src/PlatformSupport/ReusableArenaBlock.hpp - xalan-c - Git at Google

 /*
  * The Apache Software License, Version 1.1
  *
  *
  * Copyright (c) 2000 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution,
  *    if any, must include the following acknowledgment:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowledgment may appear in the software itself,
  *    if and wherever such third-party acknowledgments normally appear.
  *
  * 4. The names "Xalan" and "Apache Software Foundation" must
  *    not be used to endorse or promote products derived from this
  *    software without prior written permission. For written
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache",
  *    nor may "Apache" appear in their name, without prior written
  *    permission of the Apache Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation and was
  * originally based on software copyright (c) 1999, International
  * Business Machines, Inc., http://www.ibm.com.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  */

 #if !defined(REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680)
 #define REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680


 #include <PlatformSupport/XalanBitmap.hpp>
 #include <PlatformSupport/ArenaBlock.hpp>


 template<class ObjectType>
 class ReusableArenaBlock : public ArenaBlock<ObjectType>
 {
 public:

 	typedef ArenaBlock<ObjectType>				BaseClassType;

 	typedef typename BaseClassType::size_type	size_type;

 	/*
 	 * Construct an ArenaBlock of the specified size
 	 * of objects.
 	 *
 	 * @param theBlockSize The size of the block (the number of objects it can contain).
 	 */
 	ReusableArenaBlock(size_type	theBlockSize) :
 		BaseClassType(theBlockSize),
 		m_freeList(theBlockSize),
 		m_freeBlockCount(0)
 	{
 	}

 	~ReusableArenaBlock()
 	{
 		// Note that this-> is required by template lookup rules.
 		this->destroyAll();
 	}

 	/*
 	 * Allocate a block.  Once the object is constructed, you must call
 	 * commitAllocation().
 	 *
 	 * @return a pointer to the new block.
 	 */
 	virtual ObjectType*
 	allocateBlock()
 	{
 		if (m_freeBlockCount == 0)
 		{
 			return BaseClassType::allocateBlock();
 		}
 		else
 		{
 			return getNextFromFreeList();
 		}
 	}

 	/*
 	 * Commit the previous allocation.
 	 *
 	 * @param theBlock the address that was returned by allocateBlock()
 	 */
 	virtual void
 	commitAllocation(ObjectType*	theBlock)
 	{
 		assert(theBlock != 0);
 		assert(m_freeBlockCount == 0 ||
 			   theBlock == getNextFromFreeList());

 		if (m_freeBlockCount == 0)
 		{
 			BaseClassType::commitAllocation(theBlock);
 		}
 		else
 		{
 			removeFromFreeList(theBlock);
 		}
 	}

 	/*
 	 * Find out if there is a block available.
 	 *
 	 * @return true if one is available, false if not.
 	 */
 	virtual bool
 	blockAvailable() const
 	{
 		return m_freeBlockCount != 0 ? true : BaseClassType::blockAvailable();
 	}

 	/*
 	 * Get the number of objects currently allocated in the
 	 * block.
 	 *
 	 * @return The number of objects allocated.
 	 */
 	virtual size_type
 	getCountAllocated() const
 	{
 		return BaseClassType::getCountAllocated() - m_freeBlockCount;
 	}

 	/*
 	 * Determine if this block owns the specified object.  Note
 	 * that even if the object address is within our block, this
 	 * call will return false if no object currently occupies the
 	 * block.  See also ownsBlock().
 	 *
 	 * @param theObject the address of the object.
 	 * @return true if we own the object, false if not.
 	 */
 	virtual bool
 	ownsObject(const ObjectType*	theObject) const
 	{
 		return BaseClassType::ownsObject(theObject) && !isOnFreeList(theObject);
 	}

 	/*
 	 * Destroy the object, and return the block to the free list.
 	 * The behavior is undefined if the object pointed to is not
 	 * owned by the block.
 	 *
 	 * @param theObject the address of the object.
 	 */
 	void
 	destroyObject(ObjectType*	theObject)
 	{
 		assert(ownsObject(theObject) == true);

 		m_destroyFunction(*theObject);

 		addToFreeList(theObject);
 	}

 protected:

 	/*
 	 * Determine if the block should be destroyed.  Returns true,
 	 * unless the object is on the free list.  The behavior is
 	 * undefined if the object pointed to is not owned by the
 	 * block.
 	 *
 	 * @param theObject the address of the object
 	 * @return true if block should be destroyed, false if not.
 	 */
 	virtual bool
 	shouldDestroyBlock(const ObjectType*	theObject) const
 	{
 		return !isOnFreeList(theObject);
 	}

 private:

 	// Not implemented...
 	ReusableArenaBlock(const ReusableArenaBlock<ObjectType>&);

