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 {

    69 }

    70 

    71 HTMLParserScheduler::~HTMLParserScheduler()

    72 {

    73     m_continueNextChunkTimer.stop();

    74 }

    75 

    76 // FIXME: This belongs on Document.

    77 static bool isLayoutTimerActive(Document* doc)

    78 {

    79     ASSERT(doc);

    80     return doc->view() && doc->view()->layoutPending() && !doc->minimumLayoutDelay();

    81 }

    82 

    83 void HTMLParserScheduler::continueNextChunkTimerFired(Timer<HTMLParserScheduler>* timer)

    84 {

    85     ASSERT_UNUSED(timer, timer == &m_continueNextChunkTimer);

    86     // FIXME: The timer class should handle timer priorities instead of this code.

    87     // If a layout is scheduled, wait again to let the layout timer run first.

    88     if (isLayoutTimerActive(m_parser->document())) {

    89         m_continueNextChunkTimer.startOneShot(0);

    90         return;

    91     }

    92     m_parser->resumeParsingAfterYield();

    93 }

    94 

    95 }