org.axonframework.common.caching

Class WeakReferenceCache

java.lang.Object

org.axonframework.common.caching.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, Henrique Sena

Nested Class Summary

Nested classes/interfaces inherited from interface org.axonframework.common.caching.Cache

Cache.EntryListener, Cache.EntryListenerAdapter

Constructor Summary

Constructors

Constructor and Description
WeakReferenceCache()

Method Summary

Modifier and Type	Method and Description
<T> T	computeIfAbsent(Object key, Supplier<T> valueSupplier) Returns the value under the given key in the cache.
<V> void	computeIfPresent(Object key, UnaryOperator<V> update) Perform the update in the value behind the given key.
boolean	containsKey(Object 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
void	put(Object key, Object value) Stores the given value in the cache, under given key.
boolean	putIfAbsent(Object key, Object value) Stores the given value in the cache, under given key, if no element is yet available under that key.
Registration	registerCacheEntryListener(Cache.EntryListener entryListener) Registers the given cacheEntryListener to listen for Cache changes.
boolean	remove(Object key) Removes the entry stored under given key.
void	removeAll() Remove all stored entries in this cache.

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 Registration 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

Returns:

a handle to deregister the listener

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 void put(Object key,
                Object 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

Parameters:

key - The key under which to store the item

value - The item to cache

putIfAbsent

public boolean putIfAbsent(Object key,
                           Object 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

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.

computeIfAbsent

public <T> T computeIfAbsent(Object key,
                             Supplier<T> valueSupplier)

Description copied from interface: Cache

Returns the value under the given key in the cache. If there is no value present, will invoke the given valueSupplier, put the value in the cache and return the produced value.

Specified by:

computeIfAbsent in interface Cache

Parameters:

key - The key under which the item was cached. If not present, this key is used to cache the outcome of the valueSupplier.

valueSupplier - A supplier that lazily supplies the value if there's no key present.

Returns:

The value that is in the cache after the operation. This can be the original value or the one supplied by the valueSupplier.

remove

public boolean remove(Object 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

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.

removeAll

public void removeAll()

Description copied from interface: Cache

Remove all stored entries in this cache.

Specified by:

removeAll in interface Cache

containsKey

public boolean containsKey(Object key)

Description copied from interface: Cache

Indicates whether there is an item stored under given key.

Specified by:

containsKey in interface Cache

Parameters:

key - The key to check

Returns:

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

computeIfPresent

public <V> void computeIfPresent(Object key,
                                 UnaryOperator<V> update)

Description copied from interface: Cache

Perform the update in the value behind the given key. The update is only executed if there's an entry referencing the key.

Specified by:

computeIfPresent in interface Cache

Type Parameters:

V - The type of the value to execute the update for.

Parameters:

key - The key to perform an update for, if not empty.

update - The update to perform if the key is present.