Release Extractors on the loader's thread.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=127294338

library/src/main/java/com/google/android/exoplayer2/source/ExtractorMediaSource.java

@@ -120,8 +120,8 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
   private final EventListener eventListener;
 
   private DataSource dataSource;
-  private ExtractorHolder extractorHolder;
   private Loader loader;
+  private ExtractorHolder extractorHolder;
   private ConditionVariable loadCondition;
 
   private Callback callback;
@@ -205,8 +205,8 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
     this.allocator = allocator;
 
     dataSource = dataSourceFactory.createDataSource(bandwidthMeter);
+    loader = new Loader("Loader:ExtractorMediaSource");
     extractorHolder = new ExtractorHolder(extractorsFactory.createExtractors(), this);
-    loader = new Loader("Loader:ExtractorMediaSource", extractorHolder);
     loadCondition = new ConditionVariable();
     pendingResetPositionUs = C.UNSET_TIME_US;
     sampleQueues = new DefaultTrackOutput[0];
@@ -347,11 +347,17 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
   @Override
   public void release() {
     dataSource = null;
-    extractorHolder = null;
     if (loader != null) {
-      loader.release(); // Releases extractorHolder via its own reference on the loader's thread.
+      final ExtractorHolder extractorHolder = this.extractorHolder;
+      loader.release(new Runnable() {
+        @Override
+        public void run() {
+          extractorHolder.release();
+        }
+      });
       loader = null;
     }
+    extractorHolder = null;
     loadCondition = null;
     callback = null;
     allocator = null;
@@ -693,7 +699,7 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
   /**
    * Stores a list of extractors and a selected extractor when the format has been detected.
    */
-  private static final class ExtractorHolder implements Loader.Releasable {
+  private static final class ExtractorHolder {
 
     private final Extractor[] extractors;
     private final ExtractorOutput extractorOutput;
@@ -744,7 +750,6 @@ public final class ExtractorMediaSource implements MediaPeriod, MediaSource,
       return extractor;
     }
 
-    @Override
     public void release() {
       if (extractor != null) {
         extractor.release();

library/src/main/java/com/google/android/exoplayer2/upstream/Loader.java

@@ -72,18 +72,6 @@ public final class Loader {
 
   }
 
-  /**
-   * An object that can be released on the loading thread when {@link Loader#release()} is called.
-   */
-  public interface Releasable {
-
-    /**
-     * Releases any resources associated with the instance.
-     */
-    void release();
-
-  }
-
   /**
    * A callback to be notified of {@link Loader} events.
    */
@@ -147,7 +135,6 @@ public final class Loader {
   private static final int MSG_FATAL_ERROR = 4;
 
   private final ExecutorService downloadExecutorService;
-  private final Releasable releasable;
 
   private LoadTask<? extends Loadable> currentTask;
   private IOException fatalError;
@@ -156,17 +143,7 @@ public final class Loader {
    * @param threadName A name for the loader's thread.
    */
   public Loader(String threadName) {
-    this(threadName, null);
-  }
-
-  /**
-   * @param threadName A name for the loader's thread.
-   * @param releasable An object to release on the loader's thread when {@link Loader#release()} is
-   *     called.
-   */
-  public Loader(String threadName, Releasable releasable) {
     this.downloadExecutorService = Util.newSingleThreadExecutor(threadName);
-    this.releasable = releasable;
   }
 
   /**
@@ -243,16 +220,23 @@ public final class Loader {
    * This method should be called when the {@link Loader} is no longer required.
    */
   public void release() {
+    release(null);
+  }
+
+  /**
+   * Releases the {@link Loader}, running {@code postLoadAction} on its thread.
+   * <p>
+   * This method should be called when the {@link Loader} is no longer required.
+   *
+   * @param postLoadAction A {@link Runnable} to run on the loader's thread when
+   *     {@link Loadable#load()} is no longer running.
+   */
+  public void release(Runnable postLoadAction) {
     if (currentTask != null) {
       currentTask.cancel(true);
     }
-    if (releasable != null) {
+    if (postLoadAction != null) {
-      downloadExecutorService.submit(new Runnable() {
+      downloadExecutorService.submit(postLoadAction);
-        @Override
-        public void run() {
-          releasable.release();
-        }
-      });
     }
     downloadExecutorService.shutdown();
   }