From 527f118a44686ee29fb576384d73cab4be06901b Mon Sep 17 00:00:00 2001
From: Brian White <mscdex@mscdex.net>
Date: Fri, 11 Jan 2019 22:36:26 -0500
Subject: [PATCH] process: improve nextTick performance

PR-URL: https://github.com/nodejs/node/pull/25461
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 benchmark/process/next-tick-breadth-args.js |  2 +-
 benchmark/process/next-tick-breadth.js      |  2 +-
 benchmark/process/next-tick-depth-args.js   |  2 +-
 benchmark/process/next-tick-depth.js        |  2 +-
 benchmark/process/next-tick-exec-args.js    |  2 +-
 benchmark/process/next-tick-exec.js         |  2 +-
 lib/internal/fixed_queue.js                 |  2 +-
 lib/internal/process/task_queues.js         | 42 +++++++++++----------
 8 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/benchmark/process/next-tick-breadth-args.js b/benchmark/process/next-tick-breadth-args.js
index 6baa8d99609030..f7f9882c87e34b 100644
--- a/benchmark/process/next-tick-breadth-args.js
+++ b/benchmark/process/next-tick-breadth-args.js
@@ -2,7 +2,7 @@
 
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [4e6]
+  n: [1e7]
 });
 
 function main({ n }) {
diff --git a/benchmark/process/next-tick-breadth.js b/benchmark/process/next-tick-breadth.js
index 392d8e02093707..297bf43495d2e6 100644
--- a/benchmark/process/next-tick-breadth.js
+++ b/benchmark/process/next-tick-breadth.js
@@ -2,7 +2,7 @@
 
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [4e6]
+  n: [1e7]
 });
 
 function main({ n }) {
diff --git a/benchmark/process/next-tick-depth-args.js b/benchmark/process/next-tick-depth-args.js
index da61f90a647278..d9fc37887ec5a3 100644
--- a/benchmark/process/next-tick-depth-args.js
+++ b/benchmark/process/next-tick-depth-args.js
@@ -2,7 +2,7 @@
 
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [12e6]
+  n: [7e6]
 });
 
 function main({ n }) {
diff --git a/benchmark/process/next-tick-depth.js b/benchmark/process/next-tick-depth.js
index c88e042b965ef4..5b0f817475f9b6 100644
--- a/benchmark/process/next-tick-depth.js
+++ b/benchmark/process/next-tick-depth.js
@@ -1,7 +1,7 @@
 'use strict';
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [12e6]
+  n: [7e6]
 });
 
 function main({ n }) {
diff --git a/benchmark/process/next-tick-exec-args.js b/benchmark/process/next-tick-exec-args.js
index f5d0fb94224148..ec172ea8931e3f 100644
--- a/benchmark/process/next-tick-exec-args.js
+++ b/benchmark/process/next-tick-exec-args.js
@@ -1,7 +1,7 @@
 'use strict';
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [5e6]
+  n: [4e6]
 });
 
 function main({ n }) {
diff --git a/benchmark/process/next-tick-exec.js b/benchmark/process/next-tick-exec.js
index 936b253bfaf324..14fce9cccf8d6a 100644
--- a/benchmark/process/next-tick-exec.js
+++ b/benchmark/process/next-tick-exec.js
@@ -1,7 +1,7 @@
 'use strict';
 const common = require('../common.js');
 const bench = common.createBenchmark(main, {
-  n: [5e6]
+  n: [4e6]
 });
 
 function main({ n }) {
diff --git a/lib/internal/fixed_queue.js b/lib/internal/fixed_queue.js
index 7571a8f67e36d2..a073ab7fc327af 100644
--- a/lib/internal/fixed_queue.js
+++ b/lib/internal/fixed_queue.js
@@ -102,7 +102,7 @@ module.exports = class FixedQueue {
   }
 
   shift() {
-    const { tail } = this;
+    const tail = this.tail;
     const next = tail.shift();
     if (tail.isEmpty() && tail.next !== null) {
       // If there is another queue, it forms the new tail.
diff --git a/lib/internal/process/task_queues.js b/lib/internal/process/task_queues.js
index 68b5d8b343d206..8906b4aa1e2426 100644
--- a/lib/internal/process/task_queues.js
+++ b/lib/internal/process/task_queues.js
@@ -71,10 +71,18 @@ function processTicksAndRejections() {
 
       try {
         const callback = tock.callback;
-        if (tock.args === undefined)
+        if (tock.args === undefined) {
           callback();
-        else
-          callback(...tock.args);
+        } else {
+          const args = tock.args;
+          switch (args.length) {
+            case 1: callback(args[0]); break;
+            case 2: callback(args[0], args[1]); break;
+            case 3: callback(args[0], args[1], args[2]); break;
+            case 4: callback(args[0], args[1], args[2], args[3]); break;
+            default: callback(...args);
+          }
+        }
       } finally {
         if (destroyHooksExist())
           emitDestroy(asyncId);
@@ -88,22 +96,6 @@ function processTicksAndRejections() {
   setHasRejectionToWarn(false);
 }
 
-class TickObject {
-  constructor(callback, args) {
-    this.callback = callback;
-    this.args = args;
-
-    const asyncId = newAsyncId();
-    const triggerAsyncId = getDefaultTriggerAsyncId();
-    this[async_id_symbol] = asyncId;
-    this[trigger_async_id_symbol] = triggerAsyncId;
-
-    if (initHooksExist()) {
-      emitInit(asyncId, 'TickObject', triggerAsyncId, this);
-    }
-  }
-}
-
 // `nextTick()` will not enqueue any callback when the process is about to
 // exit since the callback would not have a chance to be executed.
 function nextTick(callback) {
@@ -127,7 +119,17 @@ function nextTick(callback) {
 
   if (queue.isEmpty())
     setHasTickScheduled(true);
-  queue.push(new TickObject(callback, args));
+  const asyncId = newAsyncId();
+  const triggerAsyncId = getDefaultTriggerAsyncId();
+  const tickObject = {
+    [async_id_symbol]: asyncId,
+    [trigger_async_id_symbol]: triggerAsyncId,
+    callback,
+    args
+  };
+  if (initHooksExist())
+    emitInit(asyncId, 'TickObject', triggerAsyncId, tickObject);
+  queue.push(tickObject);
 }
 
 let AsyncResource;