worker: allow URL in Worker constructor

The explicit goal is to let users use `import.meta.url` to re-load thecurrent module inside a Worker instance. Fixes: #30780 PR-URL: #31664 Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

Author: aduh95

doc/api/worker_threads.md

@@ -513,6 +513,10 @@ if (isMainThread) {
 <!-- YAML
 added: v10.5.0
 changes:
+ - version: REPLACEME
+ pr-url: https://github.com/nodejs/node/pull/31664
+ description: The `filename` parameter can be a WHATWG `URL` object using
+ `file:` protocol.
  - version: v13.2.0
  pr-url: https://github.com/nodejs/node/pull/26628
  description: The `resourceLimits` option was introduced.
@@ -521,9 +525,10 @@ changes:
  description: The `argv` option was introduced.
 -->
 
-* `filename` {string} The path to the Worker’s main script. Must be
- either an absolute path or a relative path (i.e. relative to the
- current working directory) starting with `./` or `../`.
+* `filename` {string|URL} The path to the Worker’s main script or module. Must
+ be either an absolute path or a relative path (i.e. relative to the
+ current working directory) starting with `./` or `../`, or a WHATWG `URL`
+ object using `file:` protocol.
  If `options.eval` is `true`, this is a string containing JavaScript code
  rather than a path.
 * `options` {Object}
@@ -536,8 +541,9 @@ changes:
  to specify that the parent thread and the child thread should share their
  environment variables; in that case, changes to one thread’s `process.env`
  object will affect the other thread as well. **Default:** `process.env`.
- * `eval` {boolean} If `true`, interpret the first argument to the constructor
- as a script that is executed once the worker is online.
+ * `eval` {boolean} If `true` and the first argument is a `string`, interpret
+ the first argument to the constructor as a script that is executed once the
+ worker is online.
  * `execArgv` {string[]} List of node CLI options passed to the worker.
  V8 options (such as `--max-old-space-size`) and options that affect the
  process (such as `--title`) are not supported. If set, this will be provided

lib/internal/errors.js

@@ -1391,9 +1391,14 @@ E('ERR_WORKER_INVALID_EXEC_ARGV', (errors, msg = 'invalid execArgv flags') =>
 E('ERR_WORKER_NOT_RUNNING', 'Worker instance not running', Error);
 E('ERR_WORKER_OUT_OF_MEMORY',
  'Worker terminated due to reaching memory limit: %s', Error);
-E('ERR_WORKER_PATH',
- 'The worker script filename must be an absolute path or a relative ' +
- 'path starting with \'./\' or \'../\'. Received "%s"',
+E('ERR_WORKER_PATH', (filename) =>
+ 'The worker script or module filename must be an absolute path or a ' +
+ 'relative path starting with \'./\' or \'../\'.' +
+ (filename.startsWith('file://') ?
+ ' If you want to pass a file:// URL, you must wrap it around `new URL`.' :
+ ''
+ ) +
+ ` Received "${filename}"`,
  TypeError);
 E('ERR_WORKER_UNSERIALIZABLE_ERROR',
  'Serializing an uncaught exception failed', Error);

lib/internal/url.js

@@ -1348,8 +1348,7 @@ function getPathFromURLPosix(url) {
 function fileURLToPath(path) {
  if (typeof path === 'string')
  path = new URL(path);
- else if (path == null || !path[searchParams] ||
- !path[searchParams][searchParams])
+ else if (!isURLInstance(path))
  throw new ERR_INVALID_ARG_TYPE('path', ['string', 'URL'], path);
  if (path.protocol !== 'file:')
  throw new ERR_INVALID_URL_SCHEME('file');
@@ -1396,9 +1395,13 @@ function pathToFileURL(filepath) {
  return outURL;
 }
 
+function isURLInstance(fileURLOrPath) {
+ return fileURLOrPath != null && fileURLOrPath[searchParams] &&
+ fileURLOrPath[searchParams][searchParams];
+}
+
 function toPathIfFileURL(fileURLOrPath) {
- if (fileURLOrPath == null || !fileURLOrPath[searchParams] ||
- !fileURLOrPath[searchParams][searchParams])
+ if (!isURLInstance(fileURLOrPath))
  return fileURLOrPath;
  return fileURLToPath(fileURLOrPath);
 }
@@ -1431,6 +1434,7 @@ module.exports = {
  fileURLToPath,
  pathToFileURL,
  toPathIfFileURL,
+ isURLInstance,
  URL,
  URLSearchParams,
  domainToASCII,

lib/internal/worker.js

@@ -27,8 +27,8 @@ const {
  ERR_INVALID_ARG_TYPE,
  // eslint-disable-next-line no-unused-vars
  ERR_WORKER_INIT_FAILED,
+ ERR_INVALID_ARG_VALUE,
 } = errorCodes;
-const { validateString } = require('internal/validators');
 const { getOptionValue } = require('internal/options');
 
 const workerIo = require('internal/worker/io');
@@ -45,7 +45,7 @@ const {
  WritableWorkerStdio
 } = workerIo;
 const { deserializeError } = require('internal/error-serdes');
-const { pathToFileURL } = require('url');
+const { fileURLToPath, isURLInstance, pathToFileURL } = require('internal/url');
 
