1368665 - stylo: Consider sorting the class list in the style sharing cache.

Status: RESOLVED FIXED

(Core :: CSS Parsing and Computation, enhancement)

Description

[Emilio Cobos Álvarez (:emilio)]

We are comparing class names in order right now.

This was suggested by Bobby in https://github.com/servo/servo/pull/17063, but I didn't do it there.

I think we should have some numbers before doing it, because I don't think it's common at all, and I don't think sorting is as cheap as Bobby suggests.

Comment 1

[Bobby Holley (:bholley)]

(In reply to Emilio Cobos Álvarez [:emilio] from comment #0)
> We are comparing class names in order right now.
> 
> This was suggested by Bobby in https://github.com/servo/servo/pull/17063,
> but I didn't do it there.
> 
> I think we should have some numbers before doing it, because I don't think
> it's common at all

What numbers, exactly? It seems entirely dependent on whether the page ever uses multiple orderings of the same class list, which is something that can easily occur with dynamic scripts that .toggle() classes, but that would non-trivial to measure for the entire web, especially given the dynamic part.

> I don't think sorting is as cheap as Bobby suggests.

Can you explain why? Sorting small lists happens in-place, and is very cheap as far as I can tell from the stdlib source. I'm totally happy to limit the sort to class lists of <= 5 or so if you're worried about pessimal cases of thousands of classes.

Comment 2

[Bobby Holley (:bholley)]

Attachment: Sort the cached class list in ValidationInfo. v1

MozReview-Commit-ID: 3vsfP5ECzds

Comment 3

[Bobby Holley (:bholley)]

https://github.com/servo/servo/pull/17110

Green try push: https://treeherder.mozilla.org/#/jobs?repo=try&revision=eb00cc7efb0defe23bd1ed55f1e89488ae7a042f