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

[Galder Zamarreno]

On 08/11/2009 05:42 PM, Manik Surtani wrote:
>
> On 11 Aug 2009, at 16:34, Galder Zamarreno wrote:
>
>>
>>
>> On 08/10/2009 01:09 PM, Galder Zamarreno wrote:
>>>
>>> On 08/10/2009 12:42 PM, Manik Surtani wrote:
>>
>> </snip>
>>
>>>> Well, I think we need both.
>>>>
>>>> getConfiguration(String name) to retrieve a configuration template and
>>>> modify it.
>>>> defineCache(String newName, String templateName, Configuration
>>>> overrides) to create a new configuration based on an existing one.
>>>> Maybe
>>>> this name should change to something more intuitive? Perhaps instead of
>>>> defineCache, we have:
>>>>
>>>> Configuration defineConfiguration(String configurationName,
>>>> Configuration overrides) // registers and names a NEW configuration,
>>>> based on the default cfg and the overrides passed in
>>>>
>>>> Configuration defineConfiguration(String configurationName, String
>>>> templateName, Configuration overrides) // registers and names a NEW
>>>> configuration, based on an existing, predefined configuration and the
>>>> overrides passed in
>>>>
>>>> WDYT?
>>>
>>> That would be a great way to combine the two API requirements. I assume
>>> that the returned Configuration instances returned would have had the
>>> overrides applied to them already.
>>>
>>> Let me work on this APIs in parallel to the work I'm doing for ISPN-6 so
>>> that I can fully exercise/test and see if there's anything we'd need to
>>> change.
>>>
>>> https://jira.jboss.org/jira/browse/ISPN-152
>>
>> A quick update on this. I have implemented ISPN-152, integrated it
>> with the cache provider and the tests I have are now passing. Just a
>> heads up on a change of behaviour.
>>
>> defineConfiguration(*) methods do no longer throw
>> DuplicateCacheNameException since this limits the API a lot disabling
>> any type of configuration redefininitions/overriding. Example:
>>
>> defineConfiguration("entity", "entity", overrides);
>>
>> This means, take the configuration for named cache "entity", apply
>> overrides and use that as new "entity" cache name configuration. If
>> we're throwing DuplicateCacheNameException(s), we wouldn't be able to
>> do this and this seems like a valid use case to me.
>>
>> By the way, I've already noted this in the javadoc but doing the
>> following:
>>
>> Configuration c = defineConfiguration("entity", new Configuration());
>>
>> is a way to return "entity" named cache's configuration! (equivalent
>> to doing something like: manager.getConfiguration("entity") if such
>> method existed!) IOW, this defineConfiguration method is saying:
>> "define a configuration, based on "entity" and apply no overrides (cos
>> no setters have been called in the Configuration instance!) and return
>> new configuration instance"
>>
>> I've detailed all this in CacheManager's javadoc that you can find
>> attached. If you get the chance, have a read to it and let me know if
>> anything is not clear enough.
>
> Most of it sounds good, but the javadoc on defineConfiguration() is a
> bit misleading.
>
> " * <p/>
> * If cache name hasn't been defined before, this method creates a clone
> of the configuration of the cache whose
> * name matches the given template cache name, then applies the
> configuration overrides passed and returns this
> * configuration instance.
> * <p/>
> * If cache name has been previously defined, this method creates a clone
> of this cache's existing configuration,
> * applies the overrides and return this configuration instance.
> * <p/>"
>
> The first bit makes sense. The second bit though, I would expect the
> behaviour to be to clone the template cfg, apply changes, and overwrite
> the existing named config rather than use the existing named config as
> the template (rather than templateCacheName).

Hmmm, right, so defineConfiguration(String, String, Configuration) 
should work the same way regardless of whether the configuration for the 
named cache exists or not, correct?

In both cases, a clone a clone of the template cache's configuration 
would be made, apply a clone of the overrides, and overwrite existing 
named cache's configuration.

In fact, a side thing, this has reminded my that "then applies the 
configuration overrides passed" should say "then applies a clone of the 
configuration overrides passed in", this makes it clear that the 
configuration passed in cannot be modified after calling 
defineConfiguration() and expect its changes to be reflected in the 
CacheManager.

>
> Cheers
> --
> 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