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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 "core/html/parser/BackgroundHTMLParser.h"
#include "core/HTMLNames.h"
#include "core/html/parser/HTMLDocumentParser.h"
#include "core/html/parser/TextResourceDecoder.h"
#include "core/html/parser/XSSAuditor.h"
#include "platform/CrossThreadFunctional.h"
#include "platform/Histogram.h"
#include "platform/TraceEvent.h"
#include "public/platform/Platform.h"
#include "public/platform/WebTaskRunner.h"
#include "wtf/CurrentTime.h"
#include "wtf/PtrUtil.h"
#include "wtf/text/TextPosition.h"
#include <memory>
namespace blink {
// 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 tokens arbitrarily to 10,000.
// Our maximal memory spent speculating will be approximately:
// (defaultOutstandingTokenLimit + defaultPendingTokenLimit) *
// 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 (10000 + 1000) * 28 bytes = ~308kb of memory.
// These numbers have not been tuned.
static const size_t defaultOutstandingTokenLimit = 10000;
// 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 defaultPendingTokenLimit = 1000;
using namespace HTMLNames;
#if ENABLE(ASSERT)
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());
}
static void checkThatXSSInfosAreSafeToSendToAnotherThread(const XSSInfoStream& infos)
{
for (size_t i = 0; i < infos.size(); ++i)
ASSERT(infos[i]->isSafeToSendToAnotherThread());
}
#endif
void BackgroundHTMLParser::start(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, std::unique_ptr<Configuration> config, const KURL& documentURL, std::unique_ptr<CachedDocumentParameters> cachedDocumentParameters, const MediaValuesCached::MediaValuesCachedData& mediaValuesCachedData, std::unique_ptr<WebTaskRunner> loadingTaskRunner)
{
new BackgroundHTMLParser(reference, std::move(config), documentURL, std::move(cachedDocumentParameters), mediaValuesCachedData, std::move(loadingTaskRunner));
// Caller must free by calling stop().
}
BackgroundHTMLParser::Configuration::Configuration()
: outstandingTokenLimit(defaultOutstandingTokenLimit)
, pendingTokenLimit(defaultPendingTokenLimit)
{
}
BackgroundHTMLParser::BackgroundHTMLParser(PassRefPtr<WeakReference<BackgroundHTMLParser>> reference, std::unique_ptr<Configuration> config, const KURL& documentURL, std::unique_ptr<CachedDocumentParameters> cachedDocumentParameters, const MediaValuesCached::MediaValuesCachedData& mediaValuesCachedData, std::unique_ptr<WebTaskRunner> loadingTaskRunner)
: m_weakFactory(reference, this)
, m_token(wrapUnique(new HTMLToken))
, m_tokenizer(HTMLTokenizer::create(config->options))
, m_treeBuilderSimulator(config->options)
, m_options(config->options)
, m_outstandingTokenLimit(config->outstandingTokenLimit)
, m_parser(config->parser)
, m_pendingTokens(wrapUnique(new CompactHTMLTokenStream))
, m_pendingTokenLimit(config->pendingTokenLimit)
, m_xssAuditor(std::move(config->xssAuditor))
, m_preloadScanner(wrapUnique(new TokenPreloadScanner(documentURL, std::move(cachedDocumentParameters), mediaValuesCachedData)))
, m_decoder(std::move(config->decoder))
, m_loadingTaskRunner(std::move(loadingTaskRunner))
, m_parsedChunkQueue(config->parsedChunkQueue.release())
, m_startingScript(false)
, m_lastBytesReceivedTime(0.0)
{
ASSERT(m_outstandingTokenLimit > 0);
ASSERT(m_pendingTokenLimit > 0);
ASSERT(m_outstandingTokenLimit >= m_pendingTokenLimit);
