New CacheLoader: DelegatingCacheLoader

[belaban]

I added a new CacheLoader, which allows for hierarchical caches, e.g. a first-level cache delegates to a second-level cache. Below is some sample code. There is also a unit test (DelegatingCacheLoaderTest) for reference.

TreeCache firstLevel, secondLevel;
DelegatingCacheLoader cache_loader;

// create and configure firstLevel
firstLevel=new TreeCache();

// create and configure secondLevel
secondLevel=new TreeCache();

// create DelegatingCacheLoader
cache_loader=new DelegatingCacheLoader(secondLevel);

// set CacheLoader in firstLevel
firstLevel.setCacheLoader(cache_loader);

// start secondLevel
secondLevel.startService();

// start firstLevel
firstLevel.startService();