[news.eclipse.tools.emf] Re: [CDO 1.0] weak references and adapters

[Thomas.M.Crockett@xxxxxxxxxxxx (Tom Crockett)]

Eike,

It seems to me that adding an adapter to an object that is in an open view 
is implicitly saying, "I am interested in this object. Please keep me 
notified of when it changes." Given that CDOViews are "partial views on 
the repository", it makes sense that things would get GC'ed out of them 
when no one is paying attention to them, but if I attach an adapter to an 
object it seems to me that I'm expressing interest in it, and therefore it 
should be maintained as part of the view. What if objects with adapters 
attached to them were maintained in a separate Strong reference map?

Eike Stepper wrote:

> Tom,

> I see it as one of the hidden but main advantages of CDO that the 
> EObjects can be silently discarded from memory when it runs low and 
> automatically recreated when they are needed again. And you're right, I 
> didn't think about existing adapters. Can you please open an enhancement 
> request and make a proposal on how exactly you'd like to have it 
> configurable?

> Cheers
> /Eike


> Tom Crockett schrieb:
> > I've been fighting a very insidious bug for the last 3 days in which 
> > adapters I attached to my shared model were mysteriously disappearing. 
> > I couldn't find any place where they were getting removed, so I was 
> > really mystified for a long time. Today I finally figured out that it 
> > was because of the fact that CDOViewImpl stores its objects in a weak 
> > ReferenceValueMap, so they were getting GC'ed, along with their 
> > adapters! I worked around this fairly easily by attaching an 
> > EContentAdapter when first loading a resource which recursively 
> > maintains strong references to every object in the view, but I just 
> > wanted to mention this for anyone who may be experiencing such 
> > problems. Also, I wanted to ask whether this behavior might be made 
> > configurable, if it already hasn't, for CDO 2.0.