[jboss-jira] [JBoss JIRA] Commented: (JBCACHE-1288) Handling of default eviction region config leads to duplicates

[Manik Surtani (JIRA)]

    [ http://jira.jboss.com/jira/browse/JBCACHE-1288?page=comments#action_12401803 ] 
            
Manik Surtani commented on JBCACHE-1288:
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>From your comments in the code:

// APPROACH 1: Scan for a default region, try to add if not there.
// This will try to add the region if it is missing but seems to break 
// some unit tests that configure one or more non-default regions and
// no default region (e.g. the eviction.minttl tests). So, doing this 
// seems to add a new semantic. For now comment this out and use APPROACH 2

// APPROACH 2: Only add a default region if there are no regions. This is
// contrary to the idea that there *must* be a default region, but some
// unit tests fail w/ APPROACH 1, so for now we go with this approach.

I think approach 2 is more "correct", at least until we formally define somewhere that a default eviction region is *required* before you can define more eviction regions.  I.e., what if I want to configure a cache with no eviction, eith the exception of a specific region?  Your NullEvictionPolicy does explicitly take care of this but this is a recent addition and I fear people may already be relying on behaviour that allows not configuring a default eviction region.

> Handling of default eviction region config leads to duplicates
> --------------------------------------------------------------
>
>                 Key: JBCACHE-1288
>                 URL: http://jira.jboss.com/jira/browse/JBCACHE-1288
>             Project: JBoss Cache
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: Eviction
>    Affects Versions: 2.1.0.CR3
>            Reporter: Brian Stansberry
>         Assigned To: Manik Surtani
>             Fix For: 2.1.0.GA
>
>
> The way the EvictionConfig.getEvictionRegionConfigs() method works leads to duplicate entries for the _default_ region when the JBoss Microcontainer builds  up a configuration.
> Problem is when there is no list of ERCs, the method builds one with a config for the _default_ region in it, and returns that.  The MC will call this method, and then try to add xml-configured ERCs to the returned list.  If a _default_ region is configured in XML, the _default_ region will end up being in the resulting list twice.
> Test org.jboss.cache.config.EvictionRegionConfigurationTest.testDuplicateDefaultRegion() shows the issue.
> I think the core problem here is that the attempt to add a default region is being done in the wrong place. It's not really the concern of the EvictionConfig class.  I think it properly belongs in RegionManager.setEvictionConfig() -- that's the class that's responsible for checking the configuration and making it conform to its requirements.
> I've got a patch along the above lines.

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