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From Luo Fucong <bayinam...@gmail.com>
Subject Re: Why PathChildrenCache does not have "cversion"?
Date Wed, 21 Oct 2015 05:25:38 GMT
Ah, found the “maxDepth” in TreeCache after revisiting the source code. Will definitely
use it. Thanks very much!

> 在 2015年10月21日,下午12:59,Cameron McKenzie <mckenzie.cam@gmail.com>
写道:
> 
> You can set a max depth for the tree cache. You should just be able to set a max depth
of 1?
> 
> On Wed, Oct 21, 2015 at 3:46 PM, Luo Fucong <bayinamine@gmail.com <mailto:bayinamine@gmail.com>>
wrote:
> My requirement is building a tree with only one level (root plus its first level children).
TreeCache, however, will build the entire tree with however many levels the root has.
> 
> So basically, I need a “NodePathChildrenCache” that’s NodeCache + PathChildrenCache
:)
> 
> > 在 2015年10月21日,下午12:37,Jordan Zimmerman <jordan@jordanzimmerman.com
<mailto:jordan@jordanzimmerman.com>> 写道:
> >
> > Well, that’s not what PathChildrenCache is for. You could start a NodeCache for
the parent node I guess. Or use TreeCache. But, I don’t know what the use case is so I can’t
comment in more detail.
> >
> > -Jordan
> >
> >> On Oct 20, 2015, at 11:34 PM, Luo Fucong <bayinamine@gmail.com <mailto:bayinamine@gmail.com>>
wrote:
> >>
> >> Thanks for the reply.
> >>
> >> Sorry for the ambiguous meaning of “path node”. By saying “path node”,
I mean the common root node of the children.
> >>
> >> So PathChildrenCach does store the children nodes Stat, but it does not store
the root node's Stat.
> >>
> >> For instance, I have created a PathChildrenCach cache = new PathChildrenCache(“/path/to/node”).
> >> I can get the Stat of “/path/to/node/child1”, but I cannot get the Stat
of “/path/to/node” directly from the cache.
> >>
> >>> 在 2015年10月21日,下午12:18,Jordan Zimmerman <jordan@jordanzimmerman.com
<mailto:jordan@jordanzimmerman.com>> 写道:
> >>>
> >>> PathChildrenCache stores the node’s Stat object in the ChildData. So,
all the data you want is there.
> >>>
> >>> -JZ
> >>>
> >>>> On Oct 20, 2015, at 11:13 PM, 罗傅聪 <bayinamine@gmail.com <mailto:bayinamine@gmail.com>>
wrote:
> >>>>
> >>>> Hi all:
> >>>>
> >>>> I recently went through the PathChildrenCache source code (in curator-recipes-2.9.0)
and found that it does not store the path node’s “cversion”, which indicating the number
of changes to the children of this znode. (Correct me if I’m wrong.)
> >>>>
> >>>> I think the “cversion” is a very important version number which
enable us to verify that the PathChildrenCache is really catch up to the remote zookeeper
znodes.
> >>>>
> >>>> So I’m wondering that:
> >>>>
> >>>> 1. why the PathChildrenCache does not store “cversion”, or furthermore,
why it does not store the path node’s status?
> >>>>
> >>>> 2. are there other means I can use to verify that the PathChildrenCache
is not falling behind the remote znodes?
> >>>>
> >>>> Thanks!
> >>>
> >>
> >
> 
> 


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