RE: [jbosscache-dev] Some new Cache usage questions

A Node is still just a wrapper. Every time you try and do anything with it, calls are passed thru the interceptor stack to the TreeCache object. If a Node no longer exists, a CacheException will be thrown. Do we foresee this as a problem, and should we not be recommending caching Nodes? > Isn't caching a Node dangerous, as you have no way of knowing it > hasn't been removed from the tree? Unless you add a CacheListener > just for that. > > jbosscache-dev-bounces(a)lists.jboss.org wrote: >> Use Cache for cache-wide operations like getRegion(), etc. >> >> Use Node to manipulate data in the node, retrieve child nodes, etc. >> This way refs to Nodes - buckets of data storage - can be cached >> since it is these that would be most frequently used. >> >>> It does. But then, does it mean I need to keep both the reference >>> for Cache and "parent" Node at the same time? Although Cache is a >>> wrapper, it does have some additional APIs like evict and also >>> getRegion() that doesn't exist in Node. Or what's your >>> recommendation? >>> >>> Actually, currently I am keeping the CacheSPI reference (and also >>> possibly NodeSPI in the future when it has life of its own) within >>> my code. Keeping the Node reference doesn't seem to make much sense >>> to me, although this can be just a pattern for the customed cache >>> provider (e.g., PojoCache). >>> >>> -Ben >>> >>> -----Original Message----- >>> From: Manik Surtani [mailto:manik@jboss.org] >>> Sent: Tuesday, September 05, 2006 12:10 AM >>> To: Ben Wang >>> Cc: Bela Ban; jbosscache-dev(a)lists.jboss.org >>> Subject: Re: [jbosscache-dev] Some new Cache usage questions >>> >>> >>> On 4 Sep 2006, at 16:58, Ben Wang wrote: >>> >>>> 1. I suspect people using JBC for session management purpose won't >>>> store the Node ref but the Cache instead. Brian can say better but >>>> for example of the http session, unless you store the root Node, >>>> otherwise caching the children Node is not that useful. >>> >>> Node jSessionNode = Cache.getChild(Fqn.fromString("/ JSESSIONID")); >>> // this can be cached... Node sessionNode = >>> jSessionNode.getChild(Fqn.fromString (sessionId)); // this can be >>> retrieved every time... >>> >>> Does this help in any way? >>> >>> >>>> >>>> 2. ic. Do we have explicit contract for Cache to be "root" Node >>>> only? I mean, even getRoot() is just a self pointer, it still >>>> serves the purpose, IMO. >>> >>> From the javadocs: "The cache is essentially a wrapper around the >>> default root Node." >>> >>> >> http://labs.jboss.com/file-access/default/members/jbosscache/ >> freezone/ >>> docs/Habanero/api/org/jboss/cache/Cache.html >>> >>> >>>> >>>> -Ben >>>> >>>> -----Original Message----- >>>> From: Manik Surtani [mailto:manik@jboss.org] >>>> Sent: Monday, September 04, 2006 7:06 PM >>>> To: Ben Wang >>>> Cc: Bela Ban; jbosscache-dev(a)lists.jboss.org >>>> Subject: Re: [jbosscache-dev] Some new Cache usage questions >>>> >>>> Not in your case, no. But many other use cases will be able to >>>> cache a node and use it directly. >>>> >>>> I too would rather keep the API clean in this regard. Also, >>>> calling cache.getRoot() is redundant since the Cache interface is >>>> a wrapper around the root Node. In fact, I even think we should >>>> get rid of the getRoot() method. >>>> >>>> Cheers, >>>> -- >>>> Manik Surtani >>>> >>>> Lead, JBoss Cache >>>> JBoss, a division of Red Hat >>>> >>>> Email: manik(a)jboss.org >>>> Telephone: +44 7786 702 706 >>>> MSN: manik(a)surtani.org >>>> Yahoo/AIM/Skype: maniksurtani >>>> >>>> >>>> On 1 Sep 2006, at 15:49, Ben Wang wrote: >>>> >>>>> Thing is I only do put to specific fqn once. So caching it >>>>> doesn't buy you anything. >>>>> >>>>> -----Original Message----- >>>>> From: Bela Ban >>>>> Sent: Friday, September 01, 2006 10:22 PM >>>>> To: Ben Wang >>>>> Cc: jbosscache-dev(a)lists.jboss.org >>>>> Subject: Re: [jbosscache-dev] Some new Cache usage questions >>>>> >>>>> My 2 cents: I'd rather keep the API clean, at the expense of >>>>> folks potentially writing wrapping code (like Ben). >>>>> >>>>> Your code samples look a bit weird: >>>>> #1 >>>>> Why do you always get the child ? Can't you get the node and >>>>> cache it, e.g. Node n=cache.getRoot().getChild(fqn); >>>>> n.containsKey(PojoInstance.KEY) >>>>> >>>>> #2 >>>>> Same as for #1: you don't need to call cache.getRoot().getChild >>>>> (fqn) all the time, for example in a loop, simply cache it >>>>> >>>>> >>>>> Ben Wang wrote: >>>>>> Manik, >>>>>> >>>>>> While trying to use the new API in PojoCache, I have found that >>>>>> I need to: >>>>>> >>>>>> 1. To check if a attribute exist, I need to do: >>>>>> cache_.getRoot().getChild(fqn_).getData().values().contains >>>>>> (PojoInstance.KEY) >>>>>> >>>>>> 2. And then, I need to do a lot of cache_.getRoot().getChild >>>>>> (fqn).put(map) >>>>>> >>>>>> So looks like I need to write a wrapper layer just to provide >>>>>> straight api for: >>>>>> >>>>>> Cache_.exists(fqn, key) >>>>>> And >>>>>> Cache_.put(fqn, map) >>>>>> >>>>>> If this is rare case, then I will bite the bullet. But if it is >>>>>> a common one, then that really begs the question whether we >>>>>> should provide additional apis or not? >>>>> >>>>> -- >>>>> Bela Ban >>>>> Lead JGroups / Manager JBoss Clustering Group JBoss - a division >>>>> of Red Hat >>>>> >>>>> _______________________________________________ >>>>> jbosscache-dev mailing list >>>>> jbosscache-dev(a)lists.jboss.org >>>>> https://lists.jboss.org/mailman/listinfo/jbosscache-dev >>>> >>> >> >> _______________________________________________ >> jbosscache-dev mailing list >> jbosscache-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/jbosscache-dev > > > > Brian Stansberry > Lead, AS Clustering > JBoss, a division of Red Hat > Ph: 510-396-3864 > skype: bstansberry