stream: pre-allocate _events

ronag · UlisesGascon · commit dd5206820c3a · 2023-12-11T11:12:10.000Z
PR-URL: #50428 Reviewed-By: Matteo Collina <matteo.collina@gmail.com> Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com> Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
diff --git a/lib/events.js b/lib/events.js
@@ -86,6 +86,7 @@ const {
 
 const kCapture = Symbol('kCapture');
 const kErrorMonitor = Symbol('events.errorMonitor');
+const kShapeMode = Symbol('shapeMode');
 const kMaxEventTargetListeners = Symbol('events.maxEventTargetListeners');
 const kMaxEventTargetListenersWarned =
   Symbol('events.maxEventTargetListenersWarned');
@@ -343,6 +344,9 @@ EventEmitter.init = function(opts) {
       this._events === ObjectGetPrototypeOf(this)._events) {
     this._events = { __proto__: null };
     this._eventsCount = 0;
+    this[kShapeMode] = false;
+  } else {
+    this[kShapeMode] = true;
   }
 
   this._maxListeners = this._maxListeners || undefined;
@@ -685,9 +689,13 @@ EventEmitter.prototype.removeListener =
         return this;
 
       if (list === listener || list.listener === listener) {
-        if (--this._eventsCount === 0)
+        this._eventsCount -= 1;
+
+        if (this[kShapeMode]) {
+          events[type] = undefined;
+        } else if (this._eventsCount === 0) {
           this._events = { __proto__: null };
-        else {
+        } else {
           delete events[type];
           if (events.removeListener)
             this.emit('removeListener', type, list.listener || listener);
@@ -749,6 +757,7 @@ EventEmitter.prototype.removeAllListeners =
           else
             delete events[type];
         }
+        this[kShapeMode] = false;
         return this;
       }
 
@@ -761,6 +770,7 @@ EventEmitter.prototype.removeAllListeners =
         this.removeAllListeners('removeListener');
         this._events = { __proto__: null };
         this._eventsCount = 0;
+        this[kShapeMode] = false;
         return this;
       }
 
diff --git a/lib/internal/streams/duplex.js b/lib/internal/streams/duplex.js
@@ -63,6 +63,24 @@ function Duplex(options) {
   if (!(this instanceof Duplex))
     return new Duplex(options);
 
+  this._events ??= {
+    close: undefined,
+    error: undefined,
+    prefinish: undefined,
+    finish: undefined,
+    drain: undefined,
+    data: undefined,
+    end: undefined,
+    readable: undefined,
+    // Skip uncommon events...
+    // pause: undefined,
+    // resume: undefined,
+    // pipe: undefined,
+    // unpipe: undefined,
+    // [destroyImpl.kConstruct]: undefined,
+    // [destroyImpl.kDestroy]: undefined,
+  };
+
   this._readableState = new Readable.ReadableState(options, this, true);
   this._writableState = new Writable.WritableState(options, this, true);
 
diff --git a/lib/internal/streams/readable.js b/lib/internal/streams/readable.js
@@ -319,6 +319,21 @@ function Readable(options) {
   if (!(this instanceof Readable))
     return new Readable(options);
 
+  this._events ??= {
+    close: undefined,
+    error: undefined,
+    data: undefined,
+    end: undefined,
+    readable: undefined,
+    // Skip uncommon events...
+    // pause: undefined,
+    // resume: undefined,
+    // pipe: undefined,
+    // unpipe: undefined,
+    // [destroyImpl.kConstruct]: undefined,
+    // [destroyImpl.kDestroy]: undefined,
+  };
+
   this._readableState = new ReadableState(options, this, false);
 
   if (options) {
diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
@@ -385,6 +385,17 @@ function Writable(options) {
   if (!(this instanceof Writable))
     return new Writable(options);
 
+  this._events ??= {
+    close: undefined,
+    error: undefined,
+    prefinish: undefined,
+    finish: undefined,
+    drain: undefined,
+    // Skip uncommon events...
+    // [destroyImpl.kConstruct]: undefined,
+    // [destroyImpl.kDestroy]: undefined,
+  };
+
   this._writableState = new WritableState(options, this, false);
 
   if (options) {
diff --git a/test/parallel/test-readline-interface.js b/test/parallel/test-readline-interface.js
@@ -44,7 +44,7 @@ class FakeInput extends EventEmitter {
 function isWarned(emitter) {
   for (const name in emitter) {
     const listeners = emitter[name];
-    if (listeners.warned) return true;
+    if (listeners && listeners.warned) return true;
   }
   return false;
 }
diff --git a/test/parallel/test-readline-promises-interface.js b/test/parallel/test-readline-promises-interface.js
@@ -22,7 +22,7 @@ class FakeInput extends EventEmitter {
 function isWarned(emitter) {
   for (const name in emitter) {
     const listeners = emitter[name];
-    if (listeners.warned) return true;
+    if (listeners && listeners.warned) return true;
   }
   return false;
 }

Original file line number	Diff line number	Diff line change
`@@ -44,7 +44,7 @@ class FakeInput extends EventEmitter {`
`44`	`44`	`function isWarned(emitter) {`
`45`	`45`	`for (const name in emitter) {`
`46`	`46`	`const listeners = emitter[name];`
`47`		`- if (listeners.warned) return true;`
	`47`	`+ if (listeners && listeners.warned) return true;`
`48`	`48`	`}`
`49`	`49`	`return false;`
`50`	`50`	`}`
Original file line number	Diff line number	Diff line change
`@@ -22,7 +22,7 @@ class FakeInput extends EventEmitter {`
`22`	`22`	`function isWarned(emitter) {`
`23`	`23`	`for (const name in emitter) {`
`24`	`24`	`const listeners = emitter[name];`
`25`		`- if (listeners.warned) return true;`
	`25`	`+ if (listeners && listeners.warned) return true;`
`26`	`26`	`}`
`27`	`27`	`return false;`
`28`	`28`	`}`