Fix delivery of onLoadCanceled to occur before thread dies.

This removes "message sent on dead thread" warnings in nearly
all cases, and guarantees delivery of load cancelation to event
listeners.

Issue: #426
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=123957691

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

@@ -166,7 +166,6 @@ public final class SingleSampleSource implements SampleSource, TrackStream,
 
 
   @Override
   @Override
   public void release() {
   public void release() {
-    streamState = STREAM_STATE_END_OF_STREAM;
     loader.release();
     loader.release();
   }
   }
 
 
@@ -221,8 +220,10 @@ public final class SingleSampleSource implements SampleSource, TrackStream,
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(SingleSampleSource loadable, long elapsedMs) {
-    maybeStartLoading();
+  public void onLoadCanceled(SingleSampleSource loadable, long elapsedMs, boolean released) {
+    if (!released) {
+      maybeStartLoading();
+    }
   }
   }
 
 
   @Override
   @Override

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

@@ -59,7 +59,6 @@ public class ChunkTrackStream<T extends ChunkSource> implements TrackStream,
   private long pendingResetPositionUs;
   private long pendingResetPositionUs;
 
 
   private boolean loadingFinished;
   private boolean loadingFinished;
-  private boolean released;
 
 
   /**
   /**
    * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
    * @param chunkSource A {@link ChunkSource} from which chunks to load are obtained.
@@ -233,7 +232,7 @@ public class ChunkTrackStream<T extends ChunkSource> implements TrackStream,
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(Chunk loadable, long elapsedMs) {
+  public void onLoadCanceled(Chunk loadable, long elapsedMs, boolean released) {
     eventDispatcher.loadCanceled(loadable.bytesLoaded());
     eventDispatcher.loadCanceled(loadable.bytesLoaded());
     if (!released) {
     if (!released) {
       restartFrom(pendingResetPositionUs);
       restartFrom(pendingResetPositionUs);

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

@@ -360,7 +360,8 @@ public final class DashSampleSource implements SampleSource {
     }
     }
 
 
     @Override
     @Override
-    public void onLoadCanceled(UriLoadable<MediaPresentationDescription> loadable, long elapsedMs) {
+    public void onLoadCanceled(UriLoadable<MediaPresentationDescription> loadable, long elapsedMs,
+        boolean released) {
       // Do nothing.
       // Do nothing.
     }
     }
 
 
@@ -380,7 +381,7 @@ public final class DashSampleSource implements SampleSource {
     }
     }
 
 
     @Override
     @Override
-    public void onLoadCanceled(UriLoadable<Long> loadable, long elapsedMs) {
+    public void onLoadCanceled(UriLoadable<Long> loadable, long elapsedMs, boolean released) {
       // Do nothing.
       // Do nothing.
     }
     }
 
 

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

@@ -479,7 +479,6 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
     for (DefaultTrackOutput sampleQueue : sampleQueues) {
     for (DefaultTrackOutput sampleQueue : sampleQueues) {
       sampleQueue.disable();
       sampleQueue.disable();
     }
     }
-    enabledTrackCount = 0;
     loader.release();
     loader.release();
   }
   }
 
 
@@ -510,9 +509,9 @@ public final class ExtractorSampleSource implements SampleSource, ExtractorOutpu
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(ExtractingLoadable loadable, long elapsedMs) {
+  public void onLoadCanceled(ExtractingLoadable loadable, long elapsedMs, boolean released) {
     copyLengthFromLoader(loadable);
     copyLengthFromLoader(loadable);
-    if (enabledTrackCount > 0) {
+    if (!released && enabledTrackCount > 0) {
       restartFrom(pendingResetPositionUs);
       restartFrom(pendingResetPositionUs);
     }
     }
   }
   }

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

@@ -249,7 +249,7 @@ public final class HlsSampleSource implements SampleSource,
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(UriLoadable<HlsPlaylist> loadable, long elapsedMs) {
+  public void onLoadCanceled(UriLoadable<HlsPlaylist> loadable, long elapsedMs, boolean released) {
     // Do nothing.
     // Do nothing.
   }
   }
 
 

