From 9c827f6201cd403081401b6fbc430df095586977 Mon Sep 17 00:00:00 2001
From: David Vacca <dvacca@fb.com>
Date: Tue, 8 Dec 2020 22:01:00 -0800
Subject: [PATCH] Prevent initialization of constants for view managers for
 users with static view config enabled

Summary:
This diff prevents the pre-calculation of ViewManager's constants for users with static view config enabled.
We still load viewManager classes and create viewManger objects for perf reasons

Changelog: [Internal]

Reviewed By: fkgozali

Differential Revision: D25414068

fbshipit-source-id: a91f6113e35b42625c03d13bd67b63e3f9f75098
---
 .../facebook/react/config/ReactFeatureFlags.java |  3 +++
 .../react/uimanager/UIManagerModule.java         | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

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 c6de0646a2b..387b9bd44c0 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/config/ReactFeatureFlags.java
@@ -100,4 +100,7 @@ public class ReactFeatureFlags {
 
   /** Enables the usage of an experimental optimized iterator for ReadableNativeMaps. */
   public static boolean enableExperimentalReadableNativeMapIterator = false;
+
+  /** Enables Static ViewConfig in RN Android native code. */
+  public static boolean enableExperimentalStaticViewConfigs = false;
 }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java
index 2f2e8257578..9d982ee29d5 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/uimanager/UIManagerModule.java
@@ -39,6 +39,7 @@ import com.facebook.react.bridge.UiThreadUtil;
 import com.facebook.react.bridge.WritableMap;
 import com.facebook.react.common.MapBuilder;
 import com.facebook.react.common.ReactConstants;
+import com.facebook.react.config.ReactFeatureFlags;
 import com.facebook.react.module.annotations.ReactModule;
 import com.facebook.react.uimanager.common.ViewUtil;
 import com.facebook.react.uimanager.debug.NotThreadSafeViewHierarchyUpdateDebugListener;
@@ -297,6 +298,15 @@ public class UIManagerModule extends ReactContextBaseJavaModule
    */
   @Deprecated
   public void preComputeConstantsForViewManager(List<String> viewManagerNames) {
+    // TODO T81145457 - Implement pre-initialization of ViewManagers in Fabric Android
+    if (ReactFeatureFlags.enableExperimentalStaticViewConfigs) {
+      preInitializeViewManagers(viewManagerNames);
+      // When Static view configs are enabled it is not necessary to pre-compute the constants for
+      // viewManagers, although the pre-initialization of viewManager objects is still necessary
+      // for performance reasons.
+      return;
+    }
+
     Map<String, WritableMap> constantsMap = new ArrayMap<>();
     for (String viewManagerName : viewManagerNames) {
       WritableMap constants = computeConstantsForViewManager(viewManagerName);
@@ -315,6 +325,12 @@ public class UIManagerModule extends ReactContextBaseJavaModule
     mViewManagerConstantsCache = Collections.unmodifiableMap(constantsMap);
   }
 
+  private void preInitializeViewManagers(List<String> viewManagerNames) {
+    for (String viewManagerName : viewManagerNames) {
+      mUIImplementation.resolveViewManager(viewManagerName);
+    }
+  }
+
   @ReactMethod(isBlockingSynchronousMethod = true)
   public @Nullable WritableMap getConstantsForViewManager(@Nullable String viewManagerName) {
     if (mViewManagerConstantsCache != null