVideoTrackRenderer extends TrackRenderer {
 
   @Override
   protected int doPrepare(long positionUs) throws ExoPlaybackException {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
-
+    int trackCount = source.getTrackCount();
-    for (int i = 0; i < source.getTrackCount(); i++) {
+    for (int i = 0; i < trackCount; i++) {
       if (source.getTrackInfo(i).mimeType.equalsIgnoreCase(MimeTypes.VIDEO_VP9)
           || source.getTrackInfo(i).mimeType.equalsIgnoreCase(MimeTypes.VIDEO_WEBM)) {
         trackIndex = i;
         return TrackRenderer.STATE_PREPARED;
       }
     }
-
     return TrackRenderer.STATE_IGNORE;
   }
 
@@ -178,28 +173,29 @@ public class LibvpxVideoTrackRenderer extends TrackRenderer {
     if (outputStreamEnded) {
       return;
     }
-    try {
+    sourceIsReady = source.continueBuffering(trackIndex, positionUs);
-      sourceIsReady = source.continueBuffering(trackIndex, positionUs);
+    checkForDiscontinuity(positionUs);
-      checkForDiscontinuity(positionUs);
-      if (format == null) {
-        readFormat(positionUs);
-      } else {
-        // TODO: Add support for dynamic switching between one type of surface to another.
-        // Create the decoder.
-        if (decoder == null) {
-          decoder = new VpxDecoderWrapper(outputRgb);
-          decoder.start();
-        }
-        processOutputBuffer(positionUs, elapsedRealtimeUs);
 
-        // Queue input buffers.
+    // Try and read a format if we don't have one already.
-        while (feedInputBuffer(positionUs)) {}
+    if (format == null && !readFormat(positionUs)) {
-      }
+      // We can't make progress without one.
+      return;
+    }
+
+    // If we don't have a decoder yet, we need to instantiate one.
+    // TODO: Add support for dynamic switching between one type of surface to another.
+    if (decoder == null) {
+      decoder = new VpxDecoderWrapper(outputRgb);
+      decoder.start();
+    }
+
+    // Rendering loop.
+    try {
+      processOutputBuffer(positionUs, elapsedRealtimeUs);
+      while (feedInputBuffer(positionUs)) {}
     } catch (VpxDecoderException e) {
       notifyDecoderError(e);
       throw new ExoPlaybackException(e);
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
   }
 
@@ -294,7 +290,7 @@ public class LibvpxVideoTrackRenderer extends TrackRenderer {
     surface.unlockCanvasAndPost(canvas);
   }
 
-  private boolean feedInputBuffer(long positionUs) throws IOException, VpxDecoderException {
+  private boolean feedInputBuffer(long positionUs) throws VpxDecoderException {
     if (inputStreamEnded) {
       return false;
     }
@@ -334,7 +330,7 @@ public class LibvpxVideoTrackRenderer extends TrackRenderer {
     return true;
   }
 
-  private void checkForDiscontinuity(long positionUs) throws IOException {
+  private void checkForDiscontinuity(long positionUs) {
     if (decoder == null) {
       return;
     }
@@ -417,11 +413,22 @@ public class LibvpxVideoTrackRenderer extends TrackRenderer {
     source.disable(trackIndex);
   }
 
-  private void readFormat(long positionUs) throws IOException {
+  @Override
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
+  private boolean readFormat(long positionUs) {
     int result = source.readData(trackIndex, positionUs, formatHolder, null, false);
     if (result == SampleSource.FORMAT_READ) {
       format = formatHolder.format;
+      return true;
     }
+    return false;
   }
 
   @Override

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

@@ -25,7 +25,7 @@ package com.google.android.exoplayer;
 public class DummyTrackRenderer extends TrackRenderer {
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
     return STATE_IGNORE;
   }
 
@@ -49,6 +49,11 @@ public class DummyTrackRenderer extends TrackRenderer {
     throw new IllegalStateException();
   }
 
+  @Override
+  protected void maybeThrowError() {
+    throw new IllegalStateException();
+  }
+
   @Override
   protected long getDurationUs() {
     throw new IllegalStateException();

