From 2a0ec9c6459f50301a989a6df1b89358c3a9158c Mon Sep 17 00:00:00 2001
From: Ruben Bridgewater <ruben@bridgewater.de>
Date: Thu, 21 Nov 2019 15:12:58 +0100
Subject: util: improve inspect's customInspect performance
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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 dde2066294..3664c15484 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,
@@ -176,13 +178,20 @@ 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 fd699c85f0..0d905b1e72 100644
--- a/test/parallel/test-util-inspect.js
+++ b/test/parallel/test-util-inspect.js
@@ -884,6 +884,10 @@ 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);
@@ -910,10 +914,11 @@ 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 });
 }
 
 {
-- 
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