On Thu, Aug 25, 2011 at 3:24 PM, Fabio Mancinelli <[email protected]> wrote: > On Thu, Aug 25, 2011 at 3:02 PM, Thomas Mortagne > <[email protected]> wrote: >> On Thu, Aug 25, 2011 at 2:23 PM, Fabio Mancinelli >> <[email protected]> wrote: >>> On Thu, Aug 25, 2011 at 12:18 PM, Caleb James DeLisle >>> <[email protected]> wrote: >>>> >>>> >>>> On 08/25/2011 05:56 AM, Thomas Mortagne wrote: >>>>> On Thu, Aug 25, 2011 at 12:00 PM, Caleb James DeLisle >>>>> <[email protected]> wrote: >>>>>> In order to fix a problem with the cache, I would like to add a pointer >>>>>> type to the storage api. >>>>>> The problem with the cache is there are multiple names which, when asked >>>>>> of the persistent store, >>>>>> return the same document. There is no effective way to know what all >>>>>> names which will return that >>>>>> document. When a document is modified, it is removed from the cache but >>>>>> the only version removed is it's >>>>>> "real" name. All of the other names for it linger in the cache eating up >>>>>> memory and threatening to >>>>>> provide someone stale data. >>>>>> Instead of caching the document, we could cache a pointer to the >>>>>> document and when it became stale, >>>>>> the pointer could be set to null and then any other name under which >>>>>> that document was cached would look >>>>>> up a null pointer and the cache logic could remove it. >>>>>> >>>>>> I would like to add it to xwiki-platform-store-api module and it will >>>>>> look roughly like this: >>>>>> >>>>>> package org.xwiki.store; >>>>>> >>>>>> public final class Pointer<T> >>>>>> { >>>>>> /** The thing which this pointer points to. */ >>>>>> public T target; >>>>>> } >>>>>> >>>>>> >>>>>> WDYT? >>>>> >>>>> Why is there several cache keys for the same document ? Can't we make >>>>> sure a same document always use the same key ? >>>> >>>> When you get a document and put it in the cache, you can put it under it's >>>> canonical key which might, >>>> for instance, be xwiki:Main.WebHome:en but most of the requests for that >>>> document will go to >>>> xwiki:Main.WebHome (which returns the same document from the store). If >>>> you refuse to cache under >>>> any key but the canonical key, you will defeat most of the cache's >>>> usefulness. >>>> >>>> BTW: This is the issue: http://jira.xwiki.org/jira/browse/XWIKI-6170 >>>> >>> Couldn't you just complete the ID with the language information when >>> it's missing before querying the cache? >> >> The problem is that each document can have its own default language so >> there is no way to complete the language information without the >> proper XWikiDocument coming from the database. >> > I see. > Well a quick&dirty solution would be to cache also the default language :) > > xwiki:Space.Document:defaultLanguage -> en > xwiki:Space.Document:en -> document in english > xwiki:Space.Document:fr -> document in french > ... > > So when a document ID doesn't have the language specified, you can > retrieve the information from the cache and complete the ID. > This is an additional get on the cache which could introduce a > performance issue: I don't know how many times an incomplete ID is > used for retrieving a document.
Sure but that's not really the issue here, what Caleb wants is to make sure every entries of the same document are removed from the cache when one is removed. > > -Fabio > >>> >>> -Fabio >>> >>>> Caleb >>>> >>>>> >>>>>> >>>>>> Caleb >>>>>> >>>>>> _______________________________________________ >>>>>> devs mailing list >>>>>> [email protected] >>>>>> http://lists.xwiki.org/mailman/listinfo/devs >>>>>> >>>>> >>>>> >>>>> >>>> >>>> _______________________________________________ >>>> devs mailing list >>>> [email protected] >>>> http://lists.xwiki.org/mailman/listinfo/devs >>>> >>> _______________________________________________ >>> devs mailing list >>> [email protected] >>> http://lists.xwiki.org/mailman/listinfo/devs >>> >> >> >> >> -- >> Thomas Mortagne >> _______________________________________________ >> devs mailing list >> [email protected] >> http://lists.xwiki.org/mailman/listinfo/devs >> > _______________________________________________ > devs mailing list > [email protected] > http://lists.xwiki.org/mailman/listinfo/devs > -- Thomas Mortagne _______________________________________________ devs mailing list [email protected] http://lists.xwiki.org/mailman/listinfo/devs