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

@@ -266,10 +266,12 @@ import java.util.List;
   private void incrementalPrepareInternal() throws ExoPlaybackException {
     long operationStartTimeMs = SystemClock.elapsedRealtime();
     boolean prepared = true;
-    for (int i = 0; i < renderers.length; i++) {
+    for (int rendererIndex = 0; rendererIndex < renderers.length; rendererIndex++) {
-      if (renderers[i].getState() == TrackRenderer.STATE_UNPREPARED) {
+      TrackRenderer renderer = renderers[rendererIndex];
-        int state = renderers[i].prepare(positionUs);
+      if (renderer.getState() == TrackRenderer.STATE_UNPREPARED) {
+        int state = renderer.prepare(positionUs);
         if (state == TrackRenderer.STATE_UNPREPARED) {
+          renderer.maybeThrowError();
           prepared = false;
         }
       }
@@ -414,7 +416,14 @@ import java.util.List;
       // invocation of this method.
       renderer.doSomeWork(positionUs, elapsedRealtimeUs);
       allRenderersEnded = allRenderersEnded && renderer.isEnded();
-      allRenderersReadyOrEnded = allRenderersReadyOrEnded && rendererReadyOrEnded(renderer);
+
+      // 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.
+      boolean rendererReadyOrEnded = rendererReadyOrEnded(renderer);
+      if (!rendererReadyOrEnded) {
+        renderer.maybeThrowError();
+      }
+      allRenderersReadyOrEnded = allRenderersReadyOrEnded && rendererReadyOrEnded;
 
       if (bufferedPositionUs == TrackRenderer.UNKNOWN_TIME_US) {
         // We've already encountered a track for which the buffered position is unknown. Hence the

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

@@ -76,6 +76,7 @@ public final class FrameworkSampleSource implements SampleSource, SampleSourceRe
   private final long fileDescriptorOffset;
   private final long fileDescriptorLength;
 
+  private IOException preparationError;
   private MediaExtractor extractor;
   private TrackInfo[] trackInfos;
   private boolean prepared;
@@ -128,13 +129,22 @@ public final class FrameworkSampleSource implements SampleSource, SampleSourceRe
   }
 
   @Override
-  public boolean prepare(long positionUs) throws IOException {
+  public boolean prepare(long positionUs) {
     if (!prepared) {
+      if (preparationError != null) {
+        return false;
+      }
+
       extractor = new MediaExtractor();
-      if (context != null) {
+      try {
-        extractor.setDataSource(context, uri, headers);
+        if (context != null) {
-      } else {
+          extractor.setDataSource(context, uri, headers);
-        extractor.setDataSource(fileDescriptor, fileDescriptorOffset, fileDescriptorLength);
+        } else {
+          extractor.setDataSource(fileDescriptor, fileDescriptorOffset, fileDescriptorLength);
+        }
+      } catch (IOException e) {
+        preparationError = e;
+        return false;
       }
 
       trackStates = new int[extractor.getTrackCount()];
@@ -232,6 +242,13 @@ public final class FrameworkSampleSource implements SampleSource, SampleSourceRe
     trackStates[track] = TRACK_STATE_DISABLED;
   }
 
+  @Override
+  public void maybeThrowError() throws IOException {
+    if (preparationError != null) {
+      throw preparationError;
+    }
+  }
+
   @Override
   public void seekToUs(long positionUs) {
     Assertions.checkState(prepared);

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

@@ -245,17 +245,13 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
   }
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
-
+    int trackCount = source.getTrackCount();
-    for (int i = 0; i < source.getTrackCount(); i++) {
+    for (int i = 0; i < trackCount; i++) {
       // TODO: Right now this is getting the mime types of the container format
       // (e.g. audio/mp4 and video/mp4 for fragmented mp4). It needs to be getting the mime types
       // of the actual samples (e.g. audio/mp4a-latm and video/avc).
@@ -264,7 +260,6 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
         return TrackRenderer.STATE_PREPARED;
       }
     }
-
     return TrackRenderer.STATE_IGNORE;
   }
 
@@ -489,39 +484,35 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
 
   @Override
   protected void doSomeWork(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
-    try {
+    sourceState = source.continueBuffering(trackIndex, positionUs)
-      sourceState = source.continueBuffering(trackIndex, positionUs)
+        ? (sourceState == SOURCE_STATE_NOT_READY ? SOURCE_STATE_READY : sourceState)
-          ? (sourceState == SOURCE_STATE_NOT_READY ? SOURCE_STATE_READY : sourceState)
+        : SOURCE_STATE_NOT_READY;
-          : SOURCE_STATE_NOT_READY;
+    checkForDiscontinuity(positionUs);
-      checkForDiscontinuity(positionUs);
+    if (format == null) {
-      if (format == null) {
+      readFormat(positionUs);
-        readFormat(positionUs);
-      }
-      if (codec == null && shouldInitCodec()) {
-        maybeInitCodec();
-      }
-      if (codec != null) {
-        TraceUtil.beginSection("drainAndFeed");
-        while (drainOutputBuffer(positionUs, elapsedRealtimeUs)) {}
-        if (feedInputBuffer(positionUs, true)) {
-          while (feedInputBuffer(positionUs, false)) {}
-        }
-        TraceUtil.endSection();
-      }
-      codecCounters.ensureUpdated();
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
+    if (codec == null && shouldInitCodec()) {
+      maybeInitCodec();
+    }
+    if (codec != null) {
+      TraceUtil.beginSection("drainAndFeed");
+      while (drainOutputBuffer(positionUs, elapsedRealtimeUs)) {}
+      if (feedInputBuffer(positionUs, true)) {
+        while (feedInputBuffer(positionUs, false)) {}
+      }
+      TraceUtil.endSection();
+    }
+    codecCounters.ensureUpdated();
   }
 
