[infinispan-dev] [hibernate-dev] [ISPN-6] (Infinispan cache provider for Hibernate) Remaining TODOs, notes and questions

[Galder Zamarreno]

On 08/07/2009 02:06 PM, Manik Surtani wrote:
>
> On 7 Aug 2009, at 12:51, Galder Zamarreno wrote:
>
>> Manik,
>>
>> While I working on this, I've noted the following. If we define
>> default cache configurations for entity/query/...etc in an infinispan
>> configuration file, currently, they cannot be overriden afterwards
>> programatically.
>>
>> IOW, imagine there's a cache named "entity" that applies to all
>> entities in a sample infinispan-configs.xml and then someone tweaks it
>> in the hibernate config like this:
>>
>> hibernate.cache.infinispan.entity.eviction.wake_up_interval=3000
>>
>> The way I'd deal with this is that I'd create a Configuration with
>> this new interval and call defineCache("entity", cfg). However, when
>> the configuration file was processed, "entity" cache was added to the
>> configuration overrides and hence when I call defineCache with
>> "entity", it throws DuplicateCacheNameException.
>>
>> So, I think DFC.initialize() shouldn't add such configurations to
>> configuration overridesm map.
>>
>> Thoughts?
>
> Hmm. Perhaps what is needed is a mechanism to retrieve these
> configurations and alter them. E.g.,
>
> CacheManager.getConfiguration(); // retrieves the default cfg
> CacheManager.getConfiguration(String name);

Yeah, without starting the cache! Right now, the only way to get a 
configuration is after doing manager.getCache() which effectively starts 
the cache and hence, the Configuration's ComponentRegistry is in RUNNING 
mode, so you can't just clone it and modify it to be used somewhere 
else. Even the clone is in running state and didn't find an easy way to 
change that.

There's a second possibility here too: My above suggestion won't just 
work cos what defineCache("entity", cfg) does is take the *default* 
cache configuration, apply the overrides and create one with name 
"entity". But I want to do is: take the "entity" named cache 
configuration, apply the overrides and create a brand new one with the 
same name "entity". So, a method like this:

defineCache(String cacheName, String baseNamedCache, Configuration 
overrides).

So, then apart from doing defineCache("entity", "entity", overrides), I 
could also do defineCache("com.acme.Person", "entity", overrides). The 
latter would define a cache for com.acme.Person entity type, based on 
"entity" named cache and applying overrides defined via hibernate.cfg.xml

>
> These Configuration objects - built based on what's in the XML file -
> can then be tweaked. These should be adequately javadoc'd to make it
> clear that caches already started using such a configuration will not be
> affected when a configuration changes.

Indeed, getConfiguration() would return clones who's running state has 
been cleared. Maybe Configuration.clone() should already be doing that?

>
> I guess this also renders CacheManager.defineCache() API
> useless/obsolete, since getConfiguration() should always return a
> configuration, even if one didn't exist /wasn't defined in XML.

Yeah, it's either enhanced defineCache() or getConfiguration(). I think 
CacheManager.getConfiguration() is likely to be a more powerful and 
simpler API than defineCache(*).

>
> Cheers
> Manik
>
> --
> Manik Surtani
> manik at jboss.org
> Lead, Infinispan
> Lead, JBoss Cache
> http://www.infinispan.org
> http://www.jbosscache.org
>
>
>
>

-- 
Galder Zamarreño
Sr. Software Engineer
Infinispan, JBoss Cache