From 77ffd5482d1e8cc98dd5efe86ac313bce8a01812 Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Thu, 21 Nov 2019 15:12:58 +0100
Subject: [PATCH] util: improve inspect's customInspect performance
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This improves the performance to copy user options that are then
passed through to the custom inspect function.

The performance improvement depends on the complexity of the custom
inspect function. For very basic cases this is 100% faster than
before.

PR-URL: https://github.com/nodejs/node/pull/30659
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
---
 lib/internal/util/inspect.js       | 23 ++++++++++++++++-------
 test/parallel/test-util-inspect.js |  9 +++++++--
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/lib/internal/util/inspect.js b/lib/internal/util/inspect.js
index f0888dc2a2dac9..219d8f1d00ef22 100644
--- a/lib/internal/util/inspect.js
+++ b/lib/internal/util/inspect.js
@@ -119,6 +119,8 @@ const builtInObjects = new Set(
   ObjectGetOwnPropertyNames(global).filter((e) => /^([A-Z][a-z]+)+$/.test(e))
 );
 
+// These options must stay in sync with `getUserOptions`. So if any option will
+// be added or removed, `getUserOptions` must also be updated accordingly.
 const inspectDefaultOptions = ObjectSeal({
   showHidden: false,
   depth: 2,
@@ -174,13 +176,20 @@ const meta = [
 ];
 
 function getUserOptions(ctx) {
-  const obj = { stylize: ctx.stylize };
-  for (const key of ObjectKeys(inspectDefaultOptions)) {
-    obj[key] = ctx[key];
-  }
-  if (ctx.userOptions === undefined)
-    return obj;
-  return { ...obj, ...ctx.userOptions };
+  return {
+    stylize: ctx.stylize,
+    showHidden: ctx.showHidden,
+    depth: ctx.depth,
+    colors: ctx.colors,
+    customInspect: ctx.customInspect,
+    showProxy: ctx.showProxy,
+    maxArrayLength: ctx.maxArrayLength,
+    breakLength: ctx.breakLength,
+    compact: ctx.compact,
+    sorted: ctx.sorted,
+    getters: ctx.getters,
+    ...ctx.userOptions
+  };
 }
 
 /**
diff --git a/test/parallel/test-util-inspect.js b/test/parallel/test-util-inspect.js
index 09ec140a19f9f1..46236dca4a31a0 100644
--- a/test/parallel/test-util-inspect.js
+++ b/test/parallel/test-util-inspect.js
@@ -883,6 +883,10 @@ util.inspect({ hasOwnProperty: null });
     assert.strictEqual(opts.budget, undefined);
     assert.strictEqual(opts.indentationLvl, undefined);
     assert.strictEqual(opts.showHidden, false);
+    assert.deepStrictEqual(
+      new Set(Object.keys(util.inspect.defaultOptions).concat(['stylize'])),
+      new Set(Object.keys(opts))
+    );
     opts.showHidden = true;
     return { [util.inspect.custom]: common.mustCall((depth, opts2) => {
       assert.deepStrictEqual(clone, opts2);
@@ -909,10 +913,11 @@ util.inspect({ hasOwnProperty: null });
 }
 
 {
-  const subject = { [util.inspect.custom]: common.mustCall((depth) => {
+  const subject = { [util.inspect.custom]: common.mustCall((depth, opts) => {
     assert.strictEqual(depth, null);
+    assert.strictEqual(opts.compact, true);
   }) };
-  util.inspect(subject, { depth: null });
+  util.inspect(subject, { depth: null, compact: true });
 }
 
 {