[infinispan-dev] Management of shared caches

[Manik Surtani]

On 15 Dec 2009, at 20:16, Brian Stansberry wrote:

> On 12/14/2009 01:12 PM, Mircea Markus wrote:
>> yep, that's a good point indeed.
>> Is there any other thing than reference counting that this release method would do?
> 
> The only other thing the AS impl of the JBC CacheManager[1] releaseCache 
> does is deregistration from JMX. But I believe that's already handled in 
> Infinispan.
> 
> OT, there are a couple other things [1] does:
> 
> 1) Supports aliasing of configuratio names; I just created 
> https://jira.jboss.org/jira/browse/ISPN-316 for that.

Yes, nice one - there will be some API impact though, how would one submit an alias map?  I wouldn't want injection to be the only path here.

> 2) Lets you configure a list of caches to start when the manager starts. 
> Idea was you deployed the cache at server start and took the startup 
> time hit from the JGroups channel discovery then. If you redeploy the 
> service using the cache (e.g. a webapp) the cache stays deployed so you 
> don't need to take the discovery hit again.  AFAIK hasn't actually been 
> used.

Hm, each Cache shares the same Transport which is bound to the CacheManager.  So even if Caches start/stop, they won't incur the cost of rediscovery.  E.g.:

CacheManager cm = createNewCacheManager(); // no discovery here
c1 = cm.getCache("clustered cache 1"); // this will involve starting the Transport, and hence discovery
c2 = cm.getCache("clustered cache 2"); // no discovery here; cache1 already started the Transport
c1.stop();
cm.getCache("clustered cache 3") // again, discovery here; cache1 already started the Transport

HTH
Manik


> 
> [1] 
> http://anonsvn.jboss.org/repos/jbossas/projects/cluster/ha-server-cache-jbc/trunk/src/main/java/org/jboss/ha/cachemanager/CacheManager.java
> 
>> TBH I think the 3) suggestion should be okay, and the users should be aware that they should only  all stop() from one thread only. That is because the cache is rather a collection of data rather than a connection to something, and destroying it shouldn't be done each time you access it but only at the beginning and the end of your app.
>> 
> 
> Agreed. With JBC there was a major use case for sharing caches across 
> unrelated applications. With Infinispan I don't see that being the case.
> 
> Also, CacheManager is an interface, so just like w/ JBC if the AS needs 
> some special behavior it can have its own implementation and push stuff 
> back upstream if appropriate.
> 
>> On Dec 14, 2009, at 12:33 PM, Manik Surtani wrote:
>> 
>>> This is a good point, Brian.
>>> 
>>> Perhaps Cache.stop() should delegate to CacheManager.stopCache(cacheName) and as you say, some form of reference counting may be in order.
>>> 
>>> However, calling CacheManager.stopCache(cacheName) could be overloaded (a boolean "force" flag?) to stop the cache, regardless of known references?
>>> 
> 
> Sounds good.
> 
>>> Cheers
>>> Manik
>>> 
>>> 
>>> On 11 Dec 2009, at 20:37, Brian Stansberry wrote:
>>> 
>>>> Had a look at DefaultCacheManager today and I see it has no mechanism
>>>> for controlling the stopping of shared caches. Multiple independent
>>>> callers to getCache("foo") can get a ref to the foo cache, and then any
>>>> of them can call stop() on it.
>>>> 
>>>> A few possibilities come to mind:
>>>> 
>>>> 1) Add a releaseCache method, do some reference counting, and stop the
>>>> cache when all refs are released. Remove the cache from the "caches" map.
>>>> 
>>>> 2) And/or, wrap the cache in a wrapper whose stop() method doesn't call
>>>> through to the wrapped cache until stop() is called on all wrappers
>>>> 
>>>> 3) Advise in the javadoc that shared caches are supported, but if they
>>>> are used it's the users responsibility to ensure that at least one but
>>>> only one caller calls stop() on the cache. At least for the AS use
>>>> cases, this should be OK, since an Infinispan Cache will be analogous to
>>>> a JBC Region, and there's only one user for a given region.
>>>> 
>>>> --
>>>> Brian Stansberry
>>>> Lead, AS Clustering
>>>> JBoss by Red Hat
>>>> _______________________________________________
>>>> infinispan-dev mailing list
>>>> infinispan-dev at lists.jboss.org
>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>> 
>>> --
>>> Manik Surtani
>>> manik at jboss.org
>>> Lead, Infinispan
>>> Lead, JBoss Cache
>>> http://www.infinispan.org
>>> http://www.jbosscache.org
>>> 
>>> 
>>> 
>>> 
>>> 
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>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>> 
>> 
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> 
> 
> -- 
> Brian Stansberry
> Lead, AS Clustering
> JBoss by Red Hat
> _______________________________________________
> infinispan-dev mailing list
> infinispan-dev at lists.jboss.org
> https://lists.jboss.org/mailman/listinfo/infinispan-dev

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