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From Andrey Razumovsky <razumovsky.and...@gmail.com>
Subject Re: Nested ROP contexts and relationships
Date Tue, 24 Nov 2009 10:42:21 GMT
Okay, I've run into same situation when trying to allow PO subclasses in DC,
but now I don't see context setting reverse arcs at user's change. The
problem is in difference between CC and DC property change processing. Sorry
about being so detailed around the code, but I don't see how i can explain
it otherwise.

So, what DC does when setting an arc:
1. Sets the value, which invokes context.propertyChanged()
2. GraphAction just registers property change, nothing else
3. Updates reverse arc
4. GraphAction just registers property change, nothing else

What CC does when setting an arc:
1. Sets the value, which invokes context.propertyChanged()
2. GraphAction just registers property change and...
3. ...updates reverse arc
4. with those ugly threadlocals in CCGraghAction ensures there are no
infinite cycles

I am sure the first approach is much better. I suggest that we:
1. Moving DO.addToManyTarget, etc to DataObjectUtils, taking Persistent
instead of DO as an argument (actually I already did it locally)
2. Make PersistentObjectHolder and other classes like that invoke
context.propertChanged() should invoke those methods instead

Ideally this will allow to:
1. Leave only OCGraphAction and get rid of DCGraphAction and CCGraphAction
with its ugly threadLocal
2. Get rid of PropertyChangeProcessingStrategy
3. Maybe, make client and server persistent holders more similiar

2009/4/5 Andrus Adamchik <andrus@objectstyle.org>

> I committed the fix per CAY-1204. I encourage everybody using nested
> contexts in ROP to test it and report any problems.
>
> The essence of the fix was to set a thread-local state for whatever complex
> sequence of events is going on when a relationship is changed, determining
> how the context should handle graph changes. Per new non-public
> PropertyChangeProcessingStrategy enum, it is either of IGNORE, RECORD,
> RECORD_AND_PROCESS_REVERSE_ARCS (default). This allows to handle 3 common
> scenarios:
>
> "update from the DataChannel"
> "update from the child context"
> "update by the user"
>
> While this particular commit diverges client and server contexts further
> from each other, contrary to our stated goal of merging them together, I
> think the approach has a potential to become *the* way to do things
> throughout the stack. Ideally this will eliminate the method pairs of
> "doSomthing / doSomethingDirectly" from the API, which was a cornerstone of
> the graph management since Cayenne 1.0.
>
> Andrus
>
>
>
> On Apr 5, 2009, at 11:31 AM, Andrus Adamchik wrote:
>
>  Cool. I got a further along in my investigation. I will put the details in
>> a Jira and work on fixing it.
>>
>> Andrus
>>
>>
>> On Apr 4, 2009, at 8:31 AM, Andrey Razumovsky wrote:
>>
>>  Hi Andrus,
>>>
>>> I'm afraid I don't remember if it was done intentionally. I only know
>>> that
>>> the code is different from normal contexts' diff processing (that's why I
>>> feel a large refactoring is needed). Feel free to change the code, of
>>> course. Alternatively, if you open a JIRA and post you JUnit there, I'll
>>> have a look.
>>>
>>> Andrey
>>>
>>> 2009/4/3 Andrus Adamchik <andrus@objectstyle.org>
>>>
>>>  I am in the middle of debugging a problem with nested ROP contexts
>>>> losing
>>>> arc changes when committing to a parent context. Since I was not
>>>> involved in
>>>> the ROP nested context work, I figured I'd post my thoughts here before
>>>> I
>>>> start changing the code.
>>>>
>>>> I noticed that per CAY-1119, there is a special subclass of
>>>> ChildDiffLoader
>>>> called CayenneContextChildDiffLoader that calls 'propertyChanged' on the
>>>> parent context after syncing a simple property change. It seems like we
>>>> need
>>>> to do the same for relationships as well, to record arc changes in the
>>>> parent diff list.
>>>>
>>>> Andrey, do you have any comments on that? I wonder if it was omitted
>>>> intentionally. I will open a Jira (I think we don't have one for this),
>>>> and
>>>> add some tests with various relationships, but before I dig any deeper
>>>> figured I'll need a sanity check.
>>>>
>>>> Thanks,
>>>> Andrus
>>>>
>>>>
>>
>>
>


-- 
Andrey

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