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=-3.6 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,NICE_REPLY_A, 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 169FC1F4B4 for ; Thu, 8 Apr 2021 09:10:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229741AbhDHJKZ (ORCPT ); Thu, 8 Apr 2021 05:10:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229600AbhDHJKY (ORCPT ); Thu, 8 Apr 2021 05:10:24 -0400 Received: from mail-pj1-x1030.google.com (mail-pj1-x1030.google.com [IPv6:2607:f8b0:4864:20::1030]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4999FC061760 for ; Thu, 8 Apr 2021 02:10:12 -0700 (PDT) Received: by mail-pj1-x1030.google.com with SMTP id il9-20020a17090b1649b0290114bcb0d6c2so2817813pjb.0 for ; Thu, 08 Apr 2021 02:10:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-transfer-encoding:content-language; bh=2qUuxED9OhBhALUcnxWZN3SXdFHEXmPhb2sj+6lntlw=; b=katYRSIFC1slkQpESPHQI+geO+gFtFftSI6VTRwyYuBHJBKHQKCSUHrsN8fl7u9dA8 JPi/rLf9Tpf9ZsG9WrnTgyDrK8aXITLCV1vETLagP/Gh5e9J/knXRylCm0mmrbFyLTqo 9+GmqcHcb3ldJLkWDrrAbtLFzDXPSo0m6d6qRyA8y6MTJzPnSapxcSf18yaXuUBNZbu2 GEJme54fshgLcQ/KUFl/8Mw4KIKrB44gUFrfqrE4jk+yRN4xylEA3UhSFD70qFFxnsMg OAupY6ug6gCFXw2mid+6q2hlqLcapIF5mbOXL50htJ8H/yNRpsm9i+3oO0HHKl37QGI1 keng== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=2qUuxED9OhBhALUcnxWZN3SXdFHEXmPhb2sj+6lntlw=; b=ObDaCfdZI1JJfGkmxRjnweV74V7gclaIvv+wvkHu7rq5O4o8uV10CZ8g4UBRg5M9Hz KMFe2tIdoOFL1B/rgxmebDM5eZ4mEW3G93a3GwFGOuUoJXdiwxQ/Rjol1AsmX+AQDRkJ YENd5NnReEZFnkTG+Lw9cuCkQMGLYwoiQ1qWIGBtvnQOvsOaigVo435C5yjBP7f/gT83 1idTaxZmifAC7tY9U0ovzSjDw3pJpwG5drfmDYil2GvK1sFst/KRWIAjOhZPYA4u6JQ0 4LdSkUiJbmo73Xa9vzpImDncumMsiN/pvEUW2X6mAD15kW1ZFpggOPPySzqKO08NqGC6 4sAQ== X-Gm-Message-State: AOAM533I54CPMXFQ4lnts5NuRLJE8oIaeX3meEGqQhtPJfUJg42EOH29 pJuNHrnAmMJbCLbBdldnEbRW7iOhhKiA6g== X-Google-Smtp-Source: ABdhPJwTuJfR7PliJ/Q6iVe36kWN0fC17wR56c1y21glHl+U+yyHRNU6vYKmolEKVS4vvn3Ad//D4g== X-Received: by 2002:a17:90b:4d0a:: with SMTP id mw10mr7313832pjb.51.1617873011168; Thu, 08 Apr 2021 02:10:11 -0700 (PDT) Received: from [192.168.0.107] ([103.112.34.122]) by smtp.gmail.com with ESMTPSA id fa6sm7780849pjb.2.2021.04.08.02.10.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Apr 2021 02:10:10 -0700 (PDT) Subject: Re: [GSoC] Draft Proposal (Convert submodule to builtin) To: Christian Couder , git@vger.kernel.org References: <195bf718-6226-43c9-8c58-167388d3d99b@gmail.com> <769c7c48-a518-2636-10be-1479997e8f15@gmail.com> From: Chinmoy Chakraborty Message-ID: <374a2b8a-0d59-4546-eab3-7229943217ba@gmail.com> Date: Thu, 8 Apr 2021 14:41:38 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org This is the V2 of the draft proposal after applying the changes suggested by Christian Couder and Kaartik Sivaraam. Thank you for you reviews :). ================================================== Convert submodule to builtin March 2021 ================================================== ##Personal Information## Name - Chinmoy Chakraborty E-mail - chinmoy12c@gmail.com Github - https://github.com/chinmoy12c Linkedin - https://www.linkedin.com/in/chinmoy12c/ Major - Information Technology Time Zone - IST (UTC+05:30) ================================================= ##Work Environment## I am fluent in C, Java, Python, and Shell script. I use Git as my VCS, Visual Studio Code as my primary code editor, and Kali Linux as my primary OS. ================================================= ##Git Contributions## [Microproject] Replace instances of `the_repository` with ‘r’. (Learning the ropes) Pull request: https://github.com/gitgitgadget/git/pull/915 Mailing List: https://lore.kernel.org/git/pull.915.git.1616701733901.gitgitgadget@gmail.com/ [column, range-diff] downcase option description Pull request: https://github.com/gitgitgadget/git/pull/920 Mailing List: https://lore.kernel.org/git/pull.920.git.1616913298624.gitgitgadget@gmail.com/ [Documentation] updated documentation for git commit --date Pull request: https://github.com/gitgitgadget/git/pull/918 