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=-3.9 required=3.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 6050B1F953 for ; Thu, 11 Nov 2021 20:33:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233588AbhKKUf6 (ORCPT ); Thu, 11 Nov 2021 15:35:58 -0500 Received: from pb-smtp2.pobox.com ([64.147.108.71]:54193 "EHLO pb-smtp2.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233372AbhKKUf5 (ORCPT ); Thu, 11 Nov 2021 15:35:57 -0500 Received: from pb-smtp2.pobox.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 59F08F235A; Thu, 11 Nov 2021 15:33:06 -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=MhmUIYIZoMqeg/u422LKcjWP/zdu0YgU/UOp50 e1Keo=; b=vnM0/kl2u55kIqFMwFdr3VQZ4nX0i8x4U3SgRk2VadrbNvfmt5A9bB +ejsE+WmJKHZMkPcvrm98Py3QrNTZm3GT46RBC7i7RUbmQ0laga6br4W1mXl87x/ ABz9OOKAyf8VTxMpTXK6OFznRJhYB/yeF+fGv0qVOzOi5KeaGT1zs= Received: from pb-smtp2.nyi.icgroup.com (unknown [127.0.0.1]) by pb-smtp2.pobox.com (Postfix) with ESMTP id 39CB1F2358; Thu, 11 Nov 2021 15:33:06 -0500 (EST) (envelope-from junio@pobox.com) Received: from pobox.com (unknown [104.133.2.91]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by pb-smtp2.pobox.com (Postfix) with ESMTPSA id 047F3F2355; Thu, 11 Nov 2021 15:33:04 -0500 (EST) (envelope-from junio@pobox.com) From: Junio C Hamano To: Jeff King Cc: Patrick Steinhardt , git@vger.kernel.org Subject: Re: [ANNOUNCE] Git v2.34.0-rc2 References: Date: Thu, 11 Nov 2021 12:33:03 -0800 In-Reply-To: (Jeff King's message of "Thu, 11 Nov 2021 15:23:08 -0500") 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: 92B4CBC4-432E-11EC-B080-CD991BBA3BAF-77302942!pb-smtp2.pobox.com Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Jeff King writes: > On Thu, Nov 11, 2021 at 09:32:29AM -0800, Junio C Hamano wrote: > >> ... So in this particular example, it would not matter if the >> new unsorted traversal is subtly broken (I think the extent of the >> damage is similar to making the SLOP problem deliberately worse), >> but I am not sure if there are other failure modes that would yield >> outright incorrect result. > > Yes, I think that framing is right: it is making SLOP much worse. We > could similarly have had bogus timestamps in those commits which would > cause the same outcome. So in that sense it is nothing new. On the other > hand, I wonder how often it will cause extra traversal work (keeping in > mind that this commit traversal is just the first stage; after we find > the commits, then we talk all of their trees, which is the more > expensive part). > > For the case of adding new commits directly on top of another branch, I > think there would be no change. But any time you have to walk down to a > common fork point (e.g., imagine I made a new branch forked from an old > bit of history), we may fail to find that. I haven't quite constructed > an example, but I have a feeling we could end up walking over > arbitrarily long segments of history. > ... > I'd be curious to hear Patrick's thoughts on the whole thing. Yes. I'm tempted to wait for him to chime in.