fs: add AbortSignal support to watch

PR-URL: #37190
Refs: #37179
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>

Author: benjamingr

doc/api/fs.md

@@ -4123,6 +4123,9 @@ this API: [`fs.utimes()`][].
 <!-- YAML
 added: v0.5.10
 changes:
+ - version: REPLACEME
+ pr-url: https://github.com/nodejs/node/pull/37190
+ description: Added support for closing the watcher with an AbortSignal.
  - version: v7.6.0
  pr-url: https://github.com/nodejs/node/pull/10739
  description: The `filename` parameter can be a WHATWG `URL` object using
@@ -4142,6 +4145,7 @@ changes:
 `false`.
 *`encoding` {string} Specifies the character encoding to be used for the
  filename passed to the listener. **Default:**`'utf8'`.
+*`signal` {AbortSignal} allows closing the watcher with an AbortSignal.
 *`listener` {Function|undefined} **Default:**`undefined`
 *`eventType` {string}
 *`filename` {string|Buffer}
@@ -4164,6 +4168,9 @@ The listener callback is attached to the `'change'` event fired by
 [`fs.FSWatcher`][], but it is not the same thing as the `'change'` value of
 `eventType`.
 
+If a `signal` is passed, aborting the corresponding AbortController will close
+the returned [`fs.FSWatcher`][].
+
 ### Caveats
 
 <!--type=misc-->

lib/fs.js

@@ -1579,6 +1579,17 @@ function watch(filename, options, listener) {
 if(listener){
 watcher.addListener('change',listener);
 }
+if(options.signal){
+if(options.signal.aborted){
+process.nextTick(()=>watcher.close());
+}else{
+constlistener=()=>watcher.close();
+options.signal.addEventListener('abort',listener);
+watcher.once('close',()=>{
+options.signal.removeEventListener('abort',listener);
+});
+}
+}
 
 returnwatcher;
 }

test/parallel/test-fs-watch-abort-signal.js

@@ -0,0 +1,32 @@
+// Flags: --expose-internals
+'use strict';
+
+// Verify that AbortSignal integration works for fs.watch
+
+constcommon=require('../common');
+
+if(common.isIBMi)
+common.skip('IBMi does not support `fs.watch()`');
+
+constfs=require('fs');
+constfixtures=require('../common/fixtures');
+
+
+{
+// Signal aborted after creating the watcher
+constfile=fixtures.path('empty.js');
+constac=newAbortController();
+const{ signal }=ac;
+constwatcher=fs.watch(file,{ signal });
+watcher.once('close',common.mustCall());
+setImmediate(()=>ac.abort());
+}
+{
+// Signal aborted before creating the watcher
+constfile=fixtures.path('empty.js');
+constac=newAbortController();
+const{ signal }=ac;
+ac.abort();
+constwatcher=fs.watch(file,{ signal });
+watcher.once('close',common.mustCall());
+}