From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B341C35247 for ; Wed, 5 Feb 2020 15:11:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 40AD420702 for ; Wed, 5 Feb 2020 15:11:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EPrSA7L5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726416AbgBEPLr (ORCPT ); Wed, 5 Feb 2020 10:11:47 -0500 Received: from mail-qv1-f67.google.com ([209.85.219.67]:41647 "EHLO mail-qv1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726119AbgBEPLr (ORCPT ); Wed, 5 Feb 2020 10:11:47 -0500 Received: by mail-qv1-f67.google.com with SMTP id s7so1240768qvn.8 for ; Wed, 05 Feb 2020 07:11:46 -0800 (PST) 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=rHxWRomDtenn4xmIht0S78XhSRMl7TDnInYJ6kv62dU=; b=EPrSA7L5/fLzZla2j0tiZPnHOvlvoDAYseC4uPQYA7BzeT8rtIpemV/4xVxwtr0OcC 1PmeXQlnRA+1G7J0oTMwdn3+9dk1ATH8INRQWO0zc8UBrZsOE1MFPNeWo3j3NA6eUH4q 7d1i5TPEqV6MEatfXCK9+lTkrmIFAE3jjSds8dl7FqdQH6JBoUETqbYyEG8SvDFV2vZq RUGC2Kgp72Z7RL0ZTiQpEAjtTQIK03YL3RYmbY8O4sEkHN7ioSFkGjxrc/RaLV7vMxaW Z778Mz4uZUws0UIFG2dWa7BD078woisskK4+pNhLpfF5gK2fozOryiy7qQiTeNVszoBD rMhQ== 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=rHxWRomDtenn4xmIht0S78XhSRMl7TDnInYJ6kv62dU=; b=qEmXBOZ/Q9DM2idsR4Yk1FlORu+tS94H60OPRp9D17Q4AcHovpLQgM6RRRhO5yfERc fyqXPoRrkoA7b4XahSTKNr5+sDfZMb7MA4ITrVy3JoeTc7ME2BRvKgm31yIY3jBfPLTG GWDxmss+zQ0ZPDtcs13PAQGodBZJj/3MrBnI9+uvaDsKyhITdI76q+aOKOEW8mxsGD1O y7SLSjH9V3MDTsMYoFCXv/NWjTpv8iO7tw8JIajGl/q/L+tgplEYqiZxPHvQGxDGo930 MHOlryNrnxsMGOyXfDu0kb9D5ykQt3o5a+xFHXDklk42eJu6lQWKz8KZJsS0+QbqeX33 TpVg== X-Gm-Message-State: APjAAAXxwf23FsS2WRwVOCOvXDDMkhRzlY6p8sX7VS9uzzjzas6W5b27 l397gVh9TBZovWOs5HxaInU= X-Google-Smtp-Source: APXvYqzWZPlATePNFM4aTQtAyfXNk2NcSBinAweSfSXkO3abE9LgqXeKz9ym4nDqgo+18maqO7dCbw== X-Received: by 2002:a0c:f412:: with SMTP id h18mr33213716qvl.124.1580915505931; Wed, 05 Feb 2020 07:11:45 -0800 (PST) Received: from ?IPv6:2001:4898:6808:13e:c9b5:7cd5:1ee4:5066? ([2001:4898:a800:1010:7aeb:7cd5:1ee4:5066]) by smtp.gmail.com with ESMTPSA id t23sm11748qtp.82.2020.02.05.07.11.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Feb 2020 07:11:45 -0800 (PST) Subject: Re: [PATCH 09/10] name-rev: generate name strings only if they are better To: =?UTF-8?Q?Ren=c3=a9_Scharfe?= , Git Mailing List Cc: =?UTF-8?Q?SZEDER_G=c3=a1bor?= , =?UTF-8?Q?Martin_=c3=85gren?= , Junio C Hamano References: <084909f8-fefa-1fe0-b2ce-74eff47c4972@web.de> <77d1d053-8680-5cbe-9182-b6aec9e9b446@web.de> From: Derrick Stolee Message-ID: <3a59d8b4-3c3d-3812-9b7e-ac7e331ccd1c@gmail.com> Date: Wed, 5 Feb 2020 10:11:44 -0500 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:73.0) Gecko/20100101 Thunderbird/73.0 MIME-Version: 1.0 In-Reply-To: <77d1d053-8680-5cbe-9182-b6aec9e9b446@web.de> 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 2/4/2020 4:25 PM, René Scharfe wrote: > - if (create_or_update_name(parent, new_name, taggerdate, > - generation, distance, > - from_tag)) { > + parent_name = create_or_update_name(parent, taggerdate, > + generation, > + distance, from_tag); > + if (parent_name) { As someone unfamiliar with the name-rev code, it took me a while to see why the algorithm isn't exponential in complexity. It technically _is_, but it is of the form 2^{N / MERGE_TRAVERSAL_WEIGHT} = 2^{N / 65535} and only if we create a particularly nasty commit history that would never appear in the wild. But, the critical section is the block above. The confusing part was that create_or_update_name() returns NULL if the name is updated, but non-NULL if a better name is created. That makes it clear that this change is saving allocations. Thanks, -Stolee