Package org.eclipse.rdf4j.federated.evaluation.join

Class ControlledWorkerLeftJoin

java.lang.Object

org.eclipse.rdf4j.common.iteration.AbstractCloseableIteration<E,X>

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

org.eclipse.rdf4j.federated.evaluation.concurrent.ParallelExecutorBase<T>

org.eclipse.rdf4j.federated.evaluation.join.JoinExecutorBase<BindingSet>

org.eclipse.rdf4j.federated.evaluation.join.ControlledWorkerLeftJoin

All Implemented Interfaces:

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

public class ControlledWorkerLeftJoin
extends JoinExecutorBase<BindingSet>

Execute the nested loop join in an asynchronous fashion, i.e. one binding after the other (but concurrently) The number of concurrent threads is controlled by a ControlledWorkerScheduler which works according to the FIFO principle. This join cursor blocks until all scheduled tasks are finished, however the result iteration can be accessed from different threads to allow for pipelining.

Author:

Andreas Schwarte

Field Summary

Fields

Modifier and Type	Field	Description
protected LeftJoin	join
protected Phaser	phaser
protected ControlledWorkerScheduler<BindingSet>	scheduler

Fields inherited from class org.eclipse.rdf4j.federated.evaluation.join.JoinExecutorBase

bindings, joinVars, leftIter, rightArg

Fields inherited from class org.eclipse.rdf4j.federated.evaluation.concurrent.ParallelExecutorBase

evaluationThread, executorId, finished, NEXT_EXECUTOR_ID, queryInfo, rightIter, rightQueue, strategy

Constructor Summary

Constructors

Constructor	Description
ControlledWorkerLeftJoin(ControlledWorkerScheduler<BindingSet> scheduler, FederationEvalStrategy strategy, CloseableIteration<BindingSet,QueryEvaluationException> leftIter, LeftJoin join, BindingSet bindings, QueryInfo queryInfo)

Method Summary

Modifier and Type	Method	Description
protected void	handleBindings()	Implementations must implement this method to handle bindings.
void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.

Methods inherited from class org.eclipse.rdf4j.federated.evaluation.join.JoinExecutorBase

getExecutorType, getJoinVars, performExecution, setJoinVars

Methods inherited from class org.eclipse.rdf4j.federated.evaluation.concurrent.ParallelExecutorBase

addResult, checkTimeout, done, getDisplayId, getId, getNextElement, getQueryInfo, isFinished, run, toss, toString

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, wait, wait, wait

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

stream

Field Detail

scheduler

protected final ControlledWorkerScheduler<BindingSet> scheduler

phaser

protected final Phaser phaser

join

protected final LeftJoin join

Constructor Detail

ControlledWorkerLeftJoin

public ControlledWorkerLeftJoin(ControlledWorkerScheduler<BindingSet> scheduler,
                                FederationEvalStrategy strategy,
                                CloseableIteration<BindingSet,QueryEvaluationException> leftIter,
                                LeftJoin join,
                                BindingSet bindings,
                                QueryInfo queryInfo)
                         throws QueryEvaluationException

Throws:

QueryEvaluationException

Method Detail

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 && 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 Note that the implementation must block until the entire join is executed.

Specified by:

handleBindings in class JoinExecutorBase<BindingSet>

Throws:

Exception

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.

Overrides:

handleClose in class JoinExecutorBase<BindingSet>

Throws:

QueryEvaluationException