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: AS53758 23.128.96.0/24 X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by dcvr.yhbt.net (Postfix) with ESMTP id 6B2C81F751 for ; Thu, 16 Apr 2020 00:52:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405196AbgDPAwv (ORCPT ); Wed, 15 Apr 2020 20:52:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405170AbgDPAwp (ORCPT ); Wed, 15 Apr 2020 20:52:45 -0400 Received: from mail-pj1-x1041.google.com (mail-pj1-x1041.google.com [IPv6:2607:f8b0:4864:20::1041]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9AB25C061A0C for ; Wed, 15 Apr 2020 17:52:44 -0700 (PDT) Received: by mail-pj1-x1041.google.com with SMTP id a32so595180pje.5 for ; Wed, 15 Apr 2020 17:52:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ttaylorr-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=2zrNzW0++4+A+szm5FfFFzC2C9b8eRKqIQNhPSdBhlI=; b=vUbDskDz8J3Im55nt3MGjBO9m44GZUJwUYVT9GICm6AsBUD10QWoWp3McLLicguCBq 3fAHkp/f3WT7Wm9B9a9/vhTtj+URUxGbanab+tY3wywZjTpLSPdEkXts/78k/29f72Kf t5RD0MpOK7n8L/fVJ/omGhS5R2qEP2WWr69BabOKe+63/VzWSbcv2TiQUaC7NPchxG4e 7GxzA9FrG0ISzK6SKmwzFChsKaJd/0uAGTyidnPC8Z/1hkX4WS/hakzdSN5/IOhyNDYW tBXgWH+vRjGdr50OIZHjAIQiXH3wg3+hNPNbSeUPORJrHZ/5Cuh9Y0N9ImK6qVFhXnkR Jrdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=2zrNzW0++4+A+szm5FfFFzC2C9b8eRKqIQNhPSdBhlI=; b=jescJGAb/ig80NH68HjYdlBhrcIabqxqnPCRgrHwSohRYI3EOLx0w77uZ2kSIydEx/ v0IOdXOJrXKTE86act91OmKoRGKB55SfRgtiryXxFK0dUGROpC6Syiy5tAyZXUrc10Kw T4fYE32kLwjhZrt59QJAwJQjK+DZD3Q4EIYX5kPLZ8Yw1beTEBKu9D7IOxO63g6XP1T3 Lks68fRVPJS2IeiJYhz4KVsrQqJyxeh/LkjVv8o0Ox/5LT1rN/UjbADBffo+Op7eJBz9 GUziHwlt2CSEgZai/aHXvSHctB8vAFwQLty24NsDohyugS89NInV4wQcvTCqiJT3Knmh 1y0g== X-Gm-Message-State: AGi0PuZ0uxzlFseYhTtAPM2QmiU7yBo3MMmZ4mF/BEEAg8RA6LpX2WtS +SByvU4IiZFflyGbO8QLwe5gtA== X-Google-Smtp-Source: APiQypKZ5J7QSCrb3cc1dLLeS5wRirTg0A+7LBFLg08l6XLd9MXORMRwLkZ5A2M0EFiYL+qevBxk2Q== X-Received: by 2002:a17:90a:ec02:: with SMTP id l2mr2039618pjy.126.1586998364058; Wed, 15 Apr 2020 17:52:44 -0700 (PDT) Received: from localhost ([8.44.146.30]) by smtp.gmail.com with ESMTPSA id a13sm15198058pfc.26.2020.04.15.17.52.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 17:52:43 -0700 (PDT) Date: Wed, 15 Apr 2020 18:52:41 -0600 From: Taylor Blau To: Jakub =?utf-8?B?TmFyxJlic2tp?= Cc: Derrick Stolee , Junio C Hamano , Derrick Stolee via GitGitGadget , git , Taylor Blau , Garima Singh , Derrick Stolee Subject: Re: [PATCH 1/3] revision: complicated pathspecs disable filters Message-ID: <20200416005241.GB36156@syl.local> References: <9cc31c289aa785f026eec84452ed68e80505d95e.1586566981.git.gitgitgadget@gmail.com> <44ce43e2-6cf0-0e48-18eb-f02543d81bf4@gmail.com> <99e0ae2c-6b65-24e4-3d2b-1dff619a5daa@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Apr 16, 2020 at 12:18:33AM +0200, Jakub Narębski wrote: > On Wed, 15 Apr 2020 at 20:37, Derrick Stolee wrote: > [...] > > -->8-- > > From 89beb9598daabb19e3c896bbceeb0fc1b9ccc6ca Mon Sep 17 00:00:00 2001 > > From: Derrick Stolee > > Date: Wed, 15 Apr 2020 18:04:25 +0000 > > Subject: [PATCH] bloom: compute all Bloom hashes from lowercase > > > > The changed-path Bloom filters currently hash path strings using > > the exact string for the path. This makes it difficult* to use the > > filters when restricting to case-insensitive pathspecs. > > > > * I say "difficult" because it is possible to generate all 2^n > > options for the case of a path and test them all, but this is > > a bad idea and should not be done. "Impossible" is an appropriate > > alternative. > > > > THIS IS A BREAKING CHANGE. Commit-graph files with changed-path > > Bloom filters computed by a previous commit will not be compatible > > with the filters computed in this commit, nor will we get correct > > results when testing across these incompatible versions. Normally, > > this would be a completely unacceptable change, but the filters > > have not been released and hence are still possible to update > > before release. > > > > TODO: If we decide to move in this direction, then the following > > steps should be done (and some of them should be done anyway): > > > > * We need to document the Bloom filter format to specify exactly > > how we compute the filter data. The details should be careful > > enough that someone can reproduce the exact file format without > > looking at the C code. > > > > * That document would include the tolower() transformation that is > > being done here. > > Why not modify the BDAT chunk to include version of > case folding transformation or other collation algorithm > (other transformation).that is done prior to computing > the Bloom filter key? Though that might be unnecessary > flexibility... If this ends up being something that we want to do, I agree with Stolee's reasoning that this should be a breaking change. If we were, say, several months into having Bloom filters in a release and decided at that point to make the change, then: sure, supporting both by writing a bit in the BDAT chunk makes sense. But, we're many months away from that state yet, and so I don't think the cost of rebuilding what few commit-graphs exist with bloom filters in them today to support both ordinary and lower-cased paths in the filter. Anyway, I'm still not sold on this idea in general (nor do I understand it that others are), so I'll respond in more detail in another part of the thread... > For example the value of 0x00 in such field of BDAT > chunk header would mean no transformation, while > the value of 0x01 would mean per-character tolower() > or Unicode equivalent of it. > > Best, > -- > Jakub Narębski Thanks, Taylor