net.sf.kdgcommons.util

Class ReadThroughCache<K,V>

java.lang.Object

net.sf.kdgcommons.util.ReadThroughCache<K,V>

public class ReadThroughCache<K,V>
extends Object

A size-limited LRU cache that uses a retriever function to load values. Instances are thread-safe (provided the retriever is thread-safe) and provide a variety of blocking options for retrieval.

Note that the cache itself implements the #Retriever interface; caches may be stacked.

Since:

1.0.15

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ReadThroughCache.Retriever<KK,VV> This interface defines the retrieval operation: given a key, it will return a value.
static class	ReadThroughCache.Synchronization Options for controlling concurrent retrieval.

Constructor Summary

Constructors

Constructor and Description
ReadThroughCache(int size, ReadThroughCache.Retriever<K,V> retriever) Convenience constructor: creates an instance with specified size and retriever, using per-key synchronization.
ReadThroughCache(int size, ReadThroughCache.Retriever<K,V> retriever, ReadThroughCache.Synchronization syncOpt) Base constructor.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all cached values.
V	retrieve(K key)
int	size() Returns the count of mappings currently in the cache.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReadThroughCache

public ReadThroughCache(int size,
                        ReadThroughCache.Retriever<K,V> retriever,
                        ReadThroughCache.Synchronization syncOpt)

Base constructor.

Parameters:

size - Maximum number of items in the cache; the least recently used item will be evicted if retrieval would exceed this limit. To prevent resizing the underlying hash table, this value is also used as the map's capacity.

retriever - The function to retrieve items.

syncOpt - The synchronization strategy.

ReadThroughCache

public ReadThroughCache(int size,
                        ReadThroughCache.Retriever<K,V> retriever)

Convenience constructor: creates an instance with specified size and retriever, using per-key synchronization.

Method Detail

retrieve

public V retrieve(K key)
           throws InterruptedException

Throws:

InterruptedException

size

public int size()

Returns the count of mappings currently in the cache.

clear

public void clear()

Removes all cached values.