RE: [jbosscache-dev] Need for CacheLoader.storeState?
Hey,
There is an interesting quirk with this whole thing. In brief,
storeState implementation of AbstractCacheLoader after it reads NodeData
from inputstream it writes it to cache like this:
if (nd.attrs != null)
put(fqn, nd.attrs, true); //void put(Fqn name, Map
attributes,boolean erase) throws Exception;
else
put(fqn, null); // void put(Fqn name, Map attributes) throws
Exception;
As you know true parameter in put clears the existing map. However,the
trick is that CacheLoader only exposes:
void put(Fqn name, Map attributes) throws Exception;
and not
void put(Fqn name, Map attributes,boolean erase) throws Exception;
So I cannot move storeState up to AbstractCacheLoader unless we expose
put with erase.
It took me like two hours to figure this out since compiler did not
complain - it automatically boxed boolean parameter and linked
invocation of put(fqn, nd.attrs, true); to method Object put(Fqn name,
Object key, Object value) throws Exception;
I did a very simple change of moving storeState to AbstractCacheLoader
and tests started to fail. I thought I was halucinating.
So what do we do?
-----Original Message-----
From: Bela Ban
Sent: Thursday, August 31, 2006 5:47 PM
To: Vladimir Blagojevic
Cc: jbosscache-dev(a)lists.jboss.org
Subject: Re: [jbosscache-dev] Need for CacheLoader.storeState?
Absolutely, I had that idea when I wrote the cache loader
interface, but never saw it through... +1 for sure, this
takes a lot of pain out of the implementations.
Are you guys thinking about a more efficient transfer format,
or is NodeData still the awy to go ?
Vladimir Blagojevic wrote:
> Hi,
>
> After we resolve streaming format incompatible cacheloader
> implementations [1][2], and as we continue to follow newly agreed
> streaming state transfer format - we do not have to require
> cacheloader implementers to write their own implementations of
> storeEntireState and storeState !
>
> CacheLoader.storeEntireState and CacheLoader.storeState are
always the
> same. They read NodeData objects from stream and call put with
> underlying cacheloader. Put method does the cacheloader
specific stuff.
>
> We can possibly keep storeEntireState and storeState in CacheLoader
> API but move default implementations to AbstractCacheLoader. Any
> suggestions or opinions?
>
>
> [1] http://jira.jboss.com/jira/browse/JBCACHE-748
> [2] http://jira.jboss.com/jira/browse/JBCACHE-749
>
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>
>
--
Bela Ban
Lead JGroups / Manager JBoss Clustering Group JBoss - a
division of Red Hat