From e67007c928e52679e149ad0229059197369763c0 Mon Sep 17 00:00:00 2001
From: Joshua Gross <joshuagross@fb.com>
Date: Mon, 14 Jun 2021 19:29:54 -0700
Subject: [PATCH] Gate early EventEmitter update during PreAllocation behind
 feature flag

Summary:
This feature is still causing some number of crashes, though prod impact is not yet determined. For safety I'm adding a feature flag so we can disable this if necessary.

Changelog: [internal]

Reviewed By: kacieb

Differential Revision: D29117957

fbshipit-source-id: 3b19bac9dd00735f51f5c9cba606378b2a62975e
---
 .../java/com/facebook/react/fabric/jni/Binding.cpp    | 11 ++++++++---
 .../main/java/com/facebook/react/fabric/jni/Binding.h |  1 +
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
index d5fd9ca7fab..9b6215596cf 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
+++ b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.cpp
@@ -564,6 +564,9 @@ void Binding::installFabricUIManager(
   disableVirtualNodePreallocation_ = reactNativeConfig_->getBool(
       "react_fabric:disable_virtual_node_preallocation");
 
+  enableEarlyEventEmitterUpdate_ = reactNativeConfig_->getBool(
+      "react_fabric:enable_early_event_emitter_update");
+
   auto toolbox = SchedulerToolbox{};
   toolbox.contextContainer = contextContainer;
   toolbox.componentRegistryFactory = componentsRegistry->buildRegistryFunction;
@@ -1162,10 +1165,12 @@ void Binding::preallocateShadowView(
   }
 
   // Do not hold a reference to javaEventEmitter from the C++ side.
-  SharedEventEmitter eventEmitter = shadowView.eventEmitter;
   auto javaEventEmitter = EventEmitterWrapper::newObjectJavaArgs();
-  EventEmitterWrapper *cEventEmitter = cthis(javaEventEmitter);
-  cEventEmitter->eventEmitter = eventEmitter;
+  if (enableEarlyEventEmitterUpdate_) {
+    SharedEventEmitter eventEmitter = shadowView.eventEmitter;
+    EventEmitterWrapper *cEventEmitter = cthis(javaEventEmitter);
+    cEventEmitter->eventEmitter = eventEmitter;
+  }
 
   local_ref<ReadableMap::javaobject> props = castReadableMap(
       ReadableNativeMap::newObjectCxxArgs(shadowView.props->rawProps));
diff --git a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.h b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.h
index 79b38d9bb2e..033e57700a3 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.h
+++ b/ReactAndroid/src/main/java/com/facebook/react/fabric/jni/Binding.h
@@ -194,6 +194,7 @@ class Binding : public jni::HybridClass<Binding>,
   bool disablePreallocateViews_{false};
   bool disableVirtualNodePreallocation_{false};
   bool enableFabricLogs_{false};
+  bool enableEarlyEventEmitterUpdate_{false};
 };
 
 } // namespace react