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/*
* Copyright (C) 2010 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:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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 "core/html/parser/HTMLParserScheduler.h"
#include "core/dom/Document.h"
#include "core/frame/FrameView.h"
#include "core/html/parser/HTMLDocumentParser.h"
#include "public/platform/Platform.h"
#include "public/platform/WebScheduler.h"
#include "public/platform/WebThread.h"
#include "wtf/CurrentTime.h"
#include "wtf/PtrUtil.h"
namespace blink {
PumpSession::PumpSession(unsigned& nestingLevel)
: NestingLevelIncrementer(nestingLevel)
{
}
PumpSession::~PumpSession()
{
}
SpeculationsPumpSession::SpeculationsPumpSession(unsigned& nestingLevel)
: NestingLevelIncrementer(nestingLevel)
, m_startTime(currentTime())
, m_processedElementTokens(0)
{
}
SpeculationsPumpSession::~SpeculationsPumpSession()
{
}
inline double SpeculationsPumpSession::elapsedTime() const
{
return currentTime() - m_startTime;
}
void SpeculationsPumpSession::addedElementTokens(size_t count)
{
m_processedElementTokens += count;
}
HTMLParserScheduler::HTMLParserScheduler(HTMLDocumentParser* parser, WebTaskRunner* loadingTaskRunner)
: m_parser(parser)
, m_loadingTaskRunner(wrapUnique(loadingTaskRunner->clone()))
, m_cancellableContinueParse(CancellableTaskFactory::create(this, &HTMLParserScheduler::continueParsing))
, m_isSuspendedWithActiveTimer(false)
{
}
HTMLParserScheduler::~HTMLParserScheduler()
{
}
DEFINE_TRACE(HTMLParserScheduler)
{
visitor->trace(m_parser);
}
void HTMLParserScheduler::scheduleForResume()
{
ASSERT(!m_isSuspendedWithActiveTimer);
m_loadingTaskRunner->postTask(BLINK_FROM_HERE, m_cancellableContinueParse->cancelAndCreate());
}
void HTMLParserScheduler::suspend()
{
ASSERT(!m_isSuspendedWithActiveTimer);
if (!m_cancellableContinueParse->isPending())
return;
m_isSuspendedWithActiveTimer = true;
m_cancellableContinueParse->cancel();
}
void HTMLParserScheduler::resume()
{
ASSERT(!m_cancellableContinueParse->isPending());
if (!m_isSuspendedWithActiveTimer)
return;
m_isSuspendedWithActiveTimer = false;
m_loadingTaskRunner->postTask(BLINK_FROM_HERE, m_cancellableContinueParse->cancelAndCreate());
}
void HTMLParserScheduler::detach()
{
m_cancellableContinueParse->cancel();
m_isSuspendedWithActiveTimer = false;
}
inline bool HTMLParserScheduler::shouldYield(const SpeculationsPumpSession& session, bool startingScript) const
{
if (Platform::current()->currentThread()->scheduler()->shouldYieldForHighPriorityWork())
return true;
const double parserTimeLimit = 0.5;
if (session.elapsedTime() > parserTimeLimit)
return true;
// Yield if a lot of DOM work has been done in this session and a script tag is
// about to be parsed. This significantly improves render performance for documents
// that place their scripts at the bottom of the page. Yielding too often
// significantly slows down the parsing so a balance needs to be struck to
// only yield when enough changes have happened to make it worthwhile.
// Emperical testing shows that anything > ~40 and < ~200 gives all of the benefit
// without impacting parser performance, only adding a few yields per page but at
// just the right times.
const size_t sufficientWork = 50;
if (startingScript && session.processedElementTokens() > sufficientWork)
return true;
return false;
}
bool HTMLParserScheduler::yieldIfNeeded(const SpeculationsPumpSession& session, bool startingScript)
{
if (shouldYield(session, startingScript)) {
scheduleForResume();
return true;
}
return false;
}
void HTMLParserScheduler::forceResumeAfterYield()
{
ASSERT(!m_cancellableContinueParse->isPending());
m_isSuspendedWithActiveTimer = true;
}
void HTMLParserScheduler::continueParsing()
{
m_parser->resumeParsingAfterYield();
}
} // namespace blink