fix: fix potential performance issue in CleanPlugin (#19735)

lib/CleanPlugin.js

@@ -87,38 +87,6 @@ function getDirectories(assets) {
 	return directories;
 }
 
-/**
- * @param {string} a First directory path to compare
- * @param {string} b Second directory path to compare
- * @returns {boolean} True if both paths have the same parent directory
- */
-function isEqualPath(a, b) {
-	return path.normalize(a) === path.normalize(b);
-}
-
-/**
- * @param {Map<string, number>|Set<string>} files Collection of files to check against
- * @param {string} file File path to check
- * @returns {boolean} True if the file or its parent exists in the collection
- */
-function hasFile(files, file) {
-	if (files instanceof Set) {
-		for (const dir of files) {
-			if (isEqualPath(dir, file)) {
-				return true;
-			}
-		}
-	}
-	if (files instanceof Map) {
-		for (const dir of files.keys()) {
-			if (isEqualPath(dir, file)) {
-				return true;
-			}
-		}
-	}
-	return false;
-}
-
 /** @typedef {Set<string>} Diff */
 
 /**
@@ -147,11 +115,11 @@ const getDiffToFs = (fs, outputPath, currentAssets, callback) => {
 				}
 				for (const entry of /** @type {string[]} */ (entries)) {
 					const file = entry;
-					const filename = directory ? `${directory}/${file}` : file;
+					// Since path.normalize("./file") === path.normalize("file"),
-					if (
+					// return file directly when directory === "."
-						!hasFile(directories, filename) &&
+					const filename =
-						!hasFile(currentAssets, filename)
+						directory && directory !== "." ? `${directory}/${file}` : file;
-					) {
+					if (!directories.has(filename) && !currentAssets.has(filename)) {
 						diff.add(filename);
 					}
 				}
@@ -518,5 +486,3 @@ class CleanPlugin {
 
 module.exports = CleanPlugin;
 module.exports._getDirectories = getDirectories;
-module.exports._hasFile = hasFile;
-module.exports._isEqualPath = isEqualPath;

test/CleanPlugin.unittest.js

@@ -1,10 +1,6 @@
 "use strict";
 
-const {
+const { _getDirectories } = require("../lib/CleanPlugin");
-	_getDirectories,
-	_hasFile,
-	_isEqualPath
-} = require("../lib/CleanPlugin");
 
 describe("CleanPlugin", () => {
 	describe("_getDirectories", () => {
@@ -54,29 +50,4 @@ describe("CleanPlugin", () => {
 			expect([...result]).toEqual([".", "./js", "./static/js", "./static"]);
 		});
 	});
-
-	describe("_isEqualPath", () => {
-		it("should normalize paths before comparison", () => {
-			expect(_isEqualPath("this", "this")).toBe(true);
-			expect(_isEqualPath("this", "./this")).toBe(true);
-			expect(_isEqualPath("this/a", "./this/a")).toBe(true);
-			expect(_isEqualPath("this", "this/a")).toBe(false);
-		});
-	});
-
-	describe("_hasFile", () => {
-		it("should find file in Set collection", () => {
-			const files = new Set(["this"]);
-			expect(_hasFile(files, "./this")).toBe(true);
-			expect(_hasFile(files, "this")).toBe(true);
-			expect(_hasFile(files, "this/a")).toBe(false);
-		});
-
-		it("should find file in Map collection", () => {
-			const files = new Map([["this", 0]]);
-			expect(_hasFile(files, "this")).toBe(true);
-			expect(_hasFile(files, "./this")).toBe(true);
-			expect(_hasFile(files, "this/a")).toBe(false);
-		});
-	});
 });