WatchableImpl: add lock when get the mObservers size.

Bug: none
Flag: EXEMPT minor optimization
Change-Id: If22e5f15bd97e2523252268824f977dc472e6b1f

1 files changed, 4 insertions, 1 deletions

diff --git a/services/core/java/com/android/server/utils/WatchableImpl.java b/services/core/java/com/android/server/utils/WatchableImpl.java
index 8a04ccf2dbc6..fec435154c83 100644
--- a/services/core/java/com/android/server/utils/WatchableImpl.java
+++ b/services/core/java/com/android/server/utils/WatchableImpl.java
@@ -33,6 +33,7 @@ public class WatchableImpl implements Watchable {
     /**
      * The list of observers.
      */
+    @GuardedBy("mObservers")
     protected final ArrayList<Watcher> mObservers = new ArrayList<>();
 
     /**
@@ -83,7 +84,9 @@ public class WatchableImpl implements Watchable {
      * @return The number of registered observers.
      */
     public int registeredObserverCount() {
-        return mObservers.size();
+        synchronized (mObservers) {
+            return mObservers.size();
+        }
     }
 
     /**