 	ReusableArenaBlock<ObjectType>&
 	operator=(const ReusableArenaBlock<ObjectType>&);

 	bool
 	operator==(const ReusableArenaBlock<ObjectType>&) const;


 	/*
 	 * Determine if the block is on the free list.  The behavior is
 	 * undefined if the object pointed to is not owned by the
 	 * block.
 	 *
 	 * @param theObject the address of the object
 	 * @return true if block is on the free list, false if not.
 	 */
 	bool
 	isOnFreeList(const ObjectType*	theObject) const
 	{
 		if (m_freeBlockCount == 0)
 		{
 			return false;
 		}
 		else
 		{
 			const size_type		theOffset =
 					getBlockOffset(theObject);

 			return m_freeList.isSet(theOffset);
 		}
 	}

 	/*
 	 * Add a block to the free list.  The behavior is
 	 * undefined if the object pointed to is not owned by the
 	 * block.
 	 *
 	 * @param theObject the address of the object
 	 */
 	void
 	addToFreeList(const ObjectType*		theObject)
 	{
 		const size_type		theOffset =
 				getBlockOffset(theObject);

 		m_freeList.set(theOffset);

 		++m_freeBlockCount;
 	}

 	/*
 	 * Remove a block from the free list.  The behavior is
 	 * undefined if the object pointed to is not owned by the
 	 * block.
 	 *
 	 * @param theObject the address of the object
 	 */
 	void
 	removeFromFreeList(const ObjectType*	theObject)
 	{
 		const size_type		theOffset =
 				getBlockOffset(theObject);

 		m_freeList.clear(theOffset);

 		--m_freeBlockCount;
 	}

 	/*
 	 * Get the next block from the free list.  Returns 0 if
 	 * the free list is empty.
 	 *
 	 * @return the address of the block
 	 */
 	ObjectType*
 	getNextFromFreeList()
 	{
 		ObjectType*		theResult = 0;

 		if (m_freeBlockCount > 0)
 		{
 			const size_type		theFreeListSize = m_freeList.getSize();

 			for(size_type i = 0; i < theFreeListSize; ++i)
 			{
 				if (m_freeList.isSet(i) == true)
 				{
 					// Note that this-> is required by template lookup rules.
 					theResult = this->getBlockAddress(i);

 					break;
 				}
 			}
 		}

 		return theResult;
 	}

 	// Bitmap which tracks which blocks are not in use
 	// and that should not be destroyed.
 	XalanBitmap		m_freeList;

 	// The number of blocks on the free list.)
 	size_type		m_freeBlockCount;
 };


 #endif	// !defined(REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680)
	/*
	* The Apache Software License, Version 1.1
	*
	*
	* Copyright (c) 2000 The Apache Software Foundation. All rights
	* reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. The end-user documentation included with the redistribution,
	* if any, must include the following acknowledgment:
	* "This product includes software developed by the
	* Apache Software Foundation (http://www.apache.org/)."
	* Alternately, this acknowledgment may appear in the software itself,
	* if and wherever such third-party acknowledgments normally appear.
	*
	* 4. The names "Xalan" and "Apache Software Foundation" must
	* not be used to endorse or promote products derived from this
	* software without prior written permission. For written
	* permission, please contact apache@apache.org.
	*
	* 5. Products derived from this software may not be called "Apache",
	* nor may "Apache" appear in their name, without prior written
	* permission of the Apache Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	* ====================================================================
	*
	* This software consists of voluntary contributions made by many
	* individuals on behalf of the Apache Software Foundation and was
	* originally based on software copyright (c) 1999, International
	* Business Machines, Inc., http://www.ibm.com. For more
	* information on the Apache Software Foundation, please see
	* <http://www.apache.org/>.
	*/

	#if !defined(REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680)
	#define REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680



	#include <PlatformSupport/XalanBitmap.hpp>
	#include <PlatformSupport/ArenaBlock.hpp>




	template<class ObjectType>
	class ReusableArenaBlock : public ArenaBlock<ObjectType>
	{
	public:

	typedef ArenaBlock<ObjectType> BaseClassType;

	typedef typename BaseClassType::size_type size_type;

	/*
	* Construct an ArenaBlock of the specified size
	* of objects.
	*
	* @param theBlockSize The size of the block (the number of objects it can contain).
	*/
	ReusableArenaBlock(size_type theBlockSize) :
	BaseClassType(theBlockSize),
	m_freeList(theBlockSize),
	m_freeBlockCount(0)
	{
	}

	~ReusableArenaBlock()
	{
	// Note that this-> is required by template lookup rules.
	this->destroyAll();
	}

	/*
	* Allocate a block. Once the object is constructed, you must call
	* commitAllocation().
	*
	* @return a pointer to the new block.
	*/
	virtual ObjectType*
	allocateBlock()
	{
	if (m_freeBlockCount == 0)
	{
	return BaseClassType::allocateBlock();
	}
	else
	{
	return getNextFromFreeList();
	}
	}