-  private void readFormat(long positionUs) throws IOException, ExoPlaybackException {
+  private void readFormat(long positionUs) throws ExoPlaybackException {
     int result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
     if (result == SampleSource.FORMAT_READ) {
       onInputFormatChanged(formatHolder);
     }
   }
 
-  private void checkForDiscontinuity(long positionUs) throws IOException, ExoPlaybackException {
+  private void checkForDiscontinuity(long positionUs) throws ExoPlaybackException {
     if (codec == null) {
       return;
     }
@@ -560,11 +551,9 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
    * @param firstFeed True if this is the first call to this method from the current invocation of
    *     {@link #doSomeWork(long, long)}. False otherwise.
    * @return True if it may be possible to feed more input data. False otherwise.
-   * @throws IOException If an error occurs reading data from the upstream source.
    * @throws ExoPlaybackException If an error occurs feeding the input buffer.
    */
-  private boolean feedInputBuffer(long positionUs, boolean firstFeed)
+  private boolean feedInputBuffer(long positionUs, boolean firstFeed) throws ExoPlaybackException {
-      throws IOException, ExoPlaybackException {
     if (inputStreamEnded
         || codecReinitializationState == REINITIALIZATION_STATE_WAIT_END_OF_STREAM) {
       // The input stream has ended, or we need to re-initialize the codec but are still waiting
@@ -785,6 +774,15 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
     return false;
   }
 
+  @Override
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
   @Override
   protected boolean isEnded() {
     return outputStreamEnded;

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

@@ -76,9 +76,8 @@ public interface SampleSource {
      *
      * @param positionUs The player's current playback position.
      * @return True if the source was prepared successfully, false otherwise.
-     * @throws IOException If an error occurred preparing the source.
      */
-    public boolean prepare(long positionUs) throws IOException;
+    public boolean prepare(long positionUs);
 
     /**
      * Returns the number of tracks exposed by the source.
@@ -116,6 +115,14 @@ public interface SampleSource {
      */
     public void disable(int track);
 
+    /**
+     * If the source is currently having difficulty preparing or loading samples, then this method
+     * throws the underlying error. Otherwise does nothing.
+     *
+     * @throws IOException The underlying error.
+     */
+    public void maybeThrowError() throws IOException;
+
     /**
      * Indicates to the source that it should still be buffering data for the specified track.
      *
@@ -123,9 +130,8 @@ public interface SampleSource {
      * @param positionUs The current playback position.
      * @return True if the track has available samples, or if the end of the stream has been
      *     reached. False if more data needs to be buffered for samples to become available.
-     * @throws IOException If an error occurred reading from the source.
      */
-    public boolean continueBuffering(int track, long positionUs) throws IOException;
+    public boolean continueBuffering(int track, long positionUs);
 
     /**
      * Attempts to read either a sample, a new format or or a discontinuity from the source.
@@ -147,10 +153,9 @@ public interface SampleSource {
      *     {@link #DISCONTINUITY_READ} or {@link #NOTHING_READ} can be returned.
      * @return The result, which can be {@link #SAMPLE_READ}, {@link #FORMAT_READ},
      *     {@link #DISCONTINUITY_READ}, {@link #NOTHING_READ} or {@link #END_OF_STREAM}.
-     * @throws IOException If an error occurred reading from the source.
      */
     public int readData(int track, long positionUs, MediaFormatHolder formatHolder,
-        SampleHolder sampleHolder, boolean onlyReadDiscontinuity) throws IOException;
+        SampleHolder sampleHolder, boolean onlyReadDiscontinuity);
 
     /**
      * Seeks to the specified time in microseconds.