Mailing List: https://lore.kernel.org/git/pull.918.git.1616926790227.gitgitgadget@gmail.com/ ================================================= ##Project Outline## A few components of git, like `git-submodule.sh` are in the form of shell scripts. This causes problems in production code in multiple platforms like windows. The goal of this project is to convert the shell script version of `git-submodule.sh` to portable c code. The end goal would be to completely remove `git-submodule.sh` and rename `builtin/submodule--helper.c` to `builtin/submodule.c` so that the `git submodule` is fully implemented using C. ================================================= ##Why is the project required?## "Issues with the portability of code" The submodule shell script uses shell commands like `echo`, `grep`, `test`, `printf` etc. When switching to non-POSIX compliant systems, one will have to re-implement these commands specifically for the system. There are also POSIX-to-Windows path conversion issues. To fix these issues, it was decided to convert these scripts into portable C code. "Large overhead in calling the command" The commands implemented in shell scripts are not builtins, so they call `fork()` and `exec()` multiple times, hence creating additional shells. This adds to the overhead in using the commands in terms of time and memory. "No access to low-level API" The shell commands don’t have access to low level commands like `git hash-object`, `git cat-file` etc. As these commands are internally required for submodule commands to work, the shell script needs to spawn a separate shell to execute these commands. ================================================= ##How have I prepared?## I have gone through all the previous works and read through their code to make myself accustomed to the intricacies of the code. I have also structured my workflow based on the observation of the previous discussions on those patches, and taken into consideration the issues faced previously. ================================================= ##Previous Work## A large part of the `git submodule--helper.c` has already been converted by Stefan Beller​, Prathamesh Chavan​ in his GSoC project in 2017, and Shourya Shukla in his GSoC project in 2020. This is the list of already ported commands. set-branch set-url summary status init deinit update foreach sync absorbgitdirs ================================================= ##Work to be done## The only command that is left to be ported is `git submodule add`. The previous work on this by Shourya Shukla in GSoC 2020, did not reach a successful merge due to some issues in design and the patch was dropped as it had been stale for long. See: https://github.com/git/git/blob/1861aa482a38ae84f597cede48167ab43e7e50a3/whats-cooking.txt#L1158-L1169 The first and foremost aim of the project will be to finish porting the `add` command. Thereafter, the end goal would be to completely replace the shell script (git-submodule.sh) with an efficient c code. Before porting the `git submodule add` command the initial work would be dedicated to the implementation of small helper functions in the form of small patches, which would be directly used by the `add` command. This workflow is based on the suggestion by Junio C Hamano on the thread: https://lore.kernel.org/git/xmqqd01sugrg.fsf@gitster.c.googlers.com/. This workflow would help in the following ways: - It would help in sending patches in a small digestible format. - It would help the reviewers easily review those small units   of patches in a single sitting. - It would help keep small logical units of code in different clean commits. An additional test tweak would also be required in `t7400-submodule-basic.sh`, to prepend the keyword ‘fatal’ since the command dies out in case of absence of commits as pointed out by Kaartic Sivaraam on the thread: https://lore.kernel.org/git/ce151a1408291bb0991ce89459e36ee13ccdfa52.camel@gmail.com/. The following helper functions would be required to be implemented - - A function to guess the path name from the repository string.   