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From Andrus Adamchik <and...@objectstyle.org>
Subject Re: Peer Context Synchronization
Date Wed, 24 Apr 2013 18:51:11 GMT
Yes, performance implications are pretty serious. To a point that in my webapps I am completely
turning off cross-context syncing via a DI property, as even async process is O(N) as far
as resource consumption, and in an app with a large number of active contexts things are going
to get bad pretty quickly.

There are a few ways you can deal with it:

1. You can listen for DataChannel.GRAPH_CHANGED_SUBJECT subject for a given context (or all
contexts at once, if that makes sense in your app) :

// here is how you access EventManager to register listeners:
EventManager em = runtime.getChannel().getEventManager();

// register listener
em.addListener(listener, "xyzMethod", GraphEvent.class, DataChannel.GRAPH_CHANGED_SUBJECT,
myContext);

2. You can override ObjectStoreFactory in DI to implement synchronous events (isn't it cool
to have a DI-based framework :)) 

// implement the factory 
public class MyObjectStoreFactory implements ObjectStoreFactory {
 // check DefaultObjectStoreFactory for details, create a sublcass of ObjectStore, 
 // overriding 'setDataRowCache'
}

// bind it in a custom module:
binder.bind(ObjectStoreFactory.class).toIn(MyObjectStoreFactory.class);

Andrus


On Apr 24, 2013, at 2:34 PM, Lon Varscsak <lon.varscsak@gmail.com> wrote:
> Is there any way to control that behavior?  Like is there a way for my code
> to wait for that to complete?  I understand the performance considerations,
> but it's a fairly common pattern for me (from the WO/EOF space) to expect
> this to be done before any more of my code gets executed.
> 
> Thanks,
> 
> Lon
> 
> 
> On Wed, Apr 24, 2013 at 11:26 AM, Andrus Adamchik <andrus@objectstyle.org>wrote:
> 
>> Hi Lon,
>> 
>> Context update is immediate, but asynchronous, so this likely explains the
>> observed behavior.
>> 
>> Andrus
>> 
>> On Apr 24, 2013, at 2:14 PM, Lon Varscsak <lon.varscsak@gmail.com> wrote:
>>> Hey all, I'm having some trouble with something that I _think_ should
>> work.
>>> :)
>>> 
>>> It's a very common pattern for me to create a new context, do work, save,
>>> and expect those changes to make it back into peer contexts that share
>>> object ids.
>>> 
>>> However, there are times where this isn't happening…and it's
>> intermittent.
>>> 
>>> My model in this situation is pretty simple, there's EntityA with a
>> to-many
>>> to EntityB.  In a peer context, I'm creating an EntityB and adding it to
>>> the relationship of EntityA (a local instance), and generally speaking,
>> in
>>> my other peer context the matching instance of EntityA is updated and has
>>> the proper EntityB in it's relationship (after commitChanges).
>>> 
>>> However, occasionally…maybe 1 in 10, the peer context doesn't get
>>> immediately updated (although will, I believe, at a later time).
>>> 
>>> So the question is, does commitChanges immediately/synchronously push all
>>> changes into peer contexts?  Or does it happen in another way?
>>> 
>>> Thanks for any insight.
>>> 
>>> -Lon
>> 
>> 


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