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

@@ -107,6 +107,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    *
    * @param positionUs The player's current playback position.
    * @return The current state (one of the STATE_* constants), for convenience.
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final int prepare(long positionUs) throws ExoPlaybackException {
     Assertions.checkState(state == TrackRenderer.STATE_UNPREPARED);
@@ -139,6 +140,7 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
    * @param joining Whether this renderer is being enabled to join an ongoing playback. If true
    *     then {@link #start} must be called immediately after this method returns (unless a
    *     {@link ExoPlaybackException} is thrown).
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final void enable(long positionUs, boolean joining) throws ExoPlaybackException {
     Assertions.checkState(state == TrackRenderer.STATE_PREPARED);
@@ -164,6 +166,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
   /**
    * Starts the renderer, meaning that calls to {@link #doSomeWork(long, long)} will cause the
    * track to be rendered.
+   *
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final void start() throws ExoPlaybackException {
     Assertions.checkState(state == TrackRenderer.STATE_ENABLED);
@@ -184,6 +188,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
 
   /**
    * Stops the renderer.
+   *
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final void stop() throws ExoPlaybackException {
     Assertions.checkState(state == TrackRenderer.STATE_STARTED);
@@ -204,6 +210,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
 
   /**
    * Disable the renderer.
+   *
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final void disable() throws ExoPlaybackException {
     Assertions.checkState(state == TrackRenderer.STATE_ENABLED);
@@ -224,6 +232,8 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
 
   /**
    * Releases the renderer.
+   *
+   * @throws ExoPlaybackException If an error occurs.
    */
   /* package */ final void release() throws ExoPlaybackException {
     Assertions.checkState(state != TrackRenderer.STATE_ENABLED
@@ -297,6 +307,15 @@ public abstract class TrackRenderer implements ExoPlayerComponent {
   protected abstract void doSomeWork(long positionUs, long elapsedRealtimeUs)
       throws ExoPlaybackException;
 
+  /**
+   * Throws an error that's preventing the renderer from making progress or buffering more data at
+   * this point in time.
+   *
+   * @throws ExoPlaybackException An error that's preventing the renderer from making progress or
+   *     buffering more data.
+   */
+  protected abstract void maybeThrowError() throws ExoPlaybackException;
+
   /**
    * Returns the duration of the media being rendered.
    * <p>

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

@@ -188,23 +188,18 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
   }
 
   @Override
-  public boolean continueBuffering(int track, long positionUs) throws IOException {
+  public boolean continueBuffering(int track, long positionUs) {
     Assertions.checkState(state == STATE_ENABLED);
     Assertions.checkState(track == 0);
     downstreamPositionUs = positionUs;
     chunkSource.continueBuffering(positionUs);
     updateLoadControl();
-
+    return loadingFinished || !sampleQueue.isEmpty();
-    boolean haveSamples = !sampleQueue.isEmpty();
-    if (!haveSamples) {
-      maybeThrowLoadableException();
-    }
-    return loadingFinished || haveSamples;
   }
 
   @Override
   public int readData(int track, long positionUs, MediaFormatHolder formatHolder,
-      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) throws IOException {
+      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) {
     Assertions.checkState(state == STATE_ENABLED);
     Assertions.checkState(track == 0);
     downstreamPositionUs = positionUs;
@@ -219,7 +214,6 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
     }
 
     if (isPendingReset()) {
-      maybeThrowLoadableException();
       return NOTHING_READ;
     }
 
@@ -252,7 +246,6 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
       if (loadingFinished) {
         return END_OF_STREAM;
       }
-      maybeThrowLoadableException();
       return NOTHING_READ;
     }
 
@@ -263,7 +256,6 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
       return SAMPLE_READ;
     }
 
-    maybeThrowLoadableException();
     return NOTHING_READ;
   }
 
@@ -295,15 +287,12 @@ public class ChunkSampleSource implements SampleSource, SampleSourceReader, Load
     pendingDiscontinuity = true;
   }
 
-  private void maybeThrowLoadableException() throws IOException {
+  @Override
+  public void maybeThrowError() throws IOException {
     if (currentLoadableException != null && currentLoadableExceptionCount > minLoadableRetryCount) {
       throw currentLoadableException;
-    }
+    } else if (currentLoadableHolder.chunk == null) {
-    if (sampleQueue.isEmpty() && currentLoadableHolder.chunk == null) {
+      chunkSource.maybeThrowError();
-      IOException chunkSourceException = chunkSource.getError();
-      if (chunkSourceException != null) {
-        throw chunkSourceException;
-      }
     }
   }
 

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

@@ -94,13 +94,12 @@ public interface ChunkSource {
       long playbackPositionUs, ChunkOperationHolder out);
 
