org.glassfish.hk2.utilities.cache

Class Cache<K,V>

java.lang.Object

org.glassfish.hk2.utilities.cache.Cache<K,V>

Type Parameters:

K - The type of the key of the cache

V - The type of the values in the cache

All Implemented Interfaces:

Computable<K,V>

public class Cache<K,V>
extends Object
implements Computable<K,V>

Cache implementation that relies on FutureTask. Desired value will only be computed once and computed value stored in the cache. The implementation is based on an example from the "Java Concurrency in Practice" book authored by Brian Goetz and company.

Author:

Jakub Podlesak (jakub.podlesak at oracle.com)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Cache.CycleHandler<K> Should a cycle be detected during computation of a value for given key, this interface allows client code to register a callback that would get invoked in such a case.

Constructor Summary

Constructors

Constructor and Description
Cache(Computable<K,V> computable) Create new cache with given computable to compute values.
Cache(Computable<K,V> computable, Cache.CycleHandler<K> cycleHandler) Create new cache with given computable and cycle handler.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Empty cache.
V	compute(K key) Defines an expensive computation to retrieve value V from key K.
boolean	containsKey(K key) Returns true if the key has already been cached.
void	remove(K key) Remove item from the cache.
int	size() Returns the size of the cache

Methods inherited from class java.lang.Object

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

Constructor Detail

Cache

public Cache(Computable<K,V> computable)

Create new cache with given computable to compute values. Detected cycles will be ignored as there is a no-op cycle handler registered by default.

Parameters:

computable -

Cache

public Cache(Computable<K,V> computable,
     Cache.CycleHandler<K> cycleHandler)

Create new cache with given computable and cycle handler.

Parameters:

computable -

cycleHandler -

Method Detail

compute

public V compute(K key)

Description copied from interface: Computable

Defines an expensive computation to retrieve value V from key K.

Specified by:

compute in interface Computable<K,V>

Parameters:

key - input data.

Returns:

output from the computation.

clear

public void clear()

Empty cache.

containsKey

public boolean containsKey(K key)

Returns true if the key has already been cached.

Parameters:

key -

Returns:

true if given key is present in the cache.

remove

public void remove(K key)

Remove item from the cache.

Parameters:

key - item key.

size

public int size()

Returns the size of the cache

Returns:

The number of elements in the cache