Package org.eclipse.rdf4j.federated.evaluation.iterator

Class QueryResultIteration

java.lang.Object

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

org.eclipse.rdf4j.federated.evaluation.iterator.QueryResultIteration

All Implemented Interfaces:

AutoCloseable, CloseableIteration<BindingSet,QueryEvaluationException>, Iteration<BindingSet,QueryEvaluationException>

public class QueryResultIteration
extends AbstractCloseableIteration<BindingSet,QueryEvaluationException>

An iteration which wraps the final result and in case of exceptions aborts query evaluation for the corresponding query in fedx (potentially subqueries are still running, and jobs are scheduled). If some external component calls close() on this iteration AND if the corresponding query is still running, the query is aborted within FedX. An example case would be RDF4J's QueryInteruptIterations, which is used to enforce maxQueryTime. If the query is finished, the FederationManager is notified that the query is done, and the query is removed from the set of running queries.

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field	Description
protected CloseableIteration<BindingSet,QueryEvaluationException>	inner
protected QueryManager	qm
protected QueryInfo	queryInfo

Constructor Summary

Constructors

Constructor	Description
QueryResultIteration(CloseableIteration<BindingSet,QueryEvaluationException> inner, QueryInfo queryInfo)

Method Summary

Modifier and Type	Method	Description
protected void	abortQuery()	Abort the query in the schedulers if it is still running.
protected void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.
boolean	hasNext()	Returns true if the iteration has more elements.
BindingSet	next()	Returns the next element in the iteration.
void	remove()	Removes from the underlying collection the last element returned by the iteration (optional operation).

Methods inherited from class org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration

close, isClosed

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.rdf4j.common.iteration.CloseableIteration

stream

Field Detail

inner

protected final CloseableIteration<BindingSet,QueryEvaluationException> inner

queryInfo

protected final QueryInfo queryInfo

qm

protected final QueryManager qm

Constructor Detail

QueryResultIteration

public QueryResultIteration(CloseableIteration<BindingSet,QueryEvaluationException> inner,
                            QueryInfo queryInfo)

Method Detail

hasNext

public boolean hasNext()
                throws QueryEvaluationException

Description copied from interface: Iteration

Returns true if the iteration has more elements. (In other words, returns true if Iteration.next() would return an element rather than throwing a NoSuchElementException.)

Returns:

true if the iteration has more elements.

Throws:

QueryEvaluationException

next

public BindingSet next()
                throws QueryEvaluationException

Description copied from interface: Iteration

Returns the next element in the iteration.

Returns:

the next element in the iteration.

Throws:

QueryEvaluationException

remove

public void remove()
            throws QueryEvaluationException

Description copied from interface: Iteration

Removes from the underlying collection the last element returned by the iteration (optional operation). This method can be called only once per call to next.

Throws:

QueryEvaluationException

handleClose

protected void handleClose()
                    throws QueryEvaluationException

Description copied from class: AbstractCloseableIteration

Called by AbstractCloseableIteration.close() when it is called for the first time. This method is only called once on each iteration. By default, this method does nothing.

Overrides:

handleClose in class AbstractCloseableIteration<BindingSet,QueryEvaluationException>

Throws:

QueryEvaluationException

abortQuery

protected void abortQuery()

Abort the query in the schedulers if it is still running.