}
BackgroundHTMLParser::~BackgroundHTMLParser()
{
}
void BackgroundHTMLParser::appendRawBytesFromMainThread(std::unique_ptr<Vector<char>> buffer, double bytesReceivedTime)
{
ASSERT(m_decoder);
m_lastBytesReceivedTime = bytesReceivedTime;
DEFINE_STATIC_LOCAL(CustomCountHistogram, queueDelay, ("Parser.AppendBytesDelay", 1, 5000, 50));
queueDelay.count(monotonicallyIncreasingTimeMS() - bytesReceivedTime);
updateDocument(m_decoder->decode(buffer->data(), buffer->size()));
}
void BackgroundHTMLParser::appendDecodedBytes(const String& input)
{
ASSERT(!m_input.current().isClosed());
m_input.append(input);
pumpTokenizer();
}
void BackgroundHTMLParser::setDecoder(std::unique_ptr<TextResourceDecoder> decoder)
{
ASSERT(decoder);
m_decoder = std::move(decoder);
}
void BackgroundHTMLParser::flush()
{
ASSERT(m_decoder);
updateDocument(m_decoder->flush());
}
void BackgroundHTMLParser::updateDocument(const String& decodedData)
{
DocumentEncodingData encodingData(*m_decoder.get());
if (encodingData != m_lastSeenEncodingData) {
m_lastSeenEncodingData = encodingData;
m_xssAuditor->setEncoding(encodingData.encoding());
runOnMainThread(crossThreadBind(&HTMLDocumentParser::didReceiveEncodingDataFromBackgroundParser, m_parser, encodingData));
}
if (decodedData.isEmpty())
return;
appendDecodedBytes(decodedData);
}
void BackgroundHTMLParser::resumeFrom(std::unique_ptr<Checkpoint> checkpoint)
{
m_parser = checkpoint->parser;
m_token = std::move(checkpoint->token);
m_tokenizer = std::move(checkpoint->tokenizer);
m_treeBuilderSimulator.setState(checkpoint->treeBuilderState);
m_input.rewindTo(checkpoint->inputCheckpoint, checkpoint->unparsedInput);
m_preloadScanner->rewindTo(checkpoint->preloadScannerCheckpoint);
m_startingScript = false;
m_parsedChunkQueue->clear();
m_lastBytesReceivedTime = monotonicallyIncreasingTimeMS();
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()
{
TRACE_EVENT0("loading", "BackgroundHTMLParser::pumpTokenizer");
HTMLTreeBuilderSimulator::SimulatedToken simulatedToken = HTMLTreeBuilderSimulator::OtherToken;
// No need to start speculating until the main thread has almost caught up.
if (m_input.totalCheckpointTokenCount() > m_outstandingTokenLimit)
return;
while (true) {
if (m_xssAuditor->isEnabled())
m_sourceTracker.start(m_input.current(), m_tokenizer.get(), *m_token);
if (!m_tokenizer->nextToken(m_input.current(), *m_token)) {
// We've reached the end of our current input.
sendTokensToMainThread();
break;
}
if (m_xssAuditor->isEnabled())
m_sourceTracker.end(m_input.current(), m_tokenizer.get(), *m_token);
{
TextPosition position = TextPosition(m_input.current().currentLine(), m_input.current().currentColumn());
if (std::unique_ptr<XSSInfo> xssInfo = m_xssAuditor->filterToken(FilterTokenRequest(*m_token, m_sourceTracker, m_tokenizer->shouldAllowCDATA()))) {
xssInfo->m_textPosition = position;
m_pendingXSSInfos.append(std::move(xssInfo));
}
CompactHTMLToken token(m_token.get(), position);
bool shouldEvaluateForDocumentWrite = false;
m_preloadScanner->scan(token, m_input.current(), m_pendingPreloads, &m_viewportDescription, &shouldEvaluateForDocumentWrite);
simulatedToken = m_treeBuilderSimulator.simulate(token, m_tokenizer.get());
// Break chunks before a script tag is inserted and flag the chunk as starting a script
// so the main parser can decide if it should yield before processing the chunk.
