casacore
Public Member Functions | Private Attributes | List of all members

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#include <ColumnCache.h>

Public Member Functions

 ColumnCache ()
 Constructor. More...
 
void setIncrement (rownr_t increment)
 Set the increment to the given value. More...
 
void set (rownr_t startRow, rownr_t endRow, const void *dataPtr)
 Set the start and end row number for which the given data pointer is valid. More...
 
void invalidate ()
 Invalidate the cache. More...
 
Int64 offset (rownr_t rownr) const
 Calculate the offset in the cached data for the given row. More...
 
const void * dataPtr () const
 Give a pointer to the data. More...
 
rownr_t start () const
 Give the start, end (including), and increment row number of the cached column values. More...
 
rownr_t end () const
 
rownr_t incr () const
 

Private Attributes

rownr_t itsStart
 
rownr_t itsEnd
 
rownr_t itsIncr
 
const void * itsData
 

Detailed Description

A caching object for a table column.

Intended use:

Internal

Review Status

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

Prerequisite

Synopsis

ColumnCache acts as a cache for a table column. It contains a pointer to data and the start and end row number for which these data are valid. An increment is part of the object and is usually 0 or 1. The value 0 is used for data which is valid for multiple rows (as used in IncrementalStMan). The value 1 is used for data stored consecutevily in a buffer for each row (as used in StManAipsIO).

The ColumnCache object is created and updated by the data manager. The top level ScalarColumn object contains a pointer to the cache object. In this way the ScalarColumn::get can often be executed by a few inlined statements which improves performance considerably.

The invalidate function can be used to invalidate the cache. This is for instance needed when a table lock is acquired or released to be sure that the cache gets refreshed.

Motivation

This class was developed to improve the performance for getting a scalar.

To Do

Definition at line 86 of file ColumnCache.h.

Constructor & Destructor Documentation

◆ ColumnCache()

casacore::ColumnCache::ColumnCache ( )

Constructor.

It sets the increment to 1 and calls invalidate.

Member Function Documentation

◆ dataPtr()

const void * casacore::ColumnCache::dataPtr ( ) const
inline

Give a pointer to the data.

The calling function has to do a proper cast after which the calculated offset can be added to get the proper data.

Definition at line 150 of file ColumnCache.h.

References itsData.

Referenced by casacore::ScalarColumn< T >::get().

◆ end()

rownr_t casacore::ColumnCache::end ( ) const
inline

Definition at line 117 of file ColumnCache.h.

References itsEnd.

◆ incr()

rownr_t casacore::ColumnCache::incr ( ) const
inline

Definition at line 119 of file ColumnCache.h.

References itsIncr.

◆ invalidate()

void casacore::ColumnCache::invalidate ( )
inline

Invalidate the cache.

This clears the data pointer and sets startRow>endRow.

Definition at line 135 of file ColumnCache.h.

References set().

◆ offset()

Int64 casacore::ColumnCache::offset ( rownr_t  rownr) const
inline

Calculate the offset in the cached data for the given row.

-1 is returned if the row is not within the cached rows.

Definition at line 140 of file ColumnCache.h.

References itsEnd, itsIncr, itsStart, and casacore::max().

Referenced by casacore::ScalarColumn< T >::get().

◆ set()

void casacore::ColumnCache::set ( rownr_t  startRow,
rownr_t  endRow,
const void *  dataPtr 
)

Set the start and end row number for which the given data pointer is valid.

Referenced by invalidate().

◆ setIncrement()

void casacore::ColumnCache::setIncrement ( rownr_t  increment)
inline

Set the increment to the given value.

Definition at line 130 of file ColumnCache.h.

References itsIncr.

◆ start()

rownr_t casacore::ColumnCache::start ( ) const
inline

Give the start, end (including), and increment row number of the cached column values.

Definition at line 115 of file ColumnCache.h.

References itsStart.

Member Data Documentation

◆ itsData

const void* casacore::ColumnCache::itsData
private

Definition at line 126 of file ColumnCache.h.

Referenced by dataPtr().

◆ itsEnd

rownr_t casacore::ColumnCache::itsEnd
private

Definition at line 124 of file ColumnCache.h.

Referenced by end(), and offset().

◆ itsIncr

rownr_t casacore::ColumnCache::itsIncr
private

Definition at line 125 of file ColumnCache.h.

Referenced by incr(), offset(), and setIncrement().

◆ itsStart

rownr_t casacore::ColumnCache::itsStart
private

Definition at line 123 of file ColumnCache.h.

Referenced by offset(), and start().


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