From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Pitre Subject: Re: [PATCH 6/6 (v4)] support for path name caching in rev-cache Date: Thu, 20 Aug 2009 20:05:46 -0400 (EDT) Message-ID: References: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Transfer-Encoding: 7BIT Cc: Junio C Hamano , Johannes Schindelin , Sam Vilain , Michael J Gruber , Jeff King , "Shawn O. Pearce" , Andreas Ericsson , Christian Couder , "git@vger.kernel.org" To: Nick Edelen X-From: git-owner@vger.kernel.org Fri Aug 21 02:06:21 2009 Return-path: Envelope-to: gcvg-git-2@lo.gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1MeHe5-0000og-6K for gcvg-git-2@lo.gmane.org; Fri, 21 Aug 2009 02:06:17 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932149AbZHUAGH (ORCPT ); Thu, 20 Aug 2009 20:06:07 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754843AbZHUAGH (ORCPT ); Thu, 20 Aug 2009 20:06:07 -0400 Received: from relais.videotron.ca ([24.201.245.36]:28711 "EHLO relais.videotron.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754117AbZHUAGG (ORCPT ); Thu, 20 Aug 2009 20:06:06 -0400 Received: from xanadu.home ([66.130.28.92]) by VL-MO-MR003.ip.videotron.ca (Sun Java(tm) System Messaging Server 6.3-4.01 (built Aug 3 2007; 32bit)) with ESMTP id <0KOP002RZ9LMK2C0@VL-MO-MR003.ip.videotron.ca> for git@vger.kernel.org; Thu, 20 Aug 2009 20:05:47 -0400 (EDT) X-X-Sender: nico@xanadu.home In-reply-to: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Fri, 21 Aug 2009, Nick Edelen wrote: > Ok we actually have a small problem, semi-related to the object > listing. By default rev-list will list everything not seen in each > tree, whereas rev-cache will only list object introduced in a given > commit. This becomes problematic if you have two different files with > the same content in the same tree: rev-cache will show the name of the > youngest file; vanilla rev-list will list the name soonest encountered > in the tree (which can even change if, e.g., a subdir is renamed so as > to be list in a different order). > > In fact, even if they're not in the same tree we could have a similar > problem. Commits are stored topologically in cache slices, so output > is always in topo order. If the same object is introduced in parallel > branches under different names, the outputted name with `rev-list > --all --objects` (vanilla) could be different from `rev-list --all > --objects` (cached) could be different from `rev-list --all > --topo-order --objects`. > > This isn't feasably changable in rev-cache, as a) the cached position > (and hence final output order) is effectively unrelated to tree > structure, and b) commits _have_ to be ordered topologically for > rev-cache to function. > > The descrepency strikes me as something of a non-issue with > pack-objects' deltafication, as the object will fit with either of its > names. It will mean that the (already sorta finicky) object names > won't have garuanteed consistency between cached/non-cached calls to > rev-list. This is something of a corner case and dosn't strike me as > a huge issue, but I figured I should consult you all before presuming > things about git's interface. The name is actually used only as a clue to delta similar objects together. So this is indeed a non issue, as long as the discrepency is well understood and, more importantly, properly documented. The above is certainly a good start. Nicolas