Source/WebCore/dom/DocumentSharedObjectPool.cpp

/*
 * Copyright (C) 2012, 2013 Apple Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions
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#include "config.h"
#include "DocumentSharedObjectPool.h"

#include "Element.h"
#include "ElementData.h"
#include "SecurityOrigin.h"
#include <wtf/StdLibExtras.h>
#include <wtf/TZoneMallocInlines.h>

namespace WebCore {

WTF_MAKE_TZONE_ALLOCATED_IMPL(DocumentSharedObjectPool);

static HashMap<SecurityOriginData, size_t>& NODELETE peakSizeInPast()
{
    static MainThreadNeverDestroyed<HashMap<SecurityOriginData, size_t>> map;
    return map;
}

DocumentSharedObjectPool::DocumentSharedObjectPool(const SecurityOrigin& origin)
    : m_domain(origin.data())
{
    m_shareableElementDataCache.reserveInitialCapacity(peakSizeInPast().get(m_domain));
}

DocumentSharedObjectPool::~DocumentSharedObjectPool()
{
    size_t currentSizeRoundedUp = roundUpToPowerOfTwo(m_shareableElementDataCache.size());
    auto result = peakSizeInPast().add(m_domain, currentSizeRoundedUp);
    if (!result.isNewEntry && currentSizeRoundedUp > result.iterator->value)
        result.iterator->value = currentSizeRoundedUp;
}

struct DocumentSharedObjectPool::ShareableElementDataHash {
    static unsigned NODELETE hash(const Ref<ShareableElementData>& data)
    {
        return computeHash(data->attributes());
    }
    static bool equal(const Ref<ShareableElementData>& a, const Ref<ShareableElementData>& b)
    {
        // We need to disable type checking because std::has_unique_object_representations_v<Attribute>
        // return false. Attribute contains pointers but memcmp() is safe because those pointers were
        // atomized.
        return equalSpans<WTF::IgnoreTypeChecks::Yes>(a->attributes(), b->attributes());
    }
    static constexpr bool safeToCompareToEmptyOrDeleted = false;
};

struct AttributeSpanTranslator {
    static unsigned NODELETE hash(std::span<const Attribute> attributes)
    {
        return computeHash(attributes);
    }

    static bool equal(const Ref<ShareableElementData>& a, std::span<const Attribute> b)
    {
        // We need to disable type checking because std::has_unique_object_representations_v<Attribute>
        // return false. Attribute contains pointers but memcmp() is safe because those pointers were
        // atomized.
        return equalSpans<WTF::IgnoreTypeChecks::Yes>(a->attributes(), b);
    }

    static void translate(Ref<ShareableElementData>& location, std::span<const Attribute> attributes, unsigned /*hash*/)
    {
        location = ShareableElementData::createWithAttributes(attributes);
    }
};

Ref<ShareableElementData> DocumentSharedObjectPool::cachedShareableElementDataWithAttributes(std::span<const Attribute> attributes)
{
    ASSERT(!attributes.empty());

    return m_shareableElementDataCache.add<AttributeSpanTranslator>(attributes).iterator->get();
}

} // namespace WebCore