Module org.apache.jena.arq

Package org.apache.jena.atlas.data

Class SortedDataBag<E>

java.lang.Object

org.apache.jena.atlas.data.AbstractDataBag<E>

org.apache.jena.atlas.data.SortedDataBag<E>

All Implemented Interfaces:

Iterable<E>, DataBag<E>, org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sink<E>

Direct Known Subclasses:

DistinctDataBag

public class SortedDataBag<E>
extends AbstractDataBag<E>

This data bag will gather items in memory until a size threshold is passed, at which point it will write out all of the items to disk using the supplied serializer.

After adding is finished, call iterator() to set up the data bag for reading back items and iterating over them. The iterator will retrieve the items in sorted order using the supplied comparator.

IMPORTANT: You may not add any more items after this call. You may subsequently call iterator() multiple times which will give you a new iterator for each invocation. If you do not consume the entire iterator, you should call Iter.close(Iterator) to close any FileInputStreams associated with the iterator.

Additionally, make sure to call close() when you are finished to free any system resources (preferably in a finally block).

Implementation Notes: Data is stored in an ArrayList as it comes in. When it is time to spill, that data is sorted and written to disk. An iterator will read in each file and perform a merge-sort as the results are returned.

Constructor Summary

Constructors

Constructor	Description
SortedDataBag(ThresholdPolicy<E> policy, SerializationFactory<E> serializerFactory, Comparator<? super E> comparator)

Method Summary

Modifier and Type	Method	Description
void	add(E item)	Add a tuple to the bag.
void	cancel()	cancel arranges that further comparisons using the supplied comparator will abandon the sort in progress.
void	close()
void	flush()
boolean	isCancelled()	isCancelled is true iff cancel has been called on this bags comparator.
boolean	isClosed()	isClosed returns true iff this bag has been closed.
boolean	isDistinct()	Find out if the bag is distinct.
boolean	isSorted()	Find out if the bag is sorted.
Iterator<E>	iterator()	Returns an iterator over a set of elements of type E.

Methods inherited from class org.apache.jena.atlas.data.AbstractDataBag

isEmpty, send, size

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.jena.atlas.data.DataBag

addAll, addAll

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Details

SortedDataBag

public SortedDataBag(ThresholdPolicy<E> policy,
 SerializationFactory<E> serializerFactory,
 Comparator<? super E> comparator)

Method Details

cancel

public void cancel()

cancel arranges that further comparisons using the supplied comparator will abandon the sort in progress.

isCancelled

public boolean isCancelled()

isCancelled is true iff cancel has been called on this bags comparator. (Used in testing.)

isClosed

public boolean isClosed()

isClosed returns true iff this bag has been closed. (Used in testing.)

isSorted

public boolean isSorted()

Description copied from interface: DataBag

Find out if the bag is sorted.

Returns:

true if this is a sorted data bag, false otherwise.

isDistinct

public boolean isDistinct()

Description copied from interface: DataBag

Find out if the bag is distinct.

Returns:

true if the bag is a distinct bag, false otherwise.

add

public void add(E item)

Description copied from interface: DataBag

Add a tuple to the bag.

Parameters:

item - tuple to add.

flush

public void flush()

iterator

public Iterator<E> iterator()

Returns an iterator over a set of elements of type E. If you do not exhaust the iterator, you should call Iter.close(Iterator) to be sure any open file handles are closed.

Returns:

an Iterator

close

public void close()