   /**
-   * If the {@link ChunkSource} is currently unable to provide chunks through
+   * If the source is currently having difficulty providing chunks, then this method throws the
-   * {@link ChunkSource#getChunkOperation}, then this method returns the underlying cause. Returns
+   * underlying error. Otherwise does nothing.
-   * null otherwise.
    *
-   * @return An {@link IOException}, or null.
+   * @throws IOException The underlying error.
    */
-  IOException getError();
+  void maybeThrowError() throws IOException;
 
   /**
    * Invoked when the {@link ChunkSampleSource} has finished loading a chunk obtained from this

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

@@ -89,8 +89,8 @@ public class MultiTrackChunkSource implements ChunkSource, ExoPlayerComponent {
   }
 
   @Override
-  public IOException getError() {
+  public void maybeThrowError() throws IOException {
-    return null;
+    selectedSource.maybeThrowError();
   }
 
   @Override

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

@@ -21,7 +21,6 @@ import com.google.android.exoplayer.TrackInfo;
 import com.google.android.exoplayer.upstream.DataSource;
 import com.google.android.exoplayer.upstream.DataSpec;
 
-import java.io.IOException;
 import java.util.List;
 
 /**
@@ -94,8 +93,8 @@ public class SingleSampleChunkSource implements ChunkSource {
   }
 
   @Override
-  public IOException getError() {
+  public void maybeThrowError() {
-    return null;
+    // Do nothing.
   }
 
   @Override

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

@@ -514,9 +514,12 @@ public class DashChunkSource implements ChunkSource {
   }
 
   @Override
-  public IOException getError() {
+  public void maybeThrowError() throws IOException {
-    return fatalError != null ? fatalError
+    if (fatalError != null) {
-        : (manifestFetcher != null ? manifestFetcher.getError() : null);
+      throw fatalError;
+    } else if (manifestFetcher != null) {
+      manifestFetcher.maybeThrowError();
+    }
   }
 
   @Override

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

@@ -172,7 +172,7 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
   }
 
   @Override
-  public boolean prepare(long positionUs) throws IOException {
+  public boolean prepare(long positionUs) {
     if (prepared) {
       return true;
     }
@@ -198,10 +198,9 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
       }
       prepared = true;
       return true;
-    } else {
-      maybeThrowLoadableException();
-      return false;
     }
+
+    return false;
   }
 
   @Override
@@ -246,7 +245,7 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
   }
 
   @Override
-  public boolean continueBuffering(int track, long playbackPositionUs) throws IOException {
+  public boolean continueBuffering(int track, long playbackPositionUs) {
     Assertions.checkState(prepared);
     Assertions.checkState(trackEnabledStates[track]);
     downstreamPositionUs = playbackPositionUs;
@@ -258,16 +257,12 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     if (isPendingReset()) {
       return false;
     }
-    if (sampleQueues.valueAt(track).isEmpty()) {
+    return !sampleQueues.valueAt(track).isEmpty();
-      maybeThrowLoadableException();
-      return false;
-    }
-    return true;
   }
 
   @Override
   public int readData(int track, long playbackPositionUs, MediaFormatHolder formatHolder,
-      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) throws IOException {
+      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) {
     downstreamPositionUs = playbackPositionUs;
 
     if (pendingDiscontinuities[track]) {
@@ -276,7 +271,6 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     }
 
     if (onlyReadDiscontinuity || isPendingReset()) {
-      maybeThrowLoadableException();
       return NOTHING_READ;
     }
 
@@ -304,10 +298,27 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
       return END_OF_STREAM;
     }
 
-    maybeThrowLoadableException();
     return NOTHING_READ;
   }
 
+  @Override
+  public void maybeThrowError() throws IOException {
+    if (currentLoadableException == null) {
+      return;
+    }
+    int minLoadableRetryCountForMedia;
+    if (minLoadableRetryCount != MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA) {
+      minLoadableRetryCountForMedia = minLoadableRetryCount;
+    } else {
+      minLoadableRetryCountForMedia = seekMap != null && !seekMap.isSeekable()
+          ? DEFAULT_MIN_LOADABLE_RETRY_COUNT_LIVE
+          : DEFAULT_MIN_LOADABLE_RETRY_COUNT_ON_DEMAND;
+    }
+    if (currentLoadableExceptionCount > minLoadableRetryCountForMedia) {
+      throw currentLoadableException;
+    }
+  }
+
   @Override
   public void seekToUs(long positionUs) {
     Assertions.checkState(prepared);
@@ -496,23 +507,6 @@ public class ExtractorSampleSource implements SampleSource, SampleSourceReader,
     loader.startLoading(loadable, this);
   }
 
