[infinispan-dev] Calling getCache with a template and defined configuration

[Radim Vansa]

I still think that if the cache is already defined, defineConfiguration 
should throw an exception. This javadoc was written 7 years ago [1], 
maybe with a different intention.
Strange and complex combinations don't help. We have made a clear 
separation between templates and cache configurations; you should not 
use regular cache configuration as a template for programmatically 
defined cache anymore, and if you really want to, there are means to 
that (load, undefine, define).

Btw., the javadoc is out of date, too, since it mentions default cache 
which has been removed recently.

R.

[1] 
https://github.com/infinispan/infinispan/commit/73d99d37ebfb8af6b64df6a7579a2448deacbde7#diff-e2b618b97769a45ec42eb5910a8c2119R62

On 02/28/2017 10:51 PM, William Burns wrote:
> So while I was trying to work on this, I have to admit I am even more 
> torn in regards to what to do.  Looking at [1] it looks like the 
> template should only be applied if the cache configuration is not 
> currently defined.  Unfortunately it doesn't work this way and always 
> applies this template to any existing configuration. So I am thinking 
> an alternative is to instead make it work as the documentation states, 
> only using the template if the cache is not currently defined. This 
> seems more logical to me at least.
>
> With that change the getCache(String, String) could stay as long as it 
> is documented that a template is only applied if no cache 
> configuration exists.
>
> What do you guys think?
>
> [1] 
> https://github.com/infinispan/infinispan/blob/master/core/src/main/java/org/infinispan/manager/EmbeddedCacheManager.java#L84 
>
>
> On Mon, Feb 27, 2017 at 10:09 AM William Burns <mudokonman at gmail.com 
> <mailto:mudokonman at gmail.com>> wrote:
>
>     On Mon, Feb 27, 2017 at 9:55 AM Dan Berindei
>     <dan.berindei at gmail.com <mailto:dan.berindei at gmail.com>> wrote:
>
>         I would go for option 2.
>
>
>     Do you think a WARN message will be enough? I am a bit weary about
>     this option myself.
>
>
>         We already started disconnecting the cache definition and
>         retrieval,
>         at least `getCache(name)` doesn't define a new cache based on the
>         default configuration any more. So I don't think it would be
>         too much,
>         even at this point, to deprecate all the overloads of
>         `getCache` that
>         can define a new cache and advise users to use
>         `defineConfiguration`
>         instead.
>
>
>     Hrmm I like the idea of deprecating the overloads :)
>
>
>
>
>         Cheers
>         Dan
>
>
>         On Mon, Feb 27, 2017 at 4:31 PM, William Burns
>         <mudokonman at gmail.com <mailto:mudokonman at gmail.com>> wrote:
>         > When working on another project using Infinispan the code
>         being used was a
>         > bit interesting and I don't think our template configuration
>         handling was
>         > expecting it do so in such a way.
>         >
>         > Essentially the code defined a template for a distributed
>         cache as well as
>         > some named caches.  Then whenever a cache is retrieved it
>         would pass the
>         > given name and always the distributed cache template. 
>         Unfortunately with
>         > the way templates work they essentially redefine a cache
>         first so the actual
>         > cache configuration was wiped out.  In this example I was
>         able to get the
>         > code to change to using a default cache instead, which is
>         the behavior that
>         > is needed.
>         >
>         > The issue though at hand is whether we should allow a user
>         to call getCache
>         > in such a way. My initial thought is to have it throw some
>         sort of
>         > configuration exception when this is invoked. But there are
>         some possible
>         > options.
>         >
>         > 1. Throw a configuration exception not allowing a user to
>         use a template
>         > with an already defined cache. This has a slight disconnect
>         between
>         > configuration and runtime, since if a user adds a new
>         definition it could
>         > cause runtime issues.
>         > 2. Log an error/warning message when this occurs. Is this
>         enough though?
>         > Still could have runtime issues that are possibly undetected.
>         > 3. Merge the configurations together applying the template
>         first.  This
>         > would be akin to how default cache works currently, but you
>         would get to
>         > define your default template configuration at runtime. This
>         sounded like the
>         > best option to me, but the problem is what if someone calls
>         getCache using
>         > the same cache name but a different template. This could get
>         hairy as well.
>         >
>         > Really thinking about the future, disconnecting the cache
>         definition and
>         > retrieval would be the best option, but we can't do that
>         this late in the
>         > game.
>         >
>         > What do you guys think?
>         >
>         >  - Will
>         >
>         > _______________________________________________
>         > infinispan-dev mailing list
>         > infinispan-dev at lists.jboss.org
>         <mailto:infinispan-dev at lists.jboss.org>
>         > https://lists.jboss.org/mailman/listinfo/infinispan-dev
>         _______________________________________________
>         infinispan-dev mailing list
>         infinispan-dev at lists.jboss.org
>         <mailto:infinispan-dev at lists.jboss.org>
>         https://lists.jboss.org/mailman/listinfo/infinispan-dev
>
>
>
> _______________________________________________
> infinispan-dev mailing list
> infinispan-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/infinispan-dev


-- 
Radim Vansa <rvansa at redhat.com>
JBoss Performance Team