[Qt-interest] [OT] How to create single instance app?

[Konrad Rosenbaum]

On Friday 07 May 2010, Oliver.Knoll at comit.ch wrote:
> Konrad Rosenbaum wrote on Friday, May 07, 2010 4:24 PM:
> > ...
> > Single instance per what?
> > ...
> > * per universe?
> >
> > Short answer: put a lock file in an appropriate place
>
> That would then be Alpha Centauri, I guess. Unfortunatelly it then takes
> some time to create and query the state of the lock file, with a "ping
> time" of 4.35 years it takes roughly 9 years for your app to start (or it
> might then even decide to quit ;) But it would be guaranteed to be unique
> - at least in the Alpha Centauri system and friends :)

Well, in that case I would recommend to use TCP(*) communication. With an 
appropriately tuned tranceiver you can easily reach acceptable ping times 
in the range of minus a few hundred milliseconds.

(*) TCP = tachion carrier pulses

Besides, Alpha Centauri is hardly an ideal place for a file server - there 
is hardly any maintenance personnel around when you need it out there. And 
calculating a good orbit that is always visible from at least the more hip 
parts of the universe can be quite tricky in a triple star system (never 
forget the effects of proxima).

If you insist on a triple star system near earth I'd recommend 40 Eridani. 
Very competent maintenance technicians are available for a fair price and 
they might even help you do the orbit calculations if you ask logically.


	SCNR,
	Konrad
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