-  private void maybeThrowLoadableException() throws IOException {
-    if (currentLoadableException == null) {
-      return;
-    }
-    int minLoadableRetryCountForMedia;
-    if (minLoadableRetryCount != MIN_RETRY_COUNT_DEFAULT_FOR_MEDIA) {
-      minLoadableRetryCountForMedia = minLoadableRetryCount;
-    } else {
-      minLoadableRetryCountForMedia = seekMap != null && !seekMap.isSeekable()
-          ? DEFAULT_MIN_LOADABLE_RETRY_COUNT_LIVE
-          : DEFAULT_MIN_LOADABLE_RETRY_COUNT_ON_DEMAND;
-    }
-    if (currentLoadableExceptionCount > minLoadableRetryCountForMedia) {
-      throw currentLoadableException;
-    }
-  }
-
   private ExtractingLoadable createLoadableFromStart() {
     return new ExtractingLoadable(uri, dataSource, extractor, allocator, requestedBufferSize, 0);
   }

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

@@ -125,7 +125,7 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
   }
 
   @Override
-  public boolean prepare(long positionUs) throws IOException {
+  public boolean prepare(long positionUs) {
     if (prepared) {
       return true;
     }
@@ -162,7 +162,6 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
       downstreamPositionUs = positionUs;
     }
     maybeStartLoading();
-    maybeThrowLoadableException();
     return false;
   }
 
@@ -218,7 +217,7 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
   }
 
   @Override
-  public boolean continueBuffering(int track, long playbackPositionUs) throws IOException {
+  public boolean continueBuffering(int track, long playbackPositionUs) {
     Assertions.checkState(prepared);
     Assertions.checkState(trackEnabledStates[track]);
     downstreamPositionUs = playbackPositionUs;
@@ -232,7 +231,6 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
     if (isPendingReset() || extractors.isEmpty()) {
       return false;
     }
-
     for (int extractorIndex = 0; extractorIndex < extractors.size(); extractorIndex++) {
       HlsExtractorWrapper extractor = extractors.get(extractorIndex);
       if (!extractor.isPrepared()) {
@@ -242,13 +240,12 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
         return true;
       }
     }
-    maybeThrowLoadableException();
     return false;
   }
 
   @Override
   public int readData(int track, long playbackPositionUs, MediaFormatHolder formatHolder,
-      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) throws IOException {
+      SampleHolder sampleHolder, boolean onlyReadDiscontinuity) {
     Assertions.checkState(prepared);
     downstreamPositionUs = playbackPositionUs;
 
@@ -262,13 +259,11 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
     }
 
     if (isPendingReset()) {
-      maybeThrowLoadableException();
       return NOTHING_READ;
     }
 
     HlsExtractorWrapper extractor = getCurrentExtractor();
     if (!extractor.isPrepared()) {
-      maybeThrowLoadableException();
       return NOTHING_READ;
     }
 
@@ -290,7 +285,6 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
       // next one for the current read.
       extractor = extractors.get(++extractorIndex);
       if (!extractor.isPrepared()) {
-        maybeThrowLoadableException();
         return NOTHING_READ;
       }
     }
@@ -313,10 +307,16 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
       return END_OF_STREAM;
     }
 
-    maybeThrowLoadableException();
     return NOTHING_READ;
   }
 
+  @Override
+  public void maybeThrowError() throws IOException {
+    if (currentLoadableException != null && currentLoadableExceptionCount > minLoadableRetryCount) {
+      throw currentLoadableException;
+    }
+  }
+
   @Override
   public void seekToUs(long positionUs) {
     Assertions.checkState(prepared);
@@ -361,6 +361,8 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
     }
   }
 
+  // Loader.Callback implementation.
+
   @Override
   public void onLoadCompleted(Loadable loadable) {
     Assertions.checkState(loadable == currentLoadable);
@@ -412,6 +414,8 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
     maybeStartLoading();
   }
 
+  // Internal stuff.
+
   /**
    * Gets the current extractor from which samples should be read.
    * <p>
@@ -455,12 +459,6 @@ public class HlsSampleSource implements SampleSource, SampleSourceReader, Loader
     return false;
   }
 
-  private void maybeThrowLoadableException() throws IOException {
-    if (currentLoadableException != null && currentLoadableExceptionCount > minLoadableRetryCount) {
-      throw currentLoadableException;
-    }
-  }
-
   private void restartFrom(long positionUs) {
     pendingResetPositionUs = positionUs;
     loadingFinished = false;

