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From: =?utf-8?Q?Cl=C3=A9ment?= Lassieur <clement@lassieur.org>
Subject: Re: Estimating build time
Date: Sat, 13 Oct 2018 01:13:17 +0200
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To: Ludovic =?utf-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: guix-devel <guix-devel@gnu.org>

Ludovic Court=C3=A8s <ludo@gnu.org> writes:

> In a similar vein, the attached module provides code to estimate package
> build time based on locally-available build logs.  It can be used to
> show hints like this:

[...]

> The obvious downside is that it works by first retrieving the names of
> the files under /var/log/guix/drvs, and then opening, decompressing, and
> parsing the candidate log files.  That typically takes a few seconds on
> a recent SSD laptop, but clearly we don=E2=80=99t want to do that every t=
ime.
> We could maintain a cache, but even then, it might still be too
> expensive.
>
> Perhaps we should keep build times in the database somehow; the daemon
> can keep it up-to-date.
>
> Thoughts?
>
> There=E2=80=99s the obvious downside that both approaches rely on having
> previously built the package, but I think that=E2=80=99s a necessary limi=
tation,
> unless we are to resort to external services (which could hardly provide
> estimates that make sense for the user=E2=80=99s machine anyway.)

I think it's an excellent idea!  I agree that the downside is necessary,
and yes, keeping the build times in the database sounds good!

Cl=C3=A9ment