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: Concurrency via isolated process/thread Date: Mon, 24 Jul 2023 15:50:34 +0300 Message-ID: <83cz0hscbp.fsf@gnu.org> References: <871qhnr4ty.fsf@localhost> <83sfa1gjns.fsf@gnu.org> <87r0plxbep.fsf@localhost> <83ilawhpi6.fsf@gnu.org> <87zg48apwr.fsf@localhost> <83edljg8ub.fsf@gnu.org> <87o7knbxr7.fsf@localhost> <838rbrg4mg.fsf@gnu.org> <87ilavbvdr.fsf@localhost> <834jmffvhy.fsf@gnu.org> <878rbrbmwr.fsf@localhost> <83fs5zecpo.fsf@gnu.org> <87351zbi72.fsf@localhost> <83351yevde.fsf@gnu.org> <87cz12ad2w.fsf@localhost> <83a5w6cwdr.fsf@gnu.org> <87pm518m0g.fsf@localhost> <83o7kl9tyj.fsf@gnu.org> <874jmd89us.fsf@localhost> <878rb53dkj.fsf@localhost> <87wmyp1vr9.fsf@yahoo.com> <875y6939jl.fsf@localhost> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="601"; mail-complaints-to="usenet@ciao.gmane.io" Cc: luangruo@yahoo.com, emacs-devel@gnu.org To: Ihor Radchenko Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Jul 24 14:50:34 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 1qNv1G-000AY7-5r for ged-emacs-devel@m.gmane-mx.org; Mon, 24 Jul 2023 14:50:34 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qNv0e-0006mH-HJ; Mon, 24 Jul 2023 08:49:57 -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 1qNv0a-0006lf-RQ for emacs-devel@gnu.org; Mon, 24 Jul 2023 08:49:53 -0400 Original-Received: from fencepost.gnu.org ([2001:470:142:3::e]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1qNv0a-0005U5-8U; Mon, 24 Jul 2023 08:49:52 -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=Pj2uwW7mWUqxsHF9XJrOMAnRwYrBpgElVTR8XZtWBxA=; b=pirNy0E5gIJH jR68Ym3sxnj52b66gsR/dAPswRpAGw2r2mUWhTQMSqOS8DQ1Qid7ZWDjXP844v8IXCrMmhXv5hCqa q4ZsPIlXWrRzsnusdmCkPFCS1xr/e+uP6Lf8HhZQBI6+hqwKBMkbp2Ra2vMjwwLK67qpDRYoxvWVJ BaPCMgMZ7yUdyC7Y2r9v0uwrF0D7275P3JlpNtpetTSRgk5zB2g6krNte2txVuw68OhI0n9MmoKds SUOVwCNCLAVPzLwYkmmUsIG1znV29jbcwTQl3QNViO1uH9U/Uh6+Nz44xjJFSJX+QN1vZOaIEDKt1 ogGuH8+Zjxa7AAOUgG1kvQ==; Original-Received: from [87.69.77.57] (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 1qNv0Z-0005J1-B1; Mon, 24 Jul 2023 08:49:52 -0400 In-Reply-To: <875y6939jl.fsf@localhost> (message from Ihor Radchenko on Mon, 24 Jul 2023 10:09:50 +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-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:308054 Archived-At: > From: Ihor Radchenko > Cc: Eli Zaretskii , emacs-devel@gnu.org > Date: Mon, 24 Jul 2023 10:09:50 +0000 > > The basic idea is to have > #define PT (current_thread->m_pt + 0) > #define PT_BYTE (current_thread->m_pt_byte + 0) Point is the attribute of a buffer. The current definition of PT, viz.: #define PT (current_buffer->pt + 0) automagically makes PT refer to the current buffer, so the code only needs to change current_buffer to have PT set correctly. By contrast, you propose to have one value of point per thread, which means a thread that switches buffers will have to manually change all of these values, one by one. Why is that a good idea? And what about C code which copies/moves text between two buffers? For example, some primitives in coding.c can decode text from one buffer while writing the decoded text into another. > Basically, use thread object slot instead of buffer object slot to store > point and restriction. This will not cause any performance degradation > and allow multiple points in the same buffer. > > What may be slightly slower is setting/getting points in other (not > current) buffers. > We will need to store point and restriction history for each thread. > Searching this history will scale with the number of buffers that have > been current previously during thread execution (though we may use hash > table if necessary). > > However, accessing and changing point in buffer that is not current is > not very common. AFAIU, it is done in (1) read operation when reading > from stream represented by a buffer; (2) when switching buffers when we > need to transfer current PT to history for current buffer and retrieve > PT from history for the buffer that will become current. Once again: please state the final goal, and please describe at least in principle how these measures are steps toward that goal. > I propose to remove buffer points completely and use thread points > instead. I don't think this could fly, because we must be able to copy text from one buffer to another in a single thread, see above.