org.sape.carbon.core.config.cache
Class SynchronizedConfigurationCache

java.lang.Object
  |
  +--org.sape.carbon.core.config.cache.SynchronizedConfigurationCache

All Implemented Interfaces:

ConfigurationCache, EventListener, NodeEventListener

public class SynchronizedConfigurationCache

extends Object

implements ConfigurationCache, NodeEventListener

This implementation uses a synchronized hash map to store all configurations. This is a bottleneck and may be a point of contention when many threads required configurations simultaniously.

Configuration objects are cached lazily, i.e. they are cached after they are requested the first time. Once a configuration object is cached, the cache will listen for Node events on the configuration. If a node event occurs, the entire cache is cleared. This is done to prevent inconsistencies between this cache and caches internal to the configuration objects themselves in the case of nested configurations.

Copyright 2002 Sapient

Since:

carbon 1.1

Version:

$Revision: 1.11 $($Author: dvoet $ / $Date: 2003/05/05 21:21:16 $)

Author:

Douglas Voet, Oct 24, 2002

Field Summary

private Map	cache Holds a synchronized cache of value.
private ConfigurationService	configService Holds the config service being cached.
private org.apache.commons.logging.Log	log Provides a handle to Apache-commons logger

Constructor Summary

SynchronizedConfigurationCache(ConfigurationService configService)
Constructs a new SynchronizedConfigurationCache.

Method Summary

Configuration	getConfiguration(String name) Gets back a configuration with the given name.
private Configuration	loadConfiguration(String name) Synchronized method to load configurations.
void	nodeChanged(Node changedNode) Updates the configuration cache with the new instance of the node.
void	nodeRemoved(String removedNodeName) Removes the node from the cache.

Methods inherited from class java.lang.Object

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

Field Detail

log

private org.apache.commons.logging.Log log

Provides a handle to Apache-commons logger

cache

private Map cache

Holds a synchronized cache of value.

configService

private ConfigurationService configService

Holds the config service being cached.

Constructor Detail

SynchronizedConfigurationCache

public SynchronizedConfigurationCache(ConfigurationService configService)

Constructs a new SynchronizedConfigurationCache.

Parameters:

configService - the service to cache

Method Detail

getConfiguration

public Configuration getConfiguration(String name)

Gets back a configuration with the given name. This will either return the configuration from the cache or load it if needed.

Specified by:

getConfiguration in interface ConfigurationCache

Parameters:

name - the name of the configuration to load

Returns:

configuration at the given name

Throws:

ConfigurationNotFoundException - indicates there is no configuration at the given name

nodeChanged

public void nodeChanged(Node changedNode)

Updates the configuration cache with the new instance of the node.

Specified by:

nodeChanged in interface NodeEventListener

Parameters:

changedNode - the node that has been changed

nodeRemoved

public void nodeRemoved(String removedNodeName)

Removes the node from the cache.

Specified by:

nodeRemoved in interface NodeEventListener

Parameters:

removedNodeName - name of the node to remove

loadConfiguration

private Configuration loadConfiguration(String name)

Synchronized method to load configurations. Ensures that any configuration is loaded only once.

Parameters:

name - name of the requested configuration

Returns:

Configuration at the given name

Throws:

ConfigurationNotFoundException - indicates there is no configuration at the given name