 const {
  ownsProcessState,
@@ -86,7 +86,6 @@ class Worker extends EventEmitter {
  constructor(filename, options = {}) {
  super();
  debug(`[${threadId}] create new worker`, filename, options);
- validateString(filename, 'filename');
  if (options.execArgv && !ArrayIsArray(options.execArgv)) {
  throw new ERR_INVALID_ARG_TYPE('options.execArgv',
  'Array',
@@ -99,11 +98,33 @@ class Worker extends EventEmitter {
  }
  argv = options.argv.map(String);
  }
- if (!options.eval) {
- if (!path.isAbsolute(filename) && !/^\.\.?[\\/]/.test(filename)) {
+
+ let url;
+ if (options.eval) {
+ if (typeof filename !== 'string') {
+ throw new ERR_INVALID_ARG_VALUE(
+ 'options.eval',
+ options.eval,
+ 'must be false when \'filename\' is not a string'
+ );
+ }
+ url = null;
+ } else {
+ if (isURLInstance(filename)) {
+ url = filename;
+ filename = fileURLToPath(filename);
+ } else if (typeof filename !== 'string') {
+ throw new ERR_INVALID_ARG_TYPE(
+ 'filename',
+ ['string', 'URL'],
+ filename
+ );
+ } else if (path.isAbsolute(filename) || /^\.\.?[\\/]/.test(filename)) {
+ filename = path.resolve(filename);
+ url = pathToFileURL(filename);
+ } else {
  throw new ERR_WORKER_PATH(filename);
  }
- filename = path.resolve(filename);
 
  const ext = path.extname(filename);
  if (ext !== '.js' && ext !== '.mjs' && ext !== '.cjs') {
@@ -125,7 +146,6 @@ class Worker extends EventEmitter {
  options.env);
  }
 
- const url = options.eval ? null : pathToFileURL(filename);
  // Set up the C++ handle for the worker, as well as some internal wiring.
  this[kHandle] = new WorkerImpl(url,
  env === process.env ? null : env,

test/parallel/test-worker-type-check.js

@@ -20,7 +20,8 @@ const { Worker } = require('worker_threads');
  {
  code: 'ERR_INVALID_ARG_TYPE',
  name: 'TypeError',
- message: 'The "filename" argument must be of type string.' +
+ message: 'The "filename" argument must be of type string ' +
+ 'or an instance of URL.' +
  common.invalidArgTypeHelper(val)
  }
  );

test/parallel/test-worker-unsupported-eval-on-url.mjs

@@ -0,0 +1,6 @@
+import '../common/index.mjs';
+import assert from 'assert';
+import { Worker } from 'worker_threads';
+
+const re = /The argument 'options\.eval' must be false when 'filename' is not a string\./;
+assert.throws(() => new Worker(new URL(import.meta.url), { eval: true }), re);

test/parallel/test-worker-unsupported-path.js

@@ -13,6 +13,7 @@ const { Worker } = require('worker_threads');
  assert.throws(() => { new Worker('/b'); }, expectedErr);
  assert.throws(() => { new Worker('/c.wasm'); }, expectedErr);
  assert.throws(() => { new Worker('/d.txt'); }, expectedErr);
+ assert.throws(() => { new Worker(new URL('file:///C:/e.wasm')); }, expectedErr);
 }
 
 {
@@ -26,3 +27,26 @@ const { Worker } = require('worker_threads');
  assert.throws(() => { new Worker('file:///file_url'); }, expectedErr);
  assert.throws(() => { new Worker('https://www.url.com'); }, expectedErr);
 }
+
+{
+ assert.throws(
+ () => { new Worker('file:///file_url'); },
+ /If you want to pass a file:\/\/ URL, you must wrap it around `new URL`/
+ );
+ assert.throws(
+ () => { new Worker('relative_no_dot'); },
+ // eslint-disable-next-line node-core/no-unescaped-regexp-dot
+ /^((?!If you want to pass a file:\/\/ URL, you must wrap it around `new URL`).)*$/s
+ );
+}
+
+{
+ const expectedErr = {
+ code: 'ERR_INVALID_URL_SCHEME',
+ name: 'TypeError'
+ };
+ assert.throws(() => { new Worker(new URL('https://www.url.com')); },
+ expectedErr);
+ assert.throws(() => { new Worker(new URL('data:application/javascript,')); },
+ expectedErr);
+}

test/parallel/test-worker.mjs

@@ -0,0 +1,18 @@
+import { mustCall } from '../common/index.mjs';
+import assert from 'assert';
+import { Worker, isMainThread, parentPort } from 'worker_threads';
+
+const TEST_STRING = 'Hello, world!';
+
+if (isMainThread) {
+ const w = new Worker(new URL(import.meta.url));
+ w.on('message', mustCall((message) => {
+ assert.strictEqual(message, TEST_STRING);
+ }));
+} else {
+ setImmediate(() => {
+ process.nextTick(() => {
+ parentPort.postMessage(TEST_STRING);
+ });
+ });
+}