[jboss-jira] [JBoss JIRA] Closed: (JBCACHE-1215) NullEvictionPolicy

[Brian Stansberry (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBCACHE-1215?page=all ]

Brian Stansberry closed JBCACHE-1215.
-------------------------------------

    Fix Version/s: 2.1.0.CR3
                       (was: 3.0.0)
       Resolution: Done

I had the code for this sitting around and could use it for AS 5, so wrote a test and checked it in (nothing about the bit on making it the policy for the _default_ region if one isn't specified.)

> NullEvictionPolicy
> ------------------
>
>                 Key: JBCACHE-1215
>                 URL: http://jira.jboss.com/jira/browse/JBCACHE-1215
>             Project: JBoss Cache
>          Issue Type: Feature Request
>      Security Level: Public(Everyone can see) 
>            Reporter: Brian Stansberry
>         Assigned To: Brian Stansberry
>            Priority: Minor
>             Fix For: 2.1.0.CR3
>
>
> An eviction policy that allows returns 'true' to EvictionPolicy.canIgnoreEvent().  Other methods are no-ops or equivalent defaults.
> Use case is situations where there are multiple eviction regions in a cache, some of which should never evict anything.  You could use an LRUPolicy with maxAge=0, maxNodes=0 to accomplish a similar thing, but then you incur wasted overhead of generating, queuing up and processing node events. NullEvictionPolicy just bypasses everything.
> Some usages:
> Hibernate timestamp caching.  The timestamp region should never be evicted.
> HttpSession caching with FIELD.  I'll probably need to use JBC eviction for the JBossInternal_ area to passivate pojos.  But passivating the sessions themselves should not be managed by JBC. So I could use NullEvictionPolicy for the session storage area.
> Could also be inserted as a global default if JBC detects that the _default_ region wasn't configured while a subregion was.
> I coded this up one night a while ago and forgot about it.  Could be added to 2.1.0.GA if not too late; otherwise later.

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