From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Marusich Subject: Re: store reference detection (was Re: JARs and reference scanning) Date: Tue, 23 May 2017 00:29:48 -0700 Message-ID: <87vaosni8j.fsf@gmail.com> References: <87a876pwaq.fsf@gmail.com> <8760hr7mwl.fsf@gmail.com> <20170426.135333.1620868924745053745.post@thomasdanckaert.be> <87fugu6jzg.fsf@gnu.org> <59022E86.1020709@crazy-compilers.com> <8760hjig4r.fsf@gnu.org> <590F179B.4060306@crazy-compilers.com> <87shkafvhu.fsf@netris.org> <87o9uyv665.fsf@gmail.com> <87inl6ht4p.fsf@netris.org> <591612F8.40408@crazy-compilers.com> <871srthhg7.fsf@netris.org> <8c8c1039-ad07-5b7a-5100-ad59bcba137c@crazy-compilers.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:43506) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dD4GR-0007KJ-LK for guix-devel@gnu.org; Tue, 23 May 2017 03:29:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dD4GQ-0001KD-Hb for guix-devel@gnu.org; Tue, 23 May 2017 03:29:55 -0400 Received: from mail-pf0-x22d.google.com ([2607:f8b0:400e:c00::22d]:33983) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1dD4GQ-0001Jw-C3 for guix-devel@gnu.org; Tue, 23 May 2017 03:29:54 -0400 Received: by mail-pf0-x22d.google.com with SMTP id 9so106108425pfj.1 for ; Tue, 23 May 2017 00:29:54 -0700 (PDT) In-Reply-To: <8c8c1039-ad07-5b7a-5100-ad59bcba137c@crazy-compilers.com> (Hartmut Goebel's message of "Sat, 13 May 2017 09:15:31 +0200") List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: Hartmut Goebel Cc: guix-devel@gnu.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hartmut Goebel writes: > Am 12.05.2017 um 23:51 schrieb Mark H Weaver: >> What's the motivation for this proposal, if not to allow the scanner to >> see references that would otherwise be obfuscated? > The motivation is to have references at all. See > for > an example of a package having propagated inputs which are not > recognized as references by the gc. Hartmut, the question of whether or not a "package" (actually, the store paths created by building the package) is eligible for garbage collection has little to do with whether or not the package is a propagated input. With that in mind, the example you provided does not seem to be a problem. If a package A happens to be a propagated input of another package B, and if package B happens to be installed in some profile (e.g., via 'guix package -i B'), then package A is also installed in the same profile. Therefore, package A is not eligible for garbage collection (i.e., it is "live") because every profile is a GC root. However, if one has just built package B with 'guix build B' without installing it into any profile, then package A hasn't been installed, either. In this case, package A is eligible for garbage collection because no GC root refers to it directly or transitively [1]. To summarize: When package A is a propagated input of package B, it is possible for package A to be live, and it is possible for package A not to be live. By itself, the fact that package A is a propagated input tells us nothing about whether or not package A should be eligible for garbage collection. And it is not the case that package A should be live simply because package B has been built. [1] This assumes, of course, that package A wasn't live to begin with. =2D-=20 Chris --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEy/WXVcvn5+/vGD+x3UCaFdgiRp0FAlkj5OwACgkQ3UCaFdgi Rp37ZxAAyNu4bmY5cyjC5kEDwVCwCYPWXlg9bVeRyqBocSYT5Sxzr0i3mlmr584w BeWmZ18ZYFTRPx2t4zaYZsMhbNNK4/6RjhHUR8c8QWq0g9aYTacTPlYayTTXGXXF 6pHqRvh6xEYzQxPVX17tbwJJK/mf8eAeJtfIZXUpBvF7xmF21p4QTUPSzQvl0S4h J8M0TP6Am8mXUpIt/7MNABdiI6Q85BPQPCetFQ0ORyNN6W92NdaCi6cw5iD3I4ru 5hk5mXs6tk6xrJcfdsCkHAH1bGy3W0aMH0n+Jg46SHZwGFnYiFZiJcehs2q9YtSg U5KG0hEi5eE2i8klqK/85oCuSMCKChOUYcyKWIbIsaK8M6HyPZaFtpApBG1xh0Oq 9N6Cz9asqj2gsBDF2gcI2bn4qjDsM65e1gK/fmaPoaS0AHuWrZPrpa6XgimGUEBL x8c25iJ7Ld/Ub4ILVCXkTXg/Ve4q+IhnClHbBiBp9s6qvYU8JzsNRFgZiLYuvscv ARP5lqM2EshpCrCKRDWEJpzWKB0czBBPRKAcvihxlH8ix0jaa/4y3LFDlo7FQq4g RrOHOwqxNXULZPsjdJW1dD7qyyH0cIMyZRJwS2o1i8NPeAefQrUBvrM/ynTv9ItN AYopDcGROHCfRzh+AUBqMr19rBgH6vOS2S4p+Dt3R6lOKu0iz2A= =7tTG -----END PGP SIGNATURE----- --=-=-=--