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/*
* Copyright (C) 2013 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "core/dom/PresentationAttributeStyle.h"
#include "core/css/StylePropertySet.h"
#include "core/dom/Attribute.h"
#include "core/dom/Element.h"
#include "core/html/HTMLInputElement.h"
#include "platform/Timer.h"
#include "wtf/HashFunctions.h"
#include "wtf/HashMap.h"
#include "wtf/text/CString.h"
namespace WebCore {
using namespace HTMLNames;
struct PresentationAttributeCacheKey {
PresentationAttributeCacheKey() : tagName(0) { }
StringImpl* tagName;
Vector<std::pair<StringImpl*, AtomicString>, 3> attributesAndValues;
};
static bool operator!=(const PresentationAttributeCacheKey& a, const PresentationAttributeCacheKey& b)
{
if (a.tagName != b.tagName)
return true;
return a.attributesAndValues != b.attributesAndValues;
}
struct PresentationAttributeCacheEntry {
WTF_MAKE_FAST_ALLOCATED;
public:
PresentationAttributeCacheKey key;
RefPtr<StylePropertySet> value;
};
typedef HashMap<unsigned, OwnPtr<PresentationAttributeCacheEntry>, AlreadyHashed> PresentationAttributeCache;
static PresentationAttributeCache& presentationAttributeCache()
{
DEFINE_STATIC_LOCAL(PresentationAttributeCache, cache, ());
return cache;
}
class PresentationAttributeCacheCleaner {
WTF_MAKE_NONCOPYABLE(PresentationAttributeCacheCleaner); WTF_MAKE_FAST_ALLOCATED;
public:
PresentationAttributeCacheCleaner()
: m_hitCount(0)
, m_cleanTimer(this, &PresentationAttributeCacheCleaner::cleanCache)
{
}
void didHitPresentationAttributeCache()
{
if (presentationAttributeCache().size() < minimumPresentationAttributeCacheSizeForCleaning)
return;
m_hitCount++;
if (!m_cleanTimer.isActive())
m_cleanTimer.startOneShot(presentationAttributeCacheCleanTimeInSeconds, FROM_HERE);
}
private:
static const unsigned presentationAttributeCacheCleanTimeInSeconds = 60;
static const unsigned minimumPresentationAttributeCacheSizeForCleaning = 100;
static const unsigned minimumPresentationAttributeCacheHitCountPerMinute = (100 * presentationAttributeCacheCleanTimeInSeconds) / 60;
void cleanCache(Timer<PresentationAttributeCacheCleaner>* timer)
{
ASSERT_UNUSED(timer, timer == &m_cleanTimer);
unsigned hitCount = m_hitCount;
m_hitCount = 0;
if (hitCount > minimumPresentationAttributeCacheHitCountPerMinute)
return;
presentationAttributeCache().clear();
}
unsigned m_hitCount;
Timer<PresentationAttributeCacheCleaner> m_cleanTimer;
};
static bool attributeNameSort(const pair<StringImpl*, AtomicString>& p1, const pair<StringImpl*, AtomicString>& p2)
{
// Sort based on the attribute name pointers. It doesn't matter what the order is as long as it is always the same.
return p1.first < p2.first;
}
static void makePresentationAttributeCacheKey(Element& element, PresentationAttributeCacheKey& result)
{
// FIXME: Enable for SVG.
if (!element.isHTMLElement())
return;
// Interpretation of the size attributes on <input> depends on the type attribute.
if (isHTMLInputElement(element))
return;
AttributeCollection attributes = element.attributes();
AttributeCollection::const_iterator end = attributes.end();
for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it) {
if (!element.isPresentationAttribute(it->name()))
continue;
if (!it->namespaceURI().isNull())
return;
// FIXME: Background URL may depend on the base URL and can't be shared. Disallow caching.
if (it->name() == backgroundAttr)
return;
result.attributesAndValues.append(std::make_pair(it->localName().impl(), it->value()));
}
if (result.attributesAndValues.isEmpty())
return;
// Attribute order doesn't matter. Sort for easy equality comparison.
std::sort(result.attributesAndValues.begin(), result.attributesAndValues.end(), attributeNameSort);
// The cache key is non-null when the tagName is set.
result.tagName = element.localName().impl();
}
static unsigned computePresentationAttributeCacheHash(const PresentationAttributeCacheKey& key)
{
if (!key.tagName)
return 0;
ASSERT(key.attributesAndValues.size());
unsigned attributeHash = StringHasher::hashMemory(key.attributesAndValues.data(), key.attributesAndValues.size() * sizeof(key.attributesAndValues[0]));
return WTF::pairIntHash(key.tagName->existingHash(), attributeHash);
}
PassRefPtr<StylePropertySet> computePresentationAttributeStyle(Element& element)
{
DEFINE_STATIC_LOCAL(PresentationAttributeCacheCleaner, cacheCleaner, ());
ASSERT(element.isStyledElement());
PresentationAttributeCacheKey cacheKey;
makePresentationAttributeCacheKey(element, cacheKey);
unsigned cacheHash = computePresentationAttributeCacheHash(cacheKey);
PresentationAttributeCache::ValueType* cacheValue;
if (cacheHash) {
cacheValue = presentationAttributeCache().add(cacheHash, nullptr).storedValue;
if (cacheValue->value && cacheValue->value->key != cacheKey)
cacheHash = 0;
} else {
cacheValue = 0;
}
RefPtr<StylePropertySet> style;
if (cacheHash && cacheValue->value) {
style = cacheValue->value->value;
cacheCleaner.didHitPresentationAttributeCache();
} else {
style = MutableStylePropertySet::create(element.isSVGElement() ? SVGAttributeMode : HTMLAttributeMode);
AttributeCollection attributes = element.attributes();
AttributeCollection::const_iterator end = attributes.end();
for (AttributeCollection::const_iterator it = attributes.begin(); it != end; ++it)
element.collectStyleForPresentationAttribute(it->name(), it->value(), toMutableStylePropertySet(style));
}
if (!cacheHash || cacheValue->value)
return style.release();
OwnPtr<PresentationAttributeCacheEntry> newEntry = adoptPtr(new PresentationAttributeCacheEntry);
newEntry->key = cacheKey;
newEntry->value = style;
static const unsigned presentationAttributeCacheMaximumSize = 4096;
if (presentationAttributeCache().size() > presentationAttributeCacheMaximumSize) {
// FIXME: Discarding the entire cache when it gets too big is probably bad
// since it creates a perf "cliff". Perhaps we should use an LRU?
presentationAttributeCache().clear();
presentationAttributeCache().set(cacheHash, newEntry.release());
} else {
cacheValue->value = newEntry.release();
}
return style.release();
}
} // namespace WebCore
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