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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:
* 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 GOOGLE 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 GOOGLE 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 "config.h"
#if ENABLE(THREADED_HTML_PARSER)
#include "BackgroundHTMLParser.h"
#include "HTMLDocumentParser.h"
#include "HTMLParserThread.h"
#include "HTMLTokenizer.h"
#include "XSSAuditor.h"
#include <wtf/MainThread.h>
#include <wtf/text/TextPosition.h>
namespace WebCore {
// On a network with high latency and high bandwidth, using a device
// with a fast CPU, we could end up speculatively tokenizing
// the whole document, well ahead of when the main-thread actually needs it.
// This is a waste of memory (and potentially time if the speculation fails).
// So we limit our outstanding speculations arbitrarily to 10.
// Our maximal memory spent speculating will be approximately:
// outstandingCheckpointLimit * pendingTokenLimit * sizeof(CompactToken)
// We use a separate low and high water mark to avoid constantly topping
// off the main thread's token buffer.
// At time of writing, this is 10 * 1000 * 28 bytes = appox 280kb of memory.
// These numbers have not been tuned.
static const size_t outstandingCheckpointLimit = 10;
// We limit our chucks to 1000 tokens, to make sure the main
// thread is never waiting on the parser thread for tokens.
// This was tuned in https://bugs.webkit.org/show_bug.cgi?id=110408.
static const size_t pendingTokenLimit = 1000;
using namespace HTMLNames;
#ifndef NDEBUG
static void checkThatTokensAreSafeToSendToAnotherThread(const CompactHTMLTokenStream* tokens)
{
for (size_t i = 0; i < tokens->size(); ++i)
ASSERT(tokens->at(i).isSafeToSendToAnotherThread());
}
static void checkThatPreloadsAreSafeToSendToAnotherThread(const PreloadRequestStream& preloads)
{
for (size_t i = 0; i < preloads.size(); ++i)
ASSERT(preloads[i]->isSafeToSendToAnotherThread());
}
#endif
BackgroundHTMLParser::BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser> > reference, PassOwnPtr<Configuration> config)
: m_weakFactory(reference, this)
, m_token(adoptPtr(new HTMLToken))
, m_tokenizer(HTMLTokenizer::create(config->options))
, m_treeBuilderSimulator(config->options)
, m_options(config->options)
, m_parser(config->parser)
, m_pendingTokens(adoptPtr(new CompactHTMLTokenStream))
, m_xssAuditor(config->xssAuditor.release())
, m_preloadScanner(config->preloadScanner.release())
{
}
void BackgroundHTMLParser::append(const String& input)
{
ASSERT(!m_input.current().isClosed());
m_input.append(input);
pumpTokenizer();
}
void BackgroundHTMLParser::resumeFrom(PassOwnPtr<Checkpoint> checkpoint)
{
m_parser = checkpoint->parser;
m_token = checkpoint->token.release();
m_tokenizer = checkpoint->tokenizer.release();
m_treeBuilderSimulator.setState(checkpoint->treeBuilderState);
m_input.rewindTo(checkpoint->inputCheckpoint, checkpoint->unparsedInput);
m_preloadScanner->rewindTo(checkpoint->preloadScannerCheckpoint);
pumpTokenizer();
}
void BackgroundHTMLParser::startedChunkWithCheckpoint(HTMLInputCheckpoint inputCheckpoint)
{
// Note, we should not have to worry about the index being invalid
// as messages from the main thread will be processed in FIFO order.
m_input.invalidateCheckpointsBefore(inputCheckpoint);
pumpTokenizer();
}
void BackgroundHTMLParser::finish()
{
markEndOfFile();
pumpTokenizer();
}
void BackgroundHTMLParser::stop()
{
delete this;
}
void BackgroundHTMLParser::forcePlaintextForTextDocument()
{
// This is only used by the TextDocumentParser (a subclass of HTMLDocumentParser)
// to force us into the PLAINTEXT state w/o using a <plaintext> tag.
// The TextDocumentParser uses a <pre> tag for historical/compatibility reasons.
m_tokenizer->setState(HTMLTokenizer::PLAINTEXTState);
}
void BackgroundHTMLParser::markEndOfFile()
{
ASSERT(!m_input.current().isClosed());
m_input.append(String(&kEndOfFileMarker, 1));
m_input.close();
}
void BackgroundHTMLParser::pumpTokenizer()
{
// No need to start speculating until the main thread has almost caught up.
if (m_input.outstandingCheckpointCount() > outstandingCheckpointLimit)
return;
while (true) {
m_sourceTracker.start(m_input.current(), m_tokenizer.get(), *m_token);
if (!m_tokenizer->nextToken(m_input.current(), *m_token.get())) {
// We've reached the end of our current input.
sendTokensToMainThread();
break;
}
m_sourceTracker.end(m_input.current(), m_tokenizer.get(), *m_token);
{
TextPosition position = TextPosition(m_input.current().currentLine(), m_input.current().currentColumn());
if (OwnPtr<XSSInfo> xssInfo = m_xssAuditor->filterToken(FilterTokenRequest(*m_token, m_sourceTracker, m_tokenizer->shouldAllowCDATA()))) {
xssInfo->m_textPosition = position;
m_pendingXSSInfos.append(xssInfo.release());
}
CompactHTMLToken token(m_token.get(), TextPosition(m_input.current().currentLine(), m_input.current().currentColumn()));
m_preloadScanner->scan(token, m_pendingPreloads);
m_pendingTokens->append(token);
}
m_token->clear();
if (!m_treeBuilderSimulator.simulate(m_pendingTokens->last(), m_tokenizer.get()) || m_pendingTokens->size() >= pendingTokenLimit) {
sendTokensToMainThread();
// If we're far ahead of the main thread, yield for a bit to avoid consuming too much memory.
if (m_input.outstandingCheckpointCount() > outstandingCheckpointLimit)
break;
}
}
}
void BackgroundHTMLParser::sendTokensToMainThread()
{
if (m_pendingTokens->isEmpty())
return;
#ifndef NDEBUG
checkThatTokensAreSafeToSendToAnotherThread(m_pendingTokens.get());
checkThatPreloadsAreSafeToSendToAnotherThread(m_pendingPreloads);
#endif
OwnPtr<HTMLDocumentParser::ParsedChunk> chunk = adoptPtr(new HTMLDocumentParser::ParsedChunk);
chunk->tokens = m_pendingTokens.release();
chunk->preloads.swap(m_pendingPreloads);
chunk->xssInfos.swap(m_pendingXSSInfos);
chunk->tokenizerState = m_tokenizer->state();
chunk->treeBuilderState = m_treeBuilderSimulator.state();
chunk->inputCheckpoint = m_input.createCheckpoint();
chunk->preloadScannerCheckpoint = m_preloadScanner->createCheckpoint();
callOnMainThread(bind(&HTMLDocumentParser::didReceiveParsedChunkFromBackgroundParser, m_parser, chunk.release()));
m_pendingTokens = adoptPtr(new CompactHTMLTokenStream);
}
}
#endif // ENABLE(THREADED_HTML_PARSER)
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