de.jungblut.datastructure

Class DiskList<E extends org.apache.hadoop.io.Writable>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

de.jungblut.datastructure.DiskList<E>

All Implemented Interfaces:

Closeable, AutoCloseable, Iterable<E>, Collection<E>, List<E>

public final class DiskList<E extends org.apache.hadoop.io.Writable>
extends AbstractList<E>
implements Iterable<E>, AutoCloseable, Closeable

A file backed disk for adding elements and reading from them in a sequential fashion.

Author:

thomas.jungblut

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DiskList.IORuntimeException

Field Summary

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor and Description
DiskList(String path) Opens a new disk list at the given path.
DiskList(String path, E reusableElement) Opens a new disk list at the given path.
DiskList(String path, int bufferSize) Opens a new disk list at the given path with the given buffersize.
DiskList(String path, int bufferSize, E reusableElement) Opens a new disk list at the given path with the given buffersize.

Method Summary

Modifier and Type	Method and Description
boolean	add(E element) Writes the given element to the disk.
void	close() Closes read and write, also deletes the file.
E	get(int index)
de.jungblut.datastructure.DiskList.State	getCurrentState()
Iterator<E>	iterator()
void	openRead() Opens for a read, closes the write implicitly.
E	poll(E element) Polls the next element from the input stream.
int	size()

Methods inherited from class java.util.AbstractList

add, addAll, clear, equals, hashCode, indexOf, lastIndexOf, listIterator, listIterator, remove, removeRange, set, subList

Methods inherited from class java.util.AbstractCollection

addAll, contains, containsAll, isEmpty, remove, removeAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Methods inherited from interface java.util.List

addAll, contains, containsAll, isEmpty, remove, removeAll, replaceAll, retainAll, sort, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Constructor Detail

DiskList

public DiskList(String path)
         throws IOException

Opens a new disk list at the given path. Buffered through a 8k BufferedOutputStream.

Throws:

IOException

DiskList

public DiskList(String path,
                int bufferSize)
         throws IOException

Opens a new disk list at the given path with the given buffersize. 64k seems quite optimal for most normal hard disks. With 7.2k rpm disk and enough cache 512k might also be optimal.

Throws:

IOException

DiskList

public DiskList(String path,
                E reusableElement)
         throws IOException

Opens a new disk list at the given path. Buffered through a 8k BufferedOutputStream.
You can add a reusable element, that will be filled. This is certainly required when using an iterator.

Throws:

IOException

DiskList

public DiskList(String path,
                int bufferSize,
                E reusableElement)
         throws IOException

Opens a new disk list at the given path with the given buffersize. 64k seems quite optimal for most normal hard disks. With 7.2k rpm disk and enough cache 512k might also be optimal. You can add a reusable element, that will be filled. This is certainly required when using an iterator.

Throws:

IOException

Method Detail

add

public boolean add(E element)

Writes the given element to the disk. Throws a DiskList.IORuntimeException in case of IO failure.

Specified by:

add in interface Collection<E extends org.apache.hadoop.io.Writable>

Specified by:

add in interface List<E extends org.apache.hadoop.io.Writable>

Overrides:

add in class AbstractList<E extends org.apache.hadoop.io.Writable>

openRead

public void openRead()
              throws IOException

Opens for a read, closes the write implicitly.

Throws:

IOException

poll

public E poll(E element)
       throws IOException

Polls the next element from the input stream.

Parameters:

element - the element to fill.

Returns:

the same element as passed through the parameter, just filled with information. Null if there is nothing more to read.

Throws:

IOException

close

public void close()
           throws IOException

Closes read and write, also deletes the file.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

getCurrentState

public de.jungblut.datastructure.DiskList.State getCurrentState()

Returns:

the current state READ or WRITE.

size

public int size()

Specified by:

size in interface Collection<E extends org.apache.hadoop.io.Writable>

Specified by:

size in interface List<E extends org.apache.hadoop.io.Writable>

Specified by:

size in class AbstractCollection<E extends org.apache.hadoop.io.Writable>

Returns:

how many items were inserted.

iterator

public Iterator<E> iterator()

Specified by:

iterator in interface Iterable<E extends org.apache.hadoop.io.Writable>

Specified by:

iterator in interface Collection<E extends org.apache.hadoop.io.Writable>

Specified by:

iterator in interface List<E extends org.apache.hadoop.io.Writable>

Overrides:

iterator in class AbstractList<E extends org.apache.hadoop.io.Writable>

get

public E get(int index)

Specified by:

get in interface List<E extends org.apache.hadoop.io.Writable>

Specified by:

get in class AbstractList<E extends org.apache.hadoop.io.Writable>