org.apache.directory.mavibot.btree

Class PageIO

java.lang.Object

org.apache.directory.mavibot.btree.PageIO

class PageIO
extends java.lang.Object

A structure containing a Page on disk. It's a byte[PageSize] plus a few more details like the page offset on disk and a link to the next page.
As we may need more than one Page to store some data, the PageIO are linked so that the list of all the PageIO contain the full data.
The first PageIO contains the size of the data.
Here is the logical structure of a PageIO :

 For a first page :

 +----------+------+----------------------+
 | nextPage | size | XXXXXXXXXXXXXXXXXXXX |
 +----------+------+----------------------+

 for any page but the first :

 +----------+-----------------------------+
 | nextPage | XXXXXXXXXXXXXXXXXXXXXXXXXXX |
 +----------+-----------------------------+

 for the last page :
 +----------+-----------------------------+
 |    -1    | XXXXXXXXXXXXXXXXXXXXXXXXXXX |
 +----------+-----------------------------+

 In any case, the page length is always PageSize.
 

Field Summary

Fields

Modifier and Type	Field and Description
private java.nio.ByteBuffer	data The contain data
private long	nextPage A pointer to the next pageIO
private long	offset The position of the page on disk
private int	size The offset on disk

Constructor Summary

Constructors

Constructor and Description
PageIO() A default constructor for a PageIO
PageIO(long offset) A constructor for a PageIO when we know the offset of this page on disk

Method Summary

Modifier and Type	Method and Description
(package private) PageIO	copy(PageIO copy)
(package private) java.nio.ByteBuffer	getData()
(package private) long	getNextPage() Get the NextPage value from the PageIO.
(package private) long	getOffset()
(package private) long	getSize()
(package private) void	setData(java.nio.ByteBuffer data)
(package private) void	setNextPage(long nextPage)
(package private) void	setOffset(long offset)
(package private) void	setSize()
(package private) void	setSize(int size)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

data

private java.nio.ByteBuffer data

The contain data

nextPage

private long nextPage

A pointer to the next pageIO

size

private int size

The offset on disk

offset

private long offset

The position of the page on disk

Constructor Detail

PageIO

PageIO()

A default constructor for a PageIO

PageIO

PageIO(long offset)

A constructor for a PageIO when we know the offset of this page on disk

Method Detail

getData

java.nio.ByteBuffer getData()

Returns:

the data

setData

void setData(java.nio.ByteBuffer data)

Parameters:

data - the data to set

getNextPage

long getNextPage()

Get the NextPage value from the PageIO. If it's -1, there is no next page

Returns:

the nextPage

setNextPage

void setNextPage(long nextPage)

Parameters:

nextPage - the nextPage to set

getSize

long getSize()

Returns:

the size

setSize

void setSize(int size)

Parameters:

size - the size to set

setSize

void setSize()

Parameters:

size - the size to set

getOffset

long getOffset()

Returns:

the offset

setOffset

void setOffset(long offset)

Parameters:

offset - the offset to set

copy

PageIO copy(PageIO copy)

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()