From b347c3949f40b33df300a31ab7f86df4d82a00b2 Mon Sep 17 00:00:00 2001
From: Andrei Shikov <ashikov@fb.com>
Date: Thu, 10 Mar 2022 04:30:37 -0800
Subject: [PATCH] Enabled blocking access for animated queues under feature
 flag

Summary:
Blocks on queue write/drain for Animated module under a feature flag to test whether it resolves race conditions.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D34752947

fbshipit-source-id: a1b1a286772d29a7a27b5e9c3f743cac84cc2bab
---
 .../java/com/facebook/react/animated/BUCK     |  1 +
 .../react/animated/NativeAnimatedModule.java  | 29 +++++++++++++++++--
 .../react/config/ReactFeatureFlags.java       |  3 ++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/animated/BUCK b/ReactAndroid/src/main/java/com/facebook/react/animated/BUCK
index 2a61c4707f6135..4bb711211fcc1f 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/animated/BUCK
+++ b/ReactAndroid/src/main/java/com/facebook/react/animated/BUCK
@@ -26,6 +26,7 @@ rn_android_library(
         react_native_target("java/com/facebook/react/common:common"),
         react_native_target("java/com/facebook/react/module/annotations:annotations"),
         react_native_target("java/com/facebook/react/modules/core:core"),
+        react_native_target("java/com/facebook/react/config:config"),
         react_native_target("java/com/facebook/react/uimanager:uimanager"),
         react_native_target("java/com/facebook/react/uimanager/annotations:annotations"),
         react_native_target("java/com/facebook/react/views/view:view"),
diff --git a/ReactAndroid/src/main/java/com/facebook/react/animated/NativeAnimatedModule.java b/ReactAndroid/src/main/java/com/facebook/react/animated/NativeAnimatedModule.java
index cc7064698a3e80..89cf5c36aab7aa 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/animated/NativeAnimatedModule.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/animated/NativeAnimatedModule.java
@@ -24,6 +24,7 @@
 import com.facebook.react.bridge.UIManagerListener;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.common.annotations.VisibleForTesting;
+import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.module.annotations.ReactModule;
 import com.facebook.react.modules.core.DeviceEventManagerModule;
 import com.facebook.react.modules.core.ReactChoreographer;
@@ -108,20 +109,40 @@ public long getBatchNumber() {
   private class ConcurrentOperationQueue {
     private final Queue<UIThreadOperation> mQueue = new ConcurrentLinkedQueue<>();
     @Nullable private UIThreadOperation mPeekedOperation = null;
+    private boolean mSynchronizedAccess = false;
 
     @AnyThread
     boolean isEmpty() {
       return mQueue.isEmpty();
     }
 
+    void setSynchronizedAccess(boolean isSynchronizedAccess) {
+      mSynchronizedAccess = isSynchronizedAccess;
+    }
+
     @AnyThread
     void add(UIThreadOperation operation) {
-      mQueue.add(operation);
+      if (mSynchronizedAccess) {
+        synchronized (this) {
+          mQueue.add(operation);
+        }
+      } else {
+        mQueue.add(operation);
+      }
     }
 
     @UiThread
     void executeBatch(long maxBatchNumber, NativeAnimatedNodesManager nodesManager) {
-      List<UIThreadOperation> operations = drainQueueIntoList(maxBatchNumber);
+
+      List<UIThreadOperation> operations;
+
+      if (mSynchronizedAccess) {
+        synchronized (this) {
+          operations = drainQueueIntoList(maxBatchNumber);
+        }
+      } else {
+        operations = drainQueueIntoList(maxBatchNumber);
+      }
       for (UIThreadOperation operation : operations) {
         operation.execute(nodesManager);
       }
@@ -210,6 +231,10 @@ protected void doFrameGuarded(final long frameTimeNanos) {
             }
           }
         };
+
+    // If shipping this flag, make sure to migrate to non-concurrent queue for efficiency
+    mOperations.setSynchronizedAccess(ReactFeatureFlags.enableSynchronizationForAnimated);
+    mPreOperations.setSynchronizedAccess(ReactFeatureFlags.enableSynchronizationForAnimated);
   }
 
   @Override
diff --git a/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java b/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
index 7ede3c7eb6038d..0010116c606221 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
@@ -71,6 +71,9 @@ public class ReactFeatureFlags {
   /** Feature flag to configure eager attachment of the root view/initialisation of the JS code */
   public static boolean enableEagerRootViewAttachment = false;
 
+  /** Feature flag to configure synchronized queue access for Animated module */
+  public static boolean enableSynchronizationForAnimated = false;
+
   private static boolean mapBufferSerializationEnabled = false;
 
   /** Enables or disables MapBuffer Serialization */