uk.ac.starlink.topcat.plot2

Class CountDataStore

java.lang.Object

uk.ac.starlink.topcat.plot2.CountDataStore

All Implemented Interfaces:

uk.ac.starlink.ttools.plot2.data.DataStore

public class CountDataStore
extends Object
implements uk.ac.starlink.ttools.plot2.data.DataStore

Wrapper data store implementation used only for counting the number of tuples requested from it.

The intention is that an operation involving data access can be run using this data store to find out how many tuples in total would be read by the operation. In order to run quickly however, this implementation does not supply all those rows, it truncates the number of tuples dispensed per sequence to a given (small) number. When the operation is complete, the getTupleCount() method can be called.

Since:

15 Nov 2013

Author:

Mark Taylor

Constructor Summary

Constructors

Constructor and Description
CountDataStore(uk.ac.starlink.ttools.plot2.data.DataStore base, int maxCount) Constructor.

Method Summary

Modifier and Type	Method and Description
long	getTupleCount() Returns the total number of tuples represented by the tuple sequences dispensed by this data store since construction time.
uk.ac.starlink.ttools.plot2.data.TupleRunner	getTupleRunner()
uk.ac.starlink.ttools.plot2.data.TupleSequence	getTupleSequence(uk.ac.starlink.ttools.plot2.data.DataSpec spec)
boolean	hasData(uk.ac.starlink.ttools.plot2.data.DataSpec spec)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CountDataStore

public CountDataStore(uk.ac.starlink.ttools.plot2.data.DataStore base,
                      int maxCount)

Constructor.

Parameters:

base - base data store to which most operations are delegated

maxCount - maximum number of tuples actually dispensed from tuplesequences acquired from this store

Method Detail

hasData

public boolean hasData(uk.ac.starlink.ttools.plot2.data.DataSpec spec)

Specified by:

hasData in interface uk.ac.starlink.ttools.plot2.data.DataStore

getTupleSequence

public uk.ac.starlink.ttools.plot2.data.TupleSequence getTupleSequence(uk.ac.starlink.ttools.plot2.data.DataSpec spec)

Specified by:

getTupleSequence in interface uk.ac.starlink.ttools.plot2.data.DataStore

getTupleRunner

public uk.ac.starlink.ttools.plot2.data.TupleRunner getTupleRunner()

Specified by:

getTupleRunner in interface uk.ac.starlink.ttools.plot2.data.DataStore

getTupleCount

public long getTupleCount()

Returns the total number of tuples represented by the tuple sequences dispensed by this data store since construction time.

Returns:

total tuple count for non-truncated tuple sequences dispensed to date, or -1 if not known