Class ControlledWorkerJoin

java.lang.Object

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

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

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

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

org.eclipse.rdf4j.federated.evaluation.join.ControlledWorkerJoin

All Implemented Interfaces:

AutoCloseable, Runnable, Iterator<BindingSet>, CloseableIteration<BindingSet>, ParallelExecutor<BindingSet>

Direct Known Subclasses:

ControlledWorkerBoundJoin

public class ControlledWorkerJoin
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 final Phaser	phaser
protected final ControlledWorkerScheduler<BindingSet>	scheduler

Fields inherited from class JoinExecutorBase

bindings, joinVars, leftIter, rightArg

Modifier and Type	Field	Description
protected final BindingSet	bindings
protected Set<String>	joinVars
protected CloseableIteration<BindingSet>	leftIter
protected final TupleExpr	rightArg

Fields inherited from class ParallelExecutorBase

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

Modifier and Type	Field	Description
protected Thread	evaluationThread
protected final long	executorId
protected boolean	finished
protected static final AtomicLong	NEXT_EXECUTOR_ID
protected final QueryInfo	queryInfo
protected CloseableIteration<BindingSet>	rightIter
protected FedXQueueCursor<BindingSet>	rightQueue
protected final FederationEvalStrategy	strategy

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
ControlledWorkerJoin(ControlledWorkerScheduler<BindingSet> scheduler, FederationEvalStrategy strategy, CloseableIteration<BindingSet> leftIter, TupleExpr rightArg, 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 JoinExecutorBase

getExecutorType, getJoinVars, performExecution, setJoinVars

Modifier and Type	Method	Description
protected String	getExecutorType()
Set<String>	getJoinVars()
protected final void	performExecution()	Perform the parallel execution.
void	setJoinVars(Set<String> joinVars)	Set the join variables

Methods inherited from class ParallelExecutorBase

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

Modifier and Type	Method	Description
void	addResult(CloseableIteration<BindingSet> res)	Handle the result appropriately, e.g. add it to the result iteration.
protected void	checkTimeout()	Checks whether the query execution has run into a timeout.
void	done()	Inform the controlling instance that some job is done from a different thread.
String	getDisplayId()
protected String	getId()
BindingSet	getNextElement()	Gets the next element.
QueryInfo	getQueryInfo()	Return the query info of the associated query
boolean	isFinished()	Return true if this executor is finished or aborted
final void	run()
void	toss(Exception e)	Toss some exception to the controlling instance
String	toString()

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, 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

scheduler

protected final ControlledWorkerScheduler<BindingSet> scheduler

phaser

protected final Phaser phaser

Constructor Details

ControlledWorkerJoin

public ControlledWorkerJoin(ControlledWorkerScheduler<BindingSet> scheduler,
 FederationEvalStrategy strategy,
 CloseableIteration<BindingSet> leftIter,
 TupleExpr rightArg,
 BindingSet bindings,
 QueryInfo queryInfo)
                     throws QueryEvaluationException

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 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