com.webmethods.caf.wsclient.cache.impl

Class WSLruCache

java.lang.Object

com.webmethods.caf.wsclient.cache.impl.WSLruCache

public class WSLruCache
extends Object

Fixed length cache with a LRU replacement policy. If cache items implement CacheListener, they will be informed when they're removed from the cache.

Null keys are not allowed. WSLruCache is synchronized.

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_cacheCapacity
protected Map<Object,com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem>	m_cacheMap
protected long	m_entryTimeout

Constructor Summary

Constructors

Constructor and Description
WSLruCache(int maxCapacity, long maxFreshTimeout) Create the LRU cache with a specific capacity and freshness timeout.

Method Summary

Modifier and Type	Method and Description
void	clear() Clears all entries from the cache
boolean	containsKey(Object key) Determines if an item is in the Cache
Object	get(Object key) Get an item from the cache and make it most recently used.
protected Object	getFresh(Object key) Get an item from the hash and return it.
Iterator<Object>	getFreshKeys() Returns the fresh keys stored in the cache Note: this is a snapshot of the keys and is therefore safe to iterate, however care needs to be taken when using these keys for cache lookups as the key may no longer exist.
Iterator<com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem>	getFreshValues() Returns the values stored in the cache Note: this is a snapshot of the values and is therefore safe to iterate but may not reflect the current state of the cache.
Iterator<Object>	getKeys() Get an iterator for the keys of the cache, including both fresh and stale entries Note: this is a snapshot of the keys and is therefore safe to iterate, however care needs to be taken when using these keys for cache lookups as the key may no longer exist.
int	getMaxCapacity() The current capacity of this cache
Iterator<com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem>	getValues() Get an iterator for the values of the cache that includes both stale and fresh enties Note: this is a snapshot of the values and is therefore safe to iterate but may not reflect the current state of the cache.
protected void	printCacheToConsole()
Object	put(Object key, Object value) Puts a new item in the cache and returns the previous value stored under that key
Object	remove(Object key) Removes an item from the cache
int	size() The current size of the cache

Methods inherited from class java.lang.Object

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

Field Detail

m_cacheMap

protected Map<Object,com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem> m_cacheMap

m_cacheCapacity

protected int m_cacheCapacity

m_entryTimeout

protected long m_entryTimeout

Constructor Detail

WSLruCache

public WSLruCache(int maxCapacity,
                  long maxFreshTimeout)

Create the LRU cache with a specific capacity and freshness timeout. Entries older than a specific staleness will act as a cache miss.

Parameters:

maxCapacity - - minimum capacity of the cache

maxCapacity - - maximum cache entry age (in milliseconds)

Method Detail

clear

public void clear()

Clears all entries from the cache

size

public int size()

The current size of the cache

Returns:

the current queue size as int

getMaxCapacity

public int getMaxCapacity()

The current capacity of this cache

Returns:

the queue capacity

containsKey

public boolean containsKey(Object key)

Determines if an item is in the Cache

Parameters:

key - the unique key to the item in the cache

Returns:

true if the cache contains an entry for the given key

get

public Object get(Object key)

Get an item from the cache and make it most recently used.

Parameters:

key - key to lookup the item

Returns:

the matching object in the cache

getFresh

protected Object getFresh(Object key)

Get an item from the hash and return it. If the item is stale, it is removed from the hash and null is returned.

Parameters:

key - - the cache key object

Returns:

the fresh cache entry if found, otherwise null

put

public Object put(Object key,
                  Object value)

Puts a new item in the cache and returns the previous value stored under that key

Parameters:

key - key to store data

value - value to be stored

Returns:

old value stored under the key

remove

public Object remove(Object key)

Removes an item from the cache

Parameters:

key - the key to remove

Returns:

the value removed

getKeys

public Iterator<Object> getKeys()

Get an iterator for the keys of the cache, including both fresh and stale entries Note: this is a snapshot of the keys and is therefore safe to iterate, however care needs to be taken when using these keys for cache lookups as the key may no longer exist.

Returns:

an Iterator containing the cache keys as Objects

getFreshKeys

public Iterator<Object> getFreshKeys()

Returns the fresh keys stored in the cache Note: this is a snapshot of the keys and is therefore safe to iterate, however care needs to be taken when using these keys for cache lookups as the key may no longer exist.

Returns:

an Iterator containing those cache keys that have not expired as Objects

getValues

public Iterator<com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem> getValues()

Get an iterator for the values of the cache that includes both stale and fresh enties Note: this is a snapshot of the values and is therefore safe to iterate but may not reflect the current state of the cache.

Returns:

an Iterator of cache value as CacheItem objects

getFreshValues

public Iterator<com.webmethods.caf.wsclient.cache.impl.WSLruCache.CacheItem> getFreshValues()

Returns the values stored in the cache Note: this is a snapshot of the values and is therefore safe to iterate but may not reflect the current state of the cache.

Returns:

an Iterator of cache values that have not expired as CacheItem objects

printCacheToConsole

protected void printCacheToConsole()