[jbosscache-dev] Storing k, v at root node of marshaled region and cache loaders.
Hi all,
Yesterday while looking at a support case, I discovered an awkward
behavior when it came to root region based marshalling nodes and cache
loaders.
Let's say you have a cache configured with a cache loader and have a
region marshaled called starting at /me. I have created an MBean so that
I can register/unregister classloader and activate/deactivate the region
upon deployment/undeployment of the classes I wanna put under /me.
Now, let's say that I put a k,v in /me which will get stored in the
cache loader. If I know touch the deployment archive to force a
redeployment and check the contents of the cache, they're empty. If I
try to get the k I put under /me, it'll return nothing. Why?
Simple: The cache instance is configured to preload from root (/) but
when the region is activated, /me node is created. When the preloading
phase comes, a check is made to see whether the node needs to be loaded:
private boolean mustLoad(DataNode n, Object key)
{
if (log.isTraceEnabled())
{
log.trace("mustLoad called with key=" + key + " and
datanode="
+ n);
}
return n == null ||
(n.containsKey(TreeCache.UNINITIALIZED) && (key == null
|| !n.containsKey(key)));
}
The problem is that nothing will be preloaded for at least the /me node,
because the node is not null, and it's not TreeCache.UNINITIALIZED. Any
child nodes under the region node do not have issues like this.
This is likely a bug: maybe when the region is activated, the node
should probably be created as TreeCache.UNINITIALIZED? I think this
would work).
It's true that you could say that putting data at the root node of the
region is not a good idea regardless, but I think deep down this is a bug.
Thoughts?
p.s. This is at least present in 1.4.x, need to check trunk. However,
wanted to gather some thoughts before I continue debugging/fixing it.
--
Galder Zamarreño
Sr. Software Maintenance Engineer
JBoss, a division of Red Hat