From 40adcbac87fac9c5ca4cee8e29d9290ac75ca8bf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@fb.com>
Date: Mon, 23 Oct 2023 05:55:11 -0700
Subject: [PATCH] Wire up configuration to use microtasks in RuntimeScheduler,
 Hermes and React (#41090)

Summary:

This propagates to enable the use of microtasks in the React reconciler, Runtime Scheduler and Hermes.

Changelog: [internal]

Reviewed By: sammy-SC

Differential Revision: D50177355
---
 .../react/renderer/scheduler/Scheduler.cpp           |  8 ++++++++
 .../react/runtime/hermes/HermesInstance.cpp          | 12 ++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.cpp b/packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.cpp
index b52841fb8ea322..df3c9ada438899 100644
--- a/packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/scheduler/Scheduler.cpp
@@ -139,6 +139,14 @@ Scheduler::Scheduler(
   reduceDeleteCreateMutationLayoutAnimation_ = true;
 #endif
 
+#ifdef ANDROID
+  CoreFeatures::enableMicrotasks =
+      reactNativeConfig_->getBool("react_fabric:enable_microtasks_android");
+#else
+  CoreFeatures::enableMicrotasks =
+      reactNativeConfig_->getBool("react_fabric:enable_microtasks_ios");
+#endif
+
   CoreFeatures::blockPaintForUseLayoutEffect = reactNativeConfig_->getBool(
       "react_fabric:block_paint_for_use_layout_effect");
 
diff --git a/packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp b/packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp
index 55efa0eb6b5bc6..d682224485af81 100644
--- a/packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp
+++ b/packages/react-native/ReactCommon/react/runtime/hermes/HermesInstance.cpp
@@ -105,6 +105,17 @@ std::unique_ptr<jsi::Runtime> HermesInstance::createJSRuntime(
   auto heapSizeMB = heapSizeConfig > 0
       ? static_cast<::hermes::vm::gcheapsize_t>(heapSizeConfig)
       : 3072;
+
+#ifdef ANDROID
+  bool enableMicrotasks = reactNativeConfig
+      ? reactNativeConfig->getBool("react_fabric:enable_microtasks_android")
+      : false;
+#else
+  bool enableMicrotasks = reactNativeConfig
+      ? reactNativeConfig->getBool("react_fabric:enable_microtasks_ios")
+      : false;
+#endif
+
   ::hermes::vm::RuntimeConfig::Builder runtimeConfigBuilder =
       ::hermes::vm::RuntimeConfig::Builder()
           .withGCConfig(::hermes::vm::GCConfig::Builder()
@@ -119,6 +130,7 @@ std::unique_ptr<jsi::Runtime> HermesInstance::createJSRuntime(
                             .build())
           .withES6Proxy(false)
           .withEnableSampleProfiling(true)
+          .withMicrotaskQueue(enableMicrotasks)
           .withVMExperimentFlags(vmExperimentFlags);
 
   if (cm) {