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      1 /*
      2  * Copyright (C) 2010 Google, Inc. All Rights Reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "HTMLParserScheduler.h"
     28 
     29 #include "FrameView.h" // Only for isLayoutTimerActive
     30 #include "HTMLDocumentParser.h"
     31 #include "Document.h"
     32 
     33 // defaultParserChunkSize is used to define how many tokens the parser will
     34 // process before checking against parserTimeLimit and possibly yielding.
     35 // This is a performance optimization to prevent checking after every token.
     36 static const int defaultParserChunkSize = 4096;
     37 
     38 // defaultParserTimeLimit is the seconds the parser will run in one write() call
     39 // before yielding.  Inline <script> execution can cause it to excede the limit.
     40 // FIXME: We would like this value to be 0.2.
     41 static const double defaultParserTimeLimit = 0.500;
     42 
     43 namespace WebCore {
     44 
     45 static double parserTimeLimit(Page* page)
     46 {
     47     // We're using the poorly named customHTMLTokenizerTimeDelay setting.
     48     if (page && page->hasCustomHTMLTokenizerTimeDelay())
     49         return page->customHTMLTokenizerTimeDelay();
     50     return defaultParserTimeLimit;
     51 }
     52 
     53 static int parserChunkSize(Page* page)
     54 {
     55     // FIXME: We may need to divide the value from customHTMLTokenizerChunkSize
     56     // by some constant to translate from the "character" based behavior of the
     57     // old LegacyHTMLDocumentParser to the token-based behavior of this parser.
     58     if (page && page->hasCustomHTMLTokenizerChunkSize())
     59         return page->customHTMLTokenizerChunkSize();
     60     return defaultParserChunkSize;
     61 }
     62 
     63 HTMLParserScheduler::HTMLParserScheduler(HTMLDocumentParser* parser)
     64     : m_parser(parser)
     65     , m_parserTimeLimit(parserTimeLimit(m_parser->document()->page()))
     66     , m_parserChunkSize(parserChunkSize(m_parser->document()->page()))
     67     , m_continueNextChunkTimer(this, &HTMLParserScheduler::continueNextChunkTimerFired)
     68     , m_isSuspendedWithActiveTimer(false)
     69 {
     70 }
     71 
     72 HTMLParserScheduler::~HTMLParserScheduler()
     73 {
     74     m_continueNextChunkTimer.stop();
     75 }
     76 
     77 void HTMLParserScheduler::continueNextChunkTimerFired(Timer<HTMLParserScheduler>* timer)
     78 {
     79     ASSERT_UNUSED(timer, timer == &m_continueNextChunkTimer);
     80     // FIXME: The timer class should handle timer priorities instead of this code.
     81     // If a layout is scheduled, wait again to let the layout timer run first.
     82     if (m_parser->document()->isLayoutTimerActive()) {
     83         m_continueNextChunkTimer.startOneShot(0);
     84         return;
     85     }
     86     m_parser->resumeParsingAfterYield();
     87 }
     88 
     89 void HTMLParserScheduler::checkForYieldBeforeScript(PumpSession& session)
     90 {
     91     // If we've never painted before and a layout is pending, yield prior to running
     92     // scripts to give the page a chance to paint earlier.
     93     Document* document = m_parser->document();
     94     bool needsFirstPaint = document->view() && !document->view()->hasEverPainted();
     95     if (needsFirstPaint && document->isLayoutTimerActive())
     96         session.needsYield = true;
     97 }
     98 
     99 void HTMLParserScheduler::scheduleForResume()
    100 {
    101     m_continueNextChunkTimer.startOneShot(0);
    102 }
    103 
    104 
    105 void HTMLParserScheduler::suspend()
    106 {
    107     ASSERT(!m_isSuspendedWithActiveTimer);
    108     if (!m_continueNextChunkTimer.isActive())
    109         return;
    110     m_isSuspendedWithActiveTimer = true;
    111     m_continueNextChunkTimer.stop();
    112 }
    113 
    114 void HTMLParserScheduler::resume()
    115 {
    116     ASSERT(!m_continueNextChunkTimer.isActive());
    117     if (!m_isSuspendedWithActiveTimer)
    118         return;
    119     m_isSuspendedWithActiveTimer = false;
    120     m_continueNextChunkTimer.startOneShot(0);
    121 }
    122 
    123 }
    124