src/FileArea.h

   1 //
   2 // This file is part of the aMule Project.
   3 //
   4 // Copyright (c) 2009 aMule Team ( admin@amule.org / http://www.amule.org )
   5 // Copyright (c) 2009 Frediano Ziglio (freddy77@gamilc.com)
   6 //
   7 // This program is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 2 of the License, or
  10 // (at your option) any later version.
  11 //
  12 // This program is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // You should have received a copy of the GNU General Public License
  18 // along with this program; if not, write to the Free Software
  19 // Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
  20 //
  21
  22 #ifndef FILEAREA_H
  23 #define FILEAREA_H
  24
  25 #include "CFile.h"              // Needed for CFile
  26
  27 /**
  28  * This class is used to optimize file read/write using mapped memory
  29  * if supported.
  30  */
  31 class CFileArea
  32 {
  33 public:
  34         /**
  35          * Creates a uninitialized file area.
  36          */
  37         CFileArea();
  38
  39
  40         /**
  41          * Destructor, closes the file if opened.
  42          */
  43         virtual ~CFileArea();
  44
  45         /**
  46          * Closes the file.
  47          */
  48         bool Close();
  49
  50         /**
  51          * Init area with a given piece of file.
  52          *
  53          * @param file   file to read.
  54          * @param count  bytes to read.
  55          *
  56          * Initialize buffer. Buffer will contain data from current file
  57          * position for count length. Buffer will be a memory mapped area
  58          * or a allocated buffer depending on systems.
  59          *
  60          * At the end file is positioned past readed area.
  61          */
  62         void Read(const CFile& file, size_t count);
  63
  64         /**
  65          * Flushes data not yet written.
  66          */
  67         bool Flush();
  68
  69         /**
  70          * Get buffer that contains data readed or to write.
  71          * @return allocated buffer or NULL if not initialized
  72          */
  73         byte *GetBuffer() const { return m_buffer; };
  74
  75 private:
  76         //! A CFileArea is neither copyable nor assignable.
  77         //@{
  78         CFileArea(const CFileArea&);
  79         CFileArea& operator=(const CFileArea&);
  80         //@}
  81
  82         /**
  83          * Pointer to buffer used for read/write operations.
  84          * If mapped points inside m_mmap_buffer area otherwise
  85          * point to an allocated buffer to be freed.
  86          */
  87         byte *m_buffer;
  88         /**
  89          * Pointer to memory mapped area or NULL if not mapped.
  90          */
  91         byte *m_mmap_buffer;
  92         /**
  93          * Length of the mapped region, currently used only for munmap.
  94          */
  95         size_t m_length;
  96         /**
  97          * File descriptor or 'fd_invalid' if not opened.
  98          * This file descriptor is used to write file if not mapped.
  99          */
 100         int m_fd;
 101 };
 102
 103 #endif // FILEAREA_H
 104 // File_checked_for_headers