[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