[infinispan-issues] [JBoss JIRA] (ISPN-2916) Group-based expiration

[Paul Ferraro (JIRA)]

    [ https://issues.jboss.org/browse/ISPN-2916?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12957380#comment-12957380 ] 

Paul Ferraro commented on ISPN-2916:
------------------------------------

Thinking about this further...
All cache entries for a given session belong to the same group - so colocation is not an issue.  However, it just occurred to me that only the primary cache entry of this group needs to define a max-idle lifespan.  The other cache entries could be immortal (meaning, they do not specify a max-idle), and rely on a cache listener to trigger removal of these "immortal" cache entries belonging the same group.  I think that solves the problem adequately.  Unless I can think of some other reason why this won't work, we can probably close this.
                
> Group-based expiration
> ----------------------
>
>                 Key: ISPN-2916
>                 URL: https://issues.jboss.org/browse/ISPN-2916
>             Project: Infinispan
>          Issue Type: Feature Request
>          Components: Core
>    Affects Versions: 5.2.5.Final
>            Reporter: Paul Ferraro
>            Assignee: Mircea Markus
>
> Now that WildFly represents a web session as a group of cache entries (instead of a single entry containing an atomic map), there are a few hurdles preventing us from leveraging infinispan-managed expiration.
> One of which is the fact that expiration of cache entries within a group *must* be atomic.  It would be very bad if a request arrives for a session whose entries are in the process of being expired.  The expiration thread should obtain a lock on *all* the keys for a group (or at least some pre-determined "primary" key), so that late session access doesn't result in session attributes mysteriously disappearing (because they were independently expired).  This can also cause integrity constraint violations if cache entries reference other entries in the group.  e.g. currently the "primary" cache entry for a session (keyed by session id), contains a set of attribute names.  These names correspond to other cache entries that contain the value of a given attribute for that session.

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