From ab0cbeffdff9ad25151646cbe9ffef6f27efd7c6 Mon Sep 17 00:00:00 2001
From: Pascal Muetschard <pmuetschard@google.com>
Date: Wed, 17 Aug 2022 17:40:30 +0200
Subject: [PATCH] DCL is broken and should not be used.

Use the acceptable instance holder pattern as a replacement.

Change-Id: I0164b8c17db4e6e15aee5a862fa8e625a9b1bbf4
---
 config/preloaded-classes-denylist                 |  1 +
 .../internal/jank/InteractionJankMonitor.java     | 15 +++++----------
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/config/preloaded-classes-denylist b/config/preloaded-classes-denylist
index 02f2df6167a57..502d8c6dadb12 100644
--- a/config/preloaded-classes-denylist
+++ b/config/preloaded-classes-denylist
@@ -9,3 +9,4 @@ android.net.rtp.AudioGroup
 android.net.rtp.AudioStream
 android.net.rtp.RtpStream
 java.util.concurrent.ThreadLocalRandom
+com.android.internal.jank.InteractionJankMonitor$InstanceHolder
diff --git a/core/java/com/android/internal/jank/InteractionJankMonitor.java b/core/java/com/android/internal/jank/InteractionJankMonitor.java
index 72de78c148f8c..d066945cb92d4 100644
--- a/core/java/com/android/internal/jank/InteractionJankMonitor.java
+++ b/core/java/com/android/internal/jank/InteractionJankMonitor.java
@@ -292,7 +292,10 @@ public class InteractionJankMonitor {
             UIINTERACTION_FRAME_INFO_REPORTED__INTERACTION_TYPE__SHADE_CLEAR_ALL,
     };
 
-    private static volatile InteractionJankMonitor sInstance;
+    private static class InstanceHolder {
+        public static final InteractionJankMonitor INSTANCE =
+            new InteractionJankMonitor(new HandlerThread(DEFAULT_WORKER_NAME));
+    }
 
     private final DeviceConfig.OnPropertiesChangedListener mPropertiesChangedListener =
             this::updateProperties;
@@ -384,15 +387,7 @@ public class InteractionJankMonitor {
      * @return instance of InteractionJankMonitor
      */
     public static InteractionJankMonitor getInstance() {
-        // Use DCL here since this method might be invoked very often.
-        if (sInstance == null) {
-            synchronized (InteractionJankMonitor.class) {
-                if (sInstance == null) {
-                    sInstance = new InteractionJankMonitor(new HandlerThread(DEFAULT_WORKER_NAME));
-                }
-            }
-        }
-        return sInstance;
+        return InstanceHolder.INSTANCE;
     }
 
     /**