Example prototype: static char *guess_dir_name(const char *repo)   Returns the path name. - A function to assure repo is absolute or relative to parent.   Example prototype: static char *get_real_repo(const char *repo)   Returns the correct repo name. - A function for normalizing path, that is, removing multiple   //; leading ./; /./; /../; trailing / .   Example prototype: static char *normalize_path(const char *path) - A function to check if the path exists and is already a git   repo, else clone it.   Example prototype: static int add_submodule(struct add_data *info)   `add_data` is a struct which stores the config of the submodule. - A function to set the submodule config properly.   Example prototype: static void config_added_submodule(struct add_data *info) - After implementation of all these helper methods, the main   `module_add()` function would be implemented using the helper   functions listed above as well as those helper functions which   are predefined. ================================================= ##Project Timeline## "Present Day - May 17" I’ll utilize this time in exploring the codebase more properly and solving more issues, which would help me properly familiarize myself with the codebase. I’ll also try to structure a more solidified, detailed workflow and come up with a draft patch based on the previous work and discussions. "May 17 - June 7 (Community bonding period)" - Get familiar with the community. - Discuss proper workflow with mentors. - Make changes in the timeline, if necessary. - Discuss the structure of the series of patches. "June 7 - June 25 (Initial coding phase)" - Finish implementation of the helper functions. - Work on a proper structure of the implementation of the   `submodule add` command and implement additional helper   functions if required. - Update proper documentation of the helper functions. "June 25 - July 5 (Binding the code)" This time would be used to code the main `submodule add` command using all the helper functions implemented in the initial phase of coding. This includes binding all the code together and then completing the command through incremental reviews. Also, the necessary documentation would be updated parallelly. "July 5 - July 12 (Initiate porting of command)" - Discuss how to go about porting the entire submodule script. - Initiate porting of the `git-submodule.sh` script. "July 12 - July 16 (Phase 1 evaluation)" "July 16 - July 26 (Semester exams)" I will be taking my semester examinations during this time. As such, I’ll try to be in touch with the mentors and take out as much time as possible (around 20 hours a week). "July 26 - August 10 (Porting the complete script)" This period would be utilized in the complete conversion of `git-submodule.sh` into c code and combine it with `submodule--helper.c` to make a single `builtin/submodule.c`. As I’ll be completely free from academics during this period, I’ll try to compensate as much time as possible for the above period of July 16 - July 26. "August 10 - August 16 (Final review and evaluation)" - Final review by the mentors. - Apply necessary changes and touch-ups. - Updating documentation, if any left. "August 16 - August 23 (Submission of final report)" Additionally: There are places in the original shell script and c code tagged as `NEEDSWORK`. My aim would be to resolve these issues within the GSoC period if time permits. ================================================= ##Post GSoC## After the GSoC period, I plan to continue my contributions for git and look for other issues to work on. I’d look into the conversion of other commands which are pending conversion, as well as work on the `NEEDSWORK` part of the code (If I’m unable to finish it within the GSoC period itself). I plan on mentoring new contributors to git and help the contributors by doing code reviews and solving their doubts and helping them out. Regards, Chinmoy Chakraborty.