Re: [xwiki-devs] Cache needs

Hi Vincent, I already sent a mail (http://markmail.org/message/euavqzjz53mxxkut) explaining the cache service -> cache components I planned/coded. You can find a first api and a complete oscache implementation at http://jira.xwiki.org/jira/browse/XWIKI-2359. I designed this api looking to all places we used the old cache service and all this used to support. Lets list here the main lines of it : 1) What the new api already contains (see http://jira.xwiki.org/jira/browse/XWIKI-2359) : 1.1) First of all, there is two different component roles : * cache : create named cache that can be local or distributed caches depends on the implementation and its configuration. Typically used for documents cache. * local cache : create only and always local caches seems to be needed by some part of XWiki core like groovy, feed plugin and image plugin That way we can set in the configuration that we want memcached for normal cache and JBossCache for local cache for example. 1.2) Factory create cache and take parameters like "capacity" 1.3) Cache contains : * get : get the value by key, can take a timing as parameter compared to the time the value was registered the last time * set : modify or add a value to the cache * remove : remove a value from the cache 1.4) Cache can call listeners on add, delete, update... 1.5) Cache support generics This api support all you listed I think (except for the way the timed cache works). It is generally based on the old cache services concepts even all the names changes but the more I'm working with JBoss cache the more I think this api need some changes as JBoss cache and OSCache has very different way to create there caches. 2) Problems/not sure yet : 2.1) old cache service provide methods taking maps of properties as parameters need by image plugin for example. My problem here is that all existing cache frameworks like OSCache, JBoss etc... are very new to me and I'm not sure of what feature I can generalize in this map. I think of starting by taking all properties setted by image plugin and list them as XWiki Cache properties and translate them for each implementations. Capacity, name all Factory take as parameters should be included in a CacheConfiguration object. Some of theses properties can also be ignored by implementation in some cases. 2.2) I think I need to change the way the timing works in this api as I did not find how to support it in JBoss yet. A more restrictive way and supported by JBoss would be to provided the limit time for the whole cache. I don"t really see a need for more. I'm thinking of introduce eviction algorithms concept like JBoss or cache4j do to replace the way restriction like capacity and timing are supported. 3) Other features the cache component could support for XWiki needs 3.1) for documents cache, Ludovic proposed the idea of something like a "meta cache" when we are using distributed cache: the idea is to only store the documents version in the distributed cache and store the reall document in a local cache. The local cache is synchronised with distributed cache based on the documents version:if it changed the document has to be reloaded from the database. This avoid the serialization/unserialization process of the whole document in the distributed cache. On Tue, May 27, 2008 at 10:43 AM, Vincent Massol <vincent(a)massol.net> wrote: Plexus cache api (http://plexus.codehaus.org/plexus-components/plexus-cache/plexus-cache-api/…) and some implementations. The problem is that the api is not very generic and the way it is designed you need to know the implementation you use to correctly configure the cache to create. But maybe I take it the wrong way and should not try to force the whole XWiki Platform to be able to use any cache component implementation... Except for the plexus one I did not found a real "framework of cache framework" but I did not search weeks for it... -- Thomas Mortagne