Bug#829751: pbuilder: Patch to make pbuilder show current package version while installing the build-deps.

[Mattia Rizzolo]

On Wed, Jul 06, 2016 at 02:42:18AM +0800, Andrew Lee wrote:
> Dear Maintainer,

Hi Andrew,

sorry for taking so long to reply.

> Here is a patch that makes pbuilder show current package version while
> installing the build-deps.
> 
> Please review and consider applying to pbuilder.

The patch itself makes sense, both how its done and what it tries to
accomplish.

There is one thing that I'm concerned about: apt-cache is very slow
whenever the cache is invalidated (and to me happens pretty often¹), to
the point that to gather such information may take even several seconds
per package, quickly ending up being unacceptable.

mattia at chase ~ % time apt-cache show hello | grep Version | head -n 1 | awk '{print $2}'
2.10-1
apt-cache show hello  1.84s user 0.05s system 99% cpu 1.884 total
grep --color=auto Version  0.00s user 0.00s system 0% cpu 1.883 total
head -n 1  0.00s user 0.00s system 0% cpu 1.882 total
awk '{print $2}'  0.00s user 0.00s system 0% cpu 1.882 total

So, verifying which version of hello is available takes nearly 2 seconds
here.
If I run `apt update` to rebuild the cache and make it valid again, it
takes 0.2 seconds, arguably still too much for me.


I'd prefer to see something faster, but I'm wouldn't know what to
suggest.

-- 
regards,
                        Mattia Rizzolo

GPG Key: 66AE 2B4A FCCF 3F52 DA18  4D18 4B04 3FCD B944 4540      .''`.
more about me:  https://mapreri.org                             : :'  :
Launchpad user: https://launchpad.net/~mapreri                  `. `'`
Debian QA page: https://qa.debian.org/developer.php?login=mattia  `-
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