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 E5F2A1F751 for ; Thu, 16 Apr 2020 00:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391845AbgDPA5A (ORCPT ); Wed, 15 Apr 2020 20:57:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391755AbgDPA4n (ORCPT ); Wed, 15 Apr 2020 20:56:43 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D0474C061A0C for ; Wed, 15 Apr 2020 17:56:42 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id a22so619926pjk.5 for ; Wed, 15 Apr 2020 17:56:42 -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:in-reply-to; bh=OxJO5PJ++NuJw9Ls544drlDjZtdR2JIYwv/b+N5n+jo=; b=NCGuF08ipllyUhsMy0DiQw9d8MDotDCS9d173AvsR3qqSpDDFFhnlom4o+lIFLlDIc eUW/clFXYuVaANV2BK0Cq0RhsPE93AO/ZShA50hDO4xKGPErGJdgSTIey1i6WWhJcfHU YYdvmLkbXeH0GzgtUthLopxKyQd3AV0OHoNOakFv2vPKyY9vDgfuZXCzUilJOIdjoDTw 1kFB1Fk59uWpWf6dKjHYEQaUswR8W14xirR481D9lubOzK+BZe/nFKBaAmu0YqUIoo1w w1MYVfuWSsXbK+z9gbGEzP5N/Rw9VMFt4Qoylykb5SFERTqENTxuYfHZ1Fx4K6688Wdx 4Znw== 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:in-reply-to; bh=OxJO5PJ++NuJw9Ls544drlDjZtdR2JIYwv/b+N5n+jo=; b=KTtL4K1oux3Vo00FqDQ4Z2brAgGu78OisMFZoODqhGBuEW5aMjjmFcOyJprXQbLCBA XFwKJt9BYr0XdCxgLg/gkQkojysEwFFaYi6Gu11OXVTHyfhdPOuGdGCWkmTvbttEuW6K tpEOcHbVRtx+qwxG2SR/gUE9zM7tu/ZYejiHfUyrcht5/y7XGzNsbnBn4vjlQ4FIBOSw dLDyY0uRzZTYhS54nZbdTj92aZPV76xW+JyiPUu/e1rat5cdLEbWKcHO3kcF1XSTDqEg 3W7uGbpOD/bOhamALJY2JiQjUo39X5BDzcRLuFCgJ41KXfY/0Z+4yfynuk5+mtQoKbDu 8XZQ== X-Gm-Message-State: AGi0PuZGTSfPF2+AjcWnuJ4hjzX45g3WUQ0AvJsv4T3RIWHe6fpwHsxA lP/pa69R7eTYGMoQVCQ+vfYZnQ== X-Google-Smtp-Source: APiQypKYK8F3QzlItqIVfCk9kubLDsYM5xdwLXGPuplyzRnhe7Ar7OxKNYS2RsZaAcvi42RoX8GiXQ== X-Received: by 2002:a17:902:694a:: with SMTP id k10mr7835299plt.82.1586998602280; Wed, 15 Apr 2020 17:56:42 -0700 (PDT) Received: from localhost ([8.44.146.30]) by smtp.gmail.com with ESMTPSA id x7sm394154pfn.165.2020.04.15.17.56.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2020 17:56:41 -0700 (PDT) Date: Wed, 15 Apr 2020 18:56:40 -0600 From: Taylor Blau To: Junio C Hamano Cc: Derrick Stolee , Derrick Stolee via GitGitGadget , git@vger.kernel.org, me@ttaylorr.com, jnareb@gmail.com, garimasigit@gmail.com, Derrick Stolee Subject: Re: [PATCH 1/3] revision: complicated pathspecs disable filters Message-ID: <20200416005640.GC36156@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 In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Wed, Apr 15, 2020 at 02:25:48PM -0700, Junio C Hamano wrote: > Derrick Stolee writes: > > > 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. > > Sure, it hasn't even hit 'next' yet. > > But I think we are both sort-of leaning towards concluding that it > does not help all that much. So I think it is OK. Yeah, I think that the only thing that it is potentially helping is the :(icase) magic. In a repository that doesn't have colliding paths in case-insensitive filesystems (i.e., having both 'foo' and 'FOO' in the same tree), this doesn't seem to be obviously hurting anything. But, it is at least semi-harmful to repositories that do have such trees, since we now can't answer "probably yes" or "definitely not" for colliding paths unless both produce the same fingerprint. That seems like a clear downside. Now, how common is that against people who would benefit from changed-path Bloom filters in their commit-graphs? I don't know one way or the other. But, the upside seems to be minimal compared to the potential cost, so I think that it may be better to just leave this one alone. > > TODO: If we decide to move in this direction, then the following > > steps should be done (and some of them should be done anyway): > > Even if we decide not to do this "downcase before hashing" thing, we > should document how exactly we compute, I think. > > And if we decide do change our mind later, it is not the end of the > world. We should be able to use a different chunk type to store the > filters computed over downcased paths. > > > * 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. > > As the tree-diff comparison done internally while running "git > blame" does not take an end-user specified pathspec in any > meaningful way, this does not matter in practice, but there is > another possible complication we would want to consider when we > extend the support to "git log" and friends---negative pathspecs > (e.g. "git log ':(exclude)COPYING'"). A commit that cannot possibly > have touched the COPYING file would be eligible for output without > actually running tree-diff between it and its parent (as long as the > trees of the two commits are different, we know it must be shown). > > Thanks. Thanks, Taylor