[buildd-tools-devel] Bug#403246: Bug#403246: #403246 not fixed as solution not used on buildds

[Roger Leigh]

On Mon, Feb 14, 2011 at 11:13:03PM +0100, Bernd Zeimetz wrote:
> 
> Unfortunately the solution for #403246 is not enough as the aptitude resolver
> is not used on buildds. Please implement a proper dependency solution in the
> traditional solver.

I'm sorry, but this is not a possible solution.

The traditional "internal" resolver will never have proper dependency
resolution WRT alternative build deps.  It's unmaintainable, fragile,
non-understandable perl.  That's the reason why the bug was not fixed
for over five years, and existed since forever.  No one has the time
or skills and understanding to add the needed functionality without
breaking it in some subtle way.  Any change could result in breakage
and cripple the buildds.

What we can do is push for the internal resolver to be replaced on the
buildds with the "apt" or "aptitude" resolvers.  The "apt" resolver is
probably a more predictable and reliable solution at this point.  The
aptitude resolver was completed in a few weeks, and the following apt
resolver in a couple of days.  That's why they are the future: they
are simple and delegate all the dependency resolving to the tools that
do the job properly.  They have had months of testing (aptitude for
nearly a year, apt a few months), and are doing an excellent job so
far.

The main sticking point to making this move is concrete testing of
the resolver behaviour for a large number of packages.  Comparison
of the difference in resolver behaviour for a large number of
packages is needed in order to determine if it is safe to switch.
A whole archive rebuild of squeeze would be even better.

While I'm not unwilling to accept patches to the internal resolver,
they would require the same amount of testing as the apt or
aptitude resolvers in order to ensure their correctness.  In
consequence, there's really no reason not to switch to a better
resolver.


Regards,
Roger

-- 
  .''`.  Roger Leigh
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