util: allow safely adding listener to abortSignal

Author: atlowChemi

doc/api/util.md

@@ -14,6 +14,64 @@ it:
 const util = require('node:util');
 ```
 
+## `util.addAbortListener(signal, resource)`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1 - Experimental
+
+* `signal` {AbortSignal}
+* `listener` {Function|EventListener}
+* Returns: {Disposable} that removes the `abort` listener.
+
+Listens once to the `abort` event on the provided `signal`.
+
+Listening to the `abort` event on abort signals is unsafe and may
+lead to resource leaks since another third party with the signal can
+call [`e.stopImmediatePropagation()`][]. Unfortunately Node.js cannot change
+this since it would violate the web standard. Additionally, the original
+API makes it easy to forget to remove listeners.
+
+This API allows safely using `AbortSignal`s in Node.js APIs by solving these
+two issues by listening to the event such that `stopImmediatePropagation` does
+not prevent the listener from running.
+
+Returns a disposable so that it may be unsubscribed from more easily.
+
+```cjs
+const { addAbortListener } = require('node:util');
+
+function example(signal) {
+  let disposable;
+  try {
+    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
+    disposable = addAbortListener(signal, (e) => {
+      // Do something when signal is aborted.
+    });
+  } finally {
+    disposable?.[Symbol.dispose]();
+  }
+}
+```
+
+```mjs
+import { addAbortListener } from 'node:util';
+
+function example(signal) {
+  let disposable;
+  try {
+    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
+    disposable = addAbortListener(signal, (e) => {
+      // Do something when signal is aborted.
+    });
+  } finally {
+    disposable?.[Symbol.dispose]();
+  }
+}
+```
+
 ## `util.callbackify(original)`
 
 <!-- YAML
@@ -3354,6 +3412,7 @@ util.log('Timestamped message.');
 [`WebAssembly.Module`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/Module
 [`assert.deepStrictEqual()`]: assert.md#assertdeepstrictequalactual-expected-message
 [`console.error()`]: console.md#consoleerrordata-args
+[`e.stopImmediatePropagation()`]: events.md#eventstopimmediatepropagation
 [`mime.toString()`]: #mimetostring
 [`mimeParams.entries()`]: #mimeparamsentries
 [`napi_create_external()`]: n-api.md#napi_create_external

lib/util.js

@@ -43,6 +43,7 @@ const {
   ObjectValues,
   ReflectApply,
   StringPrototypePadStart,
+  SymbolDispose,
 } = primordials;
 
 const {
@@ -63,6 +64,7 @@ const {
 } = require('internal/util/inspect');
 const { debuglog } = require('internal/util/debuglog');
 const {
+  validateAbortSignal,
   validateFunction,
   validateNumber,
 } = require('internal/validators');
@@ -77,6 +79,7 @@ const {
   toUSVString,
   defineLazyProperties,
 } = require('internal/util');
+const { queueMicrotask } = require('internal/process/task_queues');
 
 let abortController;
 
@@ -86,6 +89,7 @@ function lazyAbortController() {
 }
 
 let internalDeepEqual;
+let kResistStopPropagation;
 
 /**
  * @deprecated since v4.0.0
@@ -345,11 +349,38 @@ function getSystemErrorName(err) {
   return internalErrorName(err);
 }
 
+function addAbortListener(signal, listener) {
+  if (signal === undefined) {
+    throw new ERR_INVALID_ARG_TYPE('signal', 'AbortSignal', signal);
+  }
+  validateAbortSignal(signal, 'signal');
+  validateFunction(listener, 'listener');
+
+  let removeEventListener = () => {};
+  if (signal.aborted) {
+    queueMicrotask(() => listener());
+  } else {
+    kResistStopPropagation ??= require('internal/event_target').kResistStopPropagation;
+    // TODO(atlowChemi) add { subscription: true } and return directly
+    signal.addEventListener('abort', listener, { __proto__: null, once: true, [kResistStopPropagation]: true });
+    removeEventListener = () => {
+      signal.removeEventListener('abort', listener);
+    };
+  }
+  return {
+    __proto__: null,
+    [SymbolDispose]() {
+      removeEventListener();
+    },
+  };
+}
+
 // Keep the `exports =` so that various functions can still be monkeypatched
 module.exports = {
   _errnoException: errnoException,
   _exceptionWithHostPort: exceptionWithHostPort,
   _extend,
+  addAbortListener,
   callbackify,
   debug: debuglog,
   debuglog,

test/parallel/test-util-add-safe-abort-signal-abort-listener.mjs

@@ -0,0 +1,55 @@
+import * as common from '../common/index.mjs';
+import * as util from 'node:util';
+import * as assert from 'node:assert';
+import { describe, it } from 'node:test';
+
+describe('util.addAbortListener', () => {
+  it('should throw if signal not provided', () => {
+    assert.throws(() => util.addAbortListener(), { code: 'ERR_INVALID_ARG_TYPE' });
+  });
+
+  it('should throw if provided signal is invalid', () => {
+    assert.throws(() => util.addAbortListener(undefined), { code: 'ERR_INVALID_ARG_TYPE' });
+    assert.throws(() => util.addAbortListener(null), { code: 'ERR_INVALID_ARG_TYPE' });
+    assert.throws(() => util.addAbortListener({}), { code: 'ERR_INVALID_ARG_TYPE' });
+  });
+
+  it('should throw if listener is not a function', () => {
+    const { signal } = new AbortController();
+    assert.throws(() => util.addAbortListener(signal), { code: 'ERR_INVALID_ARG_TYPE' });
+    assert.throws(() => util.addAbortListener(signal, {}), { code: 'ERR_INVALID_ARG_TYPE' });
+    assert.throws(() => util.addAbortListener(signal, undefined), { code: 'ERR_INVALID_ARG_TYPE' });
+  });
+
+  it('should return a Disposable', () => {
+    const { signal } = new AbortController();
+    const disposable = util.addAbortListener(signal, common.mustNotCall());
+
+    assert.strictEqual(typeof disposable[Symbol.dispose], 'function');
+  });
+
+  it('should execute the listener immediately for aborted runners', () => {
+    const disposable = util.addAbortListener(AbortSignal.abort(), common.mustCall());
+    assert.strictEqual(typeof disposable[Symbol.dispose], 'function');
+  });
+
+  it('should execute the listener even when event propagation stopped', () => {
+    const controller = new AbortController();
+    const { signal } = controller;
+
+    signal.addEventListener('abort', (e) => e.stopImmediatePropagation());
+    util.addAbortListener(
+      signal,
+      common.mustCall((e) => assert.strictEqual(e.target, signal)),
+    );
+
+    controller.abort();
+  });
+
+  it('should remove event listeners when disposed', () => {
+    const controller = new AbortController();
+    const disposable = util.addAbortListener(controller.signal, common.mustNotCall());
+    disposable[Symbol.dispose]();
+    controller.abort();
+  });
+});

tools/doc/type-parser.mjs

@@ -270,6 +270,7 @@ const customTypesMap = {
   'Headers': 'https://developer.mozilla.org/en-US/docs/Web/API/Headers',
   'Response': 'https://developer.mozilla.org/en-US/docs/Web/API/Response',
   'Request': 'https://developer.mozilla.org/en-US/docs/Web/API/Request',
+  'Disposable': 'https://tc39.es/proposal-explicit-resource-management/#sec-disposable-interface',
 };
 
 const arrayPart = /(?:\[])+$/;