[graphiti-dev] Improvement request: execute a feature in an asynchronous

[Antoine Lorence <Antoine.Lorence@xxxxxxxxxxxxxx>]

Hi,

At some point our projects have Graphiti custom features which can take 
some time to finish (depending on the diagram size). In the basic 
CustomFeature context, execution of such features freezes Eclipse GUI. 
We wanted to:
 1. Run it asynchronously
 2. Be able to provide progress information to user

To achieve that, we tried to execute the feature in a Job instance. But 
to be able to perform updates on models, we had to define and execute a 
RecordingCommand in the Job. Indeed, the CustomFeature only schedule it 
and ends before this Job has really finished.

Please find the abstract class we wrote to get rid of these issues on 
http://pastebin.com/XBjmy2sP

Information about this feature:
 - it defines a new execute(ICustomContext, IProgressMonitor) abstract 
method
 - it set other execute() methods to final, to prevent users from 
overriding it
 - hasDoneChange() always returns false, since the feature itself does 
nothing but launching the Job. This ensures only 1 command will be added 
on the CommandStack after the full execution
 - getDiagramBehavior().getDiagramContainer().updateDirtyState(); is 
executed just after the inner command, to update diagram state only when 
it has been executed

The example code I provides is probably redundant  (run a command in a 
job in a command) but this is maybe the best I can do from a user point 
of view. I don't have enough skills to hack Graphiti source by myself, 
so I give you the code. Maybe it will be useful for users to be able to 
define some CustomFeature to be asynchronous and to use a 
IProgressMonitor. At least, having this by default in Graphiti SDL could 
be helpful for us ;)

Best regards,

Antoine Lorence

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