jdbm.btree
Class BPage<K,V>

java.lang.Object
  jdbm.btree.BPage<K,V>

All Implemented Interfaces:

Serializable, Serializer

public class BPage<K,V>
extends Object
implements Serializer

Page of a Btree.

The page contains a number of key-value pairs. Keys are ordered to allow dichotomic search.

If the page is a leaf page, the keys and values are user-defined and represent entries inserted by the user.

If the page is non-leaf, each key represents the greatest key in the underlying BPages and the values are recids pointing to the children BPages. The only exception is the rightmost BPage, which is considered to have an "infinite" key value, meaning that any insert will be to the left of this pseudo-key

Author:

Alex Boisvert

See Also:

Serialized Form

Field Summary

protected long[]	children Children pages (recids) associated with keys.
protected int	first Index of first used item at the page
protected boolean	isLeaf Flag indicating if this is a leaf BPage.
protected K[]	keys Keys of children nodes
protected long	next Next leaf BPage (only if this BPage is a leaf)
static AtomicInteger	outstandingBrowsers
protected long	previous Previous leaf BPage (only if this BPage is a leaf)
protected long	recordId This BPage's record ID in the PageManager.
protected V[]	values Values associated with keys.

Constructor Summary

BPage()
No-argument constructor used by serialization.

Method Summary

BPage<K,V>	deserialize(byte[] serialized) Deserialize the content of an object from a byte array.
long	getRecordId()
byte[]	serialize(Object obj) Serialize the content of an object into a byte array.
void	setRecordId(long recordId) Set the recordId
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

recordId

protected transient long recordId

This BPage's record ID in the PageManager.

isLeaf

protected boolean isLeaf

Flag indicating if this is a leaf BPage.

keys

protected K[] keys

Keys of children nodes

values

protected V[] values

Values associated with keys. (Only valid if leaf BPage)

children

protected long[] children

Children pages (recids) associated with keys. (Only valid if non-leaf BPage)

first

protected int first

Index of first used item at the page

previous

protected long previous

Previous leaf BPage (only if this BPage is a leaf)

next

protected long next

Next leaf BPage (only if this BPage is a leaf)

outstandingBrowsers

public static AtomicInteger outstandingBrowsers

Constructor Detail

BPage

public BPage()

No-argument constructor used by serialization.

Method Detail

getRecordId

public long getRecordId()

Returns:

The record ID

setRecordId

public void setRecordId(long recordId)

Set the recordId

Parameters:

recordId - The recordId

deserialize

public BPage<K,V> deserialize(byte[] serialized)
                       throws IOException

Deserialize the content of an object from a byte array.

Specified by:

deserialize in interface Serializer

Parameters:

serialized - Byte array representation of the object

Returns:

deserialized object

Throws:

IOException

serialize

public byte[] serialize(Object obj)
                 throws IOException

Serialize the content of an object into a byte array.

Specified by:

serialize in interface Serializer

Parameters:

obj - Object to serialize

Returns:

a byte array representing the object's state

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object