UnionExecutorBase (Eclipse RDF4J 4.2.4)

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.union.UnionExecutorBase<T>

All Implemented Interfaces:

AutoCloseable, Runnable, CloseableIteration<T,QueryEvaluationException>, Iteration<T,QueryEvaluationException>, 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 org.eclipse.rdf4j.federated.evaluation.concurrent.ParallelExecutorBase
  evaluationThread, executorId, finished, log, NEXT_EXECUTOR_ID, queryInfo, rightIter, rightQueue, strategy

Constructor Summary

Constructors
Constructor Description

UnionExecutorBase(QueryInfo queryInfo)

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`protected String`	`getExecutorType()`
`protected 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 org.eclipse.rdf4j.federated.evaluation.concurrent.ParallelExecutorBase
addResult, checkTimeout, done, getDisplayId, getId, getNextElement, getQueryInfo, handleClose, 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

- Constructor Detail
  - UnionExecutorBase
```
public UnionExecutorBase(QueryInfo queryInfo)
```
- Method Detail
  - 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"