RN: Feature Flag to Disable InteractionManager

Summary:
Creates a feature flag to evalute the impact of disabling `InteractionManager` and replacing its scheduling behavior with `setImmediate`.

Changelog:
[Internal]

Differential Revision: D65577455

packages/react-native/Libraries/Interaction/InteractionManager.js

@@ -10,6 +10,7 @@
 
 import type {Task} from './TaskQueue';
 
+import * as ReactNativeFeatureFlags from '../../src/private/featureflags/ReactNativeFeatureFlags';
 import EventEmitter from '../vendor/emitter/EventEmitter';
 
 const BatchedBridge = require('../BatchedBridge/BatchedBridge');
@@ -208,4 +209,8 @@ function _processUpdate() {
   _deleteInteractionSet.clear();
 }
 
-module.exports = InteractionManager;
+module.exports = (
+  ReactNativeFeatureFlags.disableInteractionManager()
+    ? require('./InteractionManagerStub')
+    : InteractionManager
+) as typeof InteractionManager;

packages/react-native/Libraries/Interaction/InteractionManagerStub.js

@@ -0,0 +1,176 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ */
+
+import type {EventSubscription} from '../vendor/emitter/EventEmitter';
+
+const invariant = require('invariant');
+
+export type Handle = number;
+
+type Task =
+  | {
+      name: string,
+      run: () => void,
+    }
+  | {
+      name: string,
+      gen: () => Promise<void>,
+    }
+  | (() => void);
+
+/**
+ * InteractionManager allows long-running work to be scheduled after any
+ * interactions/animations have completed. In particular, this allows JavaScript
+ * animations to run smoothly.
+ *
+ * Applications can schedule tasks to run after interactions with the following:
+ *
+ * ```
+ * InteractionManager.runAfterInteractions(() => {
+ *   // ...long-running synchronous task...
+ * });
+ * ```
+ *
+ * Compare this to other scheduling alternatives:
+ *
+ * - requestAnimationFrame(): for code that animates a view over time.
+ * - setImmediate/setTimeout(): run code later, note this may delay animations.
+ * - runAfterInteractions(): run code later, without delaying active animations.
+ *
+ * The touch handling system considers one or more active touches to be an
+ * 'interaction' and will delay `runAfterInteractions()` callbacks until all
+ * touches have ended or been cancelled.
+ *
+ * InteractionManager also allows applications to register animations by
+ * creating an interaction 'handle' on animation start, and clearing it upon
+ * completion:
+ *
+ * ```
+ * var handle = InteractionManager.createInteractionHandle();
+ * // run animation... (`runAfterInteractions` tasks are queued)
+ * // later, on animation completion:
+ * InteractionManager.clearInteractionHandle(handle);
+ * // queued tasks run if all handles were cleared
+ * ```
+ *
+ * `runAfterInteractions` takes either a plain callback function, or a
+ * `PromiseTask` object with a `gen` method that returns a `Promise`.  If a
+ * `PromiseTask` is supplied, then it is fully resolved (including asynchronous
+ * dependencies that also schedule more tasks via `runAfterInteractions`) before
+ * starting on the next task that might have been queued up synchronously
+ * earlier.
+ *
+ * By default, queued tasks are executed together in a loop in one
+ * `setImmediate` batch. If `setDeadline` is called with a positive number, then
+ * tasks will only be executed until the deadline (in terms of js event loop run
+ * time) approaches, at which point execution will yield via setTimeout,
+ * allowing events such as touches to start interactions and block queued tasks
+ * from executing, making apps more responsive.
+ *
+ * @deprecated
+ */
+const InteractionManagerStub = {
+  Events: {
+    interactionStart: 'interactionStart',
+    interactionComplete: 'interactionComplete',
+  },
+
+  /**
+   * Schedule a function to run after all interactions have completed. Returns a cancellable
+   * "promise".
+   *
+   * @deprecated
+   */
+  runAfterInteractions(task: ?Task): {
+    then: <U>(
+      onFulfill?: ?(void) => ?(Promise<U> | U),
+      onReject?: ?(error: mixed) => ?(Promise<U> | U),
+    ) => Promise<U>,
+    cancel: () => void,
+    ...
+  } {
+    let immediateID: ?$FlowIssue;
+    const promise = new Promise((resolve, reject) => {
+      immediateID = setImmediate(() => {
+        if (typeof task === 'object' && task !== null) {
+          if (typeof task.gen === 'function') {
+            task.gen().then(resolve, reject);
+          } else if (typeof task.run === 'function') {
+            try {
+              task.run();
+              resolve();
+            } catch (error) {
+              reject(error);
+            }
+          } else {
+            reject(new TypeError(`Task "${task.name}" missing gen or run.`));
+          }
+        } else if (typeof task === 'function') {
+          try {
+            task();
+            resolve();
+          } catch (error) {
+            reject(error);
+          }
+        } else {
+          reject(new TypeError('Invalid task of type: ' + typeof task));
+        }
+      });
+    });
+
+    return {
+      // $FlowFixMe[method-unbinding] added when improving typing for this parameters
+      then: promise.then.bind(promise),
+      cancel() {
+        clearImmediate(immediateID);
+      },
+    };
+  },
+
+  /**
+   * Notify manager that an interaction has started.
+   *
+   * @deprecated
+   */
+  createInteractionHandle(): Handle {
+    return -1;
+  },
+
+  /**
+   * Notify manager that an interaction has completed.
+   *
+   * @deprecated
+   */
+  clearInteractionHandle(handle: Handle) {
+    invariant(!!handle, 'InteractionManager: Must provide a handle to clear.');
+  },
+
+  /**
+   * @deprecated
+   */
+  addListener(): EventSubscription {
+    return {
+      remove() {},
+    };
+  },
+
+  /**
+   * A positive number will use setTimeout to schedule any tasks after the
+   * eventLoopRunningTime hits the deadline value, otherwise all tasks will be
+   * executed in one setImmediate batch (default).
+   *
+   * @deprecated
+   */
+  setDeadline(deadline: number) {
+    // Do nothing.
+  },
+};
+
+module.exports = InteractionManagerStub;

packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js

@@ -501,6 +501,15 @@ const definitions: FeatureFlagDefinitions = {
         purpose: 'experimentation',
       },
     },
+    disableInteractionManager: {
+      defaultValue: false,
+      metadata: {
+        dateAdded: '2024-11-06',
+        description:
+          'Disables InteractionManager and replaces its scheduler with `setImmediate`.',
+        purpose: 'experimentation',
+      },
+    },
     enableAccessToHostTreeInFabric: {
       defaultValue: false,
       metadata: {

packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js

@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<27ae96c2bc3459bd89e52063a8ed9490>>
+ * @generated SignedSource<<141c9d17083660b8726d2780813168dd>>
  * @flow strict
  */
 
@@ -30,6 +30,7 @@ export type ReactNativeFeatureFlagsJsOnly = {
   jsOnlyTestFlag: Getter<boolean>,
   animatedShouldDebounceQueueFlush: Getter<boolean>,
   animatedShouldUseSingleOp: Getter<boolean>,
+  disableInteractionManager: Getter<boolean>,
   enableAccessToHostTreeInFabric: Getter<boolean>,
   enableAnimatedAllowlist: Getter<boolean>,
   enableAnimatedClearImmediateFix: Getter<boolean>,
@@ -118,6 +119,11 @@ export const animatedShouldDebounceQueueFlush: Getter<boolean> = createJavaScrip
  */
 export const animatedShouldUseSingleOp: Getter<boolean> = createJavaScriptFlagGetter('animatedShouldUseSingleOp', false);
 
+/**
+ * Disables InteractionManager and replaces its scheduler with `setImmediate`.
+ */
+export const disableInteractionManager: Getter<boolean> = createJavaScriptFlagGetter('disableInteractionManager', false);
+
 /**
  * Enables access to the host tree in Fabric using DOM-compatible APIs.
  */