org.axonframework.cache

Class WeakReferenceCache

java.lang.Object

org.axonframework.cache.WeakReferenceCache

All Implemented Interfaces:

Cache

public class WeakReferenceCache
extends Object
implements Cache

Cache implementation that keeps values in the cache until the garbage collector has removed them. Unlike the WeakHashMap, which uses weak references on the keys, this Cache uses weak references on the values.

Values are Weakly referenced, which means they are not eligible for removal as long as any other references to the value exist.

Items expire once the garbage collector has removed them. Some time after they have been removed, the entry listeners are being notified thereof. Note that notification are emitted when the cache is being accessed (either for reading or writing). If the cache is not being accessed for a longer period of time, it may occur that listeners are not notified.

Since:

2.2.1

Author:

Allard Buijze

Nested Class Summary

Nested classes/interfaces inherited from interface org.axonframework.cache.Cache

Cache.EntryListener, Cache.EntryListenerAdapter

Constructor Summary

Constructors

Constructor and Description
WeakReferenceCache()

Method Summary

Methods

Modifier and Type	Method and Description
<K> boolean	containsKey(K key) Indicates whether there is an item stored under given key.
<K,V> V	get(K key) Returns an item from the cache, or null if no item was stored under that key
<K,V> void	put(K key, V value) Stores the given value in the cache, under given key.
<K,V> boolean	putIfAbsent(K key, V value) Stores the given value in the cache, under given key, if no element is yet available under that key.
void	registerCacheEntryListener(Cache.EntryListener entryListener) Registers the given cacheEntryListener to listen for Cache changes.
<K> boolean	remove(K key) Removes the entry stored under given key.
void	unregisterCacheEntryListener(Cache.EntryListener entryListener) Unregisters the previously registered cacheEntryListener.

Methods inherited from class java.lang.Object

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

Constructor Detail

WeakReferenceCache

public WeakReferenceCache()

Method Detail

registerCacheEntryListener

public void registerCacheEntryListener(Cache.EntryListener entryListener)

Description copied from interface: Cache

Registers the given cacheEntryListener to listen for Cache changes.

Specified by:

registerCacheEntryListener in interface Cache

Parameters:

entryListener - The listener to register

unregisterCacheEntryListener

public void unregisterCacheEntryListener(Cache.EntryListener entryListener)

Description copied from interface: Cache

Unregisters the previously registered cacheEntryListener.

Specified by:

unregisterCacheEntryListener in interface Cache

Parameters:

entryListener - The listener to unregister

get

public <K,V> V get(K key)

Description copied from interface: Cache

Returns an item from the cache, or null if no item was stored under that key

Specified by:

get in interface Cache

Type Parameters:

K - The type of key used

V - The type of value stored

Parameters:

key - The key under which the item was cached

Returns:

the item stored under the given key

put

public <K,V> void put(K key,
             V value)

Description copied from interface: Cache

Stores the given value in the cache, under given key. If an item already exists, it is updated with the new value.

Specified by:

put in interface Cache

Type Parameters:

K - The type of key used

V - The type of value stored

Parameters:

key - The key under which to store the item

value - The item to cache

putIfAbsent

public <K,V> boolean putIfAbsent(K key,
                        V value)

Description copied from interface: Cache

Stores the given value in the cache, under given key, if no element is yet available under that key. This operation is performed atomically.

Specified by:

putIfAbsent in interface Cache

Type Parameters:

K - The type of key used

V - The type of value stored

Parameters:

key - The key under which to store the item

value - The item to cache

Returns:

true if no value was previously assigned to the key, false otherwise.

remove

public <K> boolean remove(K key)

Description copied from interface: Cache

Removes the entry stored under given key. If no such entry exists, nothing happens.

Specified by:

remove in interface Cache

Type Parameters:

K - The type of key used

Parameters:

key - The key under which the item was stored

Returns:

true if a value was previously assigned to the key and has been removed, false otherwise.

containsKey

public <K> boolean containsKey(K key)

Description copied from interface: Cache

Indicates whether there is an item stored under given key.

Specified by:

containsKey in interface Cache

Type Parameters:

K - The type of key

Parameters:

key - The key to check

Returns:

true if an item is available under that key, false otherwise.