jdbm.recman

Class PageHeader

java.lang.Object

jdbm.recman.PageHeader

All Implemented Interfaces:

BlockView

public class PageHeader
extends Object
implements BlockView

This class represents a page header. It is the common superclass for all different page views. It contains the following information:

1. 2 bytes: the short block type code
2. 8 bytes: the long block id of the next block in the block list
3. 8 bytes: the long block id of the previous block in the block list

The page header block view hence sees 18 bytes of page header data.

Field Summary

Fields

Modifier and Type	Field and Description
protected BlockIo	block the page header block this view is associated with
protected static short	SIZE the size of this page header = 18 bytes

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	PageHeader(BlockIo block) Constructs a PageHeader object from a block

Method Summary

Methods

Modifier and Type	Method and Description
protected void	paranoiaMagicOk() For paranoia mode

Methods inherited from class java.lang.Object

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

Field Detail

SIZE

protected static final short SIZE

the size of this page header = 18 bytes

See Also:

Constant Field Values

block

protected BlockIo block

the page header block this view is associated with

Constructor Detail

PageHeader

protected PageHeader(BlockIo block)

Constructs a PageHeader object from a block

Parameters:

block - The block that contains the page header

Throws:

IOException - if the block is too short to keep the page header.

Method Detail

paranoiaMagicOk

protected void paranoiaMagicOk()

For paranoia mode