From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS3215 2.6.0.0/16 X-Spam-Status: No, score=0.4 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id 962471F670 for ; Thu, 24 Feb 2022 21:42:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233266AbiBXVnO (ORCPT ); Thu, 24 Feb 2022 16:43:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230375AbiBXVnN (ORCPT ); Thu, 24 Feb 2022 16:43:13 -0500 Received: from pb-smtp21.pobox.com (pb-smtp21.pobox.com [173.228.157.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CB9A1B45C3 for ; Thu, 24 Feb 2022 13:42:43 -0800 (PST) Received: from pb-smtp21.pobox.com (unknown [127.0.0.1]) by pb-smtp21.pobox.com (Postfix) with ESMTP id 2D6B11837DD; Thu, 24 Feb 2022 16:42:43 -0500 (EST) (envelope-from junio@pobox.com) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=fMcLZHGQyLi5HAndn9judg/nRuE9VQO88BpZLn 9FyPM=; b=aK+S2DfaSRupAtyY6yWySKk8+aRLJJnHS6BOo6rpe/h+qIKyhRs3Lg b8sUmQZVlGOSmcCnUupSzqTPwy70cYU5uNTSR3g4FmzjO2rC/ZqFr5P5QsqhVuGG p75Frc/8R1uF9JUxR0HbybSnCvk19KTOxX5ePtl5aOmcMB3xR4rdk= Received: from pb-smtp21.sea.icgroup.com (unknown [127.0.0.1]) by pb-smtp21.pobox.com (Postfix) with ESMTP id 25A861837DC; Thu, 24 Feb 2022 16:42:43 -0500 (EST) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [34.82.80.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp21.pobox.com (Postfix) with ESMTPSA id 977D11837DA; Thu, 24 Feb 2022 16:42:40 -0500 (EST) (envelope-from junio@pobox.com) From: Junio C Hamano To: "Derrick Stolee via GitGitGadget" Cc: git@vger.kernel.org, me@ttaylorr.com, abhishekkumar8222@gmail.com, Derrick Stolee Subject: Re: [PATCH 0/7] Commit-graph: Generation Number v2 Fixes, v3 implementation References: Date: Thu, 24 Feb 2022 13:42:39 -0800 In-Reply-To: (Derrick Stolee via GitGitGadget's message of "Thu, 24 Feb 2022 20:38:29 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Pobox-Relay-ID: B0EC2496-95BA-11EC-A8EC-CBA7845BAAA9-77302942!pb-smtp21.pobox.com Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org "Derrick Stolee via GitGitGadget" writes: > This patch series includes two distinct, but similarly-motivated parts: > > * Patches 1-4 fix some bugs in the commit-graph generation number v2. > * Patches 5-7 add a new generation number v3 by incrementing the > commit-graph file format. > > I had been thinking about generation number v3, which is the same corrected > commit date as generation number v2, but it is stored in the Commit Data > chunk, requiring a new commit-graph file format version. This breaks > compatibility with older versions of Git, so it requires opt-in via the > commitGraph.generationVersion config value. The only improvement over > version 2 is that the commit-graph file is smaller, so I/O time is reduced. Sounds exciting. Locality of on-disk data does matter. > However, while exploring this idea I found bugs in generation number v2. In > particular, Git has been ignoring them since shortly after they were > introduced. This is due to a bug I introduced when trying to make split > commit-graphs safer with mixed generation number versions. I also noticed an > issue with the offset overflows that I only noticed after writing generation > number v3 using a smaller offset size, actually triggering the bug in the > test suite. > > I'm submitting these two things together so we can see them all at once, but > I'd be happy to split this into two series. The first four patches are > important bug fixes, so we can consider them as higher-priority. > > Thanks, -Stolee Thanks, will take a look.