org.apache.directory.mavibot.btree

Class PersistedPageHolder<K,V>

java.lang.Object

org.apache.directory.mavibot.btree.PageHolder<K,V>

org.apache.directory.mavibot.btree.PersistedPageHolder<K,V>

Type Parameters:

E - The type for the stored element (either a value or a page)

K - The type of the BTree key

V - The type of the BTree value

class PersistedPageHolder<K,V>
extends PageHolder<K,V>

A Value holder. As we may not store all the values in memory (except for an in-memory BTree), we will use a SoftReference to keep a reference to a Value, and if it's null, then we will load the Value from the underlying physical support, using the offset.

Field Summary

Fields

Modifier and Type	Field and Description
private org.apache.commons.collections.map.LRUMap	cache The cache
private long	lastOffset The offset of the last PageIO storing the page on disk
private long	offset The offset of the first PageIO storing the page on disk
private RecordManager	recordManager The RecordManager

Fields inherited from class org.apache.directory.mavibot.btree.PageHolder

btree

Constructor Summary

Constructors

Constructor and Description
PersistedPageHolder(BTree<K,V> btree, Page<K,V> page) Create a new holder storing an offset and a SoftReference containing the element.
PersistedPageHolder(BTree<K,V> btree, Page<K,V> page, long offset, long lastOffset) Create a new holder storing an offset and a SoftReference containing the element.

Method Summary

Modifier and Type	Method and Description
private Page<K,V>	fetchElement() Retrieve the value from the disk, using the BTree and offset
(package private) long	getLastOffset()
(package private) long	getOffset()
Page<K,V>	getValue()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

recordManager

private RecordManager recordManager

The RecordManager

cache

private org.apache.commons.collections.map.LRUMap cache

The cache

offset

private long offset

The offset of the first PageIO storing the page on disk

lastOffset

private long lastOffset

The offset of the last PageIO storing the page on disk

Constructor Detail

PersistedPageHolder

public PersistedPageHolder(BTree<K,V> btree,
                           Page<K,V> page)

Create a new holder storing an offset and a SoftReference containing the element.

Parameters:

page - The element to store into a SoftReference

PersistedPageHolder

public PersistedPageHolder(BTree<K,V> btree,
                           Page<K,V> page,
                           long offset,
                           long lastOffset)

Create a new holder storing an offset and a SoftReference containing the element.

Parameters:

page - The element to store into a SoftReference

Method Detail

getValue

public Page<K,V> getValue()

Overrides:

getValue in class PageHolder<K,V>

Returns:

the stored page

Throws:

java.io.IOException

EndOfFileExceededException

fetchElement

private Page<K,V> fetchElement()

Retrieve the value from the disk, using the BTree and offset

Returns:

The deserialized element (

getOffset

long getOffset()

Returns:

The offset of the first PageIO storing the data on disk

getLastOffset

long getLastOffset()

Returns:

The offset of the last PageIO storing the data on disk

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

See Also:

Object.toString()