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

@@ -90,16 +90,13 @@ public class MetadataTrackRenderer<T> extends TrackRenderer implements Callback
   }
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
-    for (int i = 0; i < source.getTrackCount(); i++) {
+    int trackCount = source.getTrackCount();
+    for (int i = 0; i < trackCount; i++) {
       if (metadataParser.canParse(source.getTrackInfo(i).mimeType)) {
         trackIndex = i;
         return TrackRenderer.STATE_PREPARED;
@@ -128,29 +125,21 @@ public class MetadataTrackRenderer<T> extends TrackRenderer implements Callback
   @Override
   protected void doSomeWork(long positionUs, long elapsedRealtimeUs)
       throws ExoPlaybackException {
-    try {
+    source.continueBuffering(trackIndex, positionUs);
-      source.continueBuffering(trackIndex, positionUs);
-    } catch (IOException e) {
-      // TODO: This should be propagated, but in the current design propagation may occur too
-      // early. See [Internal b/22291244].
-      // throw new ExoPlaybackException(e);
-    }
 
     if (!inputStreamEnded && pendingMetadata == null) {
-      try {
         int result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
         if (result == SampleSource.SAMPLE_READ) {
           pendingMetadataTimestamp = sampleHolder.timeUs;
-          pendingMetadata = metadataParser.parse(sampleHolder.data.array(), sampleHolder.size);
+          try {
+            pendingMetadata = metadataParser.parse(sampleHolder.data.array(), sampleHolder.size);
+          } catch (IOException e) {
+            throw new ExoPlaybackException(e);
+          }
           sampleHolder.data.clear();
         } else if (result == SampleSource.END_OF_STREAM) {
           inputStreamEnded = true;
         }
-      } catch (IOException e) {
-        // TODO: This should be propagated, but in the current design propagation may occur too
-        // early. See [Internal b/22291244].
-        // throw new ExoPlaybackException(e);
-      }
     }
 
     if (pendingMetadata != null && pendingMetadataTimestamp <= positionUs) {
@@ -159,6 +148,15 @@ public class MetadataTrackRenderer<T> extends TrackRenderer implements Callback
     }
   }
 
+  @Override
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
   @Override
   protected void onDisabled() {
     pendingMetadata = null;

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

@@ -324,9 +324,12 @@ public class SmoothStreamingChunkSource implements ChunkSource {
   }
 
   @Override
-  public IOException getError() {
+  public void maybeThrowError() throws IOException {
-    return fatalError != null ? fatalError
+    if (fatalError != null) {
-        : (manifestFetcher != null ? manifestFetcher.getError() : null);
+      throw fatalError;
+    } else {
+      manifestFetcher.maybeThrowError();
+    }
   }
 
   @Override

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

@@ -151,17 +151,14 @@ public class TextTrackRenderer extends TrackRenderer implements Callback {
   }
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
+    int trackCount = source.getTrackCount();
     for (int i = 0; i < subtitleParsers.length; i++) {
-      for (int j = 0; j < source.getTrackCount(); j++) {
+      for (int j = 0; j < trackCount; j++) {
         if (subtitleParsers[i].canParse(source.getTrackInfo(j).mimeType)) {
           parserIndex = i;
           trackIndex = j;
@@ -197,11 +194,7 @@ public class TextTrackRenderer extends TrackRenderer implements Callback {
 
   @Override
   protected void doSomeWork(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
-    try {
+    source.continueBuffering(trackIndex, positionUs);
-      source.continueBuffering(trackIndex, positionUs);
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
-    }
 
     if (nextSubtitle == null) {
       try {
@@ -240,17 +233,13 @@ public class TextTrackRenderer extends TrackRenderer implements Callback {
 
     if (!inputStreamEnded && nextSubtitle == null && !parserHelper.isParsing()) {
       // Try and read the next subtitle from the source.
-      try {
+      SampleHolder sampleHolder = parserHelper.getSampleHolder();
-        SampleHolder sampleHolder = parserHelper.getSampleHolder();
+      sampleHolder.clearData();
-        sampleHolder.clearData();
+      int result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
-        int result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
+      if (result == SampleSource.SAMPLE_READ) {
-        if (result == SampleSource.SAMPLE_READ) {
+        parserHelper.startParseOperation();
-          parserHelper.startParseOperation();
+      } else if (result == SampleSource.END_OF_STREAM) {
-        } else if (result == SampleSource.END_OF_STREAM) {
+        inputStreamEnded = true;
-          inputStreamEnded = true;
-        }
-      } catch (IOException e) {
-        throw new ExoPlaybackException(e);
       }
     }
   }
@@ -271,6 +260,15 @@ public class TextTrackRenderer extends TrackRenderer implements Callback {
     source.release();
   }
 
