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#pragma once
27
28#include "NestingLevelIncrementer.h"
29#include "Timer.h"
30#include <wtf/RefPtr.h>
31
32#if PLATFORM(IOS_FAMILY)
33#include "WebCoreThread.h"
34#endif
35
36namespace WebCore {
37
38class Document;
39class HTMLDocumentParser;
40
41class ActiveParserSession {
42public:
43 explicit ActiveParserSession(Document*);
44 ~ActiveParserSession();
45
46private:
47 RefPtr<Document> m_document;
48};
49
50class PumpSession : public NestingLevelIncrementer, public ActiveParserSession {
51public:
52 PumpSession(unsigned& nestingLevel, Document*);
53 ~PumpSession();
54
55 unsigned processedTokens;
56 MonotonicTime startTime;
57 bool didSeeScript;
58};
59
60class HTMLParserScheduler {
61 WTF_MAKE_NONCOPYABLE(HTMLParserScheduler); WTF_MAKE_FAST_ALLOCATED;
62public:
63 explicit HTMLParserScheduler(HTMLDocumentParser&);
64 ~HTMLParserScheduler();
65
66 bool shouldYieldBeforeToken(PumpSession& session)
67 {
68#if PLATFORM(IOS_FAMILY)
69 if (WebThreadShouldYield())
70 return true;
71#endif
72 if (UNLIKELY(m_documentHasActiveParserYieldTokens))
73 return true;
74
75 if (UNLIKELY(session.processedTokens > numberOfTokensBeforeCheckingForYield || session.didSeeScript))
76 return checkForYield(session);
77
78 ++session.processedTokens;
79 return false;
80 }
81 bool shouldYieldBeforeExecutingScript(PumpSession&);
82
83 void scheduleForResume();
84 bool isScheduledForResume() const { return m_isSuspendedWithActiveTimer || m_continueNextChunkTimer.isActive() || m_documentHasActiveParserYieldTokens; }
85
86 void suspend();
87 void resume();
88
89 void didBeginYieldingParser()
90 {
91 ASSERT(!m_documentHasActiveParserYieldTokens);
92 m_documentHasActiveParserYieldTokens = true;
93 }
94
95 void didEndYieldingParser()
96 {
97 ASSERT(m_documentHasActiveParserYieldTokens);
98 m_documentHasActiveParserYieldTokens = false;
99
100 if (!isScheduledForResume())
101 scheduleForResume();
102 }
103
104private:
105 static const unsigned numberOfTokensBeforeCheckingForYield = 4096; // Performance optimization
106
107 void continueNextChunkTimerFired();
108
109 bool checkForYield(PumpSession& session)
110 {
111 session.processedTokens = 1;
112 session.didSeeScript = false;
113
114 // MonotonicTime::now() can be expensive. By delaying, we avoided calling
115 // MonotonicTime::now() when constructing non-yielding PumpSessions.
116 if (!session.startTime) {
117 session.startTime = MonotonicTime::now();
118 return false;
119 }
120
121 Seconds elapsedTime = MonotonicTime::now() - session.startTime;
122 return elapsedTime > m_parserTimeLimit;
123 }
124
125 HTMLDocumentParser& m_parser;
126
127 Seconds m_parserTimeLimit;
128 Timer m_continueNextChunkTimer;
129 bool m_isSuspendedWithActiveTimer;
130#if !ASSERT_DISABLED
131 bool m_suspended;
132#endif
133 bool m_documentHasActiveParserYieldTokens { false };
134};
135
136} // namespace WebCore
137