Re: auto-gpbs-restart (was: Re: Ivar layout change)

[Richard Frith-Macdonald]

On 25 Mar 2007, at 22:40, Alex Perez wrote:

> Fred Kiefer wrote:
> > I just moved a bunch of ivars from NSResponder to NSView. They never
> > should have been there in the first place, but now this is a big  
> > change,
> > as it requires that you recompile all of GNUstep and all your
> > applications. And don't forget to kill your gpbs daemon, I did :-)
>
> As this seems to be a *constant* issue which recurs consistently on  
> the mailing list, I'd like to propose an idea, and see if anyone  
> has any legitimate opposition to its implementation...
>
> If possible, why not make GPBS restart if its version/checksum/ 
> something has changed. This seems the logical user-friendly thing  
> to do. Obviously, the mechanism by which it would be checked would  
> need to be fast, but perhaps this can be done.
>
> This idea isn't fully-fleshed out, it's just an off-the cuff one,  
> so please feel free to tear it to shreds :)

There is already a partial solution to this one in trunk ... in that,  
if gpbs (or gdnc) is started automatically then it should shut  
itsself down automatically when there are no more processes using  
it.  So if you close down all the apps when you update software, then  
gpbs should automatically close down too.

Unfortunately this is not completely reliable ... on windows gpbs  
can't currently tell when nothing is using it any more (unless using  
a tcp/ip connection).  That's because windows doesn't have unix- 
domain sockets, and the windows alternative used for local/private  
connections does not (as far as I've been able to find) provide a  
mechanism to tell when the remote end has exited.  Perhaps some sort  
of keepalive could be implemented?

Now, the reason I mention that is that it would presumably be a bad  
idea to restart automatically if some processes are using gpbs or  
gdnc  ... you would want to wait for connected processes to close  
down and then restart.  Monitoring the binary top see if it changes  
ought to be simple, but deciding when it's safe to restart might be  
trickier.