From 87d1c3e6242f94fdbcb0359ff27ceb2a987f0281 Mon Sep 17 00:00:00 2001
From: kimvde <kimvde@google.com>
Date: Tue, 7 Mar 2023 18:48:31 +0000
Subject: [PATCH] Fix threading issueis in SequenceAssetLoaderListener

Callbacks onTrackCount and onTrackAdded can be called simultaneously
from different threads.

Before this fix, it was possible for the MuxerWrapper and
FallbackListener track count to never be set, or to be set
with incorrect values.

PiperOrigin-RevId: 514779719
---
 .../android/exoplayer2/transformer/TransformerInternal.java  | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
index b3e9411db7..43f9969a19 100644
--- a/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
+++ b/library/transformer/src/main/java/com/google/android/exoplayer2/transformer/TransformerInternal.java
@@ -440,8 +440,8 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
                 ERROR_CODE_FAILED_RUNTIME_CHECK));
         return;
       }
-      trackCountsToReport.decrementAndGet();
       tracksToAdd.addAndGet(trackCount);
+      trackCountsToReport.decrementAndGet();
     }
 
     @Override
@@ -465,12 +465,11 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
       } else {
         outputHasVideo.set(true);
       }
-      if (trackCountsToReport.get() == 0 && tracksToAdd.get() == 1) {
+      if (trackCountsToReport.get() == 0 && tracksToAdd.decrementAndGet() == 0) {
         int outputTrackCount = (outputHasAudio.get() ? 1 : 0) + (outputHasVideo.get() ? 1 : 0);
         muxerWrapper.setTrackCount(outputTrackCount);
         fallbackListener.setTrackCount(outputTrackCount);
       }
-      tracksToAdd.decrementAndGet();
 
       return trackInfo.shouldTranscode;
     }