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: Thu, 21 Sep 2023 08:35:06 +0000 Message-ID: <87msxf2abp.fsf@localhost> References: <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> <87il86nxts.fsf@localhost> <87o7hyx8h2.fsf@dataswamp.org> <87o7hx88ry.fsf@localhost> <87a5thta90.fsf@yahoo.com> <87led1865h.fsf@localhost> <875y45t7yo.fsf@yahoo.com> <874jjprmq2.fsf@yahoo.com> <83a5tgc03s.fsf@gnu.org> <87zg1gqr8q.fsf@yahoo.com> <83msxg9eb9.fsf@gnu.org> <87msxgq8rn.fsf@yahoo.com> <83jzsk9c5l.fsf@gnu.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="2077"; mail-complaints-to="usenet@ciao.gmane.io" Cc: Po Lu , emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Sep 21 10:34:59 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 1qjF9H-0000DS-G8 for ged-emacs-devel@m.gmane-mx.org; Thu, 21 Sep 2023 10:34:59 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qjF8O-0005EO-C4; Thu, 21 Sep 2023 04:34:04 -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 1qjF8M-0005ED-W3 for emacs-devel@gnu.org; Thu, 21 Sep 2023 04:34:03 -0400 Original-Received: from mout02.posteo.de ([185.67.36.66]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qjF8I-0000nb-65 for emacs-devel@gnu.org; Thu, 21 Sep 2023 04:34:01 -0400 Original-Received: from submission (posteo.de [185.67.36.169]) by mout02.posteo.de (Postfix) with ESMTPS id 3F987240101 for ; Thu, 21 Sep 2023 10:33:50 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.net; s=2017; t=1695285230; bh=w0FQ/8WM26ZGcAMAJP/Vo8wiPgrA9iyeuze8xM7gemY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version:From; b=BaARW8x/ROEoaK9m60qMUx8mE1zKzxMEojNwdcBukP5UVeCtah5HZEvBFyYFTxmqi qicAkHraWi5fAbzk/E8Sm8WZNEYPgP+BXYuXxkx2KNA2BavTtcJCGW7W0a8cpS5EGi /DW0G9bcoUYQGk4Drjt2E+CxQ5PdzmGHnlSCRnmnYjKmNKv0SreJOKcofxGlqI4AlW jSpQckVtNxElKG3WhxnEDBEXYYvUn0l0/xwx1o1Y8wIgrgaT8jLlFRBBKIPTJEeyFP J5FZMfErqKkvOsRz8g19sg5aDNNmHBhNQCXFR585Hw+KvjOMjyEGzwCckP1mQgGFli DcBT1zd7KC5Eg== Original-Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 4Rrpb15r3lz6vBX; Thu, 21 Sep 2023 10:33:49 +0200 (CEST) In-Reply-To: <83jzsk9c5l.fsf@gnu.org> Received-SPF: pass client-ip=185.67.36.66; envelope-from=yantar92@posteo.net; helo=mout02.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=unavailable 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:310872 Archived-At: Eli Zaretskii writes: >> The variable defined in C must be accessible by a C lvalue. Namely, >> >> (*current_thread->f_Vname_of_the_variable) > > How is this different from > > (setq name-of-variable SOMETHING) > > done by some thread to a global variable? For global variables defined in C sources, Emacs maintains an actual C variable that can be used directly to set and store the value. Then, (setq name-of-global-variable-defined-in-C SOMETHING) must arrange to set Vname_of_global_variable_defined_in_C C variable as well. This is not needed for global variables defined in Elisp. Under the hood, Vname binding is stored via Lisp_Objfwd. See #define DEFVAR_LISP in lisp.h. This forwarding must be accounted for in threads, if we want to make them asynchronous. Po Lu solved this by adding thread-local "globals" structs. In contrast, global Elisp variables defined in Elisp for not store Lisp_Objfwd and instead contain their symbol value directly in their Elisp symbol objects. Setting and reading these symbol values involves the common API: Fsymbol_value and Fset, which are much easier to change to work with async threads compared to the having to handle all the Vname = val; that are expected to work in C level. To sum up: Elisp-only globals are handled differently from globals defined in C code and should thus be approached differently when implementing async threads. -- Ihor Radchenko // yantar92, Org mode contributor, Learn more about Org mode at . Support Org development at , or support my work at