From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sam Vilain Subject: Re: GTP/0.1 terminology 101: commit reels and references Date: Mon, 28 Jul 2008 19:02:50 +1200 Message-ID: <1217228570.6750.24.camel@maia.lan> References: <488D42B6.4030701@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: gittorrent@lists.utsl.gen.nz, git@vger.kernel.org, Jonas Fonseca To: Joshua Roys X-From: git-owner@vger.kernel.org Mon Jul 28 09:04:14 2008 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1KNMmC-0000xJ-HN for gcvg-git-2@gmane.org; Mon, 28 Jul 2008 09:04:12 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752134AbYG1HDM convert rfc822-to-quoted-printable (ORCPT ); Mon, 28 Jul 2008 03:03:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752127AbYG1HDL (ORCPT ); Mon, 28 Jul 2008 03:03:11 -0400 Received: from watts.utsl.gen.nz ([202.78.240.73]:49759 "EHLO mail.utsl.gen.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752032AbYG1HDK (ORCPT ); Mon, 28 Jul 2008 03:03:10 -0400 Received: by mail.utsl.gen.nz (Postfix, from userid 1004) id C574E1BC527; Mon, 28 Jul 2008 19:03:08 +1200 (NZST) X-Spam-Checker-Version: SpamAssassin 3.2.3 (2007-08-08) on mail.musashi.utsl.gen.nz X-Spam-Level: X-Spam-Status: No, score=-2.6 required=5.0 tests=AWL,BAYES_00,RDNS_DYNAMIC autolearn=no version=3.2.3 Received: from [192.168.69.233] (203-97-235-49.cable.telstraclear.net [203.97.235.49]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mail.utsl.gen.nz (Postfix) with ESMTP id 4725F1BC1C8; Mon, 28 Jul 2008 19:02:56 +1200 (NZST) In-Reply-To: <488D42B6.4030701@gmail.com> X-Mailer: Evolution 2.22.3.1 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Josh, I'm cc:'ing the main list with this one as well, as I think it falls into the scope of discussions of wider interest than the rfc- and implementation-specific discussions that (I envisaged would) happen on the gittorrent list. On Sun, 2008-07-27 at 23:53 -0400, Joshua Roys wrote: > Here's some terms, as best as I understand them. >=20 > The *Commit Reel* is a sequence of objects between two reference poin= ts,=20 > sorted in a deterministic fashion. The two reference points are=20 > *Reference* objects, or a signed tag containing a collection of git r= efs=20 > (similar to the output from `git show-ref`). Yes, that's right. We have the two slightly ambiguous terms, "refs", which mean the same thing as the rest of git, and "References", which are more like .git/packed-refs. Perhaps this is a good time to pick a better name. "Slice" would be an accurate term, though it's certainly tempting to pick another term from the tape taxonomy, such as "Splice"=C2= =B9 or "Mark"=C2=B2. > Commit reels can also, and generally do, include the objects requir= ed > for a specific commit. Yes. The only times where they wouldn't contain all the objects required for the commits within the reel, is when those objects happene= d to be contained by a previous reel. This is one of the design decisions which I think may be a mistake; a less expensive to calculate definition of a reel would be *all* objects between the starting and ending Reference objects. The current definition requires a hash index of objects in each reel, which must be consulted once for all objects when creating the reel index. > As an example, a commit reel could be the set of objects between the=20 > v2.6.25 and v2.6.26 tags of the Linux kernel. The only thing we woul= d=20 > need added to those tags is the list of heads (and tags) at the time = of=20 > the tagging. Correct. It represents all of the changes in a given repository over a period of time. > Those two structures form the basis for two *Peer Wire Protocol* (PWP= )=20 > messages, Reels and References. >=20 > Any questions, corrections, or rotten vegetables? No, I think that's all good so far... Cheers, Sam. =C2=B9 - see http://en.wikipedia.org/wiki/Reel-to-reel_audio_tape_recording#Descript= ion =C2=B2 - as used by the old unix "mt", see eg http://docs.sun.com/app/docs/doc/816-0210/6m6nb7mf3?a=3Dview