From 737fdd8693a4dbe56f629e40e4eddfa5c016bbc7 Mon Sep 17 00:00:00 2001
From: tianyifeng <tianyifeng@google.com>
Date: Fri, 15 Nov 2024 08:20:00 -0800
Subject: [PATCH] Deflake the DefaultPreloadManagerTest

From [ the last change in `DefaultPreloadManagerTest`](https://github.com/androidx/media/commit/2b54b1ebbeb6f13abb6944b7ff593c168c927192), the preloadManager began to use a separate `preloadThread` in `release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased`, which unveils a bug in `PreloadMediaSource`. When `PreloadMediaSource.releasePreloadMediaSource` is called, `preloadHandler` will post a `Runnable` on the preload looper to release the internal resources. Before this `Runnable` is executed, it is possible that the [`stopPreloading`](https://github.com/androidx/media/blob/main/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java#L442) method is executed just as the result of preloading has completed. This is expected to remove the posted `Runnable`s for further preloading, however, the posted `Runnable` for releasing will also be removed from the message queue.

Ideally we should use `postDelayed(runnable, token, delayMillis)` to post the runnables so that the token will be useful to identify which messages to remove in `removeCallbacksAndMessages(token)`, but that `postDelayed` method is only available from API 28. So in this change we are using a separate handler for releasing, and then the call of `preloadHandler.removeCallbacksAndMessages` won't impact the runnable for releasing.

#cherrypick

PiperOrigin-RevId: 696894483
(cherry picked from commit 0143884cd7ac06b042532e328ea69c5ac7da2cb3)
---
 .../media3/exoplayer/source/preload/PreloadMediaSource.java  | 5 ++++-
 .../exoplayer/source/preload/DefaultPreloadManagerTest.java  | 3 +--
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java
index d2a313672e..fc3d3870ca 100644
--- a/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java
+++ b/libraries/exoplayer/src/main/java/androidx/media3/exoplayer/source/preload/PreloadMediaSource.java
@@ -221,6 +221,7 @@ public final class PreloadMediaSource extends WrappingMediaSource {
   private final RendererCapabilities[] rendererCapabilities;
   private final Allocator allocator;
   private final Handler preloadHandler;
+  private final Handler releaseHandler;
   private boolean preloadCalled;
   private boolean prepareChildSourceCalled;
   private long startPositionUs;
@@ -246,6 +247,7 @@ public final class PreloadMediaSource extends WrappingMediaSource {
     this.allocator = allocator;
 
     preloadHandler = Util.createHandler(preloadLooper, /* callback= */ null);
+    releaseHandler = Util.createHandler(preloadLooper, /* callback= */ null);
     startPositionUs = C.TIME_UNSET;
   }
 
@@ -396,7 +398,7 @@ public final class PreloadMediaSource extends WrappingMediaSource {
    * <p>Can be called from any thread.
    */
   public void releasePreloadMediaSource() {
-    preloadHandler.post(
+    releaseHandler.post(
         () -> {
           preloadCalled = false;
           startPositionUs = C.TIME_UNSET;
@@ -407,6 +409,7 @@ public final class PreloadMediaSource extends WrappingMediaSource {
           }
           releaseSourceInternal();
           preloadHandler.removeCallbacksAndMessages(null);
+          releaseHandler.removeCallbacksAndMessages(null);
         });
   }
 
diff --git a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManagerTest.java b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManagerTest.java
index 2f351868ea..c4975c9eed 100644
--- a/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManagerTest.java
+++ b/libraries/exoplayer/src/test/java/androidx/media3/exoplayer/source/preload/DefaultPreloadManagerTest.java
@@ -830,8 +830,7 @@ public class DefaultPreloadManagerTest {
   }
 
   @Test
-  public void release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased()
-      throws Exception {
+  public void release_returnZeroCount_sourcesAndRendererCapabilitiesListReleased() {
     TargetPreloadStatusControl<Integer> targetPreloadStatusControl =
         rankingData -> new DefaultPreloadManager.Status(STAGE_SOURCE_PREPARED);
     MediaSource.Factory mockMediaSourceFactory = mock(MediaSource.Factory.class);