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: Releasing the thread global_lock from the module API Date: Fri, 01 Mar 2024 23:34:25 +0200 Message-ID: <864jdpr5zy.fsf@gnu.org> References: <86cysdrja3.fsf@gnu.org> <86a5nhrdv0.fsf@gnu.org> <868r31rbxn.fsf@gnu.org> <865xy5r8e3.fsf@gnu.org> Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="1891"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Spencer Baugh Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Mar 01 22:35:22 2024 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 1rgAXK-0000CW-3x for ged-emacs-devel@m.gmane-mx.org; Fri, 01 Mar 2024 22:35:22 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rgAWX-0006qr-90; Fri, 01 Mar 2024 16:34:33 -0500 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 1rgAWV-0006qi-RM for emacs-devel@gnu.org; Fri, 01 Mar 2024 16:34:32 -0500 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 1rgAWV-0003u7-Cr; Fri, 01 Mar 2024 16:34:31 -0500 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=KU5nam5XaZJ5pEJegrtKJvJj/ySoA8H7cxH8O4A59SM=; b=HYRFK0JJMiH7 BqQlCTKWu+08YD4tAgSirS5kvfIyJ1NcJDFHl7oocvzChzjpD14MLB2iQJs7FSY2pVTUdp1YVK/Eh xi4rhKSA2ROYw1VLZCWj+3XiVAtrrLFpTTjMjsDPgPkYuULwdZSu3wineRkKuVdsiNOgo0NWebMmJ Qch7xbx2ZxiTbx16k+QbSEuK4WQbxej60g2LcFRgmOfk0usoemyoZcfd9rGOXb1rLLZ2uyT0EDt0B UO3JpGd5skHGUQDlt/8wYRY0c5RLJW7mSuld+pJXPXXLD6jrDjcJor39kG/oWK+OIt/M5u92LmR8t YFeX+Q2jBHDfErLwPvk0Kw==; In-Reply-To: (message from Spencer Baugh on Fri, 01 Mar 2024 16:21:03 -0500) 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:316683 Archived-At: > From: Spencer Baugh > Date: Fri, 01 Mar 2024 16:21:03 -0500 > > Eli Zaretskii writes: > > > Where would you take the data for opening the socket? doesn't that > > come from some Lisp program or from a Lisp variable? And how would > > you know what kind of request to send? doesn't that come from Lisp as > > well? > > Yes: I get those things as arguments from Lisp and then convert them > into the native datastructures of my library, which can be used without > further interacting with the Lisp machine. > > Then I would release the lock and call into my library, which does some > useful work which takes a while. How is this different from starting your own native thread, then releasing the lock? > > And what would you do with the stuff you get in response? don't > > you want to put this in some Lisp variable or provide as input for > > some Lisp program? Etc. etc. > > Yes: After I finish the call into my library, I would take the lock > again and call further Lisp functions to put the results back into the > Lisp machine. How is this different from doing the same when your native thread finishes? > >> Since it's useful for me, I'd like to write a patch which allow modules > >> to do this; would it be considered? > > > > Once again: what cannot you do from a native thread started by the > > module? IOW, why would you need access to the global lock machinery > > in the first place, if all you want to do is something that is > > unrelated to Emacs and its global state? > > See above: The call into my library, which takes a while, and is useful, > does not touch the Lisp machine. But other code around that call does > touch the Lisp machine, and so needs to run with the lock. The ability > to release and re-acquire the lock means my module doesn't hold the lock > when it doesn't need to. You didn't answer my question about doing this from a native thread. As for re-acquiring the lock: you cannot do that with how the Lisp threads are currently implemented. You can only wait for the lock to be released, and try re-acquiring it; whether you succeed is anyone's guess, if there are other threads competing for the lock.