cascading.pipe.joiner

Class JoinerClosure

java.lang.Object

cascading.pipe.joiner.JoinerClosure

Direct Known Subclasses:

MemoryCoGroupClosure

public abstract class JoinerClosure
extends java.lang.Object

Class JoinerClosure wraps all incoming tuple streams with iterator instances allowing for just join implementations.

This class is provided to a Joiner.getIterator(JoinerClosure) implementation, or to a Buffer via the BufferCall.getJoinerClosure() method.

All iterators returned by getIterator(int) may be retrieved more than once to restart them except for the left most iterator at position 0 (zero).

This iterator may only be iterated across once. All other iterators are backed by memory and possibly disk.

Field Summary

Fields

Modifier and Type	Field and Description
protected FlowProcess	flowProcess
protected Fields[]	joinFields
protected Fields[]	valueFields

Constructor Summary

Constructors

Constructor and Description
JoinerClosure(FlowProcess flowProcess, Fields[] joinFields, Fields[] valueFields)

Method Summary

Modifier and Type	Method and Description
FlowProcess	getFlowProcess()
abstract Tuple	getGroupTuple(Tuple keysTuple)
abstract java.util.Iterator<Tuple>	getIterator(int pos) Returns a Tuple Iterator for the given pipe position.
Fields[]	getJoinFields() Returns an array of Fields denoting the join fields or keys uses for each incoming pipe.
Fields[]	getValueFields() Returns an array of all the incoming fields for each incoming pipe.
abstract boolean	isEmpty(int pos)
boolean	isSelfJoin()
abstract int	size()

Methods inherited from class java.lang.Object

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

Field Detail

flowProcess

protected final FlowProcess flowProcess

joinFields

protected final Fields[] joinFields

valueFields

protected final Fields[] valueFields

Constructor Detail

JoinerClosure

public JoinerClosure(FlowProcess flowProcess,
                     Fields[] joinFields,
                     Fields[] valueFields)

Method Detail

getFlowProcess

public FlowProcess getFlowProcess()

getJoinFields

public Fields[] getJoinFields()

Returns an array of Fields denoting the join fields or keys uses for each incoming pipe.

The most left handed pipe will be in array position 0.

Returns:

an array of Fields

getValueFields

public Fields[] getValueFields()

Returns an array of all the incoming fields for each incoming pipe.

The most left handed pipe will be in array position 0;

Returns:

an array of Fields

isSelfJoin

public boolean isSelfJoin()

size

public abstract int size()

getIterator

public abstract java.util.Iterator<Tuple> getIterator(int pos)

Returns a Tuple Iterator for the given pipe position. Position 0 is the most left handed pipe passed to the prior CoGroup.

To restart an Iterator over a given pipe, this method must be called again.

Parameters:

pos - of type int

Returns:

an Iterator of Tuple instances.

isEmpty

public abstract boolean isEmpty(int pos)

getGroupTuple

public abstract Tuple getGroupTuple(Tuple keysTuple)