1886947 - ElementStyle#onRuleUpdated iterate as many time as we have pseudo elements , should only iterator over unique pseudo element types

Status: RESOLVED FIXED

(DevTools :: Inspector: Rules, defect, P2)

Description

[Nicolas Chevobbe [:nchevobbe]]

onRuleUpdated loops through a list of pseudo element types that are used in rules https://searchfox.org/mozilla-central/rev/a06d5a8871b1796f2dbd588ab518eaa98507e018/devtools/client/inspector/rules/models/element-style.js#271-281:

onRuleUpdated() {
  // Update declarations for matching rules for pseudo-elements.
  for (const pseudo of this.pseudoElements) {
    this.updateDeclarations(pseudo);
  }
}

Unfortunately, that list does not contain unique item, but as many item as pseudo element rules https://searchfox.org/mozilla-central/rev/a06d5a8871b1796f2dbd588ab518eaa98507e018/devtools/client/inspector/rules/models/element-style.js#143-146 :

// Store a list of all pseudo-element types found in the matching rules.
this.pseudoElements = this.rules
  .filter(r => r.pseudoElement)
  .map(r => r.pseudoElement);

This can be extremely costly when there are a lot of pseudo elements, like in Bug 1410716
We should only loop through unique pseudo element types

Comment 1

[Nicolas Chevobbe [:nchevobbe]]

Attachment: Bug 1886947 - [devtools] Fix useless and costly iteration over pseudo elements in onRuleUpdated. r=#devtools-reviewers.

Only store unique pseudo element types in this.pseudoElements, that we also
rename to this.pseudoElementTypes to be more explicit.

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/41f296e08233
[devtools] Fix useless and costly iteration over pseudo elements in onRuleUpdated. r=devtools-reviewers,ochameau.

Comment 3

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/41f296e08233

Comment 4

[Nicolas Chevobbe [:nchevobbe]]

== Change summary for alert #42072 (as of Sat, 30 Mar 2024 05:55:51 GMT) ==

Improvements:

Ratio	Test	Platform	Options	Absolute values (old vs new)
10%	damp custom.inspector.manyrules.selectnode	windows10-64-shippable-qr	e10s fission stylo webrender-sw	708.67 -> 637.00
9%	damp custom.inspector.manyrules.selectnode	windows10-64-shippable-qr	e10s fission stylo webrender	704.38 -> 638.02
9%	damp custom.inspector.manyrules.selectnode	linux1804-64-shippable-qr	e10s fission stylo webrender-sw	819.20 -> 742.32
9%	damp custom.inspector.manyrules.selectnode	linux1804-64-shippable-qr	e10s fission stylo webrender	831.07 -> 759.00

For up to date results, see: https://treeherder.mozilla.org/perfherder/alerts?id=42072