From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Yuan Fu Newsgroups: gmane.emacs.devel Subject: Re: Garbage collect and buffer-undo-list Date: Sat, 13 Mar 2021 14:16:32 -0500 Message-ID: References: <24DD7B5A-CD84-4D8B-A1D9-B7E4BA77DB1A@gmail.com> Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.60.0.2.21\)) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="13219"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Sat Mar 13 20:17:59 2021 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 1lL9lv-0003Kj-Rx for ged-emacs-devel@m.gmane-mx.org; Sat, 13 Mar 2021 20:17:59 +0100 Original-Received: from localhost ([::1]:40632 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lL9lu-0005EM-UP for ged-emacs-devel@m.gmane-mx.org; Sat, 13 Mar 2021 14:17:58 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:52366) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lL9kc-0004Sb-Mg for emacs-devel@gnu.org; Sat, 13 Mar 2021 14:16:41 -0500 Original-Received: from mail-qv1-xf36.google.com ([2607:f8b0:4864:20::f36]:41608) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1lL9kY-0003Hp-VZ for emacs-devel@gnu.org; Sat, 13 Mar 2021 14:16:38 -0500 Original-Received: by mail-qv1-xf36.google.com with SMTP id h3so5907301qvh.8 for ; Sat, 13 Mar 2021 11:16:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=kfw9ILqO4QGfK1bIYbpNTueWm/ERfuSZnMzRsCQrTZI=; b=jXBsxQvEtJibfJFLinuZ3g/5H5ECGIkmvTBtlU2+kf5Ixy9fa9Nxs7m7L++U89bnWi aPR1qzfak8mb42R3BRttep0ZsBB9wdIp8F75IeQWS28H0lYdz6dEZdml278ICcMS/Ztu uW7MUxvb2YDXCGCLIfVBOsazBERSGHJyajm01CGgAJ52TMthlIAd6uZkqPw772YjtaKO a3iOjWizRxtaYSwOy+SY7fM3tTWtfavyQgmmEYcUukHZt2htl6AVMA7Y2Ry34eTqCYnX F6SMoc+fC3cNTo5Fc6W/3i3ESc2O9lLGyUukdp/cMBlkm7QvyIIyWTIlsoYFpOvmKD/J hAqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=kfw9ILqO4QGfK1bIYbpNTueWm/ERfuSZnMzRsCQrTZI=; b=SYapVt5ThU7GDmxNclWdvpPuknzTbiXXXUr9yFwMZ6CGOEoSfENNksqUl/fHrob7aB IuD7xwb/15NBWimqch9X8RnLauEEkeRknyVp2i1fl7HVyp/UIA7gzswWh/xQPQYKaMRF INN/u8Cu6D3TWJzRWHa5BInqVH25VWcMq82DftWMLx+Xcrj7hQqf4ey1FIvzODaCLK1k BtTry2bbLCGlLnDPfZZXxs0WvT5tl1KdRGny/15EMzcLAbnXiLijaRGDPmwo6ei4VUsK dMDRlNWuYti2RcDfjlBHZlVFR2aNT3fQu6hYsynLpzsivfa1F1TtpnlcLP5E3/5aEJDP /T/Q== X-Gm-Message-State: AOAM530irupE7Iy8x+oVepI/VxZS2KAwxaK/ry+lHLCz8GtMh5ldztmv qkCm99YuClxsipmuAOCloP0= X-Google-Smtp-Source: ABdhPJzfbLKHQVZQ+ADapTJsfQ9BAQNqTpcFGv3pWEtFwVLsMQOwoIq6eXqne5ZFCWJ6LsVyJiy5wA== X-Received: by 2002:a0c:e84d:: with SMTP id l13mr3732444qvo.28.1615662994039; Sat, 13 Mar 2021 11:16:34 -0800 (PST) Original-Received: from ?IPv6:2601:98a:4102:3d80:e8f8:bb63:ee78:4255? ([2601:98a:4102:3d80:e8f8:bb63:ee78:4255]) by smtp.gmail.com with ESMTPSA id r7sm6312844qtm.88.2021.03.13.11.16.33 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 13 Mar 2021 11:16:33 -0800 (PST) In-Reply-To: X-Mailer: Apple Mail (2.3654.60.0.2.21) Received-SPF: pass client-ip=2607:f8b0:4864:20::f36; envelope-from=casouri@gmail.com; helo=mail-qv1-xf36.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.23 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" Xref: news.gmane.io gmane.emacs.devel:266440 Archived-At: > On Mar 13, 2021, at 2:01 PM, Stefan Monnier = wrote: >=20 >> I know the garbage collector trims buffer-undo-list. Does it collect = the >> cons cell if there are other references to that object (other than >> buffer-undo-list)? >=20 > No, it can't. >=20 > If you want to keep a reference to some of those cons-cells but still > want the GC to collect them when the undo-log is trimmed, then you = need > to use a weak reference. We don't currently have plain "weak > references" in ELisp, but we do have hash-tables whose keys and/or > values can be weak references (that's what I used in > `undo-equiv-table`). >=20 That=E2=80=99s cool, I do want the referenced object to survive. Thanks! Yuan=