Guillaume Nodet wrote:
What about using runtime byte-code enhancement, as you mentioned it, to extends classes to dynamically add properties for storing AKs, thus removing the need of AnonymousPersistentField ...
you stir up a hornet's nest ;-)
Many people don't like manipulation of persistent object classes (dynamically or pre-compiled). Another problem will be the use of the "correct" classloader when dynamically enhancement was used and the user can't create persistent objects by it's own.
But indeed byte code enhancement will solve or simplify many problems (e.g. anonymous fields, object state detection, object locking, ...).
I don't have experience in bytecode manipulation (only played a little with ASM) but all suggestions, pros and cons are welcome.
regards, Armin
Guillaume
-----Message d'origine----- De : Armin Waibel [mailto:[EMAIL PROTECTED] Envoy� : jeudi 22 avril 2004 15:01 � : OJB Users List Objet : Re: Problem with clearing cache
Hi Guillaume,Brian,
I think the anonymous key (AK) feature should be modified/rewriten because currently it is object identity based. This means you will loose all AK information when the object will be de-/serialized or copied. The upcoming two-level cache will do so and the OTM implementation too (and my "feeling" is that this will cause problems). The AK in conjunction with 1:1 references are always be save (I think), because when the AK information is lost, we can use the reference to re-create the AK information.
> I'm willingfull to help refactoring this part, but i'd like to > have guidelines
sorry I don't have any ideas (without byte-code enhancement ;-))
> if anonymous keys are integrated within the existing cache system, > but i have no ideas on how to do it.
this will be difficult, because AK implementation does not know about the cache and the cache could be per class-descriptor, per connection or global.
regards, Armin
Guillaume Nodet wrote:
I use both anonymous PK's and FK's. But the use i do of anonymous primary keys is limited to objects that belongs to collections of main objects. Main objects have *real* primary keys and only these ones are used directly in the broker (all collections are prefetched) and cached. So i think that using anonymous pk's in my case is safe (if my understanding is good, problems can arise when using anonymous pk's in distributed environnments).
So the main problem is the caching system for anonymous keys (either pk or fk) : * keys are kept in a cache specific to the field * this cache can not be accessed by any means so no clear is possible * this cache can not be a per-broker cache * anonymous persistent fields implementation can not be extended or overriden
I'm willingfull to help refactoring this part, but i'd like to have guidelines on how to do it... I think it would be great if anonymous keys are integrated within the existing cache system, but i have no ideas on how to do it.
Guillaume
-----Message d'origine----- De : Brian McCallister [mailto:[EMAIL PROTECTED] Envoy� : jeudi 22 avril 2004 14:06 � : OJB Users List Objet : Re: Problem with clearing cache
Anonymous PK's are risky things -- I apologize for using them in the original anonymous keys tutorial. Anonymous FK's are great, and not using them is usually a bad ida in my opinion =)
I don't think the anonymous PK issues you are having will be resolved very soon, the anonymous key functionality wasn't really designed for PK usage, but for FK usage. I completely feel that it would be good to be able to use them for PK's as well, but my slate is full at the moment with JDO stuff =(
I don't know about everyone else. Any chance *you* want to dig into it? ;-)
-Brian
On Apr 22, 2004, at 7:55 AM, Guillaume Nodet wrote:
It also seems that cached anonymous keys are not removed from the cache when an object is deleted from database. Will these problems be solved, or should i try not to use anonymous keys ?
Guillaume
-----Message d'origine----- De : Guillaume Nodet [mailto:[EMAIL PROTECTED] Envoy� : mercredi 21 avril 2004 14:42 � : OJB Users List Objet : Problem with clearing cache
I need to clear the ojb cache at some point in my program (namely after deleting all data in the database). The problem i have is that i use anonymous primary keys and the caches associated with the anonymous fields are not cleared. Would it be possible to had some mean of clearing these caches ?
The problem is that at some time, i've got errors when inserting objects. I think that the key for the failing object is in cache but not in the database so when a foreign key references it, the insertion fails.
Thanks, Guillaume Nodet
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