From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: updating list of substitutes
Date: Sun, 11 Oct 2015 20:39:32 +0200
Message-ID: <87wputz1uj.fsf@gnu.org>
References: <20150421064525.GA15795@thebird.nl> <87a8y1q49z.fsf@gnu.org>
	<20150421084028.GB16564@thebird.nl>
	<20150422114635.GA24566@thebird.nl> <20151011074654.GA8058@thebird.nl>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:53057)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1ZlLX0-0004tK-E3
	for guix-devel@gnu.org; Sun, 11 Oct 2015 14:39:39 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <ludo@gnu.org>) id 1ZlLWx-0000D3-9E
	for guix-devel@gnu.org; Sun, 11 Oct 2015 14:39:38 -0400
In-Reply-To: <20151011074654.GA8058@thebird.nl> (Pjotr Prins's message of
	"Sun, 11 Oct 2015 09:46:54 +0200")
List-Id: "Development of GNU Guix and the GNU System distribution."
	<guix-devel.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/guix-devel>
List-Post: <mailto:guix-devel@gnu.org>
List-Help: <mailto:guix-devel-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/guix-devel>,
	<mailto:guix-devel-request@gnu.org?subject=subscribe>
Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
Sender: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org
To: Pjotr Prins <pjotr.public12@thebird.nl>
Cc: guix-devel@gnu.org

Pjotr Prins <pjotr.public12@thebird.nl> skribis:

> The list of substitutes gets downloaded every time I do someting:
>
>   substitute: updating list of substitutes from 'http://hydra.gnu.org'...=
   4.6%
>
> and it is slow. Am I doing something wrong?

No!  Slowness is a longstanding issue of hydra.gnu.org, a poor little
VM.  I hope we can address it soon!  See
<https://lists.gnu.org/archive/html/guix-devel/2015-10/msg00172.html>.

> It appears to me that if the list does not change it should not be
> downloaded.

It=E2=80=99s not downloaded =E2=80=9Cevery time.=E2=80=9D

When building a package FOO, Guix looks for substitutes for FOO and its
prerequisites (those not already available locally.)  It maintains in
/var/guix/substitute/cache a cache of those lookups.

Positive caches (for substitutes that are available) expire after 36h;
negative caches (substitutes that are missing) expire after 3h.

See (guix scripts substitute) for details; look for =E2=80=98ttl=E2=80=99.

Ludo=E2=80=99.