org.diirt.datasource

Class Aggregator<R,A>

java.lang.Object

org.diirt.datasource.Aggregator<R,A>

Type Parameters:

R - result type of aggregation

A - argument type being aggregated

All Implemented Interfaces:

ReadFunction<R>

public abstract class Aggregator<R,A>
extends Object
implements ReadFunction<R>

Aggregates the data out of a Collector into a new data type.

The Aggregator uses calculate(java.util.List) to aggregate the values of the current time slice. If no values were collected in the current time slice, the last value (and only the last value, is passed so that the output remains consistent with what would be currently posted. Non calculation is done if no values were collected in the current and in the previous time slice.

Author:

carcassi

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Aggregator(ReadFunction<List<A>> collector) Creates a new aggregator.

Method Summary

Modifier and Type	Method and Description
protected abstract R	calculate(List<A> data) Calculates the new value from a set of collected value.
R	readValue() Calculates, if needed, and then returns the value for this function.

Methods inherited from class java.lang.Object

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

Constructor Detail

Aggregator

protected Aggregator(ReadFunction<List<A>> collector)

Creates a new aggregator. The given collector will be the source of data for the new aggregator.

Parameters:

collector - a suitable collector

Method Detail

readValue

public final R readValue()

Description copied from interface: ReadFunction

Calculates, if needed, and then returns the value for this function.

Specified by:

readValue in interface ReadFunction<R>

Returns:

a value

calculate

protected abstract R calculate(List<A> data)

Calculates the new value from a set of collected value. This function will never be called with an empty list

Parameters:

data - the new data to aggregate

Returns:

the aggregated value