From: Glenn Smith <glenn.ruby@...>
Date: 2006-11-08T06:48:56+09:00
Subject: Re: The way to restrict a ruby program to just once occurrence on a windows box?

------=_Part_11637_4275398.1162936132053
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

I thought that, the problem being what if the other ruby program crashed
without removing the file?  I guessed the file would remain.  I suppose the
check against whether or not the existing pid was a ruby program would
mostly remove this problem, but it seemed imperfect.  Then again, who's to
say my solution is...!




On 07/11/06, James Adam <james.adam@gmail.com> wrote:
>
> You could also take a leaf out of unix tradition and simply write a
> small file containing the current process ID into a temporary
> directory. When your program starts, it checks for this file, and if a
> corresponding running Ruby process is found then it can exit (perhaps
> with a log message or something). If not, then the starting instance
> would seem to be the only one.
>
> - james
>
> On 11/7/06, Murray Steele <murray.steele@gmail.com> wrote:
> > Is it some kind of GUI app?  I don't know what toolkit you are using,
> but I
> > do remember from my days as a wxPython jockey that the
> wxWidgets  toolkit
> > came with a api for doing exactly this: wx.SingleInstanceChecker.  I
> imagine
> > that there's a win32 API that is used to do it, and that should be
> available
> > to most other toolkits you might be using (e.g. I'm sure Java Swing has
> > something similar).
> >
> > I imagine that such an API should be available even if it isn't a GUI
> app
> > (perhaps through Win32API) and I imagine that using this would be
> slightly
> > cleaner than doing your own version.
> >
> > Admittedly this isn't much use as all I'm saying is, "yeah, there is a
> way
> > to do this" without providing much details...
> >
> > Sorry
> >
> > Muz
> >
> > On 07/11/06, Glenn Smith <glenn.ruby@gmail.com> wrote:
> > >
> > > Never mind, solved it (unless anybody knows a better way).
> > >
> > > It's a windows app, so:
> > >
> > > require 'Win32API'
> > >
> > > SW_HIDE = 0
> > > WS_OVERLAPPED = 0
> > > WS_DISABLED = 0x08000000
> > > WS_MINIMIZED = 0x20000000
> > >
> > >   def already_running
> > >     #
> > >     # Not sure of any other way to do this.
> > >     # Create a window with the title "i4FileProcessorHiddenWindow".
> > > When we come to run this program again,
> > >     # if there is already a window called
> > > "i4FileProcessorHiddenWindow" then abort that instance.
> > >     # In this way, only one instance of the script should run.
> > >     #
> > >
> > >     findwindow = Win32API.new('user32','FindWindow', ['p','p'], 'L')
> > >     return true if findwindow.call("STATIC",
> > > "i4FileProcessorHiddenWindow") != 0
> > >
> > >     createwindow = Win32API.new('user32', 'CreateWindowEx', ['l', 'p',
> > > 'p', 'l', 'i', 'i', 'i', 'i', 'l', 'l', 'l', 'P'], 'l')
> > >     dwStyle = (WS_DISABLED | WS_MINIMIZED)
> > >     cw = createwindow.call( WS_OVERLAPPED, 'STATIC',
> > > 'i4FileProcessorHiddenWindow', dwStyle, 0, 0, 0, 0, 0, 0, 0, 0 )
> > >     show = Win32API.new('user32',  'ShowWindow', ['L', 'L'], 'L')
> > >     show.call(cw, SW_HIDE)
> > >
> > >     return false
> > >   end
> > >
> > >
> > > On 07/11/06, Glenn Smith <glenn.ruby@gmail.com> wrote:
> > > > I'm rewriting a vb app to ruby (in about a quarter of the
> code!).  If I
> > > ran
> > > > the same ruby program twice in parallel, the second instance should
> > > exit.
> > > >
> > > > In VB6 I could do this:
> > > >
> > > >              If App.PrevInstance Then Exit Sub
> > > >
> > > >
> > > > Any ideas how this is done in ruby?
> > > >
> > > >
> > > > Ta muchly
> > > >
> > > >
> > >
> > >
> > > --
> > >
> > > All the best
> > > Glenn
> > > Aylesbury, UK
> > >
> > >
> >
> >
>
>
> --
> * J *
>   ~
>
>


-- 

All the best
Glenn
Aylesbury, UK

------=_Part_11637_4275398.1162936132053--