com.jivesoftware.community.cache
Class DefaultCache

java.lang.Object
  com.jivesoftware.community.cache.DefaultCache

All Implemented Interfaces:

com.jivesoftware.community.cache.Cache, com.tangosol.util.ObservableMap, java.util.Map

public class DefaultCache
extends java.lang.Object
implements com.jivesoftware.community.cache.Cache, com.tangosol.util.ObservableMap

Default, non-distributed implementation of the Cache interface. The algorithm for cache is as follows: a HashMap is maintained for fast object lookup. Two linked lists are maintained: one keeps objects in the order they are accessed from cache, the other keeps objects in the order they were originally added to cache. When objects are added to cache, they are first wrapped by a CacheObject which maintains the following pieces of information:

• The size of the object (in bytes).
• A pointer to the node in the linked list that maintains accessed order for the object. Keeping a reference to the node lets us avoid linear scans of the linked list.
• A pointer to the node in the linked list that maintains the age of the object in cache. Keeping a reference to the node lets us avoid linear scans of the linked list.

To get an object from cache, a hash lookup is performed to get a reference to the CacheObject that wraps the real object we are looking for. The object is subsequently moved to the front of the accessed linked list and any necessary cache cleanups are performed. Cache deletion and expiration is performed as needed.

Nested Class Summary

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Nested classes/interfaces inherited from interface java.util.Map

java.util.Map.Entry<K,V>

Field Summary

protected com.jivesoftware.util.LinkedList	ageList Linked list to maintain time that cache objects were initially added to the cache, most recently added to oldest added.
protected long	cacheHits Maintain the number of cache hits and misses.
protected long	cacheMisses Maintain the number of cache hits and misses.
protected int	cacheSize Maintains the current size of the cache in bytes.
protected com.jivesoftware.util.LinkedList	lastAccessedList Linked list to maintain order that cache objects are accessed in, most used to least used.
protected com.tangosol.util.Listeners	listeners
protected java.util.Map<java.lang.Object,com.jivesoftware.community.cache.CacheObject>	map The map the keys and values are stored in.
protected int	maxCacheSize Maximum size in bytes that the cache can grow to.
protected long	maxLifetime Maximum length of time objects can exist in cache before expiring.
protected java.lang.String	name The name of the cache.

Constructor Summary

DefaultCache(java.lang.String name, int maxSize, long maxLifetime)
Create a new cache and specify the maximum size of for the cache in bytes, and the maximum lifetime of objects.

Method Summary

void	addMapListener(com.tangosol.util.MapListener listener) Add a map listener.
void	addMapListener(com.tangosol.util.MapListener listener, com.tangosol.util.Filter filter, boolean bLite)
void	addMapListener(com.tangosol.util.MapListener listener, java.lang.Object key, boolean bLite)
protected int	calculateSize(java.lang.Object object) Returns the size of an object in bytes.
void	clear()
boolean	containsKey(java.lang.Object key)
boolean	containsValue(java.lang.Object value)
protected void	cullCache() Removes the least recently used elements if the cache size is greater than or equal to the maximum allowed size until the cache is at least 10% empty.
protected void	deleteExpiredEntries() Clears all entries out of cache where the entries are older than the maximum defined age.
java.util.Set	entrySet()
protected void	fireMapEvent(com.tangosol.util.MapEvent evt, int eventType)
java.lang.Object	get(java.lang.Object key)
long	getCacheHits()
long	getCacheMisses()
int	getCacheSize()
int	getMaxCacheSize()
long	getMaxLifetime()
java.lang.String	getName()
boolean	isEmpty()
java.util.Set	keySet()
java.lang.Object	put(java.lang.Object key, java.lang.Object value)
void	putAll(java.util.Map map)
java.lang.Object	remove(java.lang.Object key)
java.lang.Object	remove(java.lang.Object key, boolean internal)
void	removeMapListener(com.tangosol.util.MapListener listener) Remove a map listener.
void	removeMapListener(com.tangosol.util.MapListener listener, com.tangosol.util.Filter filter)
void	removeMapListener(com.tangosol.util.MapListener listener, java.lang.Object key)
void	setMaxCacheSize(int maxCacheSize)
void	setMaxLifetime(long maxLifetime)
void	setName(java.lang.String name)
int	size()
java.util.Collection	values()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Map

equals, hashCode

Methods inherited from interface java.util.Map

equals, hashCode

Field Detail

map

protected java.util.Map<java.lang.Object,com.jivesoftware.community.cache.CacheObject> map

The map the keys and values are stored in.

lastAccessedList

protected com.jivesoftware.util.LinkedList lastAccessedList

Linked list to maintain order that cache objects are accessed in, most used to least used.

ageList

protected com.jivesoftware.util.LinkedList ageList

Linked list to maintain time that cache objects were initially added to the cache, most recently added to oldest added.

maxCacheSize

protected int maxCacheSize

Maximum size in bytes that the cache can grow to.

cacheSize

protected int cacheSize

Maintains the current size of the cache in bytes.

maxLifetime

protected long maxLifetime

Maximum length of time objects can exist in cache before expiring.

cacheHits

protected long cacheHits

Maintain the number of cache hits and misses. A cache hit occurs every time the get method is called and the cache contains the requested object. A cache miss represents the opposite occurence.

