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BridgeAR wants to merge 6 commits into from
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util: improve util.inspect performance #14492

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ddd4de4
util: use for in instead of while hasOwnProperty
BridgeAR Jul 26, 2017
b73a399
util: use faster visibleKeys property lookup
BridgeAR Jul 26, 2017
ab497df
fixup
BridgeAR Jul 26, 2017
61119e4
fixup comments commit 1
BridgeAR Jul 27, 2017
a2574f0
fixup commit 1
BridgeAR Jul 28, 2017
4aed280
benchmarks: add inspect-array benchmark
BridgeAR Jul 28, 2017
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util: use for in instead of while hasOwnProperty 
This is a huge performance improvement in case of sparse arrays
when using util.inspect as the hole will simple be skipped.
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@BridgeAR
BridgeAR committed Jul 26, 2017
commit ddd4de4b84ed9c0efce8c657e0eb3675a5a6ad88
33 changes: 22 additions & 11 deletions lib/util.js
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Original file line number Diff line number Diff line change
Expand Up @@ -672,22 +672,33 @@ function formatArray(ctx, value, recurseTimes, visibleKeys, keys) {
var output = [];
let visibleLength = 0;
let index = 0;
while (index < value.length && visibleLength < ctx.maxArrayLength) {
let emptyItems = 0;
while (index < value.length && !hasOwnProperty(value, String(index))) {
emptyItems++;
index++;
}
if (emptyItems > 0) {
for (const elem in value) {
if (visibleLength === ctx.maxArrayLength)
break;
const i = +elem;
if (index !== i) {
if (i !== i) // Fast NaN check
continue;
const emptyItems = i - index;
const ending = emptyItems > 1 ? 's' : '';
const message = `<${emptyItems} empty item${ending}>`;
output.push(ctx.stylize(message, 'undefined'));
} else {
output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
String(index), true));
index++;
index = i;
visibleLength++;
if (visibleLength === ctx.maxArrayLength)
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@mscdex mscdex Jul 26, 2017

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Couldn't these previous two lines be merged into if (++visibleLength === ctx.maxArrayLength) ?

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@BridgeAR BridgeAR Jul 27, 2017

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Done

break;
}
output.push(formatProperty(ctx, value, recurseTimes, visibleKeys,
elem, true));
visibleLength++;
index++;
}
if (index < value.length && visibleLength !== ctx.maxArrayLength) {
const len = value.length - index;
const ending = len > 1 ? 's' : '';
const message = `<${len} empty item${ending}>`;
output.push(ctx.stylize(message, 'undefined'));
index = value.length;
}
var remaining = value.length - index;
if (remaining > 0) {
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