[pacman-dev] Idea: Merge -U and -S (half universal transaction)?

[Nagy Gabor]

> Hi!
> 
> After killing pmsyncpkg_t, there is not much difference between -S and
> -U transactions. The only difference is that trans->packages come from
> pkgcache (-S) or they are loaded from file (-U). And of course, with -S
> we have an extra step, we have to actually download the packages.
> 
> However, -U is much more "stupid" than -S atm.
> 
> Now the removes field is attached to pmpkg_t, so we could implement
> FS#3492 without pain, the conflict resolving part from sync.c can be
> reused without any modification*. Or if we allow "mixed" trans->packages
> list (pkg->origin can indicate that we have a file[-U] or repo[-S]
> package), even the implementaion of FS#5798 should be also
> straightforward. The only difference between PKG_FROM_CACHE and
> PKG_FROM_FILE packages, that PKG_FROM_CACHE needs to be downloaded.
> Then -U would become a sync transaction (internally), and add_commit
> would be a helper function only.
> 
> *: I started to work on the implementation of mixed target list, and I
> realised that the most annoying "difference" is that PKG_FROM_CACHE
> packages are not duplicated, so they are mustn't be freed (the new
> _alpm_pkg_free_trans should be used), but PKG_FROM_FILE packages must be
> freed. How much memory can we spare by not duplicating sync packages
> (not calling _alpm_pkg_dup when adding them to transaction target)? The
> whole base repo is <0.5 MB atm. Does this hack "worth"? With the old
> behaviour, implementing this idea (and so FS#3492 and FS#5798) would be
> really nice. With the new behaviour it would not. (And I don't really
> like the need for _alpm_pkg_free_trans neither.)
> 
> Bye

A proof-of-concept repo is here:
http://repo.or.cz/w/pacman-ng.git?a=shortlog;h=refs/heads/universal

This is in alpha state atm, it needs some testing, and probably I will
modify the "main patch" later (because of found bugs ;-).

Bye