From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Major modes using `widen' is a good, even essential, programming practice. Date: Mon, 08 Aug 2022 05:36:08 +0300 Message-ID: <83czdbwjfr.fsf@gnu.org> References: <6ae35c9306ade07b4c45@heytings.org> <835yj4xhh7.fsf@gnu.org> <83y1w0w0gk.fsf@gnu.org> <83pmhcvugm.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="29926"; mail-complaints-to="usenet@ciao.gmane.io" Cc: gregory@heytings.org, emacs-devel@gnu.org To: Alan Mackenzie Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Aug 08 04:37:10 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 1oKsdh-0007bQ-Fz for ged-emacs-devel@m.gmane-mx.org; Mon, 08 Aug 2022 04:37:09 +0200 Original-Received: from localhost ([::1]:42670 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oKsdg-0000x2-9P for ged-emacs-devel@m.gmane-mx.org; Sun, 07 Aug 2022 22:37:08 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:57214) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKscw-0000EC-Ih for emacs-devel@gnu.org; Sun, 07 Aug 2022 22:36:22 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]:36360) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKscw-0006vH-9U; Sun, 07 Aug 2022 22:36:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=gnu.org; s=fencepost-gnu-org; h=References:Subject:In-Reply-To:To:From:Date: mime-version; bh=gnlb0AcBjEWw4wBGLRlukvXN4G6u2ZsmwFCMtyWeMbg=; b=DlFIFvmqRXNt U9oLJzbc+AzWcSG2K0i+e3D/kDOxCLtbVNHvZoG4Y0UiLY/1velekXFExd8aK8bKQk5my0pIfKCoK eYys9I9rlJ6nXbf3rKXnd45RxzkmJ8mZB4rdxheVIS5ijq9+JV7vZPvydtn/omODZikkgODhk9+Eg O5Z2qj+G+ogQls70KOS8WmWwiFjwLeYwAm2VBpy4JcgsGEO7qvXTZT9cX+62NmaJLQcXyXLLsiapv FtARX/gTZZ0prw8zyDOv5YcuOY406AtRaTy0Qcb3/ECwtpFMGpAk+U+0EyrsFNjgublzBETva6mOT X4on59OG93umP38T4KNKkw==; Original-Received: from [87.69.77.57] (port=4517 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oKscv-0007Nh-Oc; Sun, 07 Aug 2022 22:36:22 -0400 In-Reply-To: (message from Alan Mackenzie on Sun, 7 Aug 2022 19:20:44 +0000) 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:293241 Archived-At: > Date: Sun, 7 Aug 2022 19:20:44 +0000 > Cc: gregory@heytings.org, emacs-devel@gnu.org > From: Alan Mackenzie > > > > > Either in the cache or in the buffer: the previous chunk was > > > > fontified, so its end has the font-lock-comment-face. So you know. > > > > No, you don't. The buffer might be being opened by desktop in a large > > > comment in the middle of the file. > > > You've changed the scenario, yes? > > Yes. We've got to deal with all scenarios, preferably without > special-caseing special cases. No one said that all the scenarios must have the same solution. > > > What jit-lock/font-lock actually do at the moment is to widen, then use > > > syntax-ppss, i.e. in effect scan from BOB. > > > Yes, and that's SLOOOWWWW! > > On my machine, with an optimised build, it takes just under 20 ms to > parse-partial-sexp over xdisp.c (not counting any redisplay at the end). > I don't understand any more than Dmitry does, why your unoptimised build > is taking 25 times as long. It doesn't help to know that some very fast machine can do this stuff quickly enough to remain below the annoyance threshold. 20 ms is a very long time by the current CPU speed measure: just calculate the number of CPU cycles in that time and you will see it. > > > That "needing to go too far" is an instantaneous jump, not a scanning. > > > Please tell that to someone who doesn't edit C sources as frequently > > as I do. > > Are you saying that long strings and long comments cause a particular > slowdown in C Mode, not seen when strings and comments are all short? I don't know what makes it slow, but it feels sluggish in even the simplest editing operations, and font-lock updates are slow as well. > > > The string start will be in a parse-partial-sexp result somewhere. > > > Sometimes people write long strings. They certainly write long comments. > > > Why do I have top suffer every day just because someone, somewhere, > > might do that? I'd rather we "punish" those few people who do it > > (rarely). > > I don't think we should punish people who write comments. I'm thinking > of Gerd M., who was likely the writer of the comment at the beginning of > xdisp.c. We are still talking about long lines, yes? There are no long lines in that commentary at the beginning of xdisp.c.