org.mmbase.cache
Class Cache

java.lang.Object
  java.util.Dictionary
      java.util.Hashtable
          org.mmbase.util.LRUHashtable
              org.mmbase.cache.Cache

All Implemented Interfaces:

java.lang.Cloneable, java.util.Map, java.io.Serializable, SizeMeasurable

Direct Known Subclasses:

AbstractImages.CKeyCache, Contexts.OperationsCache, FactoryCache, NodeCache, QueryResultCache, RelationsCache, ResultCache, TemplateCache, URLCache

public abstract class Cache

extends LRUHashtable

implements SizeMeasurable

A base class for all Caches. Extend this class for other caches.

Version:

$Id: Cache.java,v 1.19.2.1 2004/08/04 13:42:19 michiel Exp $

Author:

Michiel Meeuwissen

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class org.mmbase.util.LRUHashtable

LRUHashtable.LRUEntry, LRUHashtable.LRUEntrySet, LRUHashtable.LRUEntrySetIterator

Field Summary

protected int

maxEntrySize

Constructor Summary

Cache(int size)

Method Summary

java.lang.Object	get(java.lang.Object key) Like 'get' of LRUHashtable but considers if the cache is active or not.
int	getByteSize() Determins the byte-size of this object
int	getByteSize(SizeOf sizeof) Determins the byte-size of this object using the given SizeOf instance.
static Cache	getCache(java.lang.String name) Returns the Cache with a certain name.
static java.util.Set	getCaches() Returns the names of all caches.
protected int	getDefaultMaxEntrySize() This has to be overridden by Caches which support max entry size.
java.lang.String	getDescription() Gives a description for this cache type.
int	getMaxEntrySize() Return the maximum entry size for the cache in bytes.
java.lang.String	getName() Returns a name for this cache type.
static int	getTotalByteSize()
boolean	isActive() Wether this cache is active or not.
static void	main(java.lang.String[] args)
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Like 'put' of LRUHashtable but considers if the cache is active or not.
Cache	putCache() Puts this cache in the caches repository.
protected static Cache	putCache(Cache cache) Puts a cache in the caches repository.
void	setActive(boolean a) Sets this cache to active or passive.

Methods inherited from class org.mmbase.util.LRUHashtable

clear, clone, elements, entrySet, getCount, getHits, getMisses, getOrderedElements, getOrderedElements, getOrderedEntries, getOrderedEntries, getPuts, getRatio, getSize, getStats, keySet, remove, setSize, size, toString, toString, values

Methods inherited from class java.util.Hashtable

contains, containsKey, containsValue, equals, hashCode, isEmpty, keys, putAll, rehash

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

maxEntrySize

protected int maxEntrySize

Constructor Detail

Cache

public Cache(int size)

Method Detail

getName

public java.lang.String getName()

Returns a name for this cache type. Default it is the class name, but this normally will be overriden.

getDescription

public java.lang.String getDescription()

Gives a description for this cache type. This can be used in cache overviews.

getMaxEntrySize

public int getMaxEntrySize()

Return the maximum entry size for the cache in bytes. If the cache-type support it (default no), then no values bigger then this will be stored in the cache.

getDefaultMaxEntrySize

protected int getDefaultMaxEntrySize()

This has to be overridden by Caches which support max entry size.

putCache

protected static Cache putCache(Cache cache)

Puts a cache in the caches repository. This function will be called in the static of childs, therefore it is protected.

Returns:

The previous cache of the same type (stored under the same name)

putCache

public Cache putCache()

Puts this cache in the caches repository.

getCache

public static Cache getCache(java.lang.String name)

Returns the Cache with a certain name. To be used in combination with getCaches(). If you need a certain cache, you can just as well call the non-static 'getCache' which is normally in cache singletons.

See Also:

getCaches()

getCaches

public static java.util.Set getCaches()

Returns the names of all caches.

Returns:

A Set containing the names of all caches.

get

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

Like 'get' of LRUHashtable but considers if the cache is active or not.

Specified by:

get in interface java.util.Map

Overrides:

get in class LRUHashtable

Parameters:

key - the key of the element

Returns:

the value of the element, or null if it could not be found

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Like 'put' of LRUHashtable but considers if the cache is active or not.

Specified by:

put in interface java.util.Map

Overrides:

put in class LRUHashtable

Parameters:

key - the key of the element

value - the value of the element

Returns:

the original value of the element if it existed, null if it could not be found

setActive

public void setActive(boolean a)

Sets this cache to active or passive. TODO: Writing back to caches.xml if necessary (if this call was nog caused by change of caches.xml itself)

isActive

public final boolean isActive()

Wether this cache is active or not.

getByteSize

public int getByteSize()

Description copied from interface: SizeMeasurable

Determins the byte-size of this object

Specified by:

getByteSize in interface SizeMeasurable

getByteSize

public int getByteSize(SizeOf sizeof)

Description copied from interface: SizeMeasurable

Determins the byte-size of this object using the given SizeOf instance. A SizeOf instance stores a Set already counted objects. So this method is typically called by SizeOf itself (recursion).

Specified by:

getByteSize in interface SizeMeasurable

getTotalByteSize

public static int getTotalByteSize()

main

public static void main(java.lang.String[] args)