From: ludo@gnu.org (Ludovic Courtès)
To: Chris Marusich <cmmarusich@gmail.com>
Cc: guix-devel@gnu.org
Subject: Re: 'guix build' and garbage collection
Date: Mon, 03 Apr 2017 10:53:08 +0200 [thread overview]
Message-ID: <87shlprhxn.fsf@gnu.org> (raw)
In-Reply-To: <871stakn8v.fsf@gmail.com> (Chris Marusich's message of "Sun, 02 Apr 2017 23:40:16 -0700")
Hi Chris,
Chris Marusich <cmmarusich@gmail.com> skribis:
> My understanding is that Nix builds derivations in a temporary
> directory. My understanding is that eventually, we copy the results of
> the build into the final, content-addressed store path. Since we don't
> know the final, content-addressed store path until after we calculate
> the hash of the output, how do we prevent that final store path from
> being garbage collected while the build process is running? Do we use
> addTempRoot to add the final, content-addressed store path as a
> temporary root, too? I looked in the code but couldn't figure this out.
Store items are not content-addressed, except for fixed-output
derivations and things added with ‘add-to-store’ and
‘add-text-to-store’.
Leaving these two special cases aside, store file names are computed as
a function of the build inputs of a derivation. In Eelco Dolstra’s
thesis, both models are described: the “extensional model” (the one Nix
and Guix use) and the “intensional model” (content-addressability, which
has never been deployed, and which is challenging in many ways.)
HTH!
Ludo’.
next prev parent reply other threads:[~2017-04-03 8:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-02 1:06 'guix build' and garbage collection Chris Marusich
2017-04-02 9:30 ` Ludovic Courtès
2017-04-03 6:40 ` Chris Marusich
2017-04-03 8:53 ` Ludovic Courtès [this message]
2017-04-03 16:29 ` Chris Marusich
2017-04-04 12:13 ` Ludovic Courtès
2017-04-07 3:47 ` Chris Marusich
2017-04-07 19:53 ` Ludovic Courtès
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