com.google.uzaygezen.core

Class BoundedRollup<K,V extends AdditiveValue<V>>

java.lang.Object

com.google.uzaygezen.core.BoundedRollup<K,V>

Type Parameters:

K - key type

V - value type

All Implemented Interfaces:

StreamingRollup<K,V>

public class BoundedRollup<K,V extends AdditiveValue<V>>
extends Object
implements StreamingRollup<K,V>

Streaming rollup implementation that supports an upper bound on the number of nodes, upper bound which is achieved by rolling up nodes are required. The resulting tree has the property that if one were to order the nodes of a tree by the additive value inside, and do that for all possible root-sharing subtrees of size exactly min(maxNodes, nodeCount), and then order lexicographically all such trees, the one created by this class will be maximal, with ties broken arbitrarily.

Implementation notes: At every step only leaves are rolled up, and more precisely, those leaves which share a common parent with the property that it has the smallest value amongst all finished parent nodes which have only leaf children.

Author:

Daniel Aioanei

Method Summary

Methods

Modifier and Type	Method and Description
static <K,V extends AdditiveValue<V>> BoundedRollup<K,V>	create(V emptyValue, int maxNodes)
void	feedRow(Iterator<K> leafPath, V v) The rows must come in nested groups.
MapNode<K,V>	finish() Returns the tree representing the rolled-up, aggregated data.
String	toString()

Methods inherited from class java.lang.Object

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

Method Detail

create

public static <K,V extends AdditiveValue<V>> BoundedRollup<K,V> create(V emptyValue,
                                                       int maxNodes)

feedRow

public void feedRow(Iterator<K> leafPath,
           V v)

Description copied from interface: StreamingRollup

The rows must come in nested groups. For instance sorting achieves that, but it is not necessary.

Specified by:

feedRow in interface StreamingRollup<K,V extends AdditiveValue<V>>

Parameters:

leafPath - identifies the location of the node onto which the value is added, starting from the root. An empty path represents the root itself. If the node doesn't exist, it will be created.

finish

public MapNode<K,V> finish()

Description copied from interface: StreamingRollup

Returns the tree representing the rolled-up, aggregated data. If there is no data then null is returned.

Specified by:

finish in interface StreamingRollup<K,V extends AdditiveValue<V>>

toString

public String toString()

Overrides:

toString in class Object