com.bigdata.relation.accesspath

Class WrappedAsynchronousIterator<E,F>

java.lang.Object

com.bigdata.relation.accesspath.WrappedAsynchronousIterator<E,F>

All Implemented Interfaces:

IAsynchronousIterator<E>, ICloseable, ICloseableIterator<E>, Iterator<E>

public class WrappedAsynchronousIterator<E,F>
extends Object
implements IAsynchronousIterator<E>

An IAsynchronousIterator that wraps an IChunkedIterator or a ICloseableIterator.

Version:

$Id: ThickAsynchronousIterator.java 2265 2009-10-26 12:51:06Z thompsonbry $

Author:

Bryan Thompson

Constructor Summary

Constructors

Constructor and Description
WrappedAsynchronousIterator(IChunkedIterator<F> src)

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Notes that the iterator is closed and hence may no longer be read.
boolean	hasNext()
boolean	hasNext(long timeout, TimeUnit unit) Delegates to hasNext() since all data are local and timeouts can not occur.
boolean	isExhausted() Return true iff this iterator will not visit any more elements (non-blocking).
E	next()
E	next(long timeout, TimeUnit unit) Delegates to next() since all data are local and timeouts can not occur.
void	remove()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WrappedAsynchronousIterator

public WrappedAsynchronousIterator(IChunkedIterator<F> src)

Parameters:

src - The source.

Throws:

IllegalArgumentException - if src is null.

Method Detail

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<E>

next

public E next()

Specified by:

next in interface Iterator<E>

remove

public void remove()

Specified by:

remove in interface Iterator<E>

close

public void close()

Description copied from interface: IAsynchronousIterator

Notes that the iterator is closed and hence may no longer be read. It is safe to invoke this method even if the iterator is closed. However, if the producer is still running then it will be canceled (interrupted) in order to prevent the IBlockingBuffer from filling up and deadlocking. For this reason, IAsynchronousIterator.close() has consequences NOT entailed by ICloseableIterator.

Note: Depending on the semantics of the producer, it MAY choose to treat an interrupt() as normal (but eager) termination. For example, rule execution treats an interrupt() as normal (but eager) termination with the consequence that queries may be safely interrupted once some limit has been satisfied. However, the preferred way to treat LIMIT is using IRule with an IQueryOptions that specifies a LIMIT.

Specified by:

close in interface IAsynchronousIterator<E>

Specified by:

close in interface ICloseable

Specified by:

close in interface ICloseableIterator<E>

isExhausted

public boolean isExhausted()

Description copied from interface: IAsynchronousIterator

Return true iff this iterator will not visit any more elements (non-blocking).

Specified by:

isExhausted in interface IAsynchronousIterator<E>

Returns:

true iff the iterator is known to be exhausted without blocking. A false return does NOT imply that the iterator will visit more elements, only that it MIGHT visit more elements.

hasNext

public boolean hasNext(long timeout,
              TimeUnit unit)

Delegates to hasNext() since all data are local and timeouts can not occur.

Specified by:

hasNext in interface IAsynchronousIterator<E>

Parameters:

timeout - The length of time that the method may block awaiting an element to appear.

unit - The units in which the timeout is expressed.

Returns:

true iff there is an element available.

next

public E next(long timeout,
     TimeUnit unit)

Delegates to next() since all data are local and timeouts can not occur.

Specified by:

next in interface IAsynchronousIterator<E>

Parameters:

timeout - The timeout (overrides the chunkTimeout specified to the BlockingBuffer ctor).

unit - The unit in which the timeout is expressed.

Returns:

The element -or- null iff the timeout was exceeded before IAsynchronousIterator.hasNext(long, TimeUnit) returned true.

In order to have a definitive indication that the iterator is exhausted you need to invoke Iterator.hasNext() without a timeout (blocking) or IAsynchronousIterator.isExhausted() (non-blocking).