org.eclipse.rdf4j.common.iteration

Class QueueIteration<E,T extends Exception>

java.lang.Object

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

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

org.eclipse.rdf4j.common.iteration.QueueIteration<E,T>

All Implemented Interfaces:

AutoCloseable, CloseableIteration<E,T>, Iteration<E,T>

Direct Known Subclasses:

QueueCursor

public abstract class QueueIteration<E,T extends Exception>
extends LookAheadIteration<E,T>

Makes working with a queue easier by adding the methods done() and toss(Exception) and after converting the Exception to the required type using convert(Exception).

Author:

James Leigh

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	QueueIteration(BlockingQueue<E> queue) Creates an QueueIteration with the given BlockingQueue as its backing queue. It may not be threadsafe to modify or access the given BlockingQueue from other locations.
protected	QueueIteration(int capacity) Creates an QueueIteration with the given (fixed) capacity and default access policy.
protected	QueueIteration(int capacity, boolean fair) Creates an QueueIteration with the given (fixed) capacity and the specified access policy.

Method Summary

Modifier and Type	Method and Description
void	checkException()
protected abstract T	convert(Exception e) Converts an exception from the underlying iteration to an exception of type X.
void	done() Indicates the method put(Object) will not be called in the queue anymore.
E	getNextElement() Returns the next item in the queue, which may be null, or throws an exception.
void	handleClose() Called by AbstractCloseableIteration.close() when it is called for the first time.
void	put(E item) Adds another item to the queue, blocking while the queue is full.
void	toss(Exception exception) The next time LookAheadIteration.next() is called this exception will be thrown.

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

Constructor Detail

QueueIteration

protected QueueIteration(int capacity)

Creates an QueueIteration with the given (fixed) capacity and default access policy.

Parameters:

capacity - the capacity of this queue

QueueIteration

protected QueueIteration(int capacity,
                         boolean fair)

Creates an QueueIteration with the given (fixed) capacity and the specified access policy.

Parameters:

capacity - the capacity of this queue

fair - if true then queue accesses for threads blocked on insertion or removal, are processed in FIFO order; if false the access order is unspecified.

QueueIteration

protected QueueIteration(BlockingQueue<E> queue)

Creates an QueueIteration with the given BlockingQueue as its backing queue.
It may not be threadsafe to modify or access the given BlockingQueue from other locations. This method only enables the default ArrayBlockingQueue to be overridden.

Parameters:

queue - A BlockingQueue that is not used in other locations, but will be used as the backing Queue implementation for this cursor.

Method Detail

convert

protected abstract T convert(Exception e)

Converts an exception from the underlying iteration to an exception of type X.

toss

public void toss(Exception exception)

The next time LookAheadIteration.next() is called this exception will be thrown. If it is not a QueryEvaluationException or RuntimeException it will be wrapped in a QueryEvaluationException.

put

public void put(E item)
         throws InterruptedException,
                T extends Exception

Adds another item to the queue, blocking while the queue is full.

Throws:

InterruptedException

T extends Exception

done

public void done()

Indicates the method put(Object) will not be called in the queue anymore.

getNextElement

public E getNextElement()
                 throws T extends Exception

Returns the next item in the queue, which may be null, or throws an exception.

Specified by:

getNextElement in class LookAheadIteration<E,T extends Exception>

Returns:

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

Throws:

T extends Exception

handleClose

public void handleClose()
                 throws T extends Exception

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 LookAheadIteration<E,T extends Exception>

Throws:

T extends Exception

checkException

public void checkException()
                    throws T extends Exception

Throws:

T extends Exception