Keeping track of cache hits and misses lets one measure how efficient the cache is; the higher the percentage of hits, the more efficient.

cacheMisses

protected long cacheMisses

Maintain the number of cache hits and misses. A cache hit occurs every time the get method is called and the cache contains the requested object. A cache miss represents the opposite occurence.

Keeping track of cache hits and misses lets one measure how efficient the cache is; the higher the percentage of hits, the more efficient.

name

protected java.lang.String name

The name of the cache.

listeners

protected com.tangosol.util.Listeners listeners

Constructor Detail

DefaultCache

public DefaultCache(java.lang.String name,
                    int maxSize,
                    long maxLifetime)

Create a new cache and specify the maximum size of for the cache in bytes, and the maximum lifetime of objects.

Parameters:

name - a name for the cache.

maxSize - the maximum size of the cache in bytes. -1 means the cache has no max size.

maxLifetime - the maximum amount of time (in ms) objects can exist in cache before being deleted. -1 means objects never expire.

Method Detail

put

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

Specified by:

put in interface java.util.Map

get

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

Specified by:

get in interface java.util.Map

remove

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

Specified by:

remove in interface java.util.Map

remove

public java.lang.Object remove(java.lang.Object key,
                               boolean internal)

clear

public void clear()

Specified by:

clear in interface java.util.Map

size

public int size()

Specified by:

size in interface java.util.Map

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface java.util.Map

values

public java.util.Collection values()

Specified by:

values in interface java.util.Map

containsKey

public boolean containsKey(java.lang.Object key)

Specified by:

containsKey in interface java.util.Map

putAll

public void putAll(java.util.Map map)

Specified by:

putAll in interface java.util.Map

containsValue

public boolean containsValue(java.lang.Object value)

Specified by:

containsValue in interface java.util.Map

entrySet

public java.util.Set entrySet()

Specified by:

entrySet in interface java.util.Map

getName

public java.lang.String getName()

Specified by:

getName in interface com.jivesoftware.community.cache.Cache

setName

public void setName(java.lang.String name)

Specified by:

setName in interface com.jivesoftware.community.cache.Cache

keySet

public java.util.Set keySet()

Specified by:

keySet in interface java.util.Map

getCacheHits

public long getCacheHits()

Specified by:

getCacheHits in interface com.jivesoftware.community.cache.Cache

getCacheMisses

public long getCacheMisses()

Specified by:

getCacheMisses in interface com.jivesoftware.community.cache.Cache

getCacheSize

public int getCacheSize()

Specified by:

getCacheSize in interface com.jivesoftware.community.cache.Cache

getMaxCacheSize

public int getMaxCacheSize()

Specified by:

getMaxCacheSize in interface com.jivesoftware.community.cache.Cache

setMaxCacheSize

public void setMaxCacheSize(int maxCacheSize)

Specified by:

setMaxCacheSize in interface com.jivesoftware.community.cache.Cache

getMaxLifetime

public long getMaxLifetime()

Specified by:

getMaxLifetime in interface com.jivesoftware.community.cache.Cache

setMaxLifetime

public void setMaxLifetime(long maxLifetime)

Specified by:

setMaxLifetime in interface com.jivesoftware.community.cache.Cache

addMapListener

public void addMapListener(com.tangosol.util.MapListener listener)

Add a map listener.

Specified by:

addMapListener in interface com.tangosol.util.ObservableMap

addMapListener

public void addMapListener(com.tangosol.util.MapListener listener,
                           java.lang.Object key,
                           boolean bLite)

Specified by:

addMapListener in interface com.tangosol.util.ObservableMap

addMapListener

public void addMapListener(com.tangosol.util.MapListener listener,
                           com.tangosol.util.Filter filter,
                           boolean bLite)

Specified by:

addMapListener in interface com.tangosol.util.ObservableMap

removeMapListener

public void removeMapListener(com.tangosol.util.MapListener listener)

Remove a map listener.

Specified by:

removeMapListener in interface com.tangosol.util.ObservableMap

removeMapListener

public void removeMapListener(com.tangosol.util.MapListener listener,
                              java.lang.Object key)

Specified by:

removeMapListener in interface com.tangosol.util.ObservableMap

removeMapListener

public void removeMapListener(com.tangosol.util.MapListener listener,
                              com.tangosol.util.Filter filter)

Specified by:

removeMapListener in interface com.tangosol.util.ObservableMap

fireMapEvent

protected void fireMapEvent(com.tangosol.util.MapEvent evt,
                            int eventType)

calculateSize

protected int calculateSize(java.lang.Object object)

Returns the size of an object in bytes. Determining size by serialization is only used as a last resort.

Parameters:

object - the object to calculate

Returns:

the size of an object in bytes.

deleteExpiredEntries

protected void deleteExpiredEntries()

Clears all entries out of cache where the entries are older than the maximum defined age.

cullCache

protected void cullCache()

Removes the least recently used elements if the cache size is greater than or equal to the maximum allowed size until the cache is at least 10% empty.