tree b348caa24d3e9ee68af752ddc12fa0eb377808d2
parent 488e19e06a22f1be004da661cd7ad8213341011e
author antti@apple.com <antti@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1336300154 +0000
committer antti@apple.com <antti@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1336300154 +0000

Share stylesheet data structures between documents
https://bugs.webkit.org/show_bug.cgi?id=85598

Source/WebCore: 

Reviewed by Darin Adler.

We currently make a copy of the data structures when restoring a cached stylesheet. This patch lets us share
the data until someone uses CSSOM to modify the sheet.
        
The patch implements copy-on-write for the internal style sheet data structures. If any mutation CSSOM API is
invoked, we check if the stylesheet can be safely mutated (we are the only client, it is not cached). If not
then the internal structures are copied and any existing CSSOM objects are re-attached to the new tree.
        
Sharing can save significant amount of memory on sites with large stylesheets. For example if you have
multiple articles open on wsj.com this saves ~2.6MB per tab.
        
Test: http/tests/css/shared-stylesheet-mutation.html
      http/tests/css/shared-stylesheet-mutation-preconstruct.html

* css/CSSFontFaceRule.cpp:
(WebCore::CSSFontFaceRule::reattach):
(WebCore):
* css/CSSFontFaceRule.h:
(CSSFontFaceRule):
* css/CSSMediaRule.cpp:
(WebCore::CSSMediaRule::insertRule):
(WebCore::CSSMediaRule::deleteRule):
(WebCore::CSSMediaRule::reattach):
(WebCore):
* css/CSSMediaRule.h:
(CSSMediaRule):
* css/CSSPageRule.cpp:
(WebCore::CSSPageRule::setSelectorText):
(WebCore::CSSPageRule::reattach):
(WebCore):
* css/CSSPageRule.h:
(CSSPageRule):
* css/CSSRule.cpp:
(WebCore::CSSRule::reattach):
        
    After the internal stylerule tree has been copied, the existing wrappers are re-attached using recursive reattach() function.

* css/CSSRule.h:
(WebCore):
(CSSRule):
* css/CSSStyleRule.cpp:
(WebCore::CSSStyleRule::setSelectorText):
(WebCore::CSSStyleRule::reattach):
(WebCore):
* css/CSSStyleRule.h:
(CSSStyleRule):
* css/CSSStyleSheet.cpp:
(WebCore::StyleSheetInternal::StyleSheetInternal):
(WebCore::StyleSheetInternal::isCacheable):
(WebCore::StyleSheetInternal::ruleAt):
        
    Add ruleAt(), use it for both wrapper creation and reattaching.  Remove createChildRuleCSSOMWrapper .

(WebCore):
(WebCore::StyleSheetInternal::wrapperInsertRule):
(WebCore::StyleSheetInternal::wrapperDeleteRule):
        
    Invalidation moves to the calling wrapper.

(WebCore::StyleSheetInternal::addedToMemoryCache):
(WebCore::StyleSheetInternal::removedFromMemoryCache):
(WebCore::CSSStyleSheet::willMutateRules):
        
    This is called whenever StyleSheetInternal is going to be mutated. It will do copy-on-write if needed.
            
    Usually invoked by CSSStyleSheet::RuleMutation RAII type.

(WebCore::CSSStyleSheet::didMutateRules):
        
    This is called after the mutation is complete and will trigger the style recalc in the document.

(WebCore::CSSStyleSheet::didMutate):
        
    This is called directly after mutations that don't change StyleSheetInternal so don't require copy-on-write.

(WebCore::CSSStyleSheet::reattachChildRuleCSSOMWrappers):
(WebCore::CSSStyleSheet::setDisabled):
(WebCore::CSSStyleSheet::insertRule):
(WebCore::CSSStyleSheet::deleteRule):
* css/CSSStyleSheet.h:
(StyleSheetInternal):
(WebCore::StyleSheetInternal::hasOneClient):
(WebCore::StyleSheetInternal::isMutable):
(WebCore::StyleSheetInternal::setMutable):
        
    Track mutability. Mutation is allowed only after willMutate call.

(WebCore::StyleSheetInternal::isInMemoryCache):
        
    Track if the object is in memory cache.

(WebCore::CSSStyleSheet::clearOwnerRule):
(CSSStyleSheet):
* css/MediaList.cpp:
(WebCore::MediaList::setMediaText):
(WebCore::MediaList::deleteMedium):
(WebCore::MediaList::appendMedium):
(WebCore::MediaList::didMutate):
(WebCore):
(WebCore::MediaList::reattach):
* css/MediaList.h:
(MediaList):
* css/PropertySetCSSStyleDeclaration.cpp:
(WebCore::PropertySetCSSStyleDeclaration::setCssText):
(WebCore::PropertySetCSSStyleDeclaration::setProperty):
(WebCore::PropertySetCSSStyleDeclaration::removeProperty):
(WebCore::PropertySetCSSStyleDeclaration::setPropertyInternal):
(WebCore):
(WebCore::StyleRuleCSSStyleDeclaration::willMutate):
(WebCore::StyleRuleCSSStyleDeclaration::didMutate):
(WebCore::StyleRuleCSSStyleDeclaration::reattach):
(WebCore::InlineCSSStyleDeclaration::didMutate):
* css/PropertySetCSSStyleDeclaration.h:
(WebCore::PropertySetCSSStyleDeclaration::willMutate):
(WebCore::PropertySetCSSStyleDeclaration::didMutate):
(StyleRuleCSSStyleDeclaration):
* css/WebKitCSSKeyframesRule.cpp:
(WebCore::WebKitCSSKeyframesRule::setName):
(WebCore::WebKitCSSKeyframesRule::insertRule):
(WebCore::WebKitCSSKeyframesRule::deleteRule):
(WebCore::WebKitCSSKeyframesRule::reattach):
(WebCore):
* css/WebKitCSSKeyframesRule.h:
(WebKitCSSKeyframesRule):
* css/WebKitCSSRegionRule.cpp:
(WebCore::WebKitCSSRegionRule::reattach):
* css/WebKitCSSRegionRule.h:
(WebKitCSSRegionRule):
* inspector/InspectorStyleSheet.cpp:
(WebCore::InspectorStyleSheet::reparseStyleSheet):
* loader/cache/CachedCSSStyleSheet.cpp:
(WebCore::CachedCSSStyleSheet::~CachedCSSStyleSheet):
(WebCore::CachedCSSStyleSheet::destroyDecodedData):
(WebCore::CachedCSSStyleSheet::restoreParsedStyleSheet):
        
    Don't copy when restoring. It is no longer necessary.
    Set the cache bit on the stylesheet.

(WebCore::CachedCSSStyleSheet::saveParsedStyleSheet):

LayoutTests: 

Reviewed by Darin Adler.
        
Test that mutations of a shared stylesheet work as expected. 
        
This is an http test due to cross-document security restrictions with file urls
(they can be overriden in DRT but I'd like this to work in browser too).

* http/tests/css/resources/shared.css: Added.
* http/tests/css/resources/shared-stylesheet-mutation.js: Added.
* http/tests/css/shared-stylesheet-mutation-expected.txt: Added.
* http/tests/css/shared-stylesheet-mutation-preconstruct-expected.txt: Added.
* http/tests/css/shared-stylesheet-mutation-preconstruct.html: Added.
* http/tests/css/shared-stylesheet-mutation.html: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@116235 268f45cc-cd09-0410-ab3c-d52691b4dbfc