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MMapIO.h
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//# MMapIO.h: Memory-mapped IO on a file
//#
//# Copyright (C) 2009
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library is distributed in the hope that it will be useful, but WITHOUT
//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//# Internet email: casa-feedback@nrao.edu.
//# Postal address: AIPS++ Project Office
//# National Radio Astronomy Observatory
//# 520 Edgemont Road
//# Charlottesville, VA 22903-2475 USA
#ifndef CASA_MMAPIO_H
#define CASA_MMAPIO_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/IO/MMapfdIO.h>
#include <casacore/casa/OS/RegularFile.h>
namespace casacore
{
// <summary>
// Memory-mapped IO on a file.
// </summary>
// <synopsis>
// Memory-mapped IO lets the OS take care of caching file segments.
// This is particularly useful for the Tiled Storage Manager which keeps a
// cache of tiles. When using memory-mapped IO it does not need to do that
// anymore.
//
// On 32-bit systems its use is limited because for large files the 4 GB
// memory space is insufficient. However, for 64-bit systems the memory
// space is large enough to make use of it.
//
// In the general case there is direct access to the mapped file space.
// The read and write methods copies the data into/from a buffer.
// However, to avoid the copying it is possible to get a direct pointer
// to the mapped data. This should be used with care, because writing to
// it will cause a segmentation if the file is readonly. If the file is
// writable, writing into the mapped data segment means changing the file
// contents.
// </synopsis>
class MMapIO: public MMapfdIO
{
public:
// Open the given file and map it entirely into memory with read access.
// The map has write access if the file is opened for write.
explicit MMapIO (const RegularFile& regularFile,
ByteIO::OpenOption = ByteIO::Old);
// Destructor.
// It will flush and unmap the file.
~MMapIO();
// Forbid copy constructor and assignment
// <group>
MMapIO (const MMapIO&) = delete;
MMapIO& operator= (const MMapIO&) = delete;
// </group>
};
} // end namespace
#endif
casacore::ByteIO::OpenOption
OpenOption
Define the possible ByteIO open options.
Definition ByteIO.h:63
casacore::ByteIO::Old
@ Old
Definition ByteIO.h:64
casacore::MMapIO::MMapIO
MMapIO(const RegularFile &regularFile, ByteIO::OpenOption=ByteIO::Old)
Open the given file and map it entirely into memory with read access.
casacore::MMapIO::~MMapIO
~MMapIO()
Destructor.
casacore::MMapIO::operator=
MMapIO & operator=(const MMapIO &)=delete
casacore::MMapIO::MMapIO
MMapIO(const MMapIO &)=delete
Forbid copy constructor and assignment.
casacore::MMapfdIO::MMapfdIO
MMapfdIO()
Default constructor.
casacore::RegularFile
Definition RegularFile.h:90
casacore
this file contains all the compiler specific defines
Definition mainpage.dox:28