Class UnionExecutorBase<T>

java.lang.Object

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

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

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

org.eclipse.rdf4j.federated.evaluation.union.UnionExecutorBase<T>

All Implemented Interfaces:

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

Direct Known Subclasses:

WorkerUnionBase

public abstract class UnionExecutorBase<T>
extends ParallelExecutorBase<T>

Base class for any parallel union 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 inherited from class ParallelExecutorBase

evaluationThread, executorId, finished, log, 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 org.slf4j.Logger	log
protected static final AtomicLong	NEXT_EXECUTOR_ID
protected final QueryInfo	queryInfo
protected CloseableIteration<T>	rightIter
protected FedXQueueCursor<T>	rightQueue
protected final FederationEvaluationStrategy	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
UnionExecutorBase(QueryInfo queryInfo)

Method Summary

Modifier and Type	Method	Description
protected String	getExecutorType()
protected final void	performExecution()	Perform the parallel execution.
protected abstract void	union()	Note: this method must block until the union is executed completely.

Methods inherited from class ParallelExecutorBase

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

Modifier and Type	Method	Description
void	addResult(CloseableIteration<T> 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()
T	getNextElement()	Gets the next element.
QueryInfo	getQueryInfo()	Return the query info of the associated query
void	handleClose()	Called by AbstractCloseableIteration.close() when it is called for the first time.
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 T	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<T>	stream()	Convert the results to a Java 8 Stream.

Methods inherited from interface Iterator

forEachRemaining

Constructor Details

UnionExecutorBase

public UnionExecutorBase(QueryInfo queryInfo)

Method Details

performExecution

protected final void performExecution()
                               throws Exception

Description copied from class: ParallelExecutorBase

Perform the parallel execution.

Note that this method must block until the execution is completed.

Specified by:

performExecution in class ParallelExecutorBase<T>

Throws:

Exception

union

protected abstract void union()
                       throws Exception

Note: this method must block until the union is executed completely. Otherwise the result queue is marked as committed while this isn't the case. The blocking behavior in general is no problem: If you need concurrent access to the result (i.e. pipelining) just run the union in a separate thread. Access to the result iteration is synchronized.

Throws:

Exception

getExecutorType

protected String getExecutorType()

Overrides:

getExecutorType in class ParallelExecutorBase<T>

Returns:

the executor type, e.g. "Join". Default "Executor"