HTMLParserScheduler.h [plain text]
#pragma once
#include "NestingLevelIncrementer.h"
#include "Timer.h"
#include <wtf/RefPtr.h>
#if PLATFORM(IOS)
#include "WebCoreThread.h"
#endif
namespace WebCore {
class Document;
class HTMLDocumentParser;
class ActiveParserSession {
public:
explicit ActiveParserSession(Document*);
~ActiveParserSession();
private:
RefPtr<Document> m_document;
};
class PumpSession : public NestingLevelIncrementer, public ActiveParserSession {
public:
PumpSession(unsigned& nestingLevel, Document*);
~PumpSession();
unsigned processedTokens;
MonotonicTime startTime;
bool didSeeScript;
};
class HTMLParserScheduler {
WTF_MAKE_NONCOPYABLE(HTMLParserScheduler); WTF_MAKE_FAST_ALLOCATED;
public:
explicit HTMLParserScheduler(HTMLDocumentParser&);
~HTMLParserScheduler();
bool shouldYieldBeforeToken(PumpSession& session)
{
#if PLATFORM(IOS)
if (WebThreadShouldYield())
return true;
#endif
if (UNLIKELY(m_documentHasActiveParserYieldTokens))
return true;
if (UNLIKELY(session.processedTokens > numberOfTokensBeforeCheckingForYield || session.didSeeScript))
return checkForYield(session);
++session.processedTokens;
return false;
}
bool shouldYieldBeforeExecutingScript(PumpSession&);
void scheduleForResume();
bool isScheduledForResume() const { return m_isSuspendedWithActiveTimer || m_continueNextChunkTimer.isActive() || m_documentHasActiveParserYieldTokens; }
void suspend();
void resume();
void didBeginYieldingParser()
{
ASSERT(!m_documentHasActiveParserYieldTokens);
m_documentHasActiveParserYieldTokens = true;
}
void didEndYieldingParser()
{
ASSERT(m_documentHasActiveParserYieldTokens);
m_documentHasActiveParserYieldTokens = false;
if (!isScheduledForResume())
scheduleForResume();
}
private:
static const unsigned numberOfTokensBeforeCheckingForYield = 4096;
void continueNextChunkTimerFired();
bool checkForYield(PumpSession& session)
{
session.processedTokens = 1;
session.didSeeScript = false;
if (!session.startTime) {
session.startTime = MonotonicTime::now();
return false;
}
Seconds elapsedTime = MonotonicTime::now() - session.startTime;
return elapsedTime > m_parserTimeLimit;
}
HTMLDocumentParser& m_parser;
Seconds m_parserTimeLimit;
Timer m_continueNextChunkTimer;
bool m_isSuspendedWithActiveTimer;
#if !ASSERT_DISABLED
bool m_suspended;
#endif
bool m_documentHasActiveParserYieldTokens { false };
};
}