Home | History | Annotate | Download | only in parser 
      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:
     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:
     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.
     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();
     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