Initialise RuntimeScheduler before bundle is executed

Summary:
Changelog: [internal]

RuntimeScheduler can be accessed before any Fabric surface is rendered. Therefore, it needs to be created and installed in the runtime at the start up of the runtime.

Reviewed By: JoshuaGross

Differential Revision: D29091848

fbshipit-source-id: ff75ef8c4882550795e5d4a258355b651cb0e637

React/Fabric/RCTSurfacePresenter.mm

@@ -282,14 +282,16 @@ - (RCTScheduler *)_createScheduler
   toolbox.contextContainer = _contextContainer;
   toolbox.componentRegistryFactory = componentRegistryFactory;
 
-  if (reactNativeConfig && reactNativeConfig->getBool("react_fabric:enable_runtimescheduler_ios")) {
-    auto runtimeScheduler = std::make_shared<RuntimeScheduler>(_runtimeExecutor);
-    runtimeScheduler->setEnableYielding(
-        reactNativeConfig->getBool("react_native_new_architecture:runtimescheduler_enable_yielding_ios"));
-    toolbox.runtimeScheduler = runtimeScheduler;
-    runtimeExecutor = [runtimeScheduler](std::function<void(jsi::Runtime & runtime)> &&callback) {
-      runtimeScheduler->scheduleWork(std::move(callback));
-    };
+  auto runtimeScheduler = _contextContainer->find<std::weak_ptr<RuntimeScheduler>>("RuntimeScheduler");
+  if (runtimeScheduler.hasValue()) {
+    auto lockedRuntimeScheduler = runtimeScheduler.value().lock();
+    if (lockedRuntimeScheduler) {
+      lockedRuntimeScheduler->setEnableYielding(
+          reactNativeConfig->getBool("react_native_new_architecture:runtimescheduler_enable_yielding_ios"));
+      runtimeExecutor = [lockedRuntimeScheduler](std::function<void(jsi::Runtime & runtime)> &&callback) {
+        lockedRuntimeScheduler->scheduleWork(std::move(callback));
+      };
+    }
   }
 
   toolbox.runtimeExecutor = runtimeExecutor;

React/Fabric/RCTSurfacePresenterBridgeAdapter.h

@@ -6,15 +6,17 @@
  */
 
 #import <Foundation/Foundation.h>
+#import <ReactCommon/RuntimeExecutor.h>
 #import <UIKit/UIKit.h>
-
 #import <react/utils/ContextContainer.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 @class RCTSurfacePresenter;
 @class RCTBridge;
 
+facebook::react::RuntimeExecutor RCTRuntimeExecutorFromBridge(RCTBridge *bridge);
+
 /*
  * Controls a life-cycle of a Surface Presenter based on Bridge's life-cycle.
  * We are moving away from using Bridge.

React/Fabric/RCTSurfacePresenterBridgeAdapter.mm

@@ -41,7 +41,7 @@ - (void)invokeAsync:(std::function<void()> &&)func;
   return contextContainer;
 }
 
-static RuntimeExecutor RCTRuntimeExecutorFromBridge(RCTBridge *bridge)
+RuntimeExecutor RCTRuntimeExecutorFromBridge(RCTBridge *bridge)
 {
   RCTAssert(bridge, @"RCTRuntimeExecutorFromBridge: Bridge must not be nil.");