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

Class CollectingBarrierStep<S>

java.lang.Object

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

org.apache.tinkerpop.gremlin.process.traversal.step.util.CollectingBarrierStep<S>

All Implemented Interfaces:

Serializable, Cloneable, Iterator<Traverser.Admin<S>>, Step<S,S>, Barrier<TraverserSet<S>>, FilteringBarrier<TraverserSet<S>>, MemoryComputing<TraverserSet<S>>

Direct Known Subclasses:

LambdaCollectingBarrierStep, OrderGlobalStep, SampleGlobalStep

public abstract class CollectingBarrierStep<S>
extends AbstractStep<S,S>
implements FilteringBarrier<TraverserSet<S>>

Author:

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

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected TraverserSet<S>	traverserSet

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	Description
CollectingBarrierStep(Traversal.Admin traversal)
CollectingBarrierStep(Traversal.Admin traversal, int maxBarrierSize)

Method Summary

Modifier and Type	Method	Description
void	addBarrier(TraverserSet<S> barrier)	Add a barrier to the step.
abstract void	barrierConsumer(TraverserSet<S> traverserSet)
CollectingBarrierStep<S>	clone()	Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
TraverserSet<S>	getEmptyBarrier()	If a barrier is unproductive then provide an empty object suitable to the implementation which can be used to represent that state.
MemoryComputeKey<TraverserSet<S>>	getMemoryComputeKey()	The MemoryComputeKey that will be used by this step.
Set<TraverserRequirement>	getRequirements()	Provide the necessary TraverserRequirement that must be met by the traverser in order for the step to function properly.
int	hashCode()
boolean	hasNextBarrier()	Whether or not the step has an accessible barrier.
TraverserSet<S>	nextBarrier()	Get the next barrier within this step.
void	processAllStarts()	Process all left traversers by do not yield the resultant output.
Traverser.Admin<S>	processNextStart()
void	reset()	Reset the state of the step such that it has no incoming starts.
String	toString()

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

addLabel, addStart, addStarts, clearLabels, equals, getId, getLabels, getNextStep, getPreviousStep, getStarts, getTraversal, hasNext, hasStarts, isTraverserStepIdAndLabelsSetByChild, next, prepareTraversalForNextStep, removeLabel, setId, setNextStep, setPreviousStep, setTraversal

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.Barrier

done

Methods inherited from interface java.util.Iterator

forEachRemaining, remove

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

equals

Field Detail

traverserSet

protected TraverserSet<S> traverserSet

Constructor Detail

CollectingBarrierStep

public CollectingBarrierStep(Traversal.Admin traversal)

CollectingBarrierStep

public CollectingBarrierStep(Traversal.Admin traversal,
                             int maxBarrierSize)

Method Detail

barrierConsumer

public abstract void barrierConsumer(TraverserSet<S> traverserSet)

getRequirements

public Set<TraverserRequirement> getRequirements()

Description copied from interface: Step

Provide the necessary TraverserRequirement that must be met by the traverser in order for the step to function properly. The provided default implements returns an empty set.

Specified by:

getRequirements in interface Step<S,S>

Returns:

the set of requirements

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<S>

hasNextBarrier

public boolean hasNextBarrier()

Description copied from interface: Barrier

Whether or not the step has an accessible barrier.

Specified by:

hasNextBarrier in interface Barrier<S>

Returns:

whether a barrier exists or not

nextBarrier

public TraverserSet<S> nextBarrier()
                            throws NoSuchElementException

Description copied from interface: Barrier

Get the next barrier within this step. Barriers from parallel steps can be the be merged to create a single step with merge barriers.

Specified by:

nextBarrier in interface Barrier<S>

Returns:

the next barrier of the step

Throws:

NoSuchElementException

getEmptyBarrier

public TraverserSet<S> getEmptyBarrier()

Description copied from interface: Barrier

If a barrier is unproductive then provide an empty object suitable to the implementation which can be used to represent that state. This is important for cases like by(out().order().fold()) where the order() might filter but the fold() means the traversal is productive.

Specified by:

getEmptyBarrier in interface Barrier<S>

addBarrier

public void addBarrier(TraverserSet<S> barrier)

Description copied from interface: Barrier

Add a barrier to the step. This typically happens when multiple parallel barriers need to become one barrier at a single step.

Specified by:

addBarrier in interface Barrier<S>

Parameters:

barrier - the barrier to merge in

processNextStart

public Traverser.Admin<S> processNextStart()

Specified by:

processNextStart in class AbstractStep<S,S>

clone

public CollectingBarrierStep<S> 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 Step.reset() is called. Moreover, the previous and next steps should be set to EmptyStep.

Specified by:

clone in interface Step<S,S>

Overrides:

clone in class AbstractStep<S,S>

Returns:

The cloned step

toString

public String toString()

Overrides:

toString in class AbstractStep<S,S>

hashCode

public int hashCode()

Overrides:

hashCode in class AbstractStep<S,S>

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,S>

Overrides:

reset in class AbstractStep<S,S>

getMemoryComputeKey

public MemoryComputeKey<TraverserSet<S>> getMemoryComputeKey()

Description copied from interface: MemoryComputing

The MemoryComputeKey that will be used by this step.

Specified by:

getMemoryComputeKey in interface MemoryComputing<S>

Returns:

the MemoryComputeKey to use