RE: Serious problem with MRUMap -- JCS LRU and MRUMap -- RE: [si mplestore] enhancements (was: [simplestore] inital check in)

[Juozas Baliuka <ba...@mwm.lt>]

At 11:20 AM 1/31/2002 -0500, you wrote:


> > -----Original Message-----
> > From: Juozas Baliuka [mailto:baliuka@mwm.lt]
> > Sent: Thursday, January 31, 2002 12:23 PM
> > To: Jakarta Commons Developers List
> > Subject: RE: Serious problem with MRUMap -- JCS LRU and MRUMap -- RE:
> > [simplestore] enhancements (was: [simplestore] inital check in)
> >
> > <skip>
> > >You should try to build it as a memory plugin for JCS.  It might require
> > >some element attribute additions (what type of reference) if they are
> > >useful.
> > >
> > >The cache hub manages expiration at request time, this could be moved to
> > >a background thread.  Cleanup of unused items could result in spooling.
> >
> > Sorry, I can't use any "background cleanup" it has no meaning for memory
> > cache.
>
>Sure it does.
>
> > This thread can remove objects from cache, but not from memory, if
> > application has strong reference on object.
>
>Yes.  It can remove it from the cache.
>
> > "expiration at request time" has no meaning if application has strong
> > reference on object.
> >
>
>It can be removed from the cache.
>
> > example situation :
> > ...............................................
> >   User  u = cache.get(id);
> > if( u == null ){
> >   u = User.create( id  );
> >    cache.put(id,u);
> >   session.setAttribute("user",u);// I have strong reference here
> >   team.add(u);
> > }
> > ..............................................
> >
> >   request.setAttribute("player",u);
> >
> > ...............................................
> >
> > Requests, operations , but I don't remove "user" from session
> > ..............................................
> >
> > assertTrue("try to increase sessin time out", session.isValid() );
> >    // my session is valid at this time.
> >   // cache must not remove my "user" if GC not decided to do this.
> >
> >   assertEquals("cache doe's not work or bug in GC ",
> > session.getAttribute("user"), cache.get(id));
> >
> > Cache must release unused references, if memory is "low" and must never
> > remove object from cache if it used by application.
> >
>
>Why?  Is it a cached store?  It can be removed from the store.
>
>I'm not sure what you are trying to do or why.
  :) Yes, situation is trivial, but not trivial to understand me.
  I need this for store close to JDO ideas :
Object obj = store.retrieveByID(id);
..................................................
Any operations except  store.remove(obj) or store.remove(MyClass,id) ;
................................................
  if( store.retrieveByID(id) !=  obj)
      throw new FatalException("my storage doe's not work");








>Good luck.
>
> > if this test fails I don't need this kind of cache, it can be very fast,
> > but not useful.
> >
> >



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