fs: replace traverse with readdir for performance

Author: anonrig

lib/internal/fs/linux_watcher.js

@@ -6,6 +6,7 @@ const { SafeMap, Symbol, StringPrototypeStartsWith } = primordials;
 const { validateObject } = require('internal/validators');
 const { kEmptyObject } = require('internal/util');
 const { ERR_FEATURE_UNAVAILABLE_ON_PLATFORM } = require('internal/errors');
+const { Dirent, UV_DIRENT_DIR } = require('internal/fs/utils');
 
 const kFSWatchStart = Symbol('kFSWatchStart');
 
@@ -22,35 +23,20 @@ function lazyLoadFsSync() {
   return internalSync;
 }
 
-async function traverse(dir, files = new SafeMap()) {
-  const { stat, opendir } = lazyLoadFsPromises();
+function traverse(dir, files = new SafeMap()) {
+  const { readdirSync } = lazyLoadFsSync()
 
-  files.set(dir, await stat(dir));
+  const filenames = readdirSync(dir, { withFileTypes: true });
 
-  try {
-    const directory = await opendir(dir);
+  files.set(dir, new Dirent(dir, UV_DIRENT_DIR));
 
-    for await (const file of directory) {
-      const f = path.join(dir, file.name);
+  for (let file of filenames) {
+    const f = path.join(dir, file.name);
 
-      try {
-        const stats = await stat(f);
+    files.set(f, file);
 
-        files.set(f, stats);
-
-        if (stats.isDirectory()) {
-          await traverse(f, files);
-        }
-      } catch (error) {
-        if (error.code !== 'ENOENT' || error.code !== 'EPERM') {
-          this.emit('error', error);
-        }
-      }
-
-    }
-  } catch (error) {
-    if (error.code !== 'EACCES') {
-      this.emit('error', error);
+    if (file.isDirectory()) {
+      traverse(f, files);
     }
   }
 
@@ -154,7 +140,7 @@ class FSWatcher extends EventEmitter {
       persistent: this.#options.persistent,
     }, (statWatcher, previousStatWatcher) => {
       if (existingStat && !existingStat.isDirectory() &&
-        statWatcher.nlink !== 0 && existingStat.mtime.getTime() === statWatcher.mtime.getTime()) {
+        statWatcher.nlink !== 0 && existingStat.mtime?.getTime() === statWatcher.mtime?.getTime()) {
         return;
       }
 
@@ -180,10 +166,10 @@ class FSWatcher extends EventEmitter {
   /**
    * @param {string | Buffer | URL} filename
    */
-  async [kFSWatchStart](filename) {
+  [kFSWatchStart](filename) {
     this.#rootPath = filename;
     this.#closed = false;
-    this.#files = await traverse(filename);
+    this.#files = traverse(filename);
 
     for (const f of this.#files.keys()) {
       this.#watchFile(f);