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

Class SupplyingBarrierStep<S,E>

java.lang.Object

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

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

All Implemented Interfaces:

Serializable, Cloneable, Iterator<Traverser.Admin<E>>, Step<S,E>, Barrier<Boolean>, MemoryComputing<Boolean>

Direct Known Subclasses:

SideEffectCapStep

public abstract class SupplyingBarrierStep<S,E>
extends AbstractStep<S,E>
implements Barrier<Boolean>

Author:

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

See Also:

Serialized Form

Field Summary

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
SupplyingBarrierStep(Traversal.Admin traversal)

Method Summary

Modifier and Type	Method and Description
void	addBarrier(Boolean barrier) Add a barrier to the step.
void	addStart(Traverser.Admin<S> start) Add a single Traverser.Admin to the step.
void	addStarts(Iterator<Traverser.Admin<S>> starts) Add an iterator of Traverser.Admin objects of type S to the step.
SupplyingBarrierStep<S,E>	clone() Cloning is used to duplicate steps for the purpose of traversal optimization and OLTP replication.
void	done() A way to hard set that the barrier is complete.
MemoryComputeKey<Boolean>	getMemoryComputeKey() The MemoryComputeKey that will be used by this step.
boolean	hasNextBarrier() Whether or not the step has an accessible barrier.
Boolean	nextBarrier() Get the next barrier within this step.
void	processAllStarts() Process all left traversers by do not yield the resultant output.
Traverser.Admin<E>	processNextStart()
void	reset() Reset the state of the step such that it has no incoming starts.
protected abstract E	supply()

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

addLabel, equals, getId, getLabels, getNextStep, getPreviousStep, getStarts, getTraversal, hashCode, hasNext, hasStarts, isTraverserStepIdAndLabelsSetByChild, next, prepareTraversalForNextStep, 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

Constructor Detail

SupplyingBarrierStep

public SupplyingBarrierStep(Traversal.Admin traversal)

Method Detail

supply

protected abstract E supply()

addStarts

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

Description copied from interface: Step

Add an iterator of Traverser.Admin 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.Admin<S> start)

Description copied from interface: Step

Add a single Traverser.Admin to the step.

Specified by:

addStart in interface Step<S,E>

Overrides:

addStart in class AbstractStep<S,E>

Parameters:

start - The traverser to add

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>

processNextStart

public Traverser.Admin<E> processNextStart()

Specified by:

processNextStart in class AbstractStep<S,E>

clone

public SupplyingBarrierStep<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 Step.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

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<Boolean>

hasNextBarrier

public boolean hasNextBarrier()

Description copied from interface: Barrier

Whether or not the step has an accessible barrier.

Specified by:

hasNextBarrier in interface Barrier<Boolean>

Returns:

whether a barrier exists or not

nextBarrier

public Boolean 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<Boolean>

Returns:

the next barrier of the step

Throws:

NoSuchElementException

addBarrier

public void addBarrier(Boolean 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<Boolean>

Parameters:

barrier - the barrier to merge in

done

public void done()

Description copied from interface: Barrier

A way to hard set that the barrier is complete. This is necessary when parallel barriers don't all have barriers and need hard resetting. The default implementation does nothing.

Specified by:

done in interface Barrier<Boolean>

getMemoryComputeKey

public MemoryComputeKey<Boolean> getMemoryComputeKey()

Description copied from interface: MemoryComputing

The MemoryComputeKey that will be used by this step.

Specified by:

getMemoryComputeKey in interface MemoryComputing<Boolean>

Returns:

the MemoryComputeKey to use