spring ehcache integration with self-populating-cache-scope

Question

I have to integrate spring and ehcache, and trying to implement it with blockingCache pattern

<ehcache:annotation-driven/>

there is one option for self-populating-cache-scope for shared (default) and method. could you please explain what is the difference?

There is also the annotation @Cacheable with selfPopulating flag

As per what I read on some post

http://groups.google.com/group/ehcache-spring-annotations/browse_thread/thread/7dbc71ce34f6ee19/b057610167dfb815?lnk=raot

it says when shared is used only one instance is created and the same is used everytime the same cache name is used so if I use the selfPopulating flag as true for one method,

all the threads trying to access other methods annotated with @Cacheable with selfPopulating flag set to true will go on hold which I dont want

<ehcache:annotation-driven/>

when self-populating-cache-scope = method on other hand creates separate instances for all methods annotated with @Cacheable with selfPopulating flag set to true so it doesn't create a problem.

But in this case when I try to remove a element using @TriggerRemove and giving the cache name used in @Cacheable will it search in each of those separate instances to find the value? Isnt this an overhead?

Answer 1

Answered by Eric on the ehcache google group above

In all cases there is one underlying Ehcache instance. What happens when you set selfPopulating=true is a SelfPopulatingCache wrapper is created.

If cache-scope=shared then all annotations using that named cache will use the same SelfPopulatingCache wrapper If cache-scope=method then one wrapper is created per method

Note in both cases the SelfPopulatingCache is a wrapper, there is still only one actual cache backing the wrapper(s)

As for blocking, If you read the docs for SelfPopulatingCache and BlockingCache you'll notice that ehcache does a compromise between cache level locking and per-key locking via key striping. http://ehcache.org/apidocs/net/sf/ehcache/constructs/blocking/BlockingCache.html