From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Paul Eggert Newsgroups: gmane.emacs.devel Subject: Re: Using the GNU GMP Library for Bignums in Emacs Date: Sun, 22 Apr 2018 21:21:02 -0700 Organization: UCLA Computer Science Department Message-ID: References: <29f933ac-a6bf-8742-66a7-0a9d6d3e5a88@disroot.org> <87k1t05wz4.fsf@metalevel.at> <55776605-8940-0a4a-34fb-f3d1b955ab12@cs.ucla.edu> <831sf8x8o6.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: blaine.gmane.org 1524457246 12407 195.159.176.226 (23 Apr 2018 04:20:46 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Mon, 23 Apr 2018 04:20:46 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 Cc: triska@metalevel.at, emacs-devel@gnu.org To: rms@gnu.org, Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Apr 23 06:20:41 2018 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 1fASy1-00035b-KO for ged-emacs-devel@m.gmane.org; Mon, 23 Apr 2018 06:20:41 +0200 Original-Received: from localhost ([::1]:36675 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fAT06-0002OR-Ip for ged-emacs-devel@m.gmane.org; Mon, 23 Apr 2018 00:22:50 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:53530) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fASyV-0002MS-8a for emacs-devel@gnu.org; Mon, 23 Apr 2018 00:21:12 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fASyT-0002bB-GW for emacs-devel@gnu.org; Mon, 23 Apr 2018 00:21:10 -0400 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:42714) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fASyP-0002UR-0Y; Mon, 23 Apr 2018 00:21:05 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id A0BB71616DE; Sun, 22 Apr 2018 21:21:03 -0700 (PDT) Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id Iiq8HFHs-Xml; Sun, 22 Apr 2018 21:21:03 -0700 (PDT) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id E8DE51616E0; Sun, 22 Apr 2018 21:21:02 -0700 (PDT) X-Virus-Scanned: amavisd-new at zimbra.cs.ucla.edu Original-Received: from zimbra.cs.ucla.edu ([127.0.0.1]) by localhost (zimbra.cs.ucla.edu [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id VZmuHv3fahHF; Sun, 22 Apr 2018 21:21:02 -0700 (PDT) Original-Received: from [192.168.1.9] (unknown [47.154.30.119]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id AF1301616DE; Sun, 22 Apr 2018 21:21:02 -0700 (PDT) In-Reply-To: Content-Language: en-US X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 131.179.128.68 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:224798 Archived-At: Richard Stallman wrote: > There are quite a few places in the C code of Emacs > where execution can get stuck; that's why I added immediate quitting. > The problems I fixed that way have all come back. I hope they haven't come back. We tried to be methodical about preventing= Emacs=20 from getting stuck. > What was the reason for this change? Allowing immediate quitting from arbitrary points in execution causes pro= blems=20 when Emacs internals assume that actions are done in a certain order and = are not=20 just partly done when interrupted by a quit. In the old days we could ass= ume=20 that execution order at the machine level was the same order as in the C = program=20 source code, which meant that as long as the C source code did things in = the=20 right order Emacs could survive immediate quitting. That assumption is no= longer=20 true. To do things safely now, we need to either (1) add critical section= s to=20 Emacs where appropriate, or (2) test the quit flag at appropriate interva= ls. In=20 practice (2) is easier to implement and to maintain.