org.apache.excalibur.store.impl

Class MRUMemoryStore

java.lang.Object

org.apache.avalon.framework.logger.AbstractLogEnabled

org.apache.excalibur.store.impl.MRUMemoryStore

All Implemented Interfaces:

org.apache.avalon.framework.activity.Disposable, org.apache.avalon.framework.component.Component, org.apache.avalon.framework.logger.LogEnabled, org.apache.avalon.framework.parameters.Parameterizable, org.apache.avalon.framework.service.Serviceable, org.apache.avalon.framework.thread.ThreadSafe, org.apache.excalibur.instrument.Instrumentable, Store

public class MRUMemoryStore
extends org.apache.avalon.framework.logger.AbstractLogEnabled
implements Store, org.apache.avalon.framework.parameters.Parameterizable, org.apache.avalon.framework.service.Serviceable, org.apache.avalon.framework.activity.Disposable, org.apache.avalon.framework.thread.ThreadSafe, org.apache.excalibur.instrument.Instrumentable, org.apache.avalon.framework.component.Component

This class provides a cache algorithm for the requested documents. It combines a HashMap and a LinkedList to create a so called MRU (Most Recently Used) cache.

Version:

CVS $Id: MRUMemoryStore.java,v 1.5 2004/02/28 11:47:31 cziegeler Exp $

Author:

Avalon Development Team

Field Summary

Fields

Modifier and Type	Field and Description
private java.util.Hashtable	m_cache
private org.apache.excalibur.instrument.CounterInstrument	m_hitsInstrument
private java.lang.String	m_instrumentableName
private org.apache.avalon.framework.service.ServiceManager	m_manager
private int	m_maxobjects
private org.apache.excalibur.instrument.CounterInstrument	m_missesInstrument
private java.util.LinkedList	m_mrulist
private boolean	m_persistent
private Store	m_persistentStore
private org.apache.excalibur.instrument.ValueInstrument	m_sizeInstrument
private StoreJanitor	m_storeJanitor

Fields inherited from interface org.apache.excalibur.store.Store

PERSISTENT_STORE, ROLE, TRANSIENT_STORE

Fields inherited from interface org.apache.excalibur.instrument.Instrumentable

EMPTY_INSTRUMENT_ARRAY, EMPTY_INSTRUMENTABLE_ARRAY

Constructor Summary

Constructors

Constructor and Description
MRUMemoryStore()

Method Summary

Methods

Modifier and Type	Method and Description
private boolean	checkSerializable(java.lang.Object object) This method checks if an object is seriazable.
void	clear() Clear the Store of all elements
boolean	containsKey(java.lang.Object key) Indicates if the given key is associated to a contained object.
void	dispose() Dispose the component
void	free() Frees some of the fast memory used by this store.
java.lang.Object	get(java.lang.Object key) Get the object associated to the given unique key.
org.apache.excalibur.instrument.Instrumentable[]	getChildInstrumentables()
java.lang.String	getInstrumentableName()
org.apache.excalibur.instrument.Instrument[]	getInstruments()
void	hold(java.lang.Object key, java.lang.Object value) This method holds the requested object in a HashMap combined with a LinkedList to create the MRU.
java.util.Enumeration	keys() Returns the list of used keys as an Enumeration.
void	parameterize(org.apache.avalon.framework.parameters.Parameters params) Initialize the MRUMemoryStore.
void	remove(java.lang.Object key) Remove the object associated to the given key.
void	service(org.apache.avalon.framework.service.ServiceManager manager) Get components of the ComponentLocator
void	setInstrumentableName(java.lang.String name)
int	size() Returns count of the objects in the store, or -1 if could not be obtained.
void	store(java.lang.Object key, java.lang.Object value) Store the given object in a persistent state.

