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?

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On 08/25/2011 05:56 AM, Thomas Mortagne wrote: > On Thu, Aug 25, 2011 at 12:00 PM, Caleb James DeLisle > &lt;calebdelisle(a)lavabit.com&gt; 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

Caleb > >> >> Caleb >> >> _______________________________________________ >> devs mailing list >> devs(a)xwiki.org >> http://lists.xwiki.org/mailman/listinfo/devs >> > > > _______________________________________________ devs mailing list devs(a)xwiki.org http://lists.xwiki.org/mailman/listinfo/devs