Re: [gentoo-dev] Phase invariancy and exclusivity requirements

["Fernando J. Pereda" <ferdy@gentoo.org>]

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On Mon, Nov 12, 2007 at 01:26:46PM +0100, Marijn Schouten (hkBst) wrote:
> Ciaran McCreesh wrote:
> > On Fri, 9 Nov 2007 22:40:08 +0000
> > Ciaran McCreesh <ciaran.mccreesh@blueyonder.co.uk> wrote:
> >> Is the following set sufficient? Is the following set the least
> >> restrictive correct solution?
> > 
> > ... to explain the implications of these...
> > 
> > Say we have packages a, b and c, and none of them have any
> > dependencies. One valid solution to the build ordering is as follows:
> > 
> > * Install a
> > * Install b
> > * Install c
> > 
> > One of many solutions that is *not* valid is:
> > 
> > * Start doing a, b and c in parallel. Install them as they become
> > ready, doing only one merge at once.
> > 
> > Another that is not valid is:
> > 
> > * Start doing a, b and c in parallel, but don't merge them.
> > * Merge a.
> > * Merge b.
> > * Merge c.
> > 
> > One that is valid is:
> > 
> > * Build binary packages for a, b and c in parallel.
> > * Merge a's binary.
> > * Merge b's binary.
> > * Merge c's binary.
> 
> What exactly is the difference between this valid situation and the previous
> invalid one?

The state of the environment when pkg_setup is run. In the first
situation you can't trust it (it is racy and unpredictable among other
things). In the second one, you can.

That's the first thing that I can think of, there might be others.

- ferdy

-- 
Fernando J. Pereda Garcimartín
20BB BDC3 761A 4781 E6ED  ED0B 0A48 5B0C 60BD 28D4

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