	/*
	* Commit the previous allocation.
	*
	* @param theBlock the address that was returned by allocateBlock()
	*/
	virtual void
	commitAllocation(ObjectType* theBlock)
	{
	assert(theBlock != 0);
	assert(m_freeBlockCount == 0 \|\|
	theBlock == getNextFromFreeList());

	if (m_freeBlockCount == 0)
	{
	BaseClassType::commitAllocation(theBlock);
	}
	else
	{
	removeFromFreeList(theBlock);
	}
	}

	/*
	* Find out if there is a block available.
	*
	* @return true if one is available, false if not.
	*/
	virtual bool
	blockAvailable() const
	{
	return m_freeBlockCount != 0 ? true : BaseClassType::blockAvailable();
	}

	/*
	* Get the number of objects currently allocated in the
	* block.
	*
	* @return The number of objects allocated.
	*/
	virtual size_type
	getCountAllocated() const
	{
	return BaseClassType::getCountAllocated() - m_freeBlockCount;
	}

	/*
	* Determine if this block owns the specified object. Note
	* that even if the object address is within our block, this
	* call will return false if no object currently occupies the
	* block. See also ownsBlock().
	*
	* @param theObject the address of the object.
	* @return true if we own the object, false if not.
	*/
	virtual bool
	ownsObject(const ObjectType* theObject) const
	{
	return BaseClassType::ownsObject(theObject) && !isOnFreeList(theObject);
	}

	/*
	* Destroy the object, and return the block to the free list.
	* The behavior is undefined if the object pointed to is not
	* owned by the block.
	*
	* @param theObject the address of the object.
	*/
	void
	destroyObject(ObjectType* theObject)
	{
	assert(ownsObject(theObject) == true);

	m_destroyFunction(*theObject);

	addToFreeList(theObject);
	}

	protected:

	/*
	* Determine if the block should be destroyed. Returns true,
	* unless the object is on the free list. The behavior is
	* undefined if the object pointed to is not owned by the
	* block.
	*
	* @param theObject the address of the object
	* @return true if block should be destroyed, false if not.
	*/
	virtual bool
	shouldDestroyBlock(const ObjectType* theObject) const
	{
	return !isOnFreeList(theObject);
	}

	private:

	// Not implemented...
	ReusableArenaBlock(const ReusableArenaBlock<ObjectType>&);

	ReusableArenaBlock<ObjectType>&
	operator=(const ReusableArenaBlock<ObjectType>&);

	bool
	operator==(const ReusableArenaBlock<ObjectType>&) const;


	/*
	* Determine if the block is on the free list. The behavior is
	* undefined if the object pointed to is not owned by the
	* block.
	*
	* @param theObject the address of the object
	* @return true if block is on the free list, false if not.
	*/
	bool
	isOnFreeList(const ObjectType* theObject) const
	{
	if (m_freeBlockCount == 0)
	{
	return false;
	}
	else
	{
	const size_type theOffset =
	getBlockOffset(theObject);

	return m_freeList.isSet(theOffset);
	}
	}

	/*
	* Add a block to the free list. The behavior is
	* undefined if the object pointed to is not owned by the
	* block.
	*
	* @param theObject the address of the object
	*/
	void
	addToFreeList(const ObjectType* theObject)
	{
	const size_type theOffset =
	getBlockOffset(theObject);

	m_freeList.set(theOffset);

	++m_freeBlockCount;
	}

	/*
	* Remove a block from the free list. The behavior is
	* undefined if the object pointed to is not owned by the
	* block.
	*
	* @param theObject the address of the object
	*/
	void
	removeFromFreeList(const ObjectType* theObject)
	{
	const size_type theOffset =
	getBlockOffset(theObject);

	m_freeList.clear(theOffset);

	--m_freeBlockCount;
	}

	/*
	* Get the next block from the free list. Returns 0 if
	* the free list is empty.
	*
	* @return the address of the block
	*/
	ObjectType*
	getNextFromFreeList()
	{
	ObjectType* theResult = 0;

	if (m_freeBlockCount > 0)
	{
	const size_type theFreeListSize = m_freeList.getSize();

	for(size_type i = 0; i < theFreeListSize; ++i)
	{
	if (m_freeList.isSet(i) == true)
	{
	// Note that this-> is required by template lookup rules.
	theResult = this->getBlockAddress(i);

	break;
	}
	}
	}

	return theResult;
	}

	// Bitmap which tracks which blocks are not in use
	// and that should not be destroyed.
	XalanBitmap m_freeList;

	// The number of blocks on the free list.)
	size_type m_freeBlockCount;
	};



	#endif // !defined(REUSABLEARENABLOCK_INCLUDE_GUARD_1357924680)