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#ifndef HTMLParserScheduler_h
27#define HTMLParserScheduler_h
28
29#include "NestingLevelIncrementer.h"
30#include "Timer.h"
31#include <wtf/CurrentTime.h>
32#include <wtf/RefPtr.h>
33
34#if PLATFORM(IOS)
35#include "WebCoreThread.h"
36#endif
37
38namespace WebCore {
39
40class Document;
41class HTMLDocumentParser;
42
43class ActiveParserSession {
44public:
45    explicit ActiveParserSession(Document*);
46    ~ActiveParserSession();
47
48private:
49    RefPtr<Document> m_document;
50};
51
52class PumpSession : public NestingLevelIncrementer, public ActiveParserSession {
53public:
54    PumpSession(unsigned& nestingLevel, Document*);
55    ~PumpSession();
56
57    int processedTokens;
58    double startTime;
59    bool needsYield;
60    bool didSeeScript;
61};
62
63class HTMLParserScheduler {
64    WTF_MAKE_NONCOPYABLE(HTMLParserScheduler); WTF_MAKE_FAST_ALLOCATED;
65public:
66    explicit HTMLParserScheduler(HTMLDocumentParser&);
67    ~HTMLParserScheduler();
68
69    // Inline as this is called after every token in the parser.
70    void checkForYieldBeforeToken(PumpSession& session)
71    {
72#if PLATFORM(IOS)
73        if (WebThreadShouldYield())
74            session.needsYield = true;
75#endif
76        if (session.processedTokens > m_parserChunkSize || session.didSeeScript) {
77            // monotonicallyIncreasingTime() can be expensive. By delaying, we avoided calling
78            // monotonicallyIncreasingTime() when constructing non-yielding PumpSessions.
79            if (!session.startTime)
80                session.startTime = monotonicallyIncreasingTime();
81
82            session.processedTokens = 0;
83            session.didSeeScript = false;
84
85            double elapsedTime = monotonicallyIncreasingTime() - session.startTime;
86            if (elapsedTime > m_parserTimeLimit)
87                session.needsYield = true;
88        }
89        ++session.processedTokens;
90    }
91    void checkForYieldBeforeScript(PumpSession&);
92
93    void scheduleForResume();
94    bool isScheduledForResume() const { return m_isSuspendedWithActiveTimer || m_continueNextChunkTimer.isActive(); }
95
96    void suspend();
97    void resume();
98
99private:
100    void continueNextChunkTimerFired(Timer<HTMLParserScheduler>&);
101
102    HTMLDocumentParser& m_parser;
103
104    double m_parserTimeLimit;
105    int m_parserChunkSize;
106    Timer<HTMLParserScheduler> m_continueNextChunkTimer;
107    bool m_isSuspendedWithActiveTimer;
108#if !ASSERT_DISABLED
109    bool m_suspended;
110#endif
111};
112
113}
114
115#endif
116