org.apache.tinkerpop.gremlin.process.traversal.step.util

Class ReducingBarrierStep<S,E>

java.lang.Object

org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep<S,E>

org.apache.tinkerpop.gremlin.process.traversal.step.util.ReducingBarrierStep<S,E>

All Implemented Interfaces:

Serializable, Cloneable, Iterator<Traverser<E>>, Step<S,E>, Barrier, MapReducer

Direct Known Subclasses:

CountGlobalStep, FoldStep, GroupCountStep, GroupStep, GroupStepV3d0, MaxGlobalStep, MeanGlobalStep, MinGlobalStep, SumGlobalStep, TreeStep

public abstract class ReducingBarrierStep<S,E>
extends AbstractStep<S,E>
implements MapReducer, Barrier

Author:

Marko A. Rodriguez (http://markorodriguez.com)

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReducingBarrierStep.DefaultMapReduce

Field Summary

Fields

Modifier and Type	Field and Description
static String	REDUCING
protected BiFunction<E,Traverser<S>,E>	reducingBiFunction
protected Supplier<E>	seedSupplier

Fields inherited from class org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep

id, labels, nextEnd, nextStep, previousStep, starts, traversal, traverserStepIdAndLabelsSetByChild

Constructor Summary

Constructors

Constructor and Description
ReducingBarrierStep(Traversal.Admin traversal)

Method Summary

Modifier and Type	Method and Description
void	addStart(Traverser<S> start) Add a single Traverser to the step.
void	addStarts(Iterator<Traverser<S>> starts) Add a iterator of Traverser objects of type S to the step.
ReducingBarrierStep<S,E>	clone() Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
MapReduce	getMapReduce()
void	processAllStarts() Process all left traversers by do not yield the resultant output.
Traverser<E>	processNextStart()
void	reset() Reset the state of the step such that it has no incoming starts.
void	setBiFunction(BiFunction<E,Traverser<S>,E> reducingBiFunction)
void	setSeedSupplier(Supplier<E> seedSupplier)

Methods inherited from class org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep

addLabel, equals, getId, getLabels, getNextStep, getPreviousStep, getTraversal, hashCode, hasNext, next, removeLabel, setId, setNextStep, setPreviousStep, setTraversal, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.tinkerpop.gremlin.process.traversal.Step

equals, getRequirements

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

Field Detail

REDUCING

public static final String REDUCING

seedSupplier

protected Supplier<E> seedSupplier

reducingBiFunction

protected BiFunction<E,Traverser<S>,E> reducingBiFunction

Constructor Detail

ReducingBarrierStep

public ReducingBarrierStep(Traversal.Admin traversal)

Method Detail

setSeedSupplier

public void setSeedSupplier(Supplier<E> seedSupplier)

setBiFunction

public void setBiFunction(BiFunction<E,Traverser<S>,E> reducingBiFunction)

reset

public void reset()

Description copied from interface: Step

Reset the state of the step such that it has no incoming starts. Internal states are to be reset, but any sideEffect data structures are not to be recreated.

Specified by:

reset in interface Step<S,E>

Overrides:

reset in class AbstractStep<S,E>

addStarts

public void addStarts(Iterator<Traverser<S>> starts)

Description copied from interface: Step

Add a iterator of Traverser objects of type S to the step.

Specified by:

addStarts in interface Step<S,E>

Overrides:

addStarts in class AbstractStep<S,E>

Parameters:

starts - The iterator of objects to add

addStart

public void addStart(Traverser<S> start)

Description copied from interface: Step

Add a single Traverser to the step.

Specified by:

addStart in interface Step<S,E>

Overrides:

addStart in class AbstractStep<S,E>

Parameters:

start - The traverser to add

processAllStarts

public void processAllStarts()

Description copied from interface: Barrier

Process all left traversers by do not yield the resultant output. This method is useful for steps like ReducingBarrierStep, where traversers can be processed "on the fly" and thus, reduce memory consumption.

Specified by:

processAllStarts in interface Barrier

processNextStart

public Traverser<E> processNextStart()

Specified by:

processNextStart in class AbstractStep<S,E>

clone

public ReducingBarrierStep<S,E> clone()

Description copied from interface: Step

Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication. When cloning a step, it is important that the steps, the cloned step is equivalent to the state of the step when reset() is called. Moreover, the previous and next steps should be set to EmptyStep.

Specified by:

clone in interface Step<S,E>

Overrides:

clone in class AbstractStep<S,E>

Returns:

The cloned step

getMapReduce

public MapReduce getMapReduce()

Specified by:

getMapReduce in interface MapReducer