Use Node-native recursive fs.watch on macOS and Windows, replace FSEventsWatcher and fsevents dependency

packages/metro-file-map/package.json

@@ -27,9 +27,6 @@
   "devDependencies": {
     "slash": "^3.0.0"
   },
-  "optionalDependencies": {
-    "fsevents": "^2.3.2"
-  },
   "engines": {
     "node": ">=18.18"
   }

packages/metro-file-map/src/Watcher.js

@@ -14,6 +14,7 @@ import type {
   FileData,
   Path,
   PerfLogger,
+  WatcherBackend,
   WatcherBackendChangeEvent,
   WatchmanClocks,
 } from './flow-types';
@@ -22,9 +23,9 @@ import type {AbortSignal} from 'node-abort-controller';
 
 import nodeCrawl from './crawlers/node';
 import watchmanCrawl from './crawlers/watchman';
-import {ADD_EVENT, CHANGE_EVENT} from './watchers/common';
-import FSEventsWatcher from './watchers/FSEventsWatcher';
-import NodeWatcher from './watchers/NodeWatcher';
+import {TOUCH_EVENT} from './watchers/common';
+import FallbackWatcher from './watchers/FallbackWatcher';
+import NativeWatcher from './watchers/NativeWatcher';
 import WatchmanWatcher from './watchers/WatchmanWatcher';
 import EventEmitter from 'events';
 import * as fs from 'fs';
@@ -61,11 +62,6 @@ type WatcherOptions = {
   watchmanDeferStates: $ReadOnlyArray<string>,
 };
 
-interface WatcherBackend {
-  getPauseReason(): ?string;
-  close(): Promise<void>;
-}
-
 let nextInstanceId = 0;
 
 export type HealthCheckResult =
@@ -166,18 +162,18 @@ export class Watcher extends EventEmitter {
   async watch(onChange: (change: WatcherBackendChangeEvent) => void) {
     const {extensions, ignorePattern, useWatchman} = this._options;
 
-    // WatchmanWatcher > FSEventsWatcher > sane.NodeWatcher
+    // WatchmanWatcher > NativeWatcher > FallbackWatcher
     const WatcherImpl = useWatchman
       ? WatchmanWatcher
-      : FSEventsWatcher.isSupported()
-        ? FSEventsWatcher
-        : NodeWatcher;
+      : NativeWatcher.isSupported()
+        ? NativeWatcher
+        : FallbackWatcher;
 
-    let watcher = 'node';
+    let watcher = 'fallback';
     if (WatcherImpl === WatchmanWatcher) {
       watcher = 'watchman';
-    } else if (WatcherImpl === FSEventsWatcher) {
-      watcher = 'fsevents';
+    } else if (WatcherImpl === NativeWatcher) {
+      watcher = 'native';
     }
     debug(`Using watcher: ${watcher}`);
     this._options.perfLogger?.annotate({string: {watcher}});
@@ -186,7 +182,7 @@ export class Watcher extends EventEmitter {
     const createWatcherBackend = (root: Path): Promise<WatcherBackend> => {
       const watcherOptions: WatcherBackendOptions = {
         dot: true,
-        glob: [
+        globs: [
           // Ensure we always include package.json files, which are crucial for
           /// module resolution.
           '**/package.json',
@@ -197,33 +193,32 @@ export class Watcher extends EventEmitter {
         ignored: ignorePattern,
         watchmanDeferStates: this._options.watchmanDeferStates,
       };
-      const watcher = new WatcherImpl(root, watcherOptions);
+      const watcher: WatcherBackend = new WatcherImpl(root, watcherOptions);
 
-      return new Promise((resolve, reject) => {
+      return new Promise(async (resolve, reject) => {
         const rejectTimeout = setTimeout(
           () => reject(new Error('Failed to start watch mode.')),
           MAX_WAIT_TIME,
         );
 
-        watcher.once('ready', () => {
-          clearTimeout(rejectTimeout);
-          watcher.on('all', (change: WatcherBackendChangeEvent) => {
-            const basename = path.basename(change.relativePath);
-            if (basename.startsWith(this._options.healthCheckFilePrefix)) {
-              if (change.event === ADD_EVENT || change.event === CHANGE_EVENT) {
-                debug(
-                  'Observed possible health check cookie: %s in %s',
-                  change.relativePath,
-                  root,
-                );
-                this._handleHealthCheckObservation(basename);
-              }
-              return;
+        watcher.onFileEvent(change => {
+          const basename = path.basename(change.relativePath);
+          if (basename.startsWith(this._options.healthCheckFilePrefix)) {
+            if (change.event === TOUCH_EVENT) {
+              debug(
+                'Observed possible health check cookie: %s in %s',
+                change.relativePath,
+                root,
+              );
+              this._handleHealthCheckObservation(basename);
             }
-            onChange(change);
-          });
-          resolve(watcher);
+            return;
+          }
+          onChange(change);
         });
+        await watcher.startWatching();
+        clearTimeout(rejectTimeout);
+        resolve(watcher);
       });
     };
 
@@ -241,7 +236,7 @@ export class Watcher extends EventEmitter {
   }
 
   async close() {
-    await Promise.all(this._backends.map(watcher => watcher.close()));
+    await Promise.all(this._backends.map(watcher => watcher.stopWatching()));
     this._activeWatcher = null;
   }