org.glassfish.jersey.internal.guava

Class CacheLoader<K,V>

java.lang.Object

org.glassfish.jersey.internal.guava.CacheLoader<K,V>

public abstract class CacheLoader<K,V>
extends Object

Computes or retrieves values, based on a key, for use in populating a LoadingCache.

Most implementations will only need to implement load(K). Other methods may be overridden as desired.

Usage example:

   
 <p>
   CacheLoader<Key, Graph> loader = new CacheLoader<Key, Graph>() {
     public Graph load(Key key) throws AnyException {
       return createExpensiveGraph(key);
     }
   };
   LoadingCache<Key, Graph> cache = CacheBuilder.newBuilder().build(loader);

Since:

10.0

Author:

Charles Fry

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CacheLoader.InvalidCacheLoadException Thrown to indicate that an invalid response was returned from a call to CacheLoader.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CacheLoader() Constructor for use by subclasses.

Method Summary

Modifier and Type	Method and Description
abstract V	load(K key) Computes or retrieves the value corresponding to key.
ListenableFuture<V>	reload(K key, V oldValue) Computes or retrieves a replacement value corresponding to an already-cached key.

Methods inherited from class java.lang.Object

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

Constructor Detail

CacheLoader

protected CacheLoader()

Constructor for use by subclasses.

Method Detail

load

public abstract V load(K key)
                throws Exception

Computes or retrieves the value corresponding to key.

Parameters:

key - the non-null key whose value should be loaded

Returns:

the value associated with key; must not be null

Throws:

Exception - if unable to load the result

InterruptedException - if this method is interrupted. InterruptedException is treated like any other Exception in all respects except that, when it is caught, the thread's interrupt status is set

reload

public ListenableFuture<V> reload(K key,
                                  V oldValue)
                           throws Exception

Computes or retrieves a replacement value corresponding to an already-cached key. This method is called when an existing cache entry is refreshed by CacheBuilder#refreshAfterWrite, or through a call to LoadingCache#refresh.

This implementation synchronously delegates to load(K). It is recommended that it be overridden with an asynchronous implementation when using CacheBuilder#refreshAfterWrite.

Note: all exceptions thrown by this method will be logged and then swallowed.

Parameters:

key - the non-null key whose value should be loaded

oldValue - the non-null old value corresponding to key

Returns:

the future new value associated with key; must not be null, must not return null

Throws:

Exception - if unable to reload the result

InterruptedException - if this method is interrupted. InterruptedException is treated like any other Exception in all respects except that, when it is caught, the thread's interrupt status is set

Since:

11.0