From 3bc16f917d9f3416815c941cae04790020be469e Mon Sep 17 00:00:00 2001
From: Brian White <mscdex@mscdex.net>
Date: Sun, 25 Aug 2019 04:21:33 -0400
Subject: [PATCH] events: improve once() performance

PR-URL: https://github.com/nodejs/node/pull/29307
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
---
 benchmark/events/ee-once.js | 52 +++++++++++++++++++++++++++++++------
 lib/events.js               |  6 +++--
 2 files changed, 48 insertions(+), 10 deletions(-)

diff --git a/benchmark/events/ee-once.js b/benchmark/events/ee-once.js
index e1a09fb4b71167..bd0a39565332b2 100644
--- a/benchmark/events/ee-once.js
+++ b/benchmark/events/ee-once.js
@@ -2,18 +2,54 @@
 const common = require('../common.js');
 const EventEmitter = require('events').EventEmitter;
 
-const bench = common.createBenchmark(main, { n: [2e7] });
+const bench = common.createBenchmark(main, {
+  n: [2e7],
+  argc: [0, 1, 4, 5]
+});
 
-function main({ n }) {
+function main({ n, argc }) {
   const ee = new EventEmitter();
 
   function listener() {}
 
-  bench.start();
-  for (var i = 0; i < n; i += 1) {
-    const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
-    ee.once(dummy, listener);
-    ee.emit(dummy);
+  switch (argc) {
+    case 0:
+      bench.start();
+      for (let i = 0; i < n; i += 1) {
+        const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
+        ee.once(dummy, listener);
+        ee.emit(dummy);
+      }
+      bench.end(n);
+      break;
+    case 1:
+      bench.start();
+      for (let i = 0; i < n; i += 1) {
+        const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
+        ee.once(dummy, listener);
+        ee.emit(dummy, n);
+      }
+      bench.end(n);
+      break;
+    case 4:
+      bench.start();
+      for (let i = 0; i < n; i += 1) {
+        const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
+        ee.once(dummy, listener);
+        ee.emit(dummy, 'foo', argc, 'bar', false);
+      }
+      bench.end(n);
+      break;
+    case 5:
+      bench.start();
+      for (let i = 0; i < n; i += 1) {
+        const dummy = (i % 2 === 0) ? 'dummy0' : 'dummy1';
+        ee.once(dummy, listener);
+        ee.emit(dummy, true, 7.5, 'foo', null, n);
+      }
+      bench.end(n);
+      break;
+    default:
+      throw new Error('Unsupported argument count');
   }
-  bench.end(n);
 }
diff --git a/lib/events.js b/lib/events.js
index ae847dc2341032..ebde85c6ddf990 100644
--- a/lib/events.js
+++ b/lib/events.js
@@ -290,11 +290,13 @@ EventEmitter.prototype.prependListener =
       return _addListener(this, type, listener, true);
     };
 
-function onceWrapper(...args) {
+function onceWrapper() {
   if (!this.fired) {
     this.target.removeListener(this.type, this.wrapFn);
     this.fired = true;
-    return Reflect.apply(this.listener, this.target, args);
+    if (arguments.length === 0)
+      return this.listener.call(this.target);
+    return this.listener.apply(this.target, arguments);
   }
 }