Package org.exoplatform.commons.cache.future

Class FutureCache<K,V,C>

java.lang.Object
org.exoplatform.commons.cache.future.FutureCache<K,V,C>
Type Parameters:
K - the key type parameter
V - the value type parameter
C - the context type parameter
Direct Known Subclasses:
FutureExoCache, FutureMap
public abstract class FutureCache<K,V,C> extends Object

A future cache that prevents the loading of the same resource twice. This should be used when the resource to load is very expensive or cannot be concurrently retrieved (like a classloading).

The future cache should be used with the get(Object, Object) method, that retrieves an object from the cache. When the object is not found, then the Loader.retrieve(Object, Object) method is used to retrieve the data and then this data is inserted in the cache.

The class is abstract and does not implement a cache technology by itself, the cache implementation is delegated to the contractual methods get(Object) and put(Object, Object). Those methods are intended to be used by the future cache only.

The Loader interface provides a source to retrieve objects to put in the cache. The goal to maintain this interface is to decouple the cache from the object source.

Version:
$Revision$
Author:
Julien Viet

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    FutureCache(Loader<K,V,C> loader)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    final V
    get(C context, K key)
    Perform a cache lookup for the specified key within the specified context.
    protected abstract V
    get(K key)
    Retrieves the cached value corresponding to the specified key from the cache, it must returns null when the key does not exist.
    protected abstract void
    put(K key, V value)
    Updates the cache with a new key/value pair.
    protected abstract void
    putOnly(K key, V value)
    Updates the cache only local mode with a new key/value pair.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • FutureCache

      protected FutureCache(Loader<K,V,C> loader)

  • Method Details

    • get

      protected abstract V get(K key)
      Retrieves the cached value corresponding to the specified key from the cache, it must returns null when the key does not exist. This method is intended for internal use by the future cache only.
      Parameters:
      key - the key
      Returns:
      the cache value

    • put

      protected abstract void put(K key, V value)
      Updates the cache with a new key/value pair. This method is intended for internal use by the future cache only.
      Parameters:
      key - the key
      value - the cache value

    • putOnly

      protected abstract void putOnly(K key, V value)
      Updates the cache only local mode with a new key/value pair. This method is intended for internal use by the future cache only.
      Parameters:
      key - the key
      value - the cache value

    • get

      public final V get(C context, K key)
      Perform a cache lookup for the specified key within the specified context. When the value cannot be loaded (because it does not exist or it failed or anything else that does not come to my mind), the value null is returned.
      Parameters:
      context - the context in which the resource is accessed
      key - the key identifying the resource
      Returns:
      the value