org.h2.util
Class CacheLRU

java.lang.Object
  org.h2.util.CacheLRU

All Implemented Interfaces:

Cache

public class CacheLRU
extends java.lang.Object
implements Cache

A cache implementation based on the last recently used (LRU) algorithm.

Method Summary

void	clear() Clear the cache.
CacheObject	find(int pos) Get an element from the cache if it is available.
CacheObject	get(int pos) Get an element in the cache if it is available.
ObjectArray<CacheObject>	getAllChanged() Get all objects in the cache that have been changed.
static Cache	getCache(CacheWriter writer, java.lang.String cacheType, int cacheSize) Create a cache of the given type and size.
int	getMaxSize() Get the maximum size in words (4 bytes).
int	getSize() Get the used size in words (4 bytes).
java.lang.String	getTypeName() Get the name of the cache type in a human readable form.
void	put(CacheObject rec) Add an element to the cache.
void	remove(int pos) Remove an object from the cache.
void	setMaxSize(int maxKb) Set the maximum memory to be used by this cache.
CacheObject	update(int pos, CacheObject rec) Update an element in the cache.

Methods inherited from class java.lang.Object

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

Method Detail

getCache

public static Cache getCache(CacheWriter writer,
                             java.lang.String cacheType,
                             int cacheSize)
                      throws java.sql.SQLException

Create a cache of the given type and size.

Parameters:

writer - the cache writer

cacheType - the cache type

cacheSize - the size

Returns:

the cache object

Throws:

java.sql.SQLException

clear

public void clear()

Description copied from interface: Cache

Clear the cache.

Specified by:

clear in interface Cache

put

public void put(CacheObject rec)
         throws java.sql.SQLException

Description copied from interface: Cache

Add an element to the cache. Other items may fall out of the cache because of this. It is not allowed to add the same record twice.

Specified by:

put in interface Cache

Parameters:

rec - the object

Throws:

java.sql.SQLException

update

public CacheObject update(int pos,
                          CacheObject rec)
                   throws java.sql.SQLException

Description copied from interface: Cache

Update an element in the cache. This will move the item to the front of the list.

Specified by:

update in interface Cache

Parameters:

pos - the unique key of the element

rec - the element

Returns:

the element

Throws:

java.sql.SQLException

remove

public void remove(int pos)

Description copied from interface: Cache

Remove an object from the cache.

Specified by:

remove in interface Cache

Parameters:

pos - the unique key of the element

find

public CacheObject find(int pos)

Description copied from interface: Cache

Get an element from the cache if it is available. This will not move the item to the front of the list.

Specified by:

find in interface Cache

Parameters:

pos - the unique key of the element

Returns:

the element or null

get

public CacheObject get(int pos)

Description copied from interface: Cache

Get an element in the cache if it is available. This will move the item to the front of the list.

Specified by:

get in interface Cache

Parameters:

pos - the unique key of the element

Returns:

the element or null

getAllChanged

public ObjectArray<CacheObject> getAllChanged()

Description copied from interface: Cache

Get all objects in the cache that have been changed.

Specified by:

getAllChanged in interface Cache

Returns:

the list of objects

setMaxSize

public void setMaxSize(int maxKb)
                throws java.sql.SQLException

Description copied from interface: Cache

Set the maximum memory to be used by this cache.

Specified by:

setMaxSize in interface Cache

Parameters:

maxKb - in number of double words (4 bytes)

Throws:

java.sql.SQLException

getTypeName

public java.lang.String getTypeName()

Description copied from interface: Cache

Get the name of the cache type in a human readable form.

Specified by:

getTypeName in interface Cache

Returns:

the cache type name

getMaxSize

public int getMaxSize()

Description copied from interface: Cache

Get the maximum size in words (4 bytes).

Specified by:

getMaxSize in interface Cache

Returns:

the maximum size in number of double words (4 bytes)

getSize

public int getSize()

Description copied from interface: Cache

Get the used size in words (4 bytes).

Specified by:

getSize in interface Cache

Returns:

the current size in number of double words (4 bytes)