lib: lazily initialize kEvents and kHandlers maps

Signed-off-by: Guilherme Araújo <arauujogui@gmail.com>
PR-URL: #63702
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>
Reviewed-By: Gürgün Dayıoğlu <hey@gurgun.day>

Author: araujogui

benchmark/abort_controller/abort-controller-creation.js

@@ -0,0 +1,33 @@
+'use strict';
+
+constcommon=require('../common.js');
+constassert=require('node:assert');
+
+constbench=common.createBenchmark(main,{
+n: [1e6],
+kind: ['AbortController','AbortSignal.timeout'],
+});
+
+functionmain({ n, kind }){
+letresult;
+
+switch(kind){
+case'AbortController':
+bench.start();
+for(leti=0;i<n;i++)
+result=newAbortController().signal;// AbortSignal is created lazily on first .signal access
+bench.end(n);
+break;
+case'AbortSignal.timeout':
+bench.start();
+for(leti=0;i<n;i++)
+result=AbortSignal.timeout(1);
+bench.end(n);
+break;
+default:
+thrownewError('Invalid kind');
+}
+
+// Avoid V8 dead code elimination
+assert.ok(result);
+}

lib/events.js

@@ -927,7 +927,7 @@ function getEventListeners(emitterOrTarget, type) {
 // Require event target lazily to avoid always loading it
 const{ isEventTarget, kEvents }=require('internal/event_target');
 if(isEventTarget(emitterOrTarget)){
-constroot=emitterOrTarget[kEvents].get(type);
+constroot=emitterOrTarget[kEvents]?.get(type);
 constlisteners=[];
 lethandler=root?.next;
 while(handler?.listener!==undefined){
@@ -972,7 +972,7 @@ function listenerCount(emitterOrTarget, type) {
 }
 const{ isEventTarget, kEvents }=require('internal/event_target');
 if(isEventTarget(emitterOrTarget)){
-returnemitterOrTarget[kEvents].get(type)?.size??0;
+returnemitterOrTarget[kEvents]?.get(type)?.size??0;
 }
 thrownewERR_INVALID_ARG_TYPE('emitter',
 ['EventEmitter','EventTarget'],

lib/internal/event_target.js

@@ -551,10 +551,16 @@ class Listener {
 }
 
 functioninitEventTarget(self){
-self[kEvents]=newSafeMap();
+self[kEvents]=undefined;
 self[kMaxEventTargetListeners]=EventEmitter.defaultMaxListeners;
 self[kMaxEventTargetListenersWarned]=false;
-self[kHandlers]=newSafeMap();
+self[kHandlers]=undefined;
+}
+
+functiongetEventsMap(self){
+if(self[kEvents]===undefined)
+self[kEvents]=newSafeMap();
+returnself[kEvents];
 }
 
 classEventTarget{
@@ -660,7 +666,8 @@ class EventTarget {
 
 type=webidl.converters.DOMString(type);
 
-letroot=this[kEvents].get(type);
+consteventsMap=getEventsMap(this);
+letroot=eventsMap.get(type);
 
 if(root===undefined){
 root={size: 1,next: undefined,resistStopPropagation: Boolean(resistStopPropagation)};
@@ -675,7 +682,7 @@ class EventTarget {
 capture,
 passive,
 weak);
-this[kEvents].set(type,root);
+eventsMap.set(type,root);
 return;
 }
 
@@ -717,6 +724,9 @@ class EventTarget {
 type=webidl.converters.DOMString(type);
 constcapture=options?.capture===true;
 
+if(this[kEvents]===undefined)
+return;
+
 constroot=this[kEvents].get(type);
 if(root===undefined||root.next===undefined)
 return;
@@ -736,6 +746,9 @@ class EventTarget {
 }
 
 [kRemoveWeakListenerHelper](type,listener){
+if(this[kEvents]===undefined)
+return;
+
 constroot=this[kEvents].get(type);
 if(root===undefined||root.next===undefined)
 return;
@@ -791,7 +804,7 @@ class EventTarget {
 event[kIsBeingDispatched]=true;
 }
 
-constroot=this[kEvents].get(type);
+constroot=this[kEvents]?.get(type);
 if(root===undefined||root.next===undefined){
 if(event!==undefined)
 event[kIsBeingDispatched]=false;
@@ -927,6 +940,8 @@ class NodeEventTarget extends EventTarget {
 eventNames(){
 if(!isNodeEventTarget(this))
 thrownewERR_INVALID_THIS('NodeEventTarget');
+if(this[kEvents]===undefined)
+return[];
 returnArrayFrom(this[kEvents].keys());
 }
 
@@ -937,6 +952,8 @@ class NodeEventTarget extends EventTarget {
 listenerCount(type){
 if(!isNodeEventTarget(this))
 thrownewERR_INVALID_THIS('NodeEventTarget');
+if(this[kEvents]===undefined)
+return0;
 constroot=this[kEvents].get(String(type));
 returnroot!==undefined ? root.size : 0;
 }
@@ -1029,11 +1046,12 @@ class NodeEventTarget extends EventTarget {
 removeAllListeners(type){
 if(!isNodeEventTarget(this))
 thrownewERR_INVALID_THIS('NodeEventTarget');
-if(type!==undefined){
+if(this[kEvents]===undefined)
+returnthis;
+if(type!==undefined)
 this[kEvents].delete(String(type));
-}else{
+else
 this[kEvents].clear();
-}
 
 returnthis;
 }
@@ -1145,18 +1163,29 @@ function defineEventHandler(emitter, name, event = name) {
 
 functionset(value){
 validateThisInternalField(this,kHandlers,'EventTarget');
-letwrappedHandler=this[kHandlers]?.get(event);
+if(this[kHandlers]===undefined)
+this[kHandlers]=newSafeMap();
+letwrappedHandler=this[kHandlers].get(event);
 if(wrappedHandler){
+consteventsMap=getEventsMap(this);
 if(typeofwrappedHandler.handler==='function'){
-this[kEvents].get(event).size--;
-constsize=this[kEvents].get(event).size;
-this[kRemoveListener](size,event,wrappedHandler.handler,false);
+constroot=eventsMap.get(event);
+if(root!==undefined){
+root.size--;
+this[kRemoveListener](root.size,event,wrappedHandler.handler,false);
+}
 }
 wrappedHandler.handler=value;
 if(typeofwrappedHandler.handler==='function'){
-this[kEvents].get(event).size++;
-constsize=this[kEvents].get(event).size;
-this[kNewListener](size,event,value,false,false,false,false);
+constroot=eventsMap.get(event);
+if(root!==undefined){
+root.size++;
+this[kNewListener](root.size,event,value,false,false,false,false);
+}else{
+// The wrapper was externally removed from kEvents (e.g. via
+// removeEventListener); re-register it so the handler fires.
+this.addEventListener(event,wrappedHandler);
+}
 }
 }else{
 wrappedHandler=makeEventHandler(value);