fs: add .ref() and .unref() methods to watcher classes

PR-URL: https://github.com/nodejs/node/pull/33134
Fixes: https://github.com/nodejs/node/issues/33096
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1 files changed, 53 insertions, 2 deletions

diff --git a/lib/internal/fs/watchers.js b/lib/internal/fs/watchers.js
index 118f85d9ada..01db66c551c 100644
--- a/lib/internal/fs/watchers.js
+++ b/lib/internal/fs/watchers.js
@@ -31,6 +31,9 @@ const kUseBigint = Symbol('kUseBigint');
 
 const kFSWatchStart = Symbol('kFSWatchStart');
 const kFSStatWatcherStart = Symbol('kFSStatWatcherStart');
+const KFSStatWatcherRefCount = Symbol('KFSStatWatcherRefCount');
+const KFSStatWatcherMaxRefCount = Symbol('KFSStatWatcherMaxRefCount');
+const kFSStatWatcherAddOrCleanRef = Symbol('kFSStatWatcherAddOrCleanRef');
 
 function emitStop(self) {
   self.emit('stop');
@@ -42,6 +45,8 @@ function StatWatcher(bigint) {
   this._handle = null;
   this[kOldStatus] = -1;
   this[kUseBigint] = bigint;
+  this[KFSStatWatcherRefCount] = 1;
+  this[KFSStatWatcherMaxRefCount] = 1;
 }
 ObjectSetPrototypeOf(StatWatcher.prototype, EventEmitter.prototype);
 ObjectSetPrototypeOf(StatWatcher, EventEmitter);
@@ -75,7 +80,7 @@ StatWatcher.prototype[kFSStatWatcherStart] = function(filename,
   this._handle[owner_symbol] = this;
   this._handle.onchange = onchange;
   if (!persistent)
-    this._handle.unref();
+    this.unref();
 
   // uv_fs_poll is a little more powerful than ev_stat but we curb it for
   // the sake of backwards compatibility.
@@ -117,6 +122,41 @@ StatWatcher.prototype.stop = function() {
   this._handle = null;
 };
 
+// Clean up or add ref counters.
+StatWatcher.prototype[kFSStatWatcherAddOrCleanRef] = function(operate) {
+  if (operate === 'add') {
+    // Add a Ref
+    this[KFSStatWatcherRefCount]++;
+    this[KFSStatWatcherMaxRefCount]++;
+  } else if (operate === 'clean') {
+    // Clean up a single
+    this[KFSStatWatcherMaxRefCount]--;
+    this.unref();
+  } else if (operate === 'cleanAll') {
+    // Clean up all
+    this[KFSStatWatcherMaxRefCount] = 0;
+    this[KFSStatWatcherRefCount] = 0;
+    this._handle && this._handle.unref();
+  }
+};
+
+StatWatcher.prototype.ref = function() {
+  // Avoid refCount calling ref multiple times causing unref to have no effect.
+  if (this[KFSStatWatcherRefCount] === this[KFSStatWatcherMaxRefCount])
+    return this;
+  if (this._handle && this[KFSStatWatcherRefCount]++ === 0)
+    this._handle.ref();
+  return this;
+};
+
+StatWatcher.prototype.unref = function() {
+  // Avoid refCount calling unref multiple times causing ref to have no effect.
+  if (this[KFSStatWatcherRefCount] === 0) return this;
+  if (this._handle && --this[KFSStatWatcherRefCount] === 0)
+    this._handle.unref();
+  return this;
+};
+
 
 function FSWatcher() {
   EventEmitter.call(this);
@@ -208,6 +248,16 @@ FSWatcher.prototype.close = function() {
   process.nextTick(emitCloseNT, this);
 };
 
+FSWatcher.prototype.ref = function() {
+  if (this._handle) this._handle.ref();
+  return this;
+};
+
+FSWatcher.prototype.unref = function() {
+  if (this._handle) this._handle.unref();
+  return this;
+};
+
 function emitCloseNT(self) {
   self.emit('close');
 }
@@ -223,5 +273,6 @@ module.exports = {
   FSWatcher,
   StatWatcher,
   kFSWatchStart,
-  kFSStatWatcherStart
+  kFSStatWatcherStart,
+  kFSStatWatcherAddOrCleanRef,
 };