[Unison-hackers] unison and inotify principle

[Benjamin Pierce]

Hi Patrice,

This capability is something that I've wanted to add for a long time,  
and I agree with the basics of your design.  But the devil is in the  
details.  For example, exactly what should be the protocol between  
Unison and the external "filesystem watcher" facility?  (I've only  
looked at the OSX one in any detail, but it is not completely  
straightforward to use; for example, it can occasionally get  
overwhelmed and miss updates, and Unison will need to recognize this  
case and react appropriately.  Etc.)  How should the user interface  
behave?  If Unison becomes a completely "background process," how can  
it notify users of conflicts?  And so on.  There are certainly ways  
of addressing all these issues, but it adds up to a nontrivial design  
exercise.

Best,

    - Benjamin


On Jun 1, 2008, at 7:20 PM, Patrice Espié wrote:
> Hi All,
>
> I'm new to this mailling list, so I hope not to do too many  
> mistakes ...
>
> I'm using unison from a few months now, and my configuration is a  
> bit wide in a geographic point of view : I'm synchronizing (in the  
> two ways) two computers (Linux) between France and China. In  
> France, there is one laptop connected which is locally  
> synchronised ; same situation in China.
> I get more than 40.000 files, and about 50 Go.
> I need to sync very often because of internal needs.
>
> I can tell you that a huge amount of time is necessary to do the  
> job ... hopefully unison work well.
>
> I wonder if unison could be improved in this way : using inotify  
> interface (wich exist on Windows too). In many cases, it could  
> improve the sync process. Perhaps even in all cases where "almost  
> real time" sync is required.
> I'm not sure that this kind of evolution is quite complex:
> unison should run in a repeat mode
> it could check for local modifications (using inotify or so) and  
> buffer file names to be sync'ed
> an important think : the remote unison should also run in a repeat  
> mode to check it's own side
> after a (parameterized) delay (say, one minute ?), the sync could  
> occurs on the buffered names
> Yes, the more complex problem should be : unison must work on both  
> sides (I don't know if it is the case for now in repeat mode).
> Do you think this is a possible evolution of unison ? I'm a (c+ 
> +,java) programmer, and now my job has changer (I'm not in IT part  
> from e few year) but, I can give some help if needed.
>
> Any suggestion ?
> Thanks
> -- 
> Patrice Espie
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