Methods inherited from class org.apache.avalon.framework.logger.AbstractLogEnabled

enableLogging, getLogger, setupLogger, setupLogger, setupLogger

Methods inherited from class java.lang.Object

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

Field Detail

m_instrumentableName

private java.lang.String m_instrumentableName

m_maxobjects

private int m_maxobjects

m_persistent

private boolean m_persistent

m_cache

private java.util.Hashtable m_cache

m_mrulist

private java.util.LinkedList m_mrulist

m_persistentStore

private Store m_persistentStore

m_storeJanitor

private StoreJanitor m_storeJanitor

m_manager

private org.apache.avalon.framework.service.ServiceManager m_manager

m_sizeInstrument

private org.apache.excalibur.instrument.ValueInstrument m_sizeInstrument

m_hitsInstrument

private org.apache.excalibur.instrument.CounterInstrument m_hitsInstrument

m_missesInstrument

private org.apache.excalibur.instrument.CounterInstrument m_missesInstrument

Constructor Detail

MRUMemoryStore

public MRUMemoryStore()

Method Detail

service

public void service(org.apache.avalon.framework.service.ServiceManager manager)
             throws org.apache.avalon.framework.service.ServiceException

Get components of the ComponentLocator

Specified by:

service in interface org.apache.avalon.framework.service.Serviceable

Parameters:

manager - The ComponentLocator

Throws:

org.apache.avalon.framework.service.ServiceException

parameterize

public void parameterize(org.apache.avalon.framework.parameters.Parameters params)
                  throws org.apache.avalon.framework.parameters.ParameterException

Initialize the MRUMemoryStore. A few options can be used:

• maxobjects: Maximum number of objects stored in memory (Default: 100 objects)
• use-persistent-cache: Use persistent cache to keep objects persisted after container shutdown or not (Default: false)

Specified by:

parameterize in interface org.apache.avalon.framework.parameters.Parameterizable

Parameters:

params - Store parameters

Throws:

org.apache.avalon.framework.parameters.ParameterException

dispose

public void dispose()

Dispose the component

Specified by:

dispose in interface org.apache.avalon.framework.activity.Disposable

store

public void store(java.lang.Object key,
         java.lang.Object value)

Store the given object in a persistent state. It is up to the caller to ensure that the key has a persistent state across different JVM executions.

Specified by:

store in interface Store

Parameters:

key - The key for the object to store

value - The object to store

hold

public void hold(java.lang.Object key,
        java.lang.Object value)

This method holds the requested object in a HashMap combined with a LinkedList to create the MRU. It also stores objects onto the filesystem if configured.

Parameters:

key - The key of the object to be stored

value - The object to be stored

get

public java.lang.Object get(java.lang.Object key)

Get the object associated to the given unique key.

Specified by:

get in interface Store

Parameters:

key - The key of the requested object

Returns:

the requested object

remove

public void remove(java.lang.Object key)

Remove the object associated to the given key.

Specified by:

remove in interface Store

Parameters:

key - The key of to be removed object

clear

public void clear()

Clear the Store of all elements

Specified by:

clear in interface Store

containsKey

public boolean containsKey(java.lang.Object key)

Indicates if the given key is associated to a contained object.

Specified by:

containsKey in interface Store

Parameters:

key - The key of the object

Returns:

true if the key exists

keys

public java.util.Enumeration keys()

Returns the list of used keys as an Enumeration.

Specified by:

keys in interface Store

Returns:

the enumeration of the cache

size

public int size()

Returns count of the objects in the store, or -1 if could not be obtained.

Specified by:

size in interface Store

free

public void free()

Frees some of the fast memory used by this store. It removes the last element in the store.

Specified by:

free in interface Store

checkSerializable

private boolean checkSerializable(java.lang.Object object)

This method checks if an object is seriazable.

Parameters:

object - The object to be checked

Returns:

true if the object is storeable

setInstrumentableName

public void setInstrumentableName(java.lang.String name)

Specified by:

setInstrumentableName in interface org.apache.excalibur.instrument.Instrumentable

getInstrumentableName

public java.lang.String getInstrumentableName()

Specified by:

getInstrumentableName in interface org.apache.excalibur.instrument.Instrumentable

getInstruments

public org.apache.excalibur.instrument.Instrument[] getInstruments()

Specified by:

getInstruments in interface org.apache.excalibur.instrument.Instrumentable

getChildInstrumentables

public org.apache.excalibur.instrument.Instrumentable[] getChildInstrumentables()

Specified by:

getChildInstrumentables in interface org.apache.excalibur.instrument.Instrumentable