org.apache.commons.jcs.access

Class AbstractCacheAccess<K,V>

java.lang.Object

org.apache.commons.jcs.access.AbstractCacheAccess<K,V>

All Implemented Interfaces:

ICacheAccessManagement

Direct Known Subclasses:

CacheAccess, GroupCacheAccess

public abstract class AbstractCacheAccess<K,V>
extends Object
implements ICacheAccessManagement

This class provides the common methods for all types of access to the cache.

An instance of this class is tied to a specific cache region. Static methods are provided to get such instances.

Using this class you can retrieve an item, the item's wrapper, and the element's configuration. You can also put an item in the cache, remove an item, and clear a region.

The JCS class is the preferred way to access these methods.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractCacheAccess(CompositeCache<K,V> cacheControl) Constructor for the CacheAccess object.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all of the elements from a region.
void	dispose() Dispose this region.
int	freeMemoryElements(int numberToFree) This instructs the memory cache to remove the numberToFree according to its eviction policy.
ICompositeCacheAttributes	getCacheAttributes() Gets the ICompositeCacheAttributes of the cache region.
CompositeCache<K,V>	getCacheControl()
IElementAttributes	getDefaultElementAttributes() Retrieves A COPY OF the default element attributes used by this region.
ICacheStats	getStatistics() This returns the ICacheStats object with information on this region and its auxiliaries.
String	getStats()
void	setCacheAttributes(ICompositeCacheAttributes cattr) Sets the ICompositeCacheAttributes of the cache region.
void	setDefaultElementAttributes(IElementAttributes attr) This method is does not reset the attributes for items already in the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractCacheAccess

protected AbstractCacheAccess(CompositeCache<K,V> cacheControl)

Constructor for the CacheAccess object.

Parameters:

cacheControl - The cache which the created instance accesses

Method Detail

clear

public void clear()
           throws CacheException

Removes all of the elements from a region.

Specified by:

clear in interface ICacheAccessManagement

Throws:

CacheException

setDefaultElementAttributes

public void setDefaultElementAttributes(IElementAttributes attr)
                                 throws CacheException

This method is does not reset the attributes for items already in the cache. It could potentially do this for items in memory, and maybe on disk (which would be slow) but not remote items. Rather than have unpredictable behavior, this method just sets the default attributes. Items subsequently put into the cache will use these defaults if they do not specify specific attributes.

Specified by:

setDefaultElementAttributes in interface ICacheAccessManagement

Parameters:

attr - the default attributes.

Throws:

CacheException - if something goes wrong.

getDefaultElementAttributes

public IElementAttributes getDefaultElementAttributes()
                                               throws CacheException

Retrieves A COPY OF the default element attributes used by this region. This does not provide a reference to the element attributes.

Each time an element is added to the cache without element attributes, the default element attributes are cloned.

Specified by:

getDefaultElementAttributes in interface ICacheAccessManagement

Returns:

the default element attributes used by this region.

Throws:

CacheException

getStatistics

public ICacheStats getStatistics()

This returns the ICacheStats object with information on this region and its auxiliaries.

This data can be formatted as needed.

Specified by:

getStatistics in interface ICacheAccessManagement

Returns:

ICacheStats

getStats

public String getStats()

Specified by:

getStats in interface ICacheAccessManagement

Returns:

A String version of the stats.

dispose

public void dispose()

Dispose this region. Flushes objects to and closes auxiliary caches. This is a shutdown command!

To simply remove all elements from the region use clear().

Specified by:

dispose in interface ICacheAccessManagement

getCacheAttributes

public ICompositeCacheAttributes getCacheAttributes()

Gets the ICompositeCacheAttributes of the cache region.

Specified by:

getCacheAttributes in interface ICacheAccessManagement

Returns:

ICompositeCacheAttributes, the controllers config info, defined in the top section of a region definition.

setCacheAttributes

public void setCacheAttributes(ICompositeCacheAttributes cattr)

Sets the ICompositeCacheAttributes of the cache region.

Specified by:

setCacheAttributes in interface ICacheAccessManagement

Parameters:

cattr - The new ICompositeCacheAttribute value

freeMemoryElements

public int freeMemoryElements(int numberToFree)
                       throws CacheException

This instructs the memory cache to remove the numberToFree according to its eviction policy. For example, the LRUMemoryCache will remove the numberToFree least recently used items. These will be spooled to disk if a disk auxiliary is available.

Specified by:

freeMemoryElements in interface ICacheAccessManagement

Parameters:

numberToFree -

Returns:

the number that were removed. if you ask to free 5, but there are only 3, you will get 3.

Throws:

CacheException

getCacheControl

public CompositeCache<K,V> getCacheControl()