[elephant-devel] postmodern btree problem

[Ian Eslick]

Hmmmm....

Off the top of my head, I'm not sure what's going on.  I'll look into  
this tomorrow.

Cheers,
Ian

On Jan 3, 2009, at 5:18 PM, Alex Mizrahi wrote:

> HD> Which of stable/unstable do you recommend using?
>
> i think we'll eventually switch to "unstable", so if you're planning
> for the future, this would be a better option. also the more people
> use it, faster we will find all bugs in a new version. OTOH in a short
> term perspective "stable" is more tested.
>
> HD> instrumenting it shows that when the problem occurs, the crippled
> HD> pm-btree  is being recreated (not in cache).
>
> aha, thanks for finding this out -- it appears that recreation code
> in unstable is severely broken.
>
> i do not understand the idea behind these changes, i hope Ian can  
> clarify
> this
> so we'll find a way to fix this.
>
> in old version recreate-instance-using class for standard-class  
> objects was
> just called make-instance,
> so it went through the normal initialization procedure.
>
> in a new version it just calls allocate-instance, so pm-btree has  
> absolutely
> no chance to
> initialize itself -- neither initialize-instance is called to fill  
> slots
> with iniforms, nor shared-initialize is called,
> and we end up with a blank object.
>
> here's a piece of documentation:
>
> (defmethod recreate-instance-using-class ((class standard-class) &rest
> initargs &key &allow-other-keys)
>  (declare (ignore initargs))
>  "Simply allocate store, the state of the slots will be filled by  
> the data
> from the
>   database.  We do not want to call initialize-instance and re- 
> evaluate the
> initforms;
>   we are just fetching the object & values from the store"
>  (allocate-instance class))
>
> but i fail to understand the point -- how exactly are we "feching  
> the object
> & values from the store" for standard-class
> classes? is that some new object serialization mechanism or just an  
> error?
>
>
>
>
>
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