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ArenaBlock.hpp

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00001 /*
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00003  *
00004  *
00005  * Copyright (c) 2000-2002 The Apache Software Foundation.  All rights 
00006  * reserved.
00007  *
00008  * Redistribution and use in source and binary forms, with or without
00009  * modification, are permitted provided that the following conditions
00010  * are met:
00011  *
00012  * 1. Redistributions of source code must retain the above copyright
00013  *    notice, this list of conditions and the following disclaimer. 
00014  *
00015  * 2. Redistributions in binary form must reproduce the above copyright
00016  *    notice, this list of conditions and the following disclaimer in
00017  *    the documentation and/or other materials provided with the
00018  *    distribution.
00019  *
00020  * 3. The end-user documentation included with the redistribution,
00021  *    if any, must include the following acknowledgment:  
00022  *       "This product includes software developed by the
00023  *        Apache Software Foundation (http://www.apache.org/)."
00024  *    Alternately, this acknowledgment may appear in the software itself,
00025  *    if and wherever such third-party acknowledgments normally appear.
00026  *
00027  * 4. The names "Xalan" and "Apache Software Foundation" must
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00032  * 5. Products derived from this software may not be called "Apache",
00033  *    nor may "Apache" appear in their name, without prior written
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00036  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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00048  * ====================================================================
00049  *
00050  * This software consists of voluntary contributions made by many
00051  * individuals on behalf of the Apache Software Foundation and was
00052  * originally based on software copyright (c) 1999, International
00053  * Business Machines, Inc., http://www.ibm.com.  For more
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00056  */
00057 
00058 #if !defined(ARENABLOCK_INCLUDE_GUARD_1357924680)
00059 #define ARENABLOCK_INCLUDE_GUARD_1357924680
00060 
00061 
00062 
00063 #include <algorithm>
00064 #include <cassert>
00065 #include <set>
00066 #include <memory>
00067 
00068 
00069 
00070 #if defined(XALAN_NO_STD_ALLOCATORS) && !defined(XALAN_NO_SELECTIVE_TEMPLATE_INSTANTIATION)
00071 #include <xalanc/PlatformSupport/XalanAllocator.hpp>
00072 #endif
00073 
00074 
00075 
00076 XALAN_CPP_NAMESPACE_BEGIN
00077 
00078 
00079 
00080 #if defined(XALAN_NO_SELECTIVE_TEMPLATE_INSTANTIATION)
00081 
00082 template <class Type>
00083 class ArenaBlockAllocator
00084 {
00085 public:
00086 
00087     typedef size_t          size_type;
00088     typedef ptrdiff_t       difference_type;
00089     typedef Type*           pointer;
00090     typedef const Type*     const_pointer;
00091     typedef Type&           reference;
00092     typedef const Type&     const_reference;
00093     typedef Type            value_type;
00094 
00095     ArenaBlockAllocator()
00096     {
00097     }
00098 
00099     ArenaBlockAllocator(const ArenaBlockAllocator<Type>&)
00100     {
00101     };
00102 
00103     ~ArenaBlockAllocator()
00104     {
00105     }
00106 
00107     pointer
00108     allocate(
00109             size_type       size,
00110             const void*     /* hint */ = 0)
00111     {
00112         return (pointer)operator new(size * sizeof(Type));
00113     }
00114 
00115     void
00116     deallocate(
00117                 pointer     p,
00118                 size_type   /* n */)
00119     {
00120         operator delete(p);
00121     }
00122 };
00123 #endif
00124 
00125 
00126 
00127 template<class ObjectType>
00128 class ArenaBlockDestroy
00129 {
00130 public:
00131 
00132     void
00133 	operator()(ObjectType& theObject) const
00134     {
00135 #if defined(XALAN_EXPLICIT_SCOPE_IN_TEMPLATE_BUG)
00136         theObject.~ObjectType();
00137 #else
00138         theObject.ObjectType::~ObjectType();
00139 #endif
00140     }
00141 };
00142 
00143 
00144 
00145 template<class ObjectType>
00146 class ArenaBlock
00147 {
00148 public:
00149 
00150 #if defined(XALAN_NO_SELECTIVE_TEMPLATE_INSTANTIATION)
00151     typedef ArenaBlockAllocator<ObjectType>     AllocatorType;
00152 #elif defined(XALAN_NO_STD_ALLOCATORS)
00153     typedef XalanAllocator<ObjectType>          AllocatorType;
00154 #else
00155     typedef std::allocator<ObjectType>          AllocatorType;
00156 #endif
00157 
00158     typedef ArenaBlockDestroy<ObjectType>       DestroyFunctionType;
00159 
00160     typedef typename AllocatorType::size_type   size_type;
00161 
00162     /*
00163      * Construct an ArenaBlock of the specified size
00164      * of objects.
