Give access to some IncrementalStMan functions. More...

#include <IncrStManAccessor.h>

Inheritance diagram for casa::ROIncrementalStManAccessor:

Public Member Functions
	ROIncrementalStManAccessor (const Table &table, const String &name, Bool byColumn=False)
	Construct the object for a data manager in the table given the name of the data manager or the column.
virtual	~ROIncrementalStManAccessor ()
	ROIncrementalStManAccessor (const ROIncrementalStManAccessor &that)
	Copy constructor (reference semantics).
ROIncrementalStManAccessor &	operator= (const ROIncrementalStManAccessor &that)
	Assignment (reference semantics).
void	setCacheSize (uInt aSize, Bool canExceedNrBuckets=True)
	Set the cache size (in buckets) to be used by the storage manager.
uInt	cacheSize () const
	Get the cache size (in buckets).
void	clearCache ()
	Clear the caches used by the hypercubes in this storage manager.
Private Attributes
ISMBase *	dataManPtr_p

Detailed Description

Give access to some IncrementalStMan functions.

Intended use:

Public interface

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25

Prerequisite

IncrementalStMan

Synopsis

The Table system has one or more storage managers underneath. One of these possible storage managers is the IncrementalStMan . This storage manager uses a cache of buckets. The default cache size is defined when the IncrementalStMan object was constructed at the time the table was created.

Sometimes it can be useful to change the cache size. E.g. when the table is accessed in a random way, the hit rate may drop when the cache is too small. The class ROIncrStManAccessor makes it possible to change the cache size in a temporary way.
Furthermore this class makes it possible to show the cache size and to show the cache statistics.

Motivation

In principle a pointer to IncrementalStMan could be used. However, that would give access to all public functions. Furthermore it could not distinguish between read/write and readonly tables.

Example

This example shows how to set the cache size for the incremental storage manager with the name "ISMExample". The cache size is not persistent, i.e. when the same table is reopened at a later time, this cache size is not remembered.

     // Open a table.
     Table table("someName.data");
     // Set the cache size of its incremental storage manager ISMExample
     // to 5 buckets.
     ROIncrementalStManAccessor accessor(table, "ISMExample");
     accessor.setCacheSize (5);

Definition at line 100 of file IncrStManAccessor.h.

Constructor & Destructor Documentation

casa::ROIncrementalStManAccessor::ROIncrementalStManAccessor	(	const Table &	table,
		const String &	name,
		Bool	byColumn = `False`
	)

Construct the object for a data manager in the table given the name of the data manager or the column.

An exception is thrown if the data manager type is not the incremental storage manager.

virtual casa::ROIncrementalStManAccessor::~ROIncrementalStManAccessor ( ) [virtual]

casa::ROIncrementalStManAccessor::ROIncrementalStManAccessor ( const ROIncrementalStManAccessor & that )

Copy constructor (reference semantics).

Member Function Documentation

uInt casa::ROIncrementalStManAccessor::cacheSize ( ) const

Get the cache size (in buckets).

void casa::ROIncrementalStManAccessor::clearCache ( )

Clear the caches used by the hypercubes in this storage manager.

It will flush the caches as needed and remove all buckets from them resulting in a possibly large drop in memory used.

ROIncrementalStManAccessor& casa::ROIncrementalStManAccessor::operator= ( const ROIncrementalStManAccessor & that )

Assignment (reference semantics).

void casa::ROIncrementalStManAccessor::setCacheSize	(	uInt	aSize,
		Bool	canExceedNrBuckets = `True`
	)

Set the cache size (in buckets) to be used by the storage manager.

The cache size given in this way is not persistent. Only the cache size given to the constructors of the incremental storage managers, is persistent. If canExceedNrBuckets=True, the given cache size can be larger than the nr of buckets in the file. In this way the cache can be made large enough for a future file extnsion. Otherwise, it is limited to the actual number of buckets. This is useful if one wants the entire file to be cached.

Member Data Documentation

ISMBase* casa::ROIncrementalStManAccessor::dataManPtr_p [private]

Definition at line 143 of file IncrStManAccessor.h.

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

casacore/tables/Tables/IncrStManAccessor.h

Public Member Functions

Private Attributes