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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:

Component, Disposable, Instrumentable, LogEnabled, Parameterizable, Serviceable, Store, ThreadSafe

public class MRUMemoryStore

extends AbstractLogEnabled

implements Store, Parameterizable, Serviceable, Disposable, ThreadSafe, Instrumentable

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 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

MRUMemoryStore()

Method Summary

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.
Instrumentable[]	getChildInstrumentables() Any Object which implements Instrumentable can also make use of other Instrumentable child objects.
java.lang.String	getInstrumentableName() Gets the name of the Instrumentable.
Instrument[]	getInstruments() Obtain a reference to all the Instruments that the Instrumentable object wishes to expose.
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(Parameters params) Initialize the MRUMemoryStore.
void	remove(java.lang.Object key) Remove the object associated to the given key.
void	service(ServiceManager manager) Get components of the ComponentLocator
void	setInstrumentableName(java.lang.String name) Sets the name for the Instrumentable.
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

Constructor Detail

MRUMemoryStore

public MRUMemoryStore()

Method Detail

service

public void service(ServiceManager manager)
             throws ServiceException

Get components of the ComponentLocator

Specified by:

service in interface Serviceable

Parameters:

manager - The ComponentLocator

Throws:

ServiceException - if an error occurs

parameterize

public void parameterize(Parameters params)
                  throws 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 Parameterizable

Parameters:

params - Store parameters

Throws:

ParameterException

dispose

public void dispose()

Dispose the component

Specified by:

dispose in interface 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

setInstrumentableName

public void setInstrumentableName(java.lang.String name)

Description copied from interface: Instrumentable

Sets the name for the Instrumentable. The Instrumentable Name is used to uniquely identify the Instrumentable during the configuration of the InstrumentManager and to gain access to an InstrumentableDescriptor through the InstrumentManager. The value should be a string which does not contain spaces or periods.

This value may be set by a parent Instrumentable, or by the InstrumentManager using the value of the 'instrumentable' attribute in the configuration of the component.

Specified by:

setInstrumentableName in interface Instrumentable

Parameters:

name - The name used to identify a Instrumentable.

getInstrumentableName

public java.lang.String getInstrumentableName()

Description copied from interface: Instrumentable

Gets the name of the Instrumentable.

Specified by:

getInstrumentableName in interface Instrumentable

Returns:

The name used to identify a Instrumentable.

getInstruments

public Instrument[] getInstruments()

Description copied from interface: Instrumentable

Obtain a reference to all the Instruments that the Instrumentable object wishes to expose. All sampling is done directly through the Instruments as opposed to the Instrumentable interface.

Specified by:

getInstruments in interface Instrumentable

Returns:

An array of the Instruments available for profiling. Should never be null. If there are no Instruments, then EMPTY_INSTRUMENT_ARRAY can be returned. This should never be the case though unless there are child Instrumentables with Instruments.

getChildInstrumentables

public Instrumentable[] getChildInstrumentables()

Description copied from interface: Instrumentable

Any Object which implements Instrumentable can also make use of other Instrumentable child objects. This method is used to tell the InstrumentManager about them.

Specified by:

getChildInstrumentables in interface Instrumentable

Returns:

An array of child Instrumentables. This method should never return null. If there are no child Instrumentables, then EMPTY_INSTRUMENTABLE_ARRAY can be returned.