Class ServiceJoinIterator

java.lang.Object

org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<BindingSet>

org.eclipse.rdf4j.common.iteration.LookAheadIteration<BindingSet>

org.eclipse.rdf4j.repository.sparql.federation.JoinExecutorBase<BindingSet>

org.eclipse.rdf4j.query.algebra.evaluation.federation.ServiceJoinIterator

All Implemented Interfaces:

AutoCloseable, Iterator<BindingSet>, CloseableIteration<BindingSet>

public class ServiceJoinIterator
extends JoinExecutorBase<BindingSet>

Iterator for efficient SERVICE evaluation (vectored). SERVICE is the right handside argument of this join.

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field	Description
protected Service	service
protected EvaluationStrategy	strategy

Fields inherited from class JoinExecutorBase

bindings, closed, finished, leftIter, NEXT_JOIN_ID, rightArg, rightIter, rightQueue

Modifier and Type	Field	Description
protected final BindingSet	bindings
protected boolean	closed	Deprecated. Use AbstractCloseableIteration.isClosed() instead.
protected boolean	finished	Deprecated. Use JoinExecutorBase.isFinished() instead.
protected final CloseableIteration<BindingSet>	leftIter
protected static int	NEXT_JOIN_ID	Deprecated. No replacement, don't use static shared int variables.
protected final TupleExpr	rightArg
protected CloseableIteration<BindingSet>	rightIter
protected final QueueCursor<CloseableIteration<BindingSet>>	rightQueue

Fields inherited from interface CloseableIteration

EMPTY_STATEMENT_ITERATION

Modifier and Type	Field	Description
static final EmptyIteration<Statement>	EMPTY_STATEMENT_ITERATION

Constructor Summary

Constructors

Constructor	Description
ServiceJoinIterator(CloseableIteration<BindingSet> leftIter, Service service, BindingSet bindings, EvaluationStrategy strategy)	Construct a service join iteration to use vectored evaluation.

Method Summary

Modifier and Type	Method	Description
protected void	handleBindings()	Implementations must implement this method to handle bindings.

Methods inherited from class JoinExecutorBase

addResult, done, getNextElement, handleClose, isFinished, run, toss

Modifier and Type	Method	Description
void	addResult(CloseableIteration<BindingSet> res)
void	done()
BindingSet	getNextElement()	Gets the next element.
void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.
boolean	isFinished()	Gets whether this executor is finished or aborted.
final void	run()
void	toss(Exception e)

Methods inherited from class LookAheadIteration

hasNext, next, remove

Modifier and Type	Method	Description
final boolean	hasNext()
final BindingSet	next()
void	remove()	Throws an UnsupportedOperationException.

Methods inherited from class AbstractCloseableIteration

close, isClosed

Modifier and Type	Method	Description
final void	close()	Calls AbstractCloseableIteration.handleClose() upon first call and makes sure the resource closures are only executed once.
final boolean	isClosed()	Checks whether this CloseableIteration has been closed.

Methods inherited from class Object

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

Methods inherited from interface CloseableIteration

stream

Modifier and Type	Method	Description
default Stream<BindingSet>	stream()	Convert the results to a Java 8 Stream.

Methods inherited from interface Iterator

forEachRemaining

Field Details

service

protected Service service

strategy

protected EvaluationStrategy strategy

Constructor Details

ServiceJoinIterator

public ServiceJoinIterator(CloseableIteration<BindingSet> leftIter,
 Service service,
 BindingSet bindings,
 EvaluationStrategy strategy)
                    throws QueryEvaluationException

Construct a service join iteration to use vectored evaluation. The constructor automatically starts evaluation.

Parameters:

leftIter -

service -

bindings -

strategy -

Throws:

QueryEvaluationException

Method Details

handleBindings

protected void handleBindings()
                       throws Exception

Description copied from class: JoinExecutorBase

Implementations must implement this method to handle bindings. Use the following as a template while (!closed invalid input: '&'invalid input: '&' leftIter.hasNext()) { // your code } and add results to rightQueue. Note that addResult() is implemented synchronized and thus thread safe. In case you can guarantee sequential access, it is also possible to directly access rightQueue

Specified by:

handleBindings in class JoinExecutorBase<BindingSet>

Throws:

Exception