Re: [gentoo-dev] mtime preservation

[Brian Harring <ferringb@gmail.com>]

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On Wed, Nov 25, 2009 at 04:49:17PM -0800, Zac Medico wrote:
> Ciaran McCreesh wrote:
> > On Wed, 25 Nov 2009 23:59:45 +0100
> > Ulrich Mueller <ulm@gentoo.org> wrote:
> >> Real examples would be issues like bugs 83877 [1] or 263387 [2].
> >> Nothing that could be easily dismissed or worked around. Both issues
> >> are fixed with Portage since a long time.
> > 
> > Yes, those are examples of packages relying upon something that is
> > undefined behaviour, and that behaves differently depending upon the
> > Portage version you use.
> > 
> >> I don't know of any example where non-preservation of nanosecond
> >> timestamps would cause problems.
> > 
> > Not non-preservation. Partial and inconsistent corruption.
> 
> Wouldn't "loss of precision" be a more accurate description? Of the
> known packages which require timestamp preservation, do any of them
> use sub-second precision in their timestamp comparisons?

This discussion in generall is daft.  No package can rely on 
nanonsecond resolution for installation because the most common FS out 
there (ext3) does *second* level resolution only.  As such, I can 
pretty much gurantee there is *zero* packages out there that require 
nanosecond resolution for installation.

It's an academic discussion, and pointless.  We don't mandate the 
filesystems PMS implementations are run on- as such we cannot make a 
gurantee to ebuilds that nanosecond resolution is available.  It's 
daft to encode in the spec NS resolution when it's essentially 
impossible to gurantee it- I'm honestly not sure why we're having this 
discussion beyond the "python sucks" angle.

~brian

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