unixsharedmemory.hpp

"More for C++" is a class library that provides some features that are usually common for object ori

//
//  This file is part of the "More for C++" library
//
//  Copyright (c) 1999-2003 by Thorsten Goertz ([e-mail])
//
//  The "More for C++" library is free software; you can redistribute it and/or
//  modify it under the terms of the license that comes with this package.
//
//  Read "license.txt" for more details.
//
//  THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
//  WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES
//  OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

////////////////////////////////////////////////////////////////////////////////

#ifndef UNIXSHAREDMEMORY_HPP
#define UNIXSHAREDMEMORY_HPP

////////////////////////////////////////////////////////////////////////////////

#include <more/core/finalizable.hpp>
#include <more/os/sharedmemory.hpp>
#include <sys/shm.h>

////////////////////////////////////////////////////////////////////////////////

namespace more
{
  namespace os
  {
    namespace unix_
    {
      class UnixSharedMemory: public SharedMemory, public more::core::Finalizable
      {
        public:
        class Object: public SharedMemory::Object
        {
          public:
            struct SegmentHeader
            {
              size_t  m_nMagic;
              size_t  m_nSize;
              int     m_nNextSegment;
            };

            struct ChunkHeader
            {
              bool    m_bInUse;
              size_t  m_nChunkSize;
              size_t  m_nObjectSize;
            };

            Object( size_t nRootKey, size_t nSize );
            Object( const String& sObjectId );
            virtual void finalize( );
            virtual bool isValid( ) const;
            virtual String getId( ) const;
            virtual size_t getSize( ) const;
            virtual void* getData( ) const;
            virtual void destroy( );

          private:
            ChunkHeader* createChunk( size_t nRootKey, size_t nObjectSize, int& rnSegmentId, size_t& rnChunkOffset );
            ChunkHeader* allocateChunk( SegmentHeader* pSegmentHeader, size_t nObjectSize, size_t& rnChunkOffset );
            ChunkHeader* retrieveChunk( int nSegmentId, size_t rnChunkOffset );
            ChunkHeader* splitChunk( ChunkHeader* pChunkHeader, size_t nObjectSize );
            void joinChunks( SegmentHeader* pSegmentHeader );

            SegmentHeader* createSegment( size_t nSegmentKey, SegmentHeader* pPreviousSegmentHeader, size_t nSize, int& rnSegmentId );
            SegmentHeader* allocateSegment( size_t nSegmentKey, size_t nSize, int& rnSegmentId );
            SegmentHeader* retrieveSegment( size_t nSegmentKey, int& rnSegmentId );
            SegmentHeader* retrieveSegment( int nSegmentId );

            int           m_nSegmentId;
            size_t        m_nChunkOffset;
            ChunkHeader*  m_pChunkHeader;
        };
      };
    }
  }
}

////////////////////////////////////////////////////////////////////////////////

#endif