Hi, Disclaimer: I'm not a member of the release team.
On Wed, 11 May 2011, Joachim Breitner wrote: > * Do you get it? (i.e., did I explain it well enough or are there > questions left) I think so. > * Do you think it can handle all current and anticipatable > requirements? (I’m not involved in release team work and might missed > some conditions.) You mention that the tool can't deal properly with Conflicts for ensuring installability. I wonder if there aren't more similar problems related to this requirement of keeping package installable. For instance, I wonder how you'd deal with alternative dependencies? I can imagine that you can find out solutions where each package can be individually installed but where both sets of dependencies are not co-installable (in particular if you solve some dependencies with different versions of the same binary package, and here Conflicts is not involved). I don't know how britney does it either, but I know that it tries to never lower the resulting installability count of testing. > * What do you think of the advantages and improvements that I point > out? To me it looks great but I have no experience with SAT solver and I wonder whether the sheer amount of predicates that it will have to handle will not result in something dog-slow. > * Is it worth the hassle? Given your description, it doesn't look like too complicated to implement. I think it's worth trying at least if we are not able to find conceptual problems (or if we can solve them). > And before going into the details, here the high-level goals that I want > to achieve with SAT-britney (stupid working title): All of the goals outlined are great IMO. > The system is three-layered. On the lowest level is a general purpose > MAX-SAT-solver. It takes as input a propositional formula in conjunctive > normal form with some variables, and a list of “desired” variables. It Presented that way, it corresponds exactly to what is needed to implement the rolling distributions described in http://lists.debian.org/debian-devel/2011/05/msg00275.html Maybe it can be a good testbed for the concept. > * a satisfying assignment which is maximal, i.e. there is no satisfying > assignment where a strict superset of desired variables is true. FWIW, Britney tries to migrate packages one by one, starting with the most important packages. It doesn't consider them all together. > dependencies etc. It also needs to get the age and buggyness data. The > result of the solver will be used to create the new set of packages for > testing (how does this work, by the way – does britney create a new > Packages file, does she create a .changes file processed by dak or even > another way?). Initially, it could just create a large hint that can be britney generates a Heidi file. It has this format: <package> <version> <architecture> <architecture> can also have the special value "source" for the source package. The heidi file is then fed to "dak control-suite". > So here is my heuristic to handle this: If a Conflicts or Breaks has an > upper version constraint, then add a corresponding clause. If not, > ignore it. > > This might lead to uninstallable packages in testing in corner cases > (imagine some package depending on both exim4 and postfix), but such a > case is clearly an RC bug that ought to be filed by someone and which > would be detected by a run of edos-distcheck on unstable already. I think it's more likely that such problems happen with conflicting dependencies further down in the dependency tree (i.e. not directly on the same package). > what would migrate. Assume this RC bug is fixed, what would change). But > maybe so slow that it still can be used for britney, but only with one > run per migration (how often do packages migrate per day?). I think it's twice a day currently. > PS: Please give honest feedback. I’d rather been told that this is > rubbish and not spend time on it than spending time on it and afterwards > noticing that it will not be used. Remember my feedback is one of an (interested) outsider, I have almost no experience feeding hints to britney. Cheers, -- Raphaël Hertzog ◈ Debian Developer Follow my Debian News ▶ http://RaphaelHertzog.com (English) ▶ http://RaphaelHertzog.fr (Français) -- To UNSUBSCRIBE, email to debian-release-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20110513201757.ga24...@rivendell.home.ouaza.com