HTMLParserScheduler.cpp revision 81bc750723a18f21cd17d1b173cd2a4dda9cea6e 
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.
36static 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.
41static const double defaultParserTimeLimit = 0.500;
42
43namespace WebCore {
44
45static 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
53static 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
63HTMLParserScheduler::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
72HTMLParserScheduler::~HTMLParserScheduler()
73{
74    m_continueNextChunkTimer.stop();
75}
76
77void 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
89void HTMLParserScheduler::scheduleForResume()
90{
91    m_continueNextChunkTimer.startOneShot(0);
92}
93
94
95void HTMLParserScheduler::suspend()
96{
97    ASSERT(!m_isSuspendedWithActiveTimer);
98    if (!m_continueNextChunkTimer.isActive())
99        return;
100    m_isSuspendedWithActiveTimer = true;
101    m_continueNextChunkTimer.stop();
102}
103
104void HTMLParserScheduler::resume()
105{
106    ASSERT(!m_continueNextChunkTimer.isActive());
107    if (!m_isSuspendedWithActiveTimer)
108        return;
109    m_isSuspendedWithActiveTimer = false;
110    m_continueNextChunkTimer.startOneShot(0);
111}
112
113}
114