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e5eb83ac5a
This patch enables sharing of an nsAttrValue's MiscContainer between nodes for style rules. MiscContainers of type eCSSStyleRule are now refcounted (with some clever struct packing to ensure that the amount of memory allocated for MiscContainer remains unchanged on 32 and 64 bit). This infrastructure can be used to share most MiscContainer types in the future if we find advantages to sharing other types than just eCSSStyleRuley. A cache mapping strings to MiscContainers has been added to nsHTMLCSSStyleSheet. MiscContainers can be shared between nsAttrValues when one nsAttrValue is SetTo another nsAttrValue or when there is a cache hit in this cache. This patch also adds the ability to tell a style rule that it belongs to an nsHTMLCSSStyleSheet, with appropriate accessor functions to separate that from the existing case of belonging to an nsCSSStyleSheet. The primary use case is to reduce memory use for pages that have lots of inline style attributes with the same value. This can happen easily with large pages that are automatically generated. An (admittedly pathological) testcase in Bug 686975 sees over 250 MB of memory savings with this change. Reusing the same MiscContainer for multiple nodes saves the overhead of maintaining separate copies of the string containing the serialized value of the style attribute and of creating separate style rules for each node. Eliminating duplicate style rules enables further savings in layout through style context sharing. The testcase sees the amount of memory used by style contexts go from over 250 MB to 10 KB. Because the cache is based on the text value of the style attribute, it will not handle attributes that have different text values but are parsed into identical style rules. We also do not attempt to share MiscContainers when the node's base URI differs from the document URI. The effect of these limitations is expected to be low.
80 lines
3.1 KiB
C++
80 lines
3.1 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/*
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* style sheet and style rule processor representing style attributes
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*/
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#ifndef nsHTMLCSSStyleSheet_h_
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#define nsHTMLCSSStyleSheet_h_
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#include "mozilla/Attributes.h"
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#include "nsIStyleSheet.h"
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#include "nsIStyleRuleProcessor.h"
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struct MiscContainer;
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class nsHTMLCSSStyleSheet MOZ_FINAL : public nsIStyleSheet,
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public nsIStyleRuleProcessor {
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public:
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nsHTMLCSSStyleSheet();
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~nsHTMLCSSStyleSheet();
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NS_DECL_ISUPPORTS
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nsresult Init(nsIURI* aURL, nsIDocument* aDocument);
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void Reset(nsIURI* aURL);
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// nsIStyleSheet
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virtual nsIURI* GetSheetURI() const;
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virtual nsIURI* GetBaseURI() const MOZ_OVERRIDE;
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virtual void GetTitle(nsString& aTitle) const MOZ_OVERRIDE;
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virtual void GetType(nsString& aType) const MOZ_OVERRIDE;
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virtual bool HasRules() const MOZ_OVERRIDE;
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virtual bool IsApplicable() const MOZ_OVERRIDE;
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virtual void SetEnabled(bool aEnabled) MOZ_OVERRIDE;
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virtual bool IsComplete() const MOZ_OVERRIDE;
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virtual void SetComplete() MOZ_OVERRIDE;
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virtual nsIStyleSheet* GetParentSheet() const MOZ_OVERRIDE; // will be null
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virtual nsIDocument* GetOwningDocument() const MOZ_OVERRIDE;
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virtual void SetOwningDocument(nsIDocument* aDocument) MOZ_OVERRIDE;
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#ifdef DEBUG
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virtual void List(FILE* out = stdout, int32_t aIndent = 0) const MOZ_OVERRIDE;
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#endif
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// nsIStyleRuleProcessor
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virtual void RulesMatching(ElementRuleProcessorData* aData) MOZ_OVERRIDE;
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virtual void RulesMatching(PseudoElementRuleProcessorData* aData) MOZ_OVERRIDE;
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virtual void RulesMatching(AnonBoxRuleProcessorData* aData) MOZ_OVERRIDE;
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#ifdef MOZ_XUL
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virtual void RulesMatching(XULTreeRuleProcessorData* aData) MOZ_OVERRIDE;
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#endif
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virtual nsRestyleHint HasStateDependentStyle(StateRuleProcessorData* aData) MOZ_OVERRIDE;
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virtual bool HasDocumentStateDependentStyle(StateRuleProcessorData* aData) MOZ_OVERRIDE;
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virtual nsRestyleHint
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HasAttributeDependentStyle(AttributeRuleProcessorData* aData) MOZ_OVERRIDE;
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virtual bool MediumFeaturesChanged(nsPresContext* aPresContext) MOZ_OVERRIDE;
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virtual NS_MUST_OVERRIDE size_t
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SizeOfExcludingThis(nsMallocSizeOfFun aMallocSizeOf) const MOZ_OVERRIDE;
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virtual NS_MUST_OVERRIDE size_t
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SizeOfIncludingThis(nsMallocSizeOfFun aMallocSizeOf) const MOZ_OVERRIDE;
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void CacheStyleAttr(const nsAString& aSerialized, MiscContainer* aValue);
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void EvictStyleAttr(const nsAString& aSerialized, MiscContainer* aValue);
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MiscContainer* LookupStyleAttr(const nsAString& aSerialized);
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private:
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nsHTMLCSSStyleSheet(const nsHTMLCSSStyleSheet& aCopy) MOZ_DELETE;
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nsHTMLCSSStyleSheet& operator=(const nsHTMLCSSStyleSheet& aCopy) MOZ_DELETE;
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protected:
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nsCOMPtr<nsIURI> mURL;
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nsIDocument* mDocument;
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nsDataHashtable<nsStringHashKey, MiscContainer*> mCachedStyleAttrs;
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};
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#endif /* !defined(nsHTMLCSSStyleSheet_h_) */
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