[infinispan-dev] Management of shared caches

[Mircea Markus]

On Dec 16, 2009, at 11:11 AM, Manik Surtani wrote:

> 
> 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.
Coherence supports regexp for defining cache names. I guess that would also solve ISPN-316, be a more generic solution and also allow better migration from coherence. This won't work for runtime aliasing, not sure we'll be able to do this as well.
> 
>> 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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>>> 
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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
> 
> 
> 
> 
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