+  @Override
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
   @Override
   protected long getDurationUs() {
     return source.getTrackInfo(trackIndex).durationUs;

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

@@ -92,16 +92,13 @@ public class Eia608TrackRenderer extends TrackRenderer implements Callback {
   }
 
   @Override
-  protected int doPrepare(long positionUs) throws ExoPlaybackException {
+  protected int doPrepare(long positionUs) {
-    try {
+    boolean sourcePrepared = source.prepare(positionUs);
-      boolean sourcePrepared = source.prepare(positionUs);
+    if (!sourcePrepared) {
-      if (!sourcePrepared) {
+      return TrackRenderer.STATE_UNPREPARED;
-        return TrackRenderer.STATE_UNPREPARED;
-      }
-    } catch (IOException e) {
-      throw new ExoPlaybackException(e);
     }
-    for (int i = 0; i < source.getTrackCount(); i++) {
+    int trackCount = source.getTrackCount();
+    for (int i = 0; i < trackCount; i++) {
       if (eia608Parser.canParse(source.getTrackInfo(i).mimeType)) {
         trackIndex = i;
         return TrackRenderer.STATE_PREPARED;
@@ -133,13 +130,7 @@ public class Eia608TrackRenderer extends TrackRenderer implements Callback {
 
   @Override
   protected void doSomeWork(long positionUs, long elapsedRealtimeUs) throws ExoPlaybackException {
-    try {
+    source.continueBuffering(trackIndex, positionUs);
-      source.continueBuffering(trackIndex, positionUs);
-    } catch (IOException e) {
-      // TODO: This should be propagated, but in the current design propagation may occur too
-      // early. See [Internal b/22291244].
-      // throw new ExoPlaybackException(e);
-    }
 
     if (isSamplePending()) {
       maybeParsePendingSample(positionUs);
@@ -147,17 +138,11 @@ public class Eia608TrackRenderer extends TrackRenderer implements Callback {
 
     int result = inputStreamEnded ? SampleSource.END_OF_STREAM : SampleSource.SAMPLE_READ;
     while (!isSamplePending() && result == SampleSource.SAMPLE_READ) {
-      try {
+      result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
-        result = source.readData(trackIndex, positionUs, formatHolder, sampleHolder, false);
+      if (result == SampleSource.SAMPLE_READ) {
-        if (result == SampleSource.SAMPLE_READ) {
+        maybeParsePendingSample(positionUs);
-          maybeParsePendingSample(positionUs);
+      } else if (result == SampleSource.END_OF_STREAM) {
-        } else if (result == SampleSource.END_OF_STREAM) {
+        inputStreamEnded = true;
-          inputStreamEnded = true;
-        }
-      } catch (IOException e) {
-        // TODO: This should be propagated, but in the current design propagation may occur too
-        // early. See [Internal b/22291244].
-        // throw new ExoPlaybackException(e);
       }
     }
 
@@ -181,6 +166,15 @@ public class Eia608TrackRenderer extends TrackRenderer implements Callback {
     source.disable(trackIndex);
   }
 
+  @Override
+  protected void maybeThrowError() throws ExoPlaybackException {
+    try {
+      source.maybeThrowError();
+    } catch (IOException e) {
+      throw new ExoPlaybackException(e);
+    }
+  }
+
   @Override
   protected long getDurationUs() {
     return source.getTrackInfo(trackIndex).durationUs;

library/src/main/java/com/google/android/exoplayer/util/ManifestFetcher.java

@@ -186,17 +186,17 @@ public class ManifestFetcher<T> implements Loader.Callback {
   }
 
   /**
-   * Gets the error that affected the most recent attempt to load the manifest, or null if the
+   * Throws the error that affected the most recent attempt to load the manifest. Does nothing if
-   * most recent attempt was successful.
+   * the most recent attempt was successful.
    *
-   * @return The error, or null if the most recent attempt was successful.
+   * @throws IOException The error that affected the most recent attempt to load the manifest.
    */
-  public IOException getError() {
+  public void maybeThrowError() throws IOException {
-    if (loadExceptionCount <= 1) {
+    // Don't throw an exception until at least 1 retry attempt has been made.
-      // Don't report an exception until at least 1 retry attempt has been made.
+    if (loadException == null || loadExceptionCount <= 1) {
-      return null;
+      return;
     }
-    return loadException;
+    throw loadException;
   }
 
   /**