Re: does aptitude really need to lock the status database when downloading?

[Peter Samuelson <peter@p12n.org>]

[Simon Chopin]
> But I believe what Stanislas mean is to unpack while downloading the
> rest of the packages.  I often wondered why it wasn't the case, but
> I've assumed so far that there was probably a reason I just could not
> think of :)

I think it is because, in the general case, it is not at all obvious
that applying _part_ of the scheduled upgrade will leave the system in
a working state, and a state the user would approve of.

For example: say you are upgrading package A, but the new version of A
conflicts with package B1, so you are also replacing B1 with B2.  So,
what apt will do:

   Download A
   Download B2
   Remove B1
   Upgrade A
   Install B2

Now assume "Download A" has finished, but "Download B2" is still in
progress.  You could upgrade A, which involves first removing B1
because of the conflict.

Now assume B2 fails to download.  You are left with a system where
neither B1 nor B2 are installed.  Is that what the user would want?

-- 
Peter Samuelson | org-tld!p12n!peter | http://p12n.org/