Entries filtering performance optimization

lib/paths-cache.js

@@ -7,15 +7,15 @@ import gitIgnoreParser from 'git-ignore-parser';
 import _ from 'underscore-plus'
 import minimatch from 'minimatch'
 import { Directory, File } from 'atom'
-import { execPromise } from './utils'
+import { execPromise, union } from './utils'
 
 export default class PathsCache extends EventEmitter {
   constructor () {
     super()
 
     const rebuildCacheBound = this.rebuildCache.bind(this)
     this._projectChangeWatcher = atom.project.onDidChangePaths(rebuildCacheBound)
-    
+
     const _onDidChangeFilesBound = this._onDidChangeFiles.bind(this)
     this._projectWatcher = atom.project.onDidChangeFiles(_onDidChangeFilesBound)
 
@@ -154,11 +154,17 @@ export default class PathsCache extends EventEmitter {
     const entries = await this._getDirectoryEntries(directory)
     if (this._cancelled) return []
 
-    // Filter: Files that are not ignored
-    const filePaths = entries
-      .filter(entry => entry instanceof File)
-      .map(entry => entry.path)
-      .filter(path => !this._isPathIgnored(path))
+    // Filter: Files and Directories that are not ignored
+    let filePaths = []
+    let directories = []
+    for (let i = 0, len = entries.length; i < len; i++) {
+      const entry = entries[i]
+      if (entry instanceof File && !this._isPathIgnored(entry.path)) {
+        filePaths.push(entry.path)
+      } else if (entry instanceof Directory && !this._isPathIgnored(entry.path)) {
+        directories.push(entry)
+      }
+    }
 
     // Merge file paths into existing array (which contains *all* file paths)
     let filePathsArray = this._filePathsByProjectDirectory.get(projectDirectory.path) || []
@@ -178,19 +184,15 @@ export default class PathsCache extends EventEmitter {
     }
 
     this._filePathsByProjectDirectory.set(projectDirectory.path,
-      _.union(filePathsArray, filePaths)
+      union(filePathsArray, filePaths)
     )
 
     // Merge file paths into existing array (which contains file paths for a specific directory)
     filePathsArray = this._filePathsByDirectory.get(directory.path) || []
     this._filePathsByDirectory.set(directory.path,
-      _.union(filePathsArray, filePaths)
+      union(filePathsArray, filePaths)
     )
 
-    const directories = entries
-      .filter(entry => entry instanceof Directory)
-      .filter(entry => !this._isPathIgnored(entry.path))
-
     return Promise.all(directories.map(directory =>
       this._cacheDirectoryFilePaths(projectDirectory, directory)
     ))

lib/utils.js

@@ -12,3 +12,21 @@ export function execPromise(cmd, options) {
     });
   });
 }
+
+// fast merge function
+// https://uilicious.com/blog/javascript-array-push-is-945x-faster-than-array-concat/
+export function merge(arr1: Array<any>, arr2: Array<any>) {
+  if (!arr2.length) return
+  Array.prototype.push.apply(arr1, arr2)
+}
+
+// get unique entries of an array
+export function unique(arr: Array<any>) {
+  return [...new Set(arr)]
+}
+
+// fast union function (replacement for _.union)
+export function union(arr1: Array<any>, arr2: Array<any>) {
+  merge(arr1, arr2)
+  return unique(arr1)
+}