From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Ihor Radchenko Newsgroups: gmane.emacs.devel Subject: Re: Emacs design and architecture. How about copy-on-write? Date: Tue, 19 Sep 2023 12:37:19 +0000 Message-ID: <87il86nxts.fsf@localhost> References: <83edizjn0v.fsf@gnu.org> <0518f65b-1dd1-6923-8497-da4d3aeac631@gutov.dev> <87sf7fc7kd.fsf@dataswamp.org> <834jjuk68t.fsf@gnu.org> <87cyyhc7uu.fsf@dataswamp.org> <83ttrsg9nx.fsf@gnu.org> <83h6nrg4eg.fsf@gnu.org> <83v8c7elan.fsf@gnu.org> <877conk5ny.fsf@localhost> <83ttrreeu0.fsf@gnu.org> <87bkdzeas1.fsf@localhost> <83cyyfe5l8.fsf@gnu.org> <8734zbyu6o.fsf@dataswamp.org> <835y46e8o9.fsf@gnu.org> <87zg1ixvnc.fsf@dataswamp.org> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="33353"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Emanuel Berg Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Sep 19 14:36:57 2023 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 1qiZyL-0008O0-Ci for ged-emacs-devel@m.gmane-mx.org; Tue, 19 Sep 2023 14:36:57 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qiZxd-00081G-6a; Tue, 19 Sep 2023 08:36:13 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qiZxa-000817-O8 for emacs-devel@gnu.org; Tue, 19 Sep 2023 08:36:10 -0400 Original-Received: from mout01.posteo.de ([185.67.36.65]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qiZxW-0000pv-HS for emacs-devel@gnu.org; Tue, 19 Sep 2023 08:36:10 -0400 Original-Received: from submission (posteo.de [185.67.36.169]) by mout01.posteo.de (Postfix) with ESMTPS id 9C2CB240028 for ; Tue, 19 Sep 2023 14:36:04 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1695126964; bh=HPbqLTIXafm5rVy27ujCsq5QnO6YHwuVaerUcEIShsc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:From; b=psv2LfqhO/PLZPP8TUIKRGI76MIfHIQbjA1iP2REja3wZShvRK1kdhMjT+0A/9zae XT06ELU+MeHQyniJQ/vx0uhJOHM/cVA2uTWnr6GcH99lWJGbsSqr/wDLNaB7FTAbWB S0T6VHNiAy0goTw8W4TshMuLk44rKFvBCZj4yl46BSm9aGXq9tjQUYzuB5Fq3omI8v wn6ScFmB0FIv6bVrMPwg6qbzNZpO6T+bmDxGvk3PeTdEZzfXwKacFioJHDBWvK34Bs ZkUkwX0Q097OSqSOyzi/1b6vpGLjTaxnVHzib59lo8IfwyV1Z5k92zYOU+TGmRPfw2 dV/R/BCpya35g== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4Rqh3R6NPDz6tm4; Tue, 19 Sep 2023 14:36:03 +0200 (CEST) In-Reply-To: <87zg1ixvnc.fsf@dataswamp.org> Received-SPF: pass client-ip=185.67.36.65; envelope-from=yantar92@posteo.net; helo=mout01.posteo.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:310755 Archived-At: Emanuel Berg writes: >> So the problem is not how to lock and serialize access to >> a variable in general, the problem is how to do this in >> Emacs so that we won't need to lock everything. > > Okay, excellent, but then why isn't it enough to just maintain > a register of global variables and threads? > If a thread wants to use it, look in the register, is it > available? If not, get in line. And when it becomes available, > pop a thread in the line, if there is one, and start over? > > Why do we have to lock everything just because we lock > a single variable? Because implementation details are tricky - a lot of Elisp internal machinery is relying upon modifying global symbol objects, having certain global C variables assigned to the "right" value, and buffer objects having the right buffer-local values. This particular issue has been discussed in details in https://yhetil.org/emacs-devel/871qhnr4ty.fsf@localhost/ -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at