00165      *
00166      * @param theBlockSize The size of the block (the number of objects it can contain).
00167      */
00168     ArenaBlock(size_type    theBlockSize) :
00169         m_destroyFunction(DestroyFunctionType()),
00170         m_objectCount(0),
00171         m_blockSize(theBlockSize),
00172         m_objectBlock(0),
00173         m_allocator()
00174     {
00175         assert(theBlockSize > 0);
00176     }
00177 
00178     virtual 
00179     ~ArenaBlock()
00180     {
00181         destroyAll();
00182 
00183         // Release the memory...
00184         m_allocator.deallocate(m_objectBlock, m_blockSize);
00185     }
00186 
00187     /*
00188      * Allocate a block.  Once the object is constructed, you must call
00189      * commitAllocation().
00190      *
00191      * @return a pointer to the new block.
00192      */
00193     virtual ObjectType*
00194     allocateBlock()
00195     {
00196         // Any space left?
00197         if (m_objectCount == m_blockSize)
00198         {
00199             return 0;
00200         }
00201         else
00202         {
00203             // If no memory has yet been allocated, then allocate it...
00204             if (m_objectBlock == 0)
00205             {
00206 #if defined(XALAN_NEW_STD_ALLOCATOR)
00207                 m_objectBlock = m_allocator.allocate(m_blockSize);
00208 #else
00209                 m_objectBlock = m_allocator.allocate(m_blockSize, 0);
00210 #endif
00211             }
00212             assert(m_objectBlock != 0);
00213 
00214             return m_objectBlock + m_objectCount;
00215         }
00216     }
00217 
00218     /*
00219      * Commit the previous allocation.
00220      *
00221      * @param theBlock the address that was returned by allocateBlock()
00222      */
00223     virtual void
00224 #if defined (NDEBUG)
00225     commitAllocation(ObjectType*    /* theBlock */)
00226 #else
00227     commitAllocation(ObjectType*    theBlock)
00228 #endif
00229     {
00230         assert(theBlock == m_objectBlock + m_objectCount);
00231         assert(m_objectCount < m_blockSize);
00232 
00233         m_objectCount++;
00234     }
00235 
00236     /*
00237      * Find out if there is a block available.
00238      *
00239      * @return true if one is available, false if not.
00240      */
00241     virtual bool
00242     blockAvailable() const
00243     {
00244         return m_objectCount < m_blockSize ? true : false;
00245     }
00246 
00247     /*
00248      * Get the number of objects currently allocated in the
00249      * block.
00250      *
00251      * @return The number of objects allocated.
00252      */
00253     virtual size_type
00254     getCountAllocated() const
00255     {
00256         return m_objectCount;
00257     }
00258 
00259     /*
00260      * Get the block size, that is, the number
00261      * of objects in each block.
00262      *
00263      * @return The size of the block
00264      */
00265     size_type
00266     getBlockSize() const
00267     {
00268         return m_blockSize;
00269     }
00270 
00271     /*
00272      * Determine if this block owns the specified object.  Note
00273      * that even if the object address is within our block, this
00274      * call will return false if no object currently occupies the
00275      * block.  See also ownsBlock().
00276      *
00277      * @param theObject the address of the object.
00278      * @return true if we own the object, false if not.
00279      */
00280     virtual bool
00281     ownsObject(const ObjectType*    theObject) const
00282     {
00283         // Use less<>, since it's guaranteed to do pointer
00284         // comparisons correctly...
00285         XALAN_STD_QUALIFIER less<const ObjectType*>     functor;
00286 
00287         if (functor(theObject, m_objectBlock) == false &&
00288             functor(theObject, m_objectBlock + m_objectCount) == true)
00289         {
00290             return true;
00291         }
00292         else
00293         {
00294             return false;
00295         }
00296     }
00297 
00298     /*
00299      * Determine if this block owns the specified object block.