if (simulatedToken == HTMLTreeBuilderSimulator::ScriptStart) {
sendTokensToMainThread();
m_startingScript = true;
}
m_pendingTokens->append(token);
if (shouldEvaluateForDocumentWrite) {
m_likelyDocumentWriteScriptIndices.append(m_pendingTokens->size() - 1);
}
}
m_token->clear();
if (simulatedToken == HTMLTreeBuilderSimulator::ScriptEnd || m_pendingTokens->size() >= m_pendingTokenLimit) {
sendTokensToMainThread();
// If we're far ahead of the main thread, yield for a bit to avoid consuming too much memory.
if (m_input.totalCheckpointTokenCount() > m_outstandingTokenLimit)
break;
}
}
}
void BackgroundHTMLParser::sendTokensToMainThread()
{
if (m_pendingTokens->isEmpty())
return;
#if ENABLE(ASSERT)
checkThatTokensAreSafeToSendToAnotherThread(m_pendingTokens.get());
checkThatPreloadsAreSafeToSendToAnotherThread(m_pendingPreloads);
checkThatXSSInfosAreSafeToSendToAnotherThread(m_pendingXSSInfos);
#endif
double chunkStartTime = monotonicallyIncreasingTimeMS();
std::unique_ptr<HTMLDocumentParser::ParsedChunk> chunk = wrapUnique(new HTMLDocumentParser::ParsedChunk);
TRACE_EVENT_WITH_FLOW0("blink,loading", "BackgroundHTMLParser::sendTokensToMainThread", chunk.get(), TRACE_EVENT_FLAG_FLOW_OUT);
if (!m_pendingPreloads.isEmpty()) {
double delay = monotonicallyIncreasingTimeMS() - m_lastBytesReceivedTime;
DEFINE_STATIC_LOCAL(CustomCountHistogram, preloadTokenizeDelay, ("Parser.PreloadTokenizeDelay", 1, 10000, 50));
preloadTokenizeDelay.count(delay);
}
chunk->preloads.swap(m_pendingPreloads);
if (m_viewportDescription.set)
chunk->viewport = m_viewportDescription;
chunk->xssInfos.swap(m_pendingXSSInfos);
chunk->tokenizerState = m_tokenizer->getState();
chunk->treeBuilderState = m_treeBuilderSimulator.state();
chunk->inputCheckpoint = m_input.createCheckpoint(m_pendingTokens->size());
chunk->preloadScannerCheckpoint = m_preloadScanner->createCheckpoint();
chunk->tokens = std::move(m_pendingTokens);
chunk->startingScript = m_startingScript;
chunk->likelyDocumentWriteScriptIndices.swap(m_likelyDocumentWriteScriptIndices);
m_startingScript = false;
bool isEmpty = m_parsedChunkQueue->enqueue(std::move(chunk));
DEFINE_STATIC_LOCAL(CustomCountHistogram, chunkEnqueueTime, ("Parser.ChunkEnqueueTime", 1, 10000, 50));
chunkEnqueueTime.count(monotonicallyIncreasingTimeMS() - chunkStartTime);
if (isEmpty) {
runOnMainThread(crossThreadBind(&HTMLDocumentParser::notifyPendingParsedChunks, m_parser));
}
m_pendingTokens = wrapUnique(new CompactHTMLTokenStream);
}
// If the background parser is already running on the main thread, then it is
// not necessary to post a task to the main thread to run asynchronously. The
// main parser deals with chunking up its own work.
// TODO(csharrison): This is a pretty big hack because we don't actually need a
// CrossThreadClosure in these cases. This is just experimental.
void BackgroundHTMLParser::runOnMainThread(std::unique_ptr<CrossThreadClosure> closure)
{
if (isMainThread())
(*closure)();
else
m_loadingTaskRunner->postTask(BLINK_FROM_HERE, std::move(closure));
}
} // namespace blink