Package org.eclipse.rdf4j.repository.sparql.federation

Class JoinExecutorBase<T>

java.lang.Object

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

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

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

All Implemented Interfaces:

AutoCloseable, Iterator<T>, CloseableIteration<T>

Direct Known Subclasses:

ServiceJoinIterator

public abstract class JoinExecutorBase<T>
extends LookAheadIteration<T>

Base class for any join parallel join executor. Note that this class extends LookAheadIteration and thus any implementation of this class is applicable for pipelining when used in a different thread (access to shared variables is synchronized).

Author:

Andreas Schwarte

Field Summary

Fields

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

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	JoinExecutorBase(CloseableIteration<T> leftIter, TupleExpr rightArg, BindingSet bindings)

Method Summary

Modifier and Type	Method	Description
void	addResult(CloseableIteration<T> res)
void	done()
T	getNextElement()	Gets the next element.
protected abstract void	handleBindings()	Implementations must implement this method to handle bindings.
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 org.eclipse.rdf4j.common.iteration.LookAheadIteration

hasNext, next, remove

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Field Details

NEXT_JOIN_ID

protected static int NEXT_JOIN_ID

Deprecated.

No replacement, don't use static shared int variables.

rightArg

protected final TupleExpr rightArg

bindings

protected final BindingSet bindings

leftIter

protected final CloseableIteration<T> leftIter

rightIter

protected volatile CloseableIteration<T> rightIter

closed

protected volatile boolean closed

Deprecated.

Use AbstractCloseableIteration.isClosed() instead.

finished

protected volatile boolean finished

Deprecated.

Use isFinished() instead.

rightQueue

protected final QueueCursor<CloseableIteration<T>> rightQueue

Constructor Details

JoinExecutorBase

protected JoinExecutorBase(CloseableIteration<T> leftIter,
 TupleExpr rightArg,
 BindingSet bindings)
                    throws QueryEvaluationException

Throws:

QueryEvaluationException

Method Details

run

public final void run()

handleBindings

protected abstract void handleBindings()
                                throws Exception

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

Throws:

Exception

addResult

public void addResult(CloseableIteration<T> res)

done

public void done()

toss

public void toss(Exception e)

getNextElement

public T getNextElement()
                 throws QueryEvaluationException

Description copied from class: LookAheadIteration

Gets the next element. Subclasses should implement this method so that it returns the next element.

Specified by:

getNextElement in class LookAheadIteration<T>

Returns:

The next element, or null if no more elements are available.

Throws:

QueryEvaluationException

handleClose

public 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.

Specified by:

handleClose in class AbstractCloseableIteration<T>

Throws:

QueryEvaluationException

isFinished

public boolean isFinished()

Gets whether this executor is finished or aborted.

Returns:

true if this executor is finished or aborted