Re: [incquery-dev] Viewers refactoring, help needed

[Ujhelyi Zoltán <ujhelyiz@xxxxxxxxxx>]

Sadly, I am not completely surprised that it is not possible to put a ComputedSet inside another; as they try to monitor changes inside the Data binding Realm, and then manually compare the results. We have already observed some cases with forgotten notifications earlier.

What I was originally thinking is to forget about creating a two-level observable collection building and provide a single ComputedSet - it looks really bad, and it could perform quite bad, as it cannot only recalculate a single small ComputedSet but always the other. This approach is even more naive then your implemented solution, however, I have no better idea while relying on the data binding framework.

The only other think I can think about is to extend the data binding layer to create an Observable set directly on the EVM level - however, I am not entirely sure whether that is a useful thing to have outside Viewers (but possibly it is). Some recent functionality created for the transformation API could also help in this regard.

Ábel, what do you think about this approach?

Cheers,
Zoli
-- Zoltán Ujhelyi
https://www.inf.mit.bme.hu/en/members/ujhelyiz

Fault Tolerant Systems Research Group
Budapest University of Technology and Economics

On 2013.09.19., at 16:26, Istvan Rath <rath@xxxxxxxxxx> wrote:

> OK I gave this another try today, with a very naive approach: the ComputedSet of ComputedSets.  
> 
> See http://git.eclipse.org/c/incquery/org.eclipse.incquery.git/tree/plugins/org.eclipse.incquery.viewers.runtime/src/org/eclipse/incquery/viewers/runtime/model/converters/FixedUnionSet.java?id=bf99cb52e800536edd1bc7627996a51528f5c72f
> 
> At first, I thought it to be working correctly, but then it turned out that it doesn't :-(
> (Extremely weird behavior, e.g. returns semi-correct results in a debugging session, but completely bogus (empty) results when run normally…)
> 
> Any ideas?
> 
> 
> --
> Istvan RATH, PhD
> Research fellow
> Budapest University of Technology and Economics
> Fault Tolerant Systems Research Group
> 
> 
> 
> On Monday, August 12, 2013 at 7:01 PM, Ujhelyi Zoltán wrote:
> 
>> Hi,
>>> HI all,
>>> 
>>>> for now, I have sent a message to the Platform forum, as maybe we have missed something (although I am more likely to think it is a bug).
>>> 
>>> Are there any news regarding this?
>> Neither in the forum nor in Bugzilla.
>>> 
>>>> I am not entirely sure about it, but maybe a more complex computedset implementation could also solve the issue, as we did not experience the same issues with only a single ComputedSet, but maybe I have missed some corner case. (The current implementation is logically cleaner, but maybe this is required).
>>> 
>>> 
>>> So, if I understand correctly, we should do a workaround by implementing a custom computedset that would emulate the unionset correctly?
>> Yes, I was thinking among this angle.
>> 
>> Zoli
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> 
> 
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