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

[Brian Stansberry (JIRA)]

NullEvictionPolicy
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                 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


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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