casacore::BucketMapped Class Reference

More...

#include <BucketMapped.h>

Public Member Functions
	BucketMapped (BucketFile *file, Int64 startOffset, uInt bucketSize, uInt nrOfBuckets)
	Create the cache for (part of) a file. More...
	~BucketMapped ()
	Unmap the file. More...
const char *	getBucket (uInt bucketNr)
	Get a readonly pointer to the given bucket in memory. More...
char *	getrwBucket (uInt bucketNr)
	Get a writable pointer to the given bucket in memory. More...
Public Member Functions inherited from casacore::BucketBase
	BucketBase (BucketFile *file, Int64 startOffset, uInt bucketSize, uInt nrOfBuckets)
	Create the bucket access for (part of) a file. More...
virtual	~BucketBase ()
	Detach the file. More...
Bool	flush ()
	Flush the cached buckets. More...
virtual void	resync (uInt nrBucket)
	Resynchronize the object (after another process updated the file). More...
uInt	nBucket () const
	Get the current nr of buckets in the file. More...
void	extend (uInt nrBucket)
	Extend the file with the given number of buckets. More...
void	setWritten ()
	Set that data has been written. More...

Private Member Functions
	BucketMapped (const BucketMapped &)
	Copy constructor is not possible. More...
BucketMapped &	operator= (const BucketMapped &)
	Assignment is not possible. More...
virtual void	doFlush ()
	Flush the file. More...
virtual void	doResync ()
	Do the actual resync-ing. More...
virtual void	doExtend (uInt nrBucket)
	Extend the file with the given number of buckets. More...
virtual void	initializeBuckets (uInt bucketNr)
	Initialize the bucket buffer. More...

Additional Inherited Members
Protected Member Functions inherited from casacore::BucketBase
	BucketBase (const BucketBase &)
	Copy constructor is not possible. More...
BucketBase &	operator= (const BucketBase &)
	Assignment is not possible. More...
Protected Attributes inherited from casacore::BucketBase
BucketFile *	itsFile
	The file used. More...
Int64	itsStartOffset
	The starting offsets of the buckets in the file. More...
uInt	itsBucketSize
	The bucket size. More...
uInt	itsCurNrOfBuckets
	The current nr of buckets in the file. More...
uInt	itsNewNrOfBuckets
	The new nr of buckets in the file (after extension). More...
Bool	itsHasWritten
	Have data been written? More...

Detailed Description

Use file mapping for buckets in a part of a file

Intended use:

Public interface

Review Status

Reviewed By:

UNKNOWN

Date Reviewed:

before2004/08/25

Prerequisite

• BucketFile

Etymology

BucketMapped uses memory-mapped files for bucket access.

Synopsis

BucketMapped is similar to class BucketCache 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 extend needs to be added to this class. Also support for a free bucket list needs to be added.

Motivation

Use of BucketCache is sub-optimal when having large buckets and more or less random IO. Memory-mapping behaves much better.

Definition at line 76 of file BucketMapped.h.

Constructor & Destructor Documentation

BucketMapped() [1/2]

casacore::BucketMapped::BucketMapped	(	BucketFile *	file,
		Int64	startOffset,
		uInt	bucketSize,
		uInt	nrOfBuckets
	)

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()

casacore::BucketMapped::~BucketMapped

(

)

Unmap the file.

BucketMapped() [2/2]

casacore::BucketMapped::BucketMapped ( const BucketMapped &  )

private

Copy constructor is not possible.

Member Function Documentation

doExtend()

virtual void casacore::BucketMapped::doExtend ( uInt  nrBucket )

privatevirtual

Extend the file with the given number of buckets.

Implements casacore::BucketBase.

doFlush()

virtual void casacore::BucketMapped::doFlush ( )

privatevirtual

Flush the file.

Implements casacore::BucketBase.

doResync()

virtual void casacore::BucketMapped::doResync ( )

privatevirtual

Do the actual resync-ing.

Implements casacore::BucketBase.

getBucket()

const char* casacore::BucketMapped::getBucket

(

uInt

bucketNr

)

Get a readonly pointer to the given bucket in memory.

Referenced by getrwBucket().

getrwBucket()

char* casacore::BucketMapped::getrwBucket ( uInt  bucketNr )

inline

Get a writable pointer to the given bucket in memory.

It sets the hasWritten flag.

Definition at line 95 of file BucketMapped.h.

References getBucket(), casacore::BucketBase::itsHasWritten, and casacore::True.

initializeBuckets()

virtual void casacore::BucketMapped::initializeBuckets ( uInt  bucketNr )

privatevirtual

Initialize the bucket buffer.

The uninitialized buckets before this bucket are also initialized.

Implements casacore::BucketBase.

operator=()

BucketMapped& casacore::BucketMapped::operator= ( const BucketMapped &  )

private

Assignment is not possible.

---

The documentation for this class was generated from the following file:

• casa/IO/BucketMapped.h