Hello, Jeff Johnson <[email protected]> writes:
> On Jul 10, 2010, at 6:58 PM, Ludovic Courtès wrote: > >> >>> The killer design issue is scripting with --rollback. Its extremely >>> hard to permit general scripting side-effects whose effects can ALWAYS >>> be reversed by --rollback. >> >> You’ve already partly answered. :-) >> >> Are you saying that RPM-based distros already allow ‘--rollback’? Or >> that the RPM package manager has a ‘--rollback’ option that happens to >> work *if* packages are side-effect-free, etc.? Are upgrades atomic? [...] > Its --rollback v2 that is sending SMS in Brazil. The major change there was > to add doubly linked upgrade chains. Each upgraded package includes > backward links to the package(s) that it erased, each erased package > (re-rolled into a *.rpm with the content that was present at time of erasure) > includes forward links to the package(s) that caused erasure. OK. [...] > The latest version (presented briefly @FOSDEM 2010, you really > can't say much in 45 minutes about --rollback) is > Transactionally Protected Package Management > aka TPPM or "RPM ACID". In a nut-shell, the side effects of > package management are broken into 2 categories > 1) databased ACID (yes the traditional technical term, fully > implemented, level 2 isolation) > 2) syscall ACID (i.e the set of operations to install package payloads > on file systems like write(2) and mkdir(2) etc. Prototyped using the > abstract log mechanism within Berkeley DB extended in simple ways so > that, say, rmdir(2) reverses mkdir(2). Content goes into the log > before it goes onto the file system which is a bit bloaty but > eaxctly what is entailed with --rollback insturmentation). > 3) scriptlet ACID this is the piece that Mancoosi WP3 is focussed > on, modeling and simulating common debhelper-like scriptlet operations > for transactional logging. Also presented @FOSDEM 2010 and actively > being > worked on). OK, I wasn’t aware of this work. [...] > But the killer design flaw for --rollback is _STILL_ general scriptlet > side-effects, > which are highly non-trivial to reliably invert generally. Yes, of course. So, at this time, which RPM-based distro actually claims to support rollback? And which distro(s) does Mancoosi’s WP3 target? Thanks, Ludo’. _______________________________________________ nix-dev mailing list [email protected] https://mail.cs.uu.nl/mailman/listinfo/nix-dev
