From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Dmitry Gutov Newsgroups: gmane.emacs.devel Subject: Re: My plans for VC mode Date: Sat, 22 Nov 2014 16:33:19 +0200 Message-ID: <86r3wvb900.fsf@yandex.ru> References: <20141122133351.46279382C23@snark.thyrsus.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1416666836 27954 80.91.229.3 (22 Nov 2014 14:33:56 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 22 Nov 2014 14:33:56 +0000 (UTC) Cc: emacs-devel@gnu.org To: "Eric S. Raymond" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Nov 22 15:33:50 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XsBl0-0002tf-9N for ged-emacs-devel@m.gmane.org; Sat, 22 Nov 2014 15:33:50 +0100 Original-Received: from localhost ([::1]:45640 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XsBkz-0005G4-Oo for ged-emacs-devel@m.gmane.org; Sat, 22 Nov 2014 09:33:49 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:60013) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XsBkg-0005Eo-Hi for emacs-devel@gnu.org; Sat, 22 Nov 2014 09:33:35 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XsBkb-0006Rl-2t for emacs-devel@gnu.org; Sat, 22 Nov 2014 09:33:30 -0500 Original-Received: from mail-wi0-x235.google.com ([2a00:1450:400c:c05::235]:33469) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XsBka-0006Pn-Si for emacs-devel@gnu.org; Sat, 22 Nov 2014 09:33:25 -0500 Original-Received: by mail-wi0-f181.google.com with SMTP id r20so1890320wiv.2 for ; Sat, 22 Nov 2014 06:33:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:from:to:cc:subject:references:date:in-reply-to:message-id :user-agent:mime-version:content-type; bh=VapHNoveNy6bN1/tiRypP3Z3ku832J/Ssi513e+OAVc=; b=J9sWrkUYn1wjepklng2p4H/xFjMcIMMHHqjBJguW9FjzubjbKYXt/VQiLjtW/ihitq QnphYqvNgQczvgV8yXgjsJYfgGZY6nKYvNLTXIvDiBSHhZx0b4gitjo/l0qOB+1/pQgY SMMMoXSZW30TDMsyvs0smjnR+sxXUXBtX+gdsLaiO8l4rtIKogYIK/kgvn5+ifd3w2Vm zr08dK6DGNM4aP6GvTIRns2OT4rCjFgMRj94NNaLC7j8AGnn6u0wG3HF5bXtodbs0Tpa J2Dtt0Hn1wAGKYc5pj5Uk0jql4fkfGLvsRbhZ0f5DivpXeKtlkoVdBK/QDj920lNpHFl T3tg== X-Received: by 10.180.184.163 with SMTP id ev3mr6346398wic.66.1416666803562; Sat, 22 Nov 2014 06:33:23 -0800 (PST) Original-Received: from axl (213-71-217.netrun.cytanet.com.cy. [213.7.71.217]) by mx.google.com with ESMTPSA id bj7sm12420083wjc.33.2014.11.22.06.33.22 for (version=TLSv1.2 cipher=RC4-SHA bits=128/128); Sat, 22 Nov 2014 06:33:23 -0800 (PST) In-Reply-To: <20141122133351.46279382C23@snark.thyrsus.com> (unknown@unknown.invalid's message of "Sat, 22 Nov 2014 08:33:50 -0500 (EST)") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.4.51 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2a00:1450:400c:c05::235 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:178010 Archived-At: Hi Eric, > Accordingly, I have concluded that it is time to chuck backward > compatibility and rewrite tha back-end API, simplifying as radically > as I can and enforcing much stricter separation between the VC upper > layer and the back ends. Here's hoping it won't be a full rewrite. Aside from serving as a plumbing for a set of commands, VC is a helpful VCS-agnostic (to a certain degree) wrapper over a set of commands which third-party packages can use. http://elpa.gnu.org/packages/diff-hl.html, for example, uses `vc-state', as well as `diff', `dir-status' and `dir-status-files', and relies on their current semantics (even if they're a bit broken in certain implementations; I intend to improve that). > While I do branching I'm also going to look at removing the elaborate > caching the older back ends use to avoid disk traffic as much as > possible. That made sense when I first wrote it twenty-odd years > ago, but it's been a chronic source of TOCTOU bugs and other > coherency problems ever since. Disks are much faster now; it's > probably time for the state-heuristic stuff to die. Not exactly sure which functions you're referring to here, but an example of a function in a "newer" backend that uses caching is `vc-git-root'. Correctness should trump performance most of the time, but there are still traffic-sensitive workflows out there, such as TRAMP.