00300      * Note that, unlike ownsObject(), there does not need to
00301      * be an object at the address.
00302      *
00303      * @param theObject the address of the object
00304      * @return true if we own the object block, false if not.
00305      */
00306     bool
00307     ownsBlock(const ObjectType*     theObject) const
00308     {
00309         // Use less<>, since it's guaranteed to do pointer
00310         // comparisons correctly...
00311         XALAN_STD_QUALIFIER less<const ObjectType*>     functor;
00312 
00313         if (functor(theObject, m_objectBlock) == false &&
00314             functor(theObject, m_objectBlock + m_blockSize) == true)
00315         {
00316             return true;
00317         }
00318         else
00319         {
00320             return false;
00321         }
00322     }
00323 
00324     /*
00325      * Destroy all objects in the block.  You can then reuse the
00326      * block.
00327      */
00328     void
00329     destroyAll()
00330     {
00331         // Destroy all existing objects...
00332         XALAN_STD_QUALIFIER for_each(m_objectBlock,
00333                  m_objectBlock + m_objectCount,
00334                  DeleteFunctor(*this, m_destroyFunction));
00335 
00336         m_objectCount = 0;
00337     }
00338 
00339 protected:
00340 
00341     /*
00342      * Determine if the block should be destroyed.  Called by
00343      * an instance of DeleteFunctor, this function is for
00344      * deriving classes that might want to control the destruction
00345      * of things.
00346      *
00347      * @param theObject the address of the object
00348      * @return true if block should be destroyed, false if not.
00349      */
00350     virtual bool
00351     shouldDestroyBlock(const ObjectType*    /* theObject */) const
00352     {
00353         return true;
00354     }
00355 
00356     /*
00357      * Determine the offset into the block for the given address.
00358      * Behavior is undefined if the address is not within our
00359      * block
00360      *
00361      * @param theObject the address of the object
00362      * @return the offset
00363      */
00364     size_type
00365     getBlockOffset(const ObjectType*    theObject) const
00366     {
00367         assert(size_type(theObject - m_objectBlock) < m_blockSize);
00368 
00369         return theObject - m_objectBlock;
00370     }
00371 
00372     /*
00373      * Determine the address within our block of the object
00374      * at the specified offset.
00375      * Behavior is undefined if the offset is greater than the
00376      * block size.
00377      *
00378      * @param theObject the address of the object
00379      * @return the offset
00380      */
00381     ObjectType*
00382     getBlockAddress(size_type   theOffset) const
00383     {
00384         assert(theOffset < m_blockSize);
00385 
00386         return m_objectBlock + theOffset;
00387     }
00388 
00389     struct DeleteFunctor
00390     {
00391         DeleteFunctor(
00392                 const ArenaBlock<ObjectType>&   theArenaBlock,
00393                 const DestroyFunctionType&      theDestroyFunction) :
00394             m_arenaBlock(theArenaBlock),
00395             m_destroyFunction(theDestroyFunction)
00396         {
00397         }
00398 
00399         void
00400 		operator()(ObjectType&    theObject) const
00401         {
00402             if (m_arenaBlock.shouldDestroyBlock(&theObject) == true)
00403             {
00404                 m_destroyFunction(theObject);
00405             }
00406         }
00407 
00408     private:
00409 
00410         const ArenaBlock<ObjectType>&   m_arenaBlock;
00411         const DestroyFunctionType&      m_destroyFunction;
00412     };
00413 
00414     friend struct DeleteFunctor;
00415 
00416     const DestroyFunctionType   m_destroyFunction;
00417 
00418 private:
00419 
00420     // Not implemented...
00421     ArenaBlock(const ArenaBlock<ObjectType>&);
00422 
00423     ArenaBlock<ObjectType>&
00424     operator=(const ArenaBlock<ObjectType>&);
00425 
00426     bool
00427     operator==(const ArenaBlock<ObjectType>&) const;
00428 
00429 
00430     // data members...
00431     size_type           m_objectCount;
00432 
00433     const size_type     m_blockSize;
00434 
00435     ObjectType*         m_objectBlock;
00436 
00437     AllocatorType       m_allocator;
00438 };
00439 
00440 
00441 
00442 XALAN_CPP_NAMESPACE_END
00443 
00444 
00445 
00446 #endif  // !defined(ARENABLOCK_INCLUDE_GUARD_1357924680)

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