Bug 119568 – Inserting multiple rules into an empty style sheet should avoid style recalc if possible.

• Status: RESOLVED
• Resolution: FIXED
• Component: CSS

[Andreas Kling]

Spin-off from bug 119475. Let's take this to the next level.

[Andreas Kling]

Created attachment 208321 [details]
Short patch name

[Antti Koivisto]

Comment on attachment 208321 [details]
Short patch name

View in context: https://bugs.webkit.org/attachment.cgi?id=208321&action=review

> Source/WebCore/css/CSSStyleSheet.cpp:289
> -    RuleMutationScope mutationScope(this, mutationType);
> +    RuleMutationScope mutationScope(this, RuleInsertion);

The mutation can trigger copy-on-write. In that case we might be left with dangling pointers in StyleResolver.

[Andreas Kling]

Created attachment 208341 [details]
More hardcore version

[Andreas Kling]

Created attachment 208342 [details]
Totally rad patch

[Antti Koivisto]

Comment on attachment 208342 [details]
Totally rad patch

View in context: https://bugs.webkit.org/attachment.cgi?id=208342&action=review

> Source/WebCore/css/CSSStyleSheet.h:89
> +    enum WhetherContentsWereClonedForMutation { ContentsWereNotClonedForMutation = 0, ContentsWereClonedForMutation };

poetic!

> Source/WebCore/dom/DocumentStyleSheetCollection.h:74
> +    enum UpdateFlag { NoUpdate = 0, OptimizedUpdate, FullUpdate };

Does the = 0 do something here?

> Source/WebCore/dom/DocumentStyleSheetCollection.h:137
> +    // This is a mirror of m_activeAuthorStyleSheets that gets populated on demand for activeStyleSheetsContains().
> +    mutable OwnPtr<HashSet<const CSSStyleSheet*>> m_weakCopyOfActiveStyleSheetListForFastLookup;

Bit clunky but I don't have great suggestions.

[Antti Koivisto]

It would also be good to check we have test coverage for insertion that causes cloning.

[Andreas Kling]

Committed r153829: <http://trac.webkit.org/changeset/153829>

[Radar WebKit Bug Importer]

<rdar://problem/14687740>