fix: don't add listeners to the same signal more than once

lib/api/abort-signal.js

@@ -1,8 +1,9 @@
 const { addAbortListener } = require('../core/util')
 const { RequestAbortedError } = require('../core/errors')
 
-const kListener = Symbol('kListener')
 const kSignal = Symbol('kSignal')
+const kListenerList = Symbol('kListenersList')
+const kHandler = Symbol('kHandler')
 
 function abort (self) {
   if (self.abort) {
@@ -13,11 +14,26 @@ function abort (self) {
   removeSignal(self)
 }
 
+function clearListeners (signal) {
+  const listenerList = signal[kListenerList]
+  if (!listenerList) {
+    return
+  }
+  if ('removeEventListener' in signal) {
+    signal.removeEventListener('abort', signal[kHandler])
+  } else {
+    signal.removeListener('abort', signal[kHandler])
+  }
+  if (listenerList.size !== 0) {
+    listenerList.clear()
+  }
+  signal[kListenerList] = null
+}
+
 function addSignal (self, signal) {
   self.reason = null
 
   self[kSignal] = null
-  self[kListener] = null
 
   if (!signal) {
     return
@@ -29,26 +45,35 @@ function addSignal (self, signal) {
   }
 
   self[kSignal] = signal
-  self[kListener] = () => {
-    abort(self)
+
+  if (!signal[kListenerList]) {
+    signal[kListenerList] = new Set()
+    signal[kHandler] = () => {
+      for (const listener of signal[kListenerList]) {
+        abort(listener)
+      }
+      clearListeners(signal)
+    }
+    addAbortListener(signal, signal[kHandler])
   }
 
-  addAbortListener(self[kSignal], self[kListener])
+  signal[kListenerList].add(self)
 }
 
 function removeSignal (self) {
-  if (!self[kSignal]) {
+  const signal = self[kSignal]
+
+  if (!signal) {
     return
   }
 
-  if ('removeEventListener' in self[kSignal]) {
-    self[kSignal].removeEventListener('abort', self[kListener])
-  } else {
-    self[kSignal].removeListener('abort', self[kListener])
+  signal[kListenerList].delete(self)
+
+  if (signal[kListenerList].size === 0) {
+    clearListeners(signal)
   }
 
   self[kSignal] = null
-  self[kListener] = null
 }
 
 module.exports = {