allow Locator#load to be called concurrently

- Until now, Locator could recursively load multiple css files.
- However, with the change in the loader interface, this no longer happens.
- We now allow concurrent calls to `Locator#load`.

packages/happy-css-modules/src/locator/index.test.ts

@@ -1,10 +1,7 @@
-import { readFile, writeFile } from 'fs/promises';
 import { randomUUID } from 'node:crypto';
-import { jest } from '@jest/globals';
 import dedent from 'dedent';
 import { Locator, createDefaultTransformer } from '../index.js';
 import { createFixtures, getFixturePath } from '../test-util/util.js';
-import { sleepSync } from '../util.js';
 
 const locator = new Locator();
 
@@ -159,48 +156,6 @@ test('normalizes tokens', async () => {
   `);
 });
 
-test('returns the result from the cache when the file has not been modified', async () => {
-  createFixtures({
-    '/test/1.css': dedent`
-    @import './2.css';
-    @import './3.css';
-    `,
-    '/test/2.css': dedent`
-    .b {}
-    `,
-    '/test/3.css': dedent`
-    .c {}
-    .d {}
-    `,
-  });
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  const readCSSSpy = jest.spyOn(locator, 'readCSS' as any);
-  await locator.load(getFixturePath('/test/1.css'));
-  expect(readCSSSpy).toHaveBeenCalledTimes(3);
-  expect(readCSSSpy).toHaveBeenNthCalledWith(1, getFixturePath('/test/1.css'));
-  expect(readCSSSpy).toHaveBeenNthCalledWith(2, getFixturePath('/test/2.css'));
-  expect(readCSSSpy).toHaveBeenNthCalledWith(3, getFixturePath('/test/3.css'));
-  readCSSSpy.mockClear();
-
-  // update `/test/2.css`
-  sleepSync(1); // wait for the file system to update the mtime
-  await writeFile(getFixturePath('/test/2.css'), await readFile(getFixturePath('/test/2.css'), 'utf-8'));
-
-  // `3.css` is not updated, so the cache is used. Therefore, `readFile` is not called.
-  await locator.load(getFixturePath('/test/3.css'));
-  expect(readCSSSpy).toHaveBeenCalledTimes(0);
-
-  // `1.css` is not updated, but dependencies are updated, so the cache is used. Therefore, `readFile` is called.
-  await locator.load(getFixturePath('/test/1.css'));
-  expect(readCSSSpy).toHaveBeenCalledTimes(2);
-  expect(readCSSSpy).toHaveBeenNthCalledWith(1, getFixturePath('/test/1.css'));
-  expect(readCSSSpy).toHaveBeenNthCalledWith(2, getFixturePath('/test/2.css'));
-
-  // ``2.css` is updated, but the cache is already available because it was updated in the previous step. Therefore, `readFile` is not called.
-  await locator.load(getFixturePath('/test/2.css'));
-  expect(readCSSSpy).toHaveBeenCalledTimes(2);
-});
-
 describe('supports sourcemap', () => {
   test('restores original locations from sourcemap', async () => {
     const transformer = createDefaultTransformer();
@@ -309,12 +264,3 @@ test('ignores http(s) protocol file', async () => {
   const result = await locator.load(getFixturePath('/test/1.css'));
   expect(result).toStrictEqual({ tokenInfos: [], transpileDependencies: [] });
 });
-
-test('block concurrent calls to load method', async () => {
-  createFixtures({
-    '/test/1.css': `.a {}`,
-  });
-  await expect(async () => {
-    await Promise.all([locator.load(getFixturePath('/test/1.css')), locator.load(getFixturePath('/test/1.css'))]);
-  }).rejects.toThrowError('Cannot call `Locator#load` concurrently.');
-});

packages/happy-css-modules/src/locator/index.ts

@@ -68,7 +68,6 @@ export class Locator {
   private readonly cache: Map<string, CacheEntry> = new Map();
   private readonly transformer: Transformer | undefined;
   private readonly resolver: StrictlyResolver;
-  private loading = false;
 
   constructor(options?: LocatorOptions) {
     this.transformer = options?.transformer ?? createDefaultTransformer();
@@ -114,15 +113,6 @@ export class Locator {
 
   /** Returns information about the tokens exported from the CSS Modules file. */
   async load(filePath: string): Promise<LoadResult> {
-    if (this.loading) throw new Error('Cannot call `Locator#load` concurrently.');
-    this.loading = true;
-    const result = await this._load(filePath).finally(() => {
-      this.loading = false;
-    });
-    return result;
-  }
-
-  private async _load(filePath: string): Promise<LoadResult> {
     const mtime = (await stat(filePath)).mtime.getTime();
 
     const { css, map, dependencies: transpileDependencies } = await this.readCSS(filePath);

packages/happy-css-modules/src/runner.ts

@@ -133,6 +133,7 @@ export async function run(options: RunnerOptions): Promise<Watcher | void> {
     }
 
     // Locator#load cannot be called concurrently. Therefore, it takes a lock and waits.
+    // TODO: Concurrent calls to Locator#load are now allowed. Therefore, it is necessary to remove the lock.
     await lock.acquireAsync();
 
     try {