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

@@ -276,7 +276,6 @@ import java.util.List;
       sampleQueues.valueAt(i).disable();
       sampleQueues.valueAt(i).disable();
     }
     }
     if (enabledTrackCount > 0) {
     if (enabledTrackCount > 0) {
-      enabledTrackCount = 0;
       loadControl.unregister(this);
       loadControl.unregister(this);
     }
     }
     loader.release();
     loader.release();
@@ -331,9 +330,9 @@ import java.util.List;
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(Chunk loadable, long elapsedMs) {
+  public void onLoadCanceled(Chunk loadable, long elapsedMs, boolean released) {
     eventDispatcher.loadCanceled(loadable.bytesLoaded());
     eventDispatcher.loadCanceled(loadable.bytesLoaded());
-    if (enabledTrackCount > 0) {
+    if (!released && enabledTrackCount > 0) {
       restartFrom(pendingResetPositionUs);
       restartFrom(pendingResetPositionUs);
     }
     }
   }
   }

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

@@ -237,7 +237,8 @@ public final class SmoothStreamingSampleSource implements SampleSource,
   }
   }
 
 
   @Override
   @Override
-  public void onLoadCanceled(UriLoadable<SmoothStreamingManifest> loadable, long elapsedMs) {
+  public void onLoadCanceled(UriLoadable<SmoothStreamingManifest> loadable, long elapsedMs,
+      boolean released) {
     // Do nothing.
     // Do nothing.
   }
   }
 
 

library/src/main/java/com/google/android/exoplayer/upstream/Loader.java

@@ -79,14 +79,24 @@ public final class Loader {
 
 
     /**
     /**
      * Invoked when a load has been canceled.
      * Invoked when a load has been canceled.
+     * <p>
+     * If the {@link Loader} has not been released then there is guaranteed to exist a memory
+     * barrier between {@link Loadable#load()} exiting and this callback being invoked. If the
+     * {@link Loader} has been released then this callback may be invoked before
+     * {@link Loadable#load()} exits.
      *
      *
      * @param loadable The loadable whose load has been canceled.
      * @param loadable The loadable whose load has been canceled.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
+     * @param released True if the load was canceled because the {@link Loader} was released. False
+     *     otherwise.
      */
      */
-    void onLoadCanceled(T loadable, long elapsedMs);
+    void onLoadCanceled(T loadable, long elapsedMs, boolean released);
 
 
     /**
     /**
      * Invoked when a load has completed.
      * Invoked when a load has completed.
+     * <p>
+     * There is guaranteed to exist a memory barrier between {@link Loadable#load()} exiting and
+     * this callback being invoked.
      *
      *
      * @param loadable The loadable whose load has completed.
      * @param loadable The loadable whose load has completed.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
@@ -95,6 +105,9 @@ public final class Loader {
 
 
     /**
     /**
      * Invoked when a load encounters an error.
      * Invoked when a load encounters an error.
+     * <p>
+     * There is guaranteed to exist a memory barrier between {@link Loadable#load()} exiting and
+     * this callback being invoked.
      *
      *
      * @param loadable The loadable whose load has encountered an error.
      * @param loadable The loadable whose load has encountered an error.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
      * @param elapsedMs The elapsed time in milliseconds since loading started.
@@ -179,7 +192,7 @@ public final class Loader {
    * This method should only be called when a load is in progress.
    * This method should only be called when a load is in progress.
    */
    */
   public void cancelLoading() {
   public void cancelLoading() {
-    currentTask.cancel();
+    currentTask.cancel(false);
   }
   }
 
 
   /**
   /**
@@ -189,7 +202,7 @@ public final class Loader {
    */
    */
   public void release() {
   public void release() {
     if (currentTask != null) {
     if (currentTask != null) {
-      cancelLoading();
+      currentTask.cancel(true);
     }
     }
     downloadExecutorService.shutdown();
     downloadExecutorService.shutdown();
   }
   }
@@ -208,6 +221,7 @@ public final class Loader {
     private int errorCount;
     private int errorCount;
 
 
     private volatile Thread executorThread;
     private volatile Thread executorThread;
+    private volatile boolean released;
 
 
     public LoadTask(Looper looper, T loadable, Loader.Callback<T> callback, int minRetryCount) {
     public LoadTask(Looper looper, T loadable, Loader.Callback<T> callback, int minRetryCount) {
       super(looper);
       super(looper);
@@ -233,17 +247,24 @@ public final class Loader {
       }
       }
     }
     }
 
