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: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.7 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 409721F45F for ; Thu, 9 May 2019 12:25:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726563AbfEIMZE (ORCPT ); Thu, 9 May 2019 08:25:04 -0400 Received: from mail-qt1-f181.google.com ([209.85.160.181]:35220 "EHLO mail-qt1-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726426AbfEIMZE (ORCPT ); Thu, 9 May 2019 08:25:04 -0400 Received: by mail-qt1-f181.google.com with SMTP id a39so1387765qtk.2 for ; Thu, 09 May 2019 05:25:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=g1Ao74qfLstq//GU9AtV9Oyuzl2hA5CgrvXXc00VESw=; b=Z1cGwLLVoqpeeeeXN06GJb+ShlnJakzhcf7f/n7+XO8cML8twz/aXH/0K5b4EzImFz tBQqxScEjpFbwxCgJWTvtE0vx8k9LXP/VHYYN7Ci7esDl349r44cPytwO2Jbmvwv+jce 3sv95O3+liB2JygVpmgPD885tMwNLXi6AOcCzAGCY+P3rT3ThwolU60K4E+xeTeQG+Cy CYKplP3DOjtLNLgl5Z5k/IOJ9neGZmLFUoINu32v0h33exIc+lpHqAjpPpFrNCH3YtfP G2cEzQcyN5aZc5LHhwmVNhP0Vpj9S70fYmKMh8jhERS1h/zuPpywcJP7a/EBhwgunpCS YkNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=g1Ao74qfLstq//GU9AtV9Oyuzl2hA5CgrvXXc00VESw=; b=GRIZABHxR80yXhGIPDEmTW7IZJ6xghhWLbuQRtdGEjHM0IRwdjVzqAmEVtC8Gl1N3a DoQ9gLd6T3JHBJq9CbgAa6ULN6w/awugEqk3UX7NoACOeXRkHQwiTNixs17JehlT6waN qz6TZvdy98AKn8HT1QU3Fu2rAFiKPAfqG0LxAZc8u5bR3cdMOwXvLGP6zjbgHGdar2k8 okYYBkVYByMUdq/at5ytO/SSbkNaMCGENhL0iba+BpBz5WpcPq+6dkL7gWG/S5tv4Sx6 ifaZcgVMLxtfQHg3mkxzrkLYJdHRDIBcbXrtLxcNYuxrRtCZ+2wsos9wRakb7kl9G/0z 5s/g== X-Gm-Message-State: APjAAAXuArlbZXzzQ95NTuIEiHnaqCLiL6Pe1paZw3jBucc8oak7FAVE dhCAUkf6ZjbZOTs+c2oWCFc= X-Google-Smtp-Source: APXvYqyJlXxmAnDyH/iqLXpmoRnOsjvPdb8/+URWJFDmdh123VbwxNQinYs6FJqRLI1fuMAFYXDVhw== X-Received: by 2002:ac8:298d:: with SMTP id 13mr3314198qts.174.1557404703165; Thu, 09 May 2019 05:25:03 -0700 (PDT) Received: from ?IPv6:2001:4898:6808:13e:d14c:17a3:d28e:9336? ([2001:4898:8010:2:ba80:17a3:d28e:9336]) by smtp.gmail.com with ESMTPSA id w184sm941773qkc.48.2019.05.09.05.25.01 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Thu, 09 May 2019 05:25:02 -0700 (PDT) Subject: Re: [PATCH 12/17] Documentation: describe split commit-graphs To: Junio C Hamano , =?UTF-8?B?w4Z2YXIgQXJuZmrDtnLDsCBCamFybWFzb24=?= Cc: =?UTF-8?Q?SZEDER_G=c3=a1bor?= , Derrick Stolee via GitGitGadget , git@vger.kernel.org, peff@peff.net, git@jeffhostetler.com, jrnieder@google.com, steadmon@google.com, Derrick Stolee References: <7bbe8d9150a623ea684c94d129eda1607dd32a79.1557330827.git.gitgitgadget@gmail.com> <20190508172029.GP14763@szeder.dev> <87pnoshfkq.fsf@evledraar.gmail.com> From: Derrick Stolee Message-ID: <8195f9a4-1808-e23e-f633-7e6809cc3656@gmail.com> Date: Thu, 9 May 2019 08:25:01 -0400 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:67.0) Gecko/20100101 Thunderbird/67.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On 5/9/2019 12:49 AM, Junio C Hamano wrote: > Ævar Arnfjörð Bjarmason writes: > >> With commit-graph- all these unlink() race conditions go away, >> partial reads due to concurrent graph writing becomes a non-issue (we'd >> just leave the old files, "gc" deals with them later..), no need to >> carefully fsync() files/dirs etc as we need to carefully juggle N and >> N+1 files. > > The above would give a nice course correction to be in line with the > rest of the system, like how split index knows about and chains to > its base. Thanks for a dose of sanity. I'm working on a detailed response to Ævar's ideas, to be sure we are talking about the same thing, because the original motivation for the commit-graph format v2 was to allow the 'commit-graph' file to point to a chain of base files by a list of hashes (like the split index does). The current proposal was created in response to an unwillingness to break the file format for the 'commit-graph' file. -Stolee