From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: How the long-lines "optimisation" breaks font locking. Date: Thu, 4 Aug 2022 14:44:05 +0000 Message-ID: References: <87y1w5tahv.fsf@gnus.org> <83sfmc2mph.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="7094"; mail-complaints-to="usenet@ciao.gmane.io" Cc: larsi@gnus.org, emacs-devel@gnu.org, gregory@heytings.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Aug 04 16:46:01 2022 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oJc6q-0001fO-W6 for ged-emacs-devel@m.gmane-mx.org; Thu, 04 Aug 2022 16:46:00 +0200 Original-Received: from localhost ([::1]:45924 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oJc6p-00058O-Fj for ged-emacs-devel@m.gmane-mx.org; Thu, 04 Aug 2022 10:45:59 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:44362) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oJc58-00048V-KJ for emacs-devel@gnu.org; Thu, 04 Aug 2022 10:44:14 -0400 Original-Received: from colin.muc.de ([193.149.48.1]:29692 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1oJc56-0000eS-Gf for emacs-devel@gnu.org; Thu, 04 Aug 2022 10:44:14 -0400 Original-Received: (qmail 29494 invoked by uid 3782); 4 Aug 2022 14:44:09 -0000 Original-Received: from acm.muc.de (p4fe15d23.dip0.t-ipconnect.de [79.225.93.35]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Thu, 04 Aug 2022 16:44:09 +0200 Original-Received: (qmail 7516 invoked by uid 1000); 4 Aug 2022 14:44:05 -0000 Content-Disposition: inline In-Reply-To: <83sfmc2mph.fsf@gnu.org> X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:293065 Archived-At: Hello, Eli. On Thu, Aug 04, 2022 at 15:54:34 +0300, Eli Zaretskii wrote: > > Date: Thu, 4 Aug 2022 10:44:05 +0000 > > Cc: emacs-devel@gnu.org, Gregory Heytings > > From: Alan Mackenzie > > Hello, Lars. > > On Wed, Aug 03, 2022 at 21:03:56 +0200, Lars Ingebrigtsen wrote: > > > Alan Mackenzie writes: > > > > I don't think it is improbable that a C++ hacker will create a long line > > > > in a raw string. > > > If you don't think that's improbable, then you should like the new > > > optimisations a lot -- .... > > These "optimisations" break CC Mode. > They don't "break" it, they cause it occasionally produce inaccurate > fontifications. And only when otherwise Emacs becomes unusable. > > > .... because if you, instead of a 10K line in that C++ file, inserted > > > a 1M line, then Emacs would previously hang indefinitely, but with the > > > optimisation, it doesn't. > > Well I tried CC Mode with a 1,000,000 character raw string. It was > > indeed a bit sluggish but "hang indefinitely" is an exaggeration. > Try it with a 20MB raw string, then. And, for good measure, in an > unoptimized build. These are the cases we are trying to make > workable. No matter what criterion one deems "workable", there will be some size of buffer, or line, which renders Emacs "unworkable". > If all you are saying is that the default value of long-line-threshold > is too low, we can definitely discuss a better value. > > Having loaded the file in C++ Mode (without the spiking of > > narrow-to-region and widen), it took 90 seconds for M-> (first time). > And you consider that reasonable? No, I don't. I was just correcting Lars's mistaken assertion that such a line would make Emacs "hang indefinitely". [ .... ] > > Doing these things in the current master branch indeed appeared to be > > fast, but at one point an error in an after-change-function caused > > after-change-functions to get set to nil, crashing CC Mode. > If you can show a recipe for this problem, we will fix it. This code > is WIP, so some problems definitely remain and should be reported and > fixed. I'll see if I can recreate it. -- Alan Mackenzie (Nuremberg, Germany).