On Sat, Apr 3, 2021 at 4:13 PM Chinmoy Chakraborty <chinmoy12c@xxxxxxxxx> wrote: > > Here is a textual format of the draft proposal. > > > Convert submodule to builtin > March 2021 > > ================================================== > ##Personal Information## > > > Name - Chinmoy Chakraborty > E-mail - chinmoy12c@xxxxxxxxx > 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@xxxxxxxxx/ > > > [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@xxxxxxxxx/ > > > [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@xxxxxxxxx/ > ================================================= Ok. > ##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 s/c/C/ > to completely remove `git-submodule.sh` and rename > `builtin/submodule--helper.c` to `builtin/submodule.c`. You could add something like "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. > ================================================= Ok. > ##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 > was kicked out because it has been stale for so long. Maybe you could explain a bit what "kicked out" means, or replace it with something more explicit, for people who don't know well how Git development works. > The first > and foremost aim of the project will be to finish porting this > command. You mean the "add" sub-command, or the full "submodule" command? > Thereafter, the end goal would be to completely replace > the shell script (git-submodule.sh) with an efficient c code. s/c/C/ > 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@xxxxxxxxxxxxxxxxxxxxxx/. > > 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. Yeah, nice! How does this compare with Shourya's work? Will this avoid the design issues in Shourya's work? > 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. > > > The following helper functions would be required to be implemented - > > - A function to guess the directory name from the repository string. > - A function for normalizing path, that is, removing multiple > //; leading ./; /./; /../; trailing / . > > - A function to check for tracked directories properly as pointed > out by Kaartic Sivaraam on the thread: > https://lore.kernel.org/git/ce151a1408291bb0991ce89459e36ee13ccdfa52.camel@xxxxxxxxx/. > > - A function to check if the path exists and is already a git > repo, else clone it. > > - A function to set the submodule config properly. Nice! Maybe you could give an example and tell: - how you would name one of the above function, - what would be its arguments, - perhaps how you would test it ... > - 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. > ================================================= Ok, I will review the other parts later. Thanks!
