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: wait_reading_process_ouput hangs in certain cases (w/ patches) Date: Sat, 18 Nov 2017 23:07:37 -0800 Organization: UCLA Computer Science Department Message-ID: References: <83tvyj62qg.fsf@gnu.org> <83r2tetf90.fsf@gnu.org> <5150d198-8dd3-9cf4-5914-b7e945294452@binary-island.eu> <83tvy7s6wi.fsf@gnu.org> <83inemrqid.fsf@gnu.org> <398f8d17-b727-d5d6-4a31-772448c7ca0d@binary-island.eu> <56e722a6-95a4-0e42-185c-f26845d4f4bf@binary-island.eu> <21237e45-a353-92f9-01ec-7b51640d2031@cs.ucla.edu> <83vaickfu2.fsf@gnu.org> <83tvxwkexg.fsf@gnu.org> <03261534-6bf5-1a5d-915f-d3c55aaa35e9@binary-island.eu> <206ebefa-7583-f049-140c-c8fd041b0719@cs.ucla.edu> 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 1511075276 23102 195.159.176.226 (19 Nov 2017 07:07:56 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sun, 19 Nov 2017 07:07:56 +0000 (UTC) User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 Cc: emacs-devel@gnu.org To: Matthias Dahl , Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sun Nov 19 08:07:50 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 1eGJhk-0005WF-Nm for ged-emacs-devel@m.gmane.org; Sun, 19 Nov 2017 08:07:48 +0100 Original-Received: from localhost ([::1]:52139 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eGJhr-0000PH-LK for ged-emacs-devel@m.gmane.org; Sun, 19 Nov 2017 02:07:55 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:42629) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eGJhk-0000P0-JV for emacs-devel@gnu.org; Sun, 19 Nov 2017 02:07:49 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eGJhj-0000OW-IN for emacs-devel@gnu.org; Sun, 19 Nov 2017 02:07:48 -0500 Original-Received: from zimbra.cs.ucla.edu ([131.179.128.68]:39008) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eGJhf-0000IC-O5; Sun, 19 Nov 2017 02:07:43 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id 2CF141610A8; Sat, 18 Nov 2017 23:07:40 -0800 (PST) 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 lqDOj-nTgLY3; Sat, 18 Nov 2017 23:07:37 -0800 (PST) Original-Received: from localhost (localhost [127.0.0.1]) by zimbra.cs.ucla.edu (Postfix) with ESMTP id D1D3E161159; Sat, 18 Nov 2017 23:07:37 -0800 (PST) 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 X5ZvMGal8hqw; Sat, 18 Nov 2017 23:07:37 -0800 (PST) Original-Received: from [192.168.1.9] (unknown [47.154.30.119]) by zimbra.cs.ucla.edu (Postfix) with ESMTPSA id AC4B3161074; Sat, 18 Nov 2017 23:07:37 -0800 (PST) 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:220273 Archived-At: Matthias Dahl wrote: > If you treat the process as a shared resource, it is your sole > responsibility to take care of proper management and synchronization of > the process as well. OK, but this is all news to me. Shouldn't this be documented? As things s= tand,=20 it is not obvious. So, getting back to the patch proposed in=20 , this discuss= ion=20 convinced me that the approach will work well enough. I have the followin= g=20 suggestions for improvement: * Fix the bug with carryover that I mentioned in=20 . * Document in the Elisp manual that filters and timers are supposed to do= =20 "proper management and synchronization", and be clear about how this cons= trains=20 filters and timers. (This is probably the hardest part of the fix....) * Change the type of infd_num_bytes_read from EMACS_UINT to uintmax_t. Th= is will=20 provide an extra margin of safety on some platforms. infd_num_bytes_read = has=20 nothing to do with Emacs integers, and wider counts are safer. * Document in its comment that infd_num_bytes_read is actually the count = modulo=20 UINTMAX_MAX + 1. * When assigning to got_some_output, ceiling it at INT_MAX to avoid overf= low=20 problems. Something like the following, say: got_some_output =3D min (INT_MAX, (wait_proc->infd_num_bytes_read - initial_wait_proc_num_bytes_read))= ; This removes the need for that long comment about overflow, since this=20 assignment cannot overflow. Thanks.