 
-    public void cancel() {
+    public void cancel(boolean released) {
+      this.released = released;
       currentError = null;
       currentError = null;
       if (hasMessages(MSG_START)) {
       if (hasMessages(MSG_START)) {
         removeMessages(MSG_START);
         removeMessages(MSG_START);
-        sendEmptyMessage(MSG_CANCEL);
+        if (!released) {
+          sendEmptyMessage(MSG_CANCEL);
+        }
       } else {
       } else {
         loadable.cancelLoad();
         loadable.cancelLoad();
         if (executorThread != null) {
         if (executorThread != null) {
           executorThread.interrupt();
           executorThread.interrupt();
         }
         }
       }
       }
+      if (released) {
+        finish();
+        callback.onLoadCanceled(loadable, SystemClock.elapsedRealtime() - startTimeMs, true);
+      }
     }
     }
 
 
     @Override
     @Override
@@ -258,29 +279,42 @@ public final class Loader {
             TraceUtil.endSection();
             TraceUtil.endSection();
           }
           }
         }
         }
-        sendEmptyMessage(MSG_END_OF_SOURCE);
+        if (!released) {
+          sendEmptyMessage(MSG_END_OF_SOURCE);
+        }
       } catch (IOException e) {
       } catch (IOException e) {
-        obtainMessage(MSG_IO_EXCEPTION, e).sendToTarget();
+        if (!released) {
+          obtainMessage(MSG_IO_EXCEPTION, e).sendToTarget();
+        }
       } catch (InterruptedException e) {
       } catch (InterruptedException e) {
         // The load was canceled.
         // The load was canceled.
         Assertions.checkState(loadable.isLoadCanceled());
         Assertions.checkState(loadable.isLoadCanceled());
-        sendEmptyMessage(MSG_END_OF_SOURCE);
+        if (!released) {
+          sendEmptyMessage(MSG_END_OF_SOURCE);
+        }
       } catch (Exception e) {
       } catch (Exception e) {
         // This should never happen, but handle it anyway.
         // This should never happen, but handle it anyway.
         Log.e(TAG, "Unexpected exception loading stream", e);
         Log.e(TAG, "Unexpected exception loading stream", e);
-        obtainMessage(MSG_IO_EXCEPTION, new UnexpectedLoaderException(e)).sendToTarget();
+        if (!released) {
+          obtainMessage(MSG_IO_EXCEPTION, new UnexpectedLoaderException(e)).sendToTarget();
+        }
       } catch (Error e) {
       } catch (Error e) {
         // We'd hope that the platform would kill the process if an Error is thrown here, but the
         // We'd hope that the platform would kill the process if an Error is thrown here, but the
         // executor may catch the error (b/20616433). Throw it here, but also pass and throw it from
         // executor may catch the error (b/20616433). Throw it here, but also pass and throw it from
         // the handler thread so that the process dies even if the executor behaves in this way.
         // the handler thread so that the process dies even if the executor behaves in this way.
         Log.e(TAG, "Unexpected error loading stream", e);
         Log.e(TAG, "Unexpected error loading stream", e);
-        obtainMessage(MSG_FATAL_ERROR, e).sendToTarget();
+        if (!released) {
+          obtainMessage(MSG_FATAL_ERROR, e).sendToTarget();
+        }
         throw e;
         throw e;
       }
       }
     }
     }
 
 
     @Override
     @Override
     public void handleMessage(Message msg) {
     public void handleMessage(Message msg) {
+      if (released) {
+        return;
+      }
       if (msg.what == MSG_START) {
       if (msg.what == MSG_START) {
         submitToExecutor();
         submitToExecutor();
         return;
         return;
@@ -291,12 +325,12 @@ public final class Loader {
       finish();
       finish();
       long elapsedMs = SystemClock.elapsedRealtime() - startTimeMs;
       long elapsedMs = SystemClock.elapsedRealtime() - startTimeMs;
       if (loadable.isLoadCanceled()) {
       if (loadable.isLoadCanceled()) {
-        callback.onLoadCanceled(loadable, elapsedMs);
+        callback.onLoadCanceled(loadable, elapsedMs, false);
         return;
         return;
       }
       }
       switch (msg.what) {
       switch (msg.what) {
         case MSG_CANCEL:
         case MSG_CANCEL:
-          callback.onLoadCanceled(loadable, elapsedMs);
+          callback.onLoadCanceled(loadable, elapsedMs, false);
           break;
           break;
         case MSG_END_OF_SOURCE:
         case MSG_END_OF_SOURCE:
           callback.onLoadCompleted(loadable, elapsedMs);
           callback.onLoadCompleted(loadable, elapsedMs);