I think both options are valid.The db cache should certainly have timestamps column to decide when to purge an item.
So a purge could be a DELETE .. WHERE enddate<....
We could put an abstract method clear_old_data in the parent Cache class and leave implementation details to the child classes.
Those implementation that don't need it can implement an empty method. Le 27.04.2011 14:10, Philippe Van Eerdenbrugghe a écrit :
I would personally go for a file cache because it's much more easy to purge.If the Caching engine is responsible to get any cached data, we can have it check how old it is and either return the old data or recompute and return the data.What do you think o that idea ? Systho Le 27/04/2011 14:02, Sven Vanpoucke a écrit :Triggering these actions on an event like a user logout isn't a very good idea either. Because not many users actually use the logout button. In fact, triggering this with any event, like for example the login could make this event very slow...I am very much in favor of introducing caching into the code. But i'm more the person who likes to cache the things for reuse in the same run (like we already did with registrations, settings...). I don't really like the idea that we start caching between multiple runs due to the fact that it's much harder to debug these things. I'm much more in favor to solve these performance issues by denormalizing your database layer and storing some of these values locally in your application instead of recalculating them everytime.Best regards Sven Op 27/04/11 13:49, Laurent Opprecht schreef:I would rather go for serialize/unserialize as it is meant to store objects.As for file serialization this is certainly doable but I would make that just another implementation. In this case we have to ensure we use a shared cache if we use several application servers.I didn't realize that cron may not be available. A good point indeed. So in this case we can have a clean up script and trigger it on some recurring event - for example when the user logout.Le 27.04.2011 12:56, Philippe Van Eerdenbrugghe a écrit :If you go for cron, don't forget that chamilo should be usable on mutalised hosting where cron is not available. What about file serialization and var_export /__set_state() functions ?the mtime can be checked directly in php code Systho Le 27/04/2011 12:46, Laurent Opprecht a écrit :I believe a DB implementation would be a good first move - at least we are sure it will be available :-). I would just ensure the implementation is compatible in term of interface with APC - which should be more or less a standard by now.I.e. have functions such as add($key, $value, $time_to_leave) etcI don't think we should clear the cache by logout. After all some caching may still be usefull after logout. Cron would be my favorite.Le 27.04.2011 11:29, Nathalie Blocry a écrit :I have made a wiki page on this subject: http://support.chamilo.org/projects/chamilo-20/wiki/Caching I know striclty speaking this is a new feature but I am convinced wereally need some kind or caching before we can release the handbook app.I could implement it for now just for the handbook, but if I am makingthe effort anyway I think it would be better to implement the platform-wide classes right-away, no?So I propose making the Cache class and just doing one implementationfor now. Still not sure what this one implementation should be. nobody has any experience with caching data/objects (not pages)? short-term serializing and storing in the database might be the best default system? With some cron-script to periodically clean out the table, because we can clean-up at logout, but not many users will actualy do that I think (I never do ;-)) Op 04/26/2011 01:32 PM, Hans De Bisschop schreef:That's the Chamilo 2.0 spirit *thumbs up* 8-) :-) Hans On 26/04/2011 12:42, Laurent Opprecht wrote:We may abstract the caching mecanism. Something like: class Cache class ApcCache extends Cache class MemCache extends Cache class DatabaseCache extends Cache class SessionCache extends Cache class EmptyCache extends Cache //Empty pattern ...With a factory method inside the Cache class. If the cache is not available - because memcach is not installed for example - then we can return the Empty cache that does nothing or defaults toanoter implementation.That would make Chamilo independant from specific cache implemenationyet providing the service for those applications that need it. Le 26.04.2011 12:26, Sven Vanpoucke a écrit :I would not use memcached or another tool for caching because this would mean that we would demand yet another package to be installedon the server before chamilo can be used.-- ____________________________________ Meilleures salutations Laurent Opprecht chat:laurent.oppre...@gmail.com blog:http://ciel.unige.ch/ _______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev-- *Hans De Bisschop* Hoofddeskundige ICTO | Lead Developer Chamilo 2.0 Software Coordinator Chamilo Association Erasmushogeschool Brussel Nijverheidskaai 170 | B-1070 Brussel T 02 559 02 54 | i 254 hans.de.bissc...@ehb.be <mailto:hans.de.bissc...@ehb.be> | www.erasmushogeschool.be <http://www.erasmushogeschool.be/> Kom eens langs:www.erasmushogeschool.be/infodagen <http://www.erasmushogeschool.be/infodagen> of lees onze elektronische nieuwsbrief: ehbrief.ehb.be <http://ehbrief.ehb.be/> P Before printing, think about the environment _______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev_______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev-- ____________________________________ Meilleures salutations Laurent Opprecht chat: laurent.oppre...@gmail.com blog: http://ciel.unige.ch/ _______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev_______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev-- Met vriendelijke groeten Sven Vanpoucke Digitaal Leren Directie Onderwijs Hogeschool Gent http://digitaal-leren.hogent.be/ _______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev_______________________________________________ Dev mailing list Dev@lists.chamilo.org http://lists.chamilo.org/listinfo/dev
-- ____________________________________ Meilleures salutations Laurent Opprecht chat: laurent.oppre...@gmail.com blog: http://ciel.unige.ch/
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