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BucketMapped.h
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//# BucketMapped.h: File buckets by means of file mapping
//# 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_BUCKETMAPPED_H
#define CASA_BUCKETMAPPED_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/IO/BucketBase.h>
#include <casacore/casa/IO/MMapfdIO.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
// <summary>
// Use file mapping for buckets in a part of a file
// </summary>
// <use visibility=export>
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="" demos="">
// </reviewed>
// <prerequisite>
//# Classes you should understand before using this one.
// <li> <linkto class=BucketFile>BucketFile</linkto>
// </prerequisite>
// <etymology>
// BucketMapped uses memory-mapped files for bucket access.
// </etymology>
// <synopsis>
// BucketMapped is similar to class
// <linkto class=BucketCache>BucketCache</linkto> and is meant to be used by
// the storage managers of the Table System.
//
// It gives access to buckets in a file by means of memory-mapped files.
// However, its functionality is a subset of BucketCache and is only meant
// to be used by the Tiled Storage Managers. If The Standard and Incremental
// Storage Manager also want to use it, functions like <src>extend</src>
// needs to be added to this class. Also support for a free bucket list needs
// to be added.
// </synopsis>
// <motivation>
// Use of BucketCache is sub-optimal when having large buckets and more or
// less random IO. Memory-mapping behaves much better.
// </motivation>
class BucketMapped: public BucketBase
{
public:
// Create the cache for (part of) a file.
// The file part mapped into memory starts at startOffset. Its length is
// bucketSize*nrOfBuckets bytes.
// If the file is smaller, the remainder is indicated as an extension
// similarly to the behaviour of function extend.
BucketMapped (BucketFile* file, Int64 startOffset, uInt bucketSize,
uInt nrOfBuckets);
// Unmap the file
~BucketMapped();
// Get a readonly pointer to the given bucket in memory.
const char* getBucket (uInt bucketNr);
// Get a writable pointer to the given bucket in memory.
// It sets the hasWritten flag.
char* getrwBucket (uInt bucketNr)
{
itsHasWritten = True;
return const_cast<char*>(getBucket(bucketNr));
}
private:
// Copy constructor is not possible.
BucketMapped (const BucketMapped&);
// Assignment is not possible.
BucketMapped& operator= (const BucketMapped&);
// Flush the file.
virtual void doFlush();
// Do the actual resync-ing.
virtual void doResync();
// Extend the file with the given number of buckets.
virtual void doExtend (uInt nrBucket);
// Initialize the bucket buffer.
// The uninitialized buckets before this bucket are also initialized.
virtual void initializeBuckets (uInt bucketNr);
};
} //# NAMESPACE CASACORE - END
#endif
casacore::BucketBase::itsHasWritten
Bool itsHasWritten
Have data been written?
Definition BucketBase.h:129
casacore::BucketBase::BucketBase
BucketBase(BucketFile *file, Int64 startOffset, uInt bucketSize, uInt nrOfBuckets)
Create the bucket access for (part of) a file.
casacore::BucketFile
Definition BucketFile.h:105
casacore::BucketMapped::getBucket
const char * getBucket(uInt bucketNr)
Get a readonly pointer to the given bucket in memory.
casacore::BucketMapped::~BucketMapped
~BucketMapped()
Unmap the file.
casacore::BucketMapped::operator=
BucketMapped & operator=(const BucketMapped &)
Assignment is not possible.
casacore::BucketMapped::initializeBuckets
virtual void initializeBuckets(uInt bucketNr)
Initialize the bucket buffer.
casacore::BucketMapped::doExtend
virtual void doExtend(uInt nrBucket)
Extend the file with the given number of buckets.
casacore::BucketMapped::BucketMapped
BucketMapped(const BucketMapped &)
Copy constructor is not possible.
casacore::BucketMapped::doResync
virtual void doResync()
Do the actual resync-ing.
casacore::BucketMapped::doFlush
virtual void doFlush()
Flush the file.
casacore::BucketMapped::getrwBucket
char * getrwBucket(uInt bucketNr)
Get a writable pointer to the given bucket in memory.
Definition BucketMapped.h:93
casacore::BucketMapped::BucketMapped
BucketMapped(BucketFile *file, Int64 startOffset, uInt bucketSize, uInt nrOfBuckets)
Create the cache for (part of) a file.
casacore
this file contains all the compiler specific defines
Definition mainpage.dox:28
casacore::uInt
unsigned int uInt
Definition aipstype.h:49
casacore::Int64
long long Int64
Define the extra non-standard types used by Casacore (like proposed uSize, Size).
Definition aipsxtype.h:36
casacore::True
const Bool True
Definition aipstype.h:41