bytecode/EvalCodeCache.h

   1 /*
   2  * Copyright (C) 2008, 2009 Apple 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  *
   8  * 1.  Redistributions of source code must retain the above copyright
   9  *     notice, this list of conditions and the following disclaimer.
  10  * 2.  Redistributions in binary form must reproduce the above copyright
  11  *     notice, this list of conditions and the following disclaimer in the
  12  *     documentation and/or other materials provided with the distribution.
  13  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  14  *     its contributors may be used to endorse or promote products derived
  15  *     from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  18  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  20  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  22  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  23  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  24  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27  */
  28
  29 #ifndef EvalCodeCache_h
  30 #define EvalCodeCache_h
  31
  32 #include "Executable.h"
  33 #include "JSGlobalObject.h"
  34 #include "Nodes.h"
  35 #include "Parser.h"
  36 #include "SourceCode.h"
  37 #include "UString.h"
  38 #include <wtf/HashMap.h>
  39 #include <wtf/RefPtr.h>
  40 #include <wtf/text/StringHash.h>
  41
  42 namespace JSC {
  43
  44     class SlotVisitor;
  45
  46     class EvalCodeCache {
  47     public:
  48         EvalExecutable* tryGet(bool inStrictContext, const UString& evalSource, ScopeChainNode* scopeChain)
  49         {
  50             if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject())
  51                 return m_cacheMap.get(evalSource.impl()).get();
  52             return 0;
  53         }
  54
  55         EvalExecutable* getSlow(ExecState* exec, ScriptExecutable* owner, bool inStrictContext, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)
  56         {
  57             EvalExecutable* evalExecutable = EvalExecutable::create(exec, makeSource(evalSource), inStrictContext);
  58             exceptionValue = evalExecutable->compile(exec, scopeChain);
  59             if (exceptionValue)
  60                 return 0;
  61
  62             if (!inStrictContext && evalSource.length() < maxCacheableSourceLength && (*scopeChain->begin())->isVariableObject() && m_cacheMap.size() < maxCacheEntries)
  63                 m_cacheMap.set(evalSource.impl(), WriteBarrier<EvalExecutable>(exec->globalData(), owner, evalExecutable));
  64
  65             return evalExecutable;
  66         }
  67
  68         EvalExecutable* get(ExecState* exec, ScriptExecutable* owner, bool inStrictContext, const UString& evalSource, ScopeChainNode* scopeChain, JSValue& exceptionValue)
  69         {
  70             EvalExecutable* evalExecutable = tryGet(inStrictContext, evalSource, scopeChain);
  71
  72             if (!evalExecutable)
  73                 evalExecutable = getSlow(exec, owner, inStrictContext, evalSource, scopeChain, exceptionValue);
  74
  75             return evalExecutable;
  76         }
  77
  78         bool isEmpty() const { return m_cacheMap.isEmpty(); }
  79
  80         void visitAggregate(SlotVisitor&);
  81
  82         void clear()
  83         {
  84             m_cacheMap.clear();
  85         }
  86
  87     private:
  88         static const unsigned maxCacheableSourceLength = 256;
  89         static const int maxCacheEntries = 64;
  90
  91         typedef HashMap<RefPtr<StringImpl>, WriteBarrier<EvalExecutable> > EvalCacheMap;
  92         EvalCacheMap m_cacheMap;
  93     };
  94
  95 } // namespace JSC
  96
  97 #endif // EvalCodeCache_h