source: XMLIO_V2/external/src/POCO/Foundation.save/Poco/MemoryPool.h @ 80

//
// MemoryPool.h
//
// $Id: //poco/1.3/Foundation/include/Poco/MemoryPool.h#1 $
//
// Library: Foundation
// Package: Core
// Module:  MemoryPool
//
// Definition of the MemoryPool class.
//
// Copyright (c) 2005-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// Permission is hereby granted, free of charge, to any person or organization
// obtaining a copy of the software and accompanying documentation covered by
// this license (the "Software") to use, reproduce, display, distribute,
// execute, and transmit the Software, and to prepare derivative works of the
// Software, and to permit third-parties to whom the Software is furnished to
// do so, all subject to the following:
// 
// The copyright notices in the Software and this entire statement, including
// the above license grant, this restriction and the following disclaimer,
// must be included in all copies of the Software, in whole or in part, and
// all derivative works of the Software, unless such copies or derivative
// works are solely in the form of machine-executable object code generated by
// a source language processor.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//


#ifndef Foundation_MemoryPool_INCLUDED
#define Foundation_MemoryPool_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include <vector>
#include <cstddef>


namespace Poco {


class Foundation_API MemoryPool
        /// A simple pool for fixed-size memory blocks.
        ///
        /// The main purpose of this class is to speed-up
        /// memory allocations, as well as to reduce memory
        /// fragmentation in situations where the same blocks
        /// are allocated all over again, such as in server
        /// applications.
        ///
        /// All allocated blocks are retained for future use.
        /// A limit on the number of blocks can be specified.
        /// Blocks can be preallocated.
{
public:
        MemoryPool(std::size_t blockSize, int preAlloc = 0, int maxAlloc = 0);
                /// Creates a MemoryPool for blocks with the given blockSize.
                /// The number of blocks given in preAlloc are preallocated.
                
        ~MemoryPool();

        void* get();
                /// Returns a memory block. If there are no more blocks
                /// in the pool, a new block will be allocated.
                ///
                /// If maxAlloc blocks are already allocated, an
                /// OutOfMemoryException is thrown.
                
        void release(void* ptr);
                /// Releases a memory block and returns it to the pool.
        
        std::size_t blockSize() const;
                /// Returns the block size.
                
        int allocated() const;
                /// Returns the number of allocated blocks.
                
        int available() const;
                /// Returns the number of available blocks in the pool.

private:
        MemoryPool();
        MemoryPool(const MemoryPool&);
        MemoryPool& operator = (const MemoryPool&);
        
        enum
        {
                BLOCK_RESERVE = 128
        };
        
        typedef std::vector<char*> BlockVec;
        
        std::size_t _blockSize;
        int         _maxAlloc;
        int         _allocated;
        BlockVec    _blocks;
        FastMutex   _mutex;
};


//
// inlines
//
inline std::size_t MemoryPool::blockSize() const
{
        return _blockSize;
}


inline int MemoryPool::allocated() const
{
        return _allocated;
}


inline int MemoryPool::available() const
{
        return (int) _blocks.size();
}


} // namespace Poco


#endif // Foundation_MemoryPool_INCLUDED