anthill.storage.impl
Class LRUKeyStorage

java.lang.Object
  |
  +--anthill.storage.impl.LRUKeyStorage

All Implemented Interfaces:

Clearable, GenericStorage, ResourceManager, Storage

Direct Known Subclasses:

LRUQueryStorage

public class LRUKeyStorage

extends Object

implements GenericStorage

Implementation of an LRU based key storage. This is a wrapper class for storing resources based on using a key to access the resources.

Version:

$Revision: 1.9 $

Author:

Hein Meling

, Alberto Montresor

Field Summary

protected Factory	factory Factory used to instantiate objects
protected HashList	list HashList use to implement the LRU policy of the LRU key storage.
protected String	name Name used to identify this component in the factory
static String	PAR_STORAGENAME The identifier of the configuration parameter
protected GenericStorage	storage A generic storage.

Fields inherited from interface anthill.storage.Storage

DOC_STORAGE, PHR_STORAGE, URL_STORAGE

Constructor Summary

LRUKeyStorage()

LRUKeyStorage(Factory factory, String name)

Method Summary

void	addResource(Object key, Resource resource) Adds a resource to the storage and associates it to the specified key.
void	clear() Restore the object to its initial state
boolean	containsResource(Object key) Returns true if the resource associated to key is contained in the storage, false otherwise.
long	getCapacity() Returns the initial capacity of this generic storage.
long	getRemainingCapacity() Returns the remaining capacity of this generic storage.
Resource	getResource(Object key) Returns the resource associated with the specified key.
Iterator	iterator() Returns the complete set of resources stored in this storage object using an iterator.
void	removeResource(Object key) Removes the resource associated with the specified key from the storage.

Methods inherited from class java.lang.Object

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

Field Detail

PAR_STORAGENAME

public static final String PAR_STORAGENAME

The identifier of the configuration parameter

See Also:

Constant Field Values

factory

protected Factory factory

Factory used to instantiate objects

name

protected String name

Name used to identify this component in the factory

storage

protected GenericStorage storage

A generic storage.

list

protected HashList list

HashList use to implement the LRU policy of the LRU key storage.

Constructor Detail

LRUKeyStorage

public LRUKeyStorage()

LRUKeyStorage

public LRUKeyStorage(Factory factory,
                     String name)

Parameters:

factory - the factory to be used to read configuration arguments and to create other configurable objects

name - the name that is associated to this instance in the configuration file

Method Detail

clear

public void clear()

Restore the object to its initial state

Specified by:

clear in interface Clearable

containsResource

public boolean containsResource(Object key)

Returns true if the resource associated to key is contained in the storage, false otherwise.

Specified by:

containsResource in interface GenericStorage

Parameters:

key - the key to be searched

Returns:

true if the resource associated to key is contained in the storage

getResource

public Resource getResource(Object key)

Returns the resource associated with the specified key. If the key is not associated with any resource, a null value is returned.

Specified by:

getResource in interface GenericStorage

Parameters:

key - whose associated resource to retreive.

Returns:

resource with which the specified key is associated.

addResource

public void addResource(Object key,
                        Resource resource)
                 throws CapacityException

Adds a resource to the storage and associates it to the specified key. If the remaining capacity of the storage is not sufficient to store the resource, a CapacityException is thrown containing information about the remaining capacity. Method size() may be invoked on the resource to determine the amount of space required by the resource. In order to be stored on persistent storage, resource must implement the Serializable interface.

Specified by:

addResource in interface GenericStorage

Parameters:

key - the key identifying the resource

resource - the resource to be added

Throws:

CapacityException - raised if the given resource object exceeds the total available capacity for this storage.

removeResource

public void removeResource(Object key)

Removes the resource associated with the specified key from the storage.

Specified by:

removeResource in interface GenericStorage

Parameters:

key - the identifier of the resource to be removed

iterator

public Iterator iterator()

Returns the complete set of resources stored in this storage object using an iterator.

Specified by:

iterator in interface GenericStorage

Returns:

iterator representing this storage object, allowing to inspect its content.

getCapacity

public long getCapacity()

Returns the initial capacity of this generic storage.

Specified by:

getCapacity in interface GenericStorage

getRemainingCapacity

public long getRemainingCapacity()

Returns the remaining capacity of this generic storage.

Specified by:

getRemainingCapacity in interface GenericStorage