From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: tramp-sh-handle-vc-registered (was: vc with svn and git) Date: Sat, 25 Feb 2017 08:36:46 -0500 Message-ID: References: <87bmtrsdkl.fsf@kwork> <87innzqvfi.fsf@kwork> <87inny66mt.fsf@detlef> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1488029857 7142 195.159.176.226 (25 Feb 2017 13:37:37 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 25 Feb 2017 13:37:37 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Feb 25 14:37:32 2017 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1chcXT-0001FA-UF for ged-emacs-devel@m.gmane.org; Sat, 25 Feb 2017 14:37:32 +0100 Original-Received: from localhost ([::1]:42768 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chcXZ-0002qc-LR for ged-emacs-devel@m.gmane.org; Sat, 25 Feb 2017 08:37:37 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:40388) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1chcWx-0002lo-6L for emacs-devel@gnu.org; Sat, 25 Feb 2017 08:37:00 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1chcWu-0002zg-2u for emacs-devel@gnu.org; Sat, 25 Feb 2017 08:36:59 -0500 Original-Received: from [195.159.176.226] (port=34907 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1chcWt-0002y3-SD for emacs-devel@gnu.org; Sat, 25 Feb 2017 08:36:55 -0500 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1chcWl-0005PU-KY for emacs-devel@gnu.org; Sat, 25 Feb 2017 14:36:47 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 25 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:5ZVifdwSY8HgiDNsP4wbquEnvRw= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 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" Xref: news.gmane.org gmane.emacs.devel:212594 Archived-At: >> I don't know the situation with tarballs, but for Tramp it is >> implemented and useful. Tramp's implementation uses some caching indeed >> for performance improvement. See the comment in tramp-sh.el, heading >> `tramp-sh-handle-vc-registered'. > That's odd. Why doesn't it rely on the file-process and > start-file-process handlers? OK, I now looked at the code and I see why it's used. I guess the caching part of tramp-sh-handle-vc-registered is not indispensable (i.e. there must be a way to make the generic caching mechanism work well enough for vc-registered), but batching all requests into a single one is indeed pretty much impossible without some ad-hoc hack like this one (which relies on the property that vc-registered doesn't have too many side-effects, so you can do a "dry run" just to see what it would do). The only way I can see to get a similar result without ad-hoc hacks would be to introduce async file operations and then make vc-registered use them (since IIUC the benefit of tramp-sh-handle-vc-registered's batching is to avoid paying the latency N times). So vc-registered would start by firing all file-exists-p tests (an other operations) asynchronously and then collect their answers. Stefan