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 <limits.h>
30 
31 #include "NestingLevelIncrementer.h"
32 #include "Timer.h"
33 #include <wtf/CurrentTime.h>
34 #include <wtf/PassOwnPtr.h>
35 
36 namespace WebCore {
37 
38 class HTMLDocumentParser;
39 
40 class PumpSession : public NestingLevelIncrementer {
41 public:
PumpSession(unsigned & nestingLevel)42     PumpSession(unsigned& nestingLevel)
43         : NestingLevelIncrementer(nestingLevel)
44         // Setting processedTokens to INT_MAX causes us to check for yields
45         // after any token during any parse where yielding is allowed.
46         // At that time we'll initialize startTime.
47         , processedTokens(INT_MAX)
48         , startTime(0)
49         , needsYield(false)
50     {
51     }
52 
53     int processedTokens;
54     double startTime;
55     bool needsYield;
56 };
57 
58 class HTMLParserScheduler {
59     WTF_MAKE_NONCOPYABLE(HTMLParserScheduler); WTF_MAKE_FAST_ALLOCATED;
60 public:
create(HTMLDocumentParser * parser)61     static PassOwnPtr<HTMLParserScheduler> create(HTMLDocumentParser* parser)
62     {
63         return adoptPtr(new HTMLParserScheduler(parser));
64     }
65     ~HTMLParserScheduler();
66 
67     // Inline as this is called after every token in the parser.
checkForYieldBeforeToken(PumpSession & session)68     void checkForYieldBeforeToken(PumpSession& session)
69     {
70         if (session.processedTokens > m_parserChunkSize) {
71             // currentTime() can be expensive.  By delaying, we avoided calling
72             // currentTime() when constructing non-yielding PumpSessions.
73             if (!session.startTime)
74                 session.startTime = currentTime();
75 
76             session.processedTokens = 0;
77             double elapsedTime = currentTime() - session.startTime;
78             if (elapsedTime > m_parserTimeLimit)
79                 session.needsYield = true;
80         }
81         ++session.processedTokens;
82     }
83     void checkForYieldBeforeScript(PumpSession&);
84 
85     void scheduleForResume();
isScheduledForResume()86     bool isScheduledForResume() const { return m_isSuspendedWithActiveTimer || m_continueNextChunkTimer.isActive(); }
87 
88     void suspend();
89     void resume();
90 
91 private:
92     HTMLParserScheduler(HTMLDocumentParser*);
93 
94     void continueNextChunkTimerFired(Timer<HTMLParserScheduler>*);
95 
96     HTMLDocumentParser* m_parser;
97 
98     double m_parserTimeLimit;
99     int m_parserChunkSize;
100     Timer<HTMLParserScheduler> m_continueNextChunkTimer;
101     bool m_isSuspendedWithActiveTimer;
102 };
103 
104 }
105 
106 #endif
107