Re: ‘xdg-mime-database’ profile hook is slow

[zimoun]

Dear,

On Wed, 28 Oct 2020 at 21:48, Luis Felipe <luis.felipe.la@protonmail.com> wrote:

>> #+BEGIN_SRC sh :results output :exports both
>> time guix build --check $(guix gc -R $(guix gc --derivers $(readlink -f 
>> ~/.guix-profile)) |grep xdg-mime-database.drv)
>> #+END_SRC
>
> I haven't run this command because I don't know what it does (how will
> it affect my profile?), but if you think the results from this command
> would be more useful than what I posted to issue #44053, please let me
> know and I'll run it.

The command will not affect your profile.

1. Get the real file of all the symlinks forest

        $ readlink -f ~/.guix-profile
        /gnu/store/z32aid8bjbz7ylwbjfh5x6lbg2g7fiv0-profile

2. Get the derivation that generated this file

        $ guix gc --derivers /gnu/store/z32aid8bjbz7ylwbjfh5x6lbg2g7fiv0-profile
        /gnu/store/wnjk3zsrw6s55hqj0qbbwhx635i5s6n0-profile.drv

3. Get all that it is used by the previous derivation

        $ guix gc -R /gnu/store/wnjk3zsrw6s55hqj0qbbwhx635i5s6n0-profile.drv
        /gnu/store/z41v36kbd8xa1l2ga2lsaa287yyk7wdb-nasm-2.14.02-guile-builder
        /gnu/store/ich43zbavdqphzshfr5q5d00arissxa7-nasm-2.14.02.tar.xz.drv
        /gnu/store/0rifkf1snq6fjz7l4dpg5j3i2wgj7gxp-nasm-2.14.02.drv

        [...] a **lot** of items

        /gnu/store/3x2kak8abb6z2klch72kfff2qxzv00pj-libpng-1.6.37
        /gnu/store/3qrm6z400hh66x1kxd4zrbnkkylwcvg8-ca-certificate-bundle.drv
        /gnu/store/2jlwri28aycsayql85rfphrks721ny1k-xdg-mime-database.drv
        /gnu/store/1i57pf9q71sm7gpqkh15h677794y61dz-profile-builder
        /gnu/store/0llx3y194278l5ksr4xh9kc64mh8nn8d-nss-certs-3.52.1
        /gnu/store/wnjk3zsrw6s55hqj0qbbwhx635i5s6n0-profile.drv

4. Get only the one you are interested in

        $ guix gc -R /gnu/store/wnjk3zsrw6s55hqj0qbbwhx635i5s6n0-profile.drv | 
grep xdg-mime-database.drv
        /gnu/store/2jlwri28aycsayql85rfphrks721ny1k-xdg-mime-database.drv

5. Build again this derivation (--check)

        $ time guix build --check 
/gnu/store/2jlwri28aycsayql85rfphrks721ny1k-xdg-mime-database.drv
        The following profile hook will be built:
           /gnu/store/2jlwri28aycsayql85rfphrks721ny1k-xdg-mime-database.drv
        building XDG MIME database...
        successfully built 
/gnu/store/2jlwri28aycsayql85rfphrks721ny1k-xdg-mime-database.drv
        /gnu/store/hrcj1h0hl9f6hm1akh682zj1mhpwbx4c-xdg-mime-database

        real    0m3.493s
        user    0m0.435s
        sys     0m0.066s

Does it make sense?

Well from my POV, the information is #44053 is enough for now. :-)


All the best,
simon