Add feature flag to use microtasks in the React Native Fabric renderer

Author: rubennorte

packages/react-native-renderer/src/ReactFiberConfigFabric.js

@@ -47,6 +47,8 @@ const {
   unstable_getCurrentEventPriority: fabricGetCurrentEventPriority,
 } = nativeFabricUIManager;
 
+import {useMicrotasksForSchedulingInFabric} from 'shared/ReactFeatureFlags';
+
 const {get: getViewConfigForType} = ReactNativeViewConfigRegistry;
 
 // Counter for uniquely identifying views.
@@ -119,7 +121,6 @@ export * from 'react-reconciler/src/ReactFiberConfigWithNoMutation';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoHydration';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoScopes';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoTestSelectors';
-export * from 'react-reconciler/src/ReactFiberConfigWithNoMicrotasks';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoResources';
 export * from 'react-reconciler/src/ReactFiberConfigWithNoSingletons';
 
@@ -470,3 +471,10 @@ export function waitForCommitToBeReady(): null {
 }
 
 export const NotPendingTransition: TransitionStatus = null;
+
+// -------------------
+//     Microtasks
+// -------------------
+export const supportsMicrotasks = useMicrotasksForSchedulingInFabric;
+export const scheduleMicrotask: any =
+  typeof queueMicrotask === 'function' ? queueMicrotask : scheduleTimeout;

packages/shared/ReactFeatureFlags.js

@@ -122,6 +122,8 @@ export const enableAsyncActions = __EXPERIMENTAL__;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // -----------------------------------------------------------------------------
 // Chopping Block
 //

packages/shared/forks/ReactFeatureFlags.native-fb-dynamic.js

@@ -23,6 +23,7 @@ import typeof * as DynamicFlagsType from 'ReactNativeInternalFeatureFlags';
 export const enableUseRefAccessWarning = __VARIANT__;
 export const enableDeferRootSchedulingToMicrotask = __VARIANT__;
 export const alwaysThrottleRetries = __VARIANT__;
+export const useMicrotasksForSchedulingInFabric = __VARIANT__;
 
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): DynamicFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.native-fb.js

@@ -21,6 +21,7 @@ export const {
   enableUseRefAccessWarning,
   enableDeferRootSchedulingToMicrotask,
   alwaysThrottleRetries,
+  useMicrotasksForSchedulingInFabric,
 } = dynamicFlags;
 
 // The rest of the flags are static for better dead code elimination.

packages/shared/forks/ReactFeatureFlags.native-oss.js

@@ -77,5 +77,7 @@ export const enableAsyncActions = false;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.test-renderer.js

@@ -77,5 +77,7 @@ export const enableAsyncActions = false;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.test-renderer.native.js

@@ -74,5 +74,7 @@ export const enableAsyncActions = false;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.test-renderer.www.js

@@ -77,5 +77,7 @@ export const enableAsyncActions = false;
 
 export const alwaysThrottleRetries = true;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

packages/shared/forks/ReactFeatureFlags.www.js

@@ -108,5 +108,7 @@ export const enableFizzExternalRuntime = true;
 
 export const forceConcurrentByDefaultForTesting = false;
 
+export const useMicrotasksForSchedulingInFabric = false;
+
 // Flow magic to verify the exports of this file match the original version.
 ((((null: any): ExportsType): FeatureFlagsType): ExportsType);

scripts/flow/xplat.js

@@ -11,4 +11,5 @@ declare module 'ReactNativeInternalFeatureFlags' {
   declare export var enableUseRefAccessWarning: boolean;
   declare export var enableDeferRootSchedulingToMicrotask: boolean;
   declare export var alwaysThrottleRetries: boolean;
+  declare export var useMicrotasksForSchedulingInFabric: boolean;
 }