Signed-off-by: Vivan Garg <gvivan6@xxxxxxxxx> --- .../More-Sparse-Index-Integrations.txt | 319 ++++++++++++++++++ 1 file changed, 319 insertions(+) create mode 100644 Documentation/More-Sparse-Index-Integrations.txt diff --git a/Documentation/More-Sparse-Index-Integrations.txt b/Documentation/More-Sparse-Index-Integrations.txt new file mode 100644 index 0000000000..a1812b4e64 --- /dev/null +++ b/Documentation/More-Sparse-Index-Integrations.txt @@ -0,0 +1,319 @@ +# More Sparse Index Integrations + +# Personal Information + +Full name: Vivan Garg + +E-mail: gvivan6@xxxxxxxxx +Alternate E-mail: v.garg.work@xxxxxxxxx +Tel: (+1)437-987-2678 + +Education: University of Waterloo (Canada) +Major: Computer Science and Financial Management (Double-Major) +Year: Rising Junior + +LinkedIn: https://www.linkedin.com/in/gvivan/ +GitHub: https://github.com/gvivan +Website: https://gvivan.me/ + +# Before GSoC + +## Synopsis + +I've chosen the "More Sparse Index Integrations" project idea from the +SoC 2023 Ideas page. The goal of this project is to integrate the +experimental "sparse-index" feature and "sparse-checkout" command with +existing Git commands. + +Git 2.25.0 introduced a new experimental `git sparse-checkout` command, +which simplified the existing feature and improved performance for +large repositories. It allows users to restrict their working directory +to only the files they care about, allowing them to ensure the developer +workflow is as fast as possible while maintaining all the benefits of a +monorepo. +(Bring your monorepo down to size with sparse-checkout [1], Stolee). + +The pattern matching process in Git's sparse-checkout feature becomes +expensive as the sparse-checkout file and repository size increase, +growing quadratically. This can result in billions of pattern checks +for large repositories. However, Git's new mechanism for matching based +on folder prefix matches drops the quadratic growth, matching M patterns +across N files in O(M+N*d) time, where d is the maximum folder depth of a file. +To further optimize the matching process, Git inspects files in a sorted +order instead of an arbitrary order. When Git evaluates a file path, it +checks whether the start of the folder path matches a recursive pattern exactly. +If so, it marks everything in that folder as "included" without doing any further +hashset lookups. Similarly, when Git detects the start of a folder that's outside +of the specified cone, it marks everything in that folder as "excluded" without +doing any further hashset lookups. This reduces the time to be closer to O(M+N) +(Bring your monorepo down to size with sparse-checkout [1], Stolee). + +[1]: https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/ + +The Git Fundamentals team at GitHub has contributed a new feature to Git called +the sparse index, which allows the index to focus on the files within the +sparse-checkout cone in a monorepo. The sparse index stores only the information +about the files within the sparse-checkout definition, instead of storing information +for every file at HEAD, which can make the index much larger in a monorepo. When +enabled with other performance features, the sparse index can have a significant +impact on performance (Make your monorepo feel small with Git’s sparse index [2], Stolee). + +[2]: https://github.blog/2021-11-10-make-your-monorepo-feel-small-with-gits-sparse-index/ + +The sparse index differs from a normal "full" index in that it can store directory +paths with the object ID for its tree object. It can be used to determine if an +entire directory is out of the sparse-checkout cone and replace all of its contained +file paths with a single directory path. The use of sparse index can significantly +reduce the size of the index, resulting in faster operations +(Make your monorepo feel small with Git’s sparse index [3], Stolee). + +[3]: https://github.blog/2021-11-10-make-your-monorepo-feel-small-with-gits-sparse-index/ + +Because "sparse-checkout" and "sparse-index" may potentially influence the logics of +other Git commands and the internal data structure of Git, some work is required to +optimize compatibility and user experience. That is exactly what my chosen idea proposed. + +## Benefits to Community + +By joining the community and working on this idea, I can collaborate with my mentor +and fellow community members to improve the user experience for people who are working +with large monorepos. Furthermore, I am committed to continuing my involvement beyond +the GSoC program, not only by contributing to the community but also by sharing my +experiences and mentoring future potential newcomers. + + +## Microproject + +t4121: modernize test style [4] +Status: WIP +Description: Test scripts in file t4121-apply-diffs.sh are written in old style, +where the test_expect_success command and test title are written on +separate lines. Therefore update the tests to adhere to the new style. + +## Other Contributions + +### Reviewing + +t9700: modernize test script [5] +Status: WIP +Description: I reviewed this patch and pointed the contributor in the right direction +by providing examples, links and mentioning the best practices. + +### Patches + +MyFirstContribution: add note about SMTP server config [6] +Status: WIP +Description: The documentation on using git-send-email previously mentioned the need +to configure git for your operating system and email provider, but did not provide +specific details on the relevant configuration settings. This commit adds a note +specifying that the relevant settings can be found under the 'sendemail' section of +Git's configuration file, with a link to the relevant documentation. The aim is to +provide users with a more complete understanding of the configuration process and +help them avoid potential roadblocks in setting up git-send-email. + +[4]: https://lore.kernel.org/git/CACzddJrZ8YdJ72ng3UpMGN9CJx0qW1+fZfyi3q01z2487V8fxw@xxxxxxxxxxxxxx/T/#md53157af31a3f347dd899679fafdea7fcaf7ecfc +[5]: https://lore.kernel.org/git/CADupsJPpZnjA=Pu_RZZZXy7Titj3UD7ppww48KvcHHHbrGx=rw@xxxxxxxxxxxxxx/T/#m122db9bdca463c12f0b9ccb259fd1d3229d75945 +[6]: https://lore.kernel.org/git/20230222011317.97943-1-gvivan6@xxxxxxxxx/ + + +### Related Work + +Prior works on the idea have been completed by my mentors and other community members, +and these works provide a good approximation of the approach I intend to take. Here +are some previous examples of commits: + +Integration with “mv” [7] +Integration with “reset” [8] +Integration with “sparse-checkout” [9] +Integration with “clean” [10] +Integration with “blame” [11] + +[7]: https://lore.kernel.org/git/20220331091755.385961-1-shaoxuan.yuan02@xxxxxxxxx/ +[8]: https://lore.kernel.org/git/pull.1048.v6.git.1638201164.gitgitgadget@xxxxxxxxx/ +[9]: https://lore.kernel.org/git/pull.1208.v3.git.1653313726.gitgitgadget@xxxxxxxxx/ +[10]: https://github.com/git/git/commit/1e9e10e04891a13e5ccd52b36cfadc55dfaa5066 +[11]: https://github.com/git/git/commit/add4c864b60766174ad4f74ba7be17e66d61ef16 + +# In GSoC + +## Plan + +Plan + +The proposed idea of increasing "sparse-index" integrations may appear straightforward +initially. However, after reviewing previous implementations, I have found that this +idea can present unforeseen difficulties for some functions. For example, to enable +"sparse-index," we must ensure that "sparse-checkout" is compatible with the target +Git command. Achieving this compatibility requires modifying the original command +logic, which can lead to other unanticipated issues. Therefore, I have incorporated +additional steps in the plan, to the steps proposed by the community and mentors, +outlined below to proactively address potential complications. + +1. Conduct an investigation to determine if a Git command functions properly with + sparse-checkout. This step is estimated to take approximately 7-14 days. + +2. Modify the logic of the Git command, if necessary, to ensure it functions + properly with sparse-checkout. Develop corresponding tests to validate the + modifications. This step is estimated to take approximately 7-14 days. + +3. Add tests to t1092-sparse-checkout-compatibility.sh for the built-in, focusing + on what happens for paths outside of the sparse-checkout cone. + +4. Disable the command_requires_full_index setting in the built-in and ensure + the tests pass. + +5. If the tests do not pass, then alter the logic to work with the sparse index. + +6. Add tests to check that a sparse index stays sparse. + +7. Add performance tests to demonstrate speedup. + +8. If any changes are made that affect the behavior of the Git command, update + the documentation accordingly. Note that such changes should be rare. + +Points 3-8 combined should take approximately 15-30 days. + +To summarize, each integration will follow a similar schedule to the one outlined +above. Therefore, without extending the timeline, we can expect to complete 2-3 i +ntegrations during the GSoC program period. + +Timeline + +Determining the exact time arrangement for each integration is difficult, as there +may be unforeseen challenges that arise during the process. However, based on my +estimation, I anticipate that each integration will take approximately 1.5 - 2 months +to complete, starting from May 29th. Please refer to the detailed breakdown of each +step in the plan section for a more accurate estimate. +The proposed integration schedule is as follows: + +• git describe +• git write-tree +• git diff-files + +This schedule is based on the order of difficulty outlined in GSoC 2023 Ideas. + +It's worth noting that each integration may require different amounts of time +and attention, and modifications to the schedule may be necessary as I delve +deeper into each command. Nevertheless, I am committed to delivering quality +results within the given timeframe. + +In summary, I anticipate that each integration will take an average of 1.5 months, +but I remain flexible and open to adjusting the schedule as needed to ensure the +success of the project. + +Availability + +I commit to responding to all communication daily and being available throughout +the duration of the program. While I will be taking some summer courses at my +university, I will not be enrolled in a typical full course load. As part of GSOC, +I plan to commit to a medium-sized project of 175 hours. I have experience managing +my time effectively while taking courses and working full-time internships in the +past. + +The program is officially 16 weeks long. To ensure timely completion of the project, +I plan to spend 8 hours per week until August 15th, which is when my semester ends. +From August 16th until September 1st, I plan to dedicate 8 hours per day to the project. +There are only three weeks during which I would prefer to focus on other things: +June 23rd-30th (midterm week) and August 1st-15th (finals season). However, as I will be +committing 8 hours per day following Aug 15th, it should be ample enough to make up for it. + +I am confident that I will have ample time to complete the project within the allocated +time frame. Additionally, I am hoping to continue working on the project even after +GSOC ends, as there are several functions that need to be implemented. + + +# After GSoC + +I recognize the value of having our GSoC participants continue to engage with +our community beyond the event. This is why I am committed to doing so myself. +Participating in open-source projects, especially with a community that supports +a widely-used development tool, is not only cool but also offers an opportunity +to learn and grow. By continuing to participate in this community, I believe +that I can make important contributions and continue to develop my skills. + +I am planning to establish an open source club at my university in the near +future. The University of Waterloo is known for its strong emphasis on +computer science and engineering, earning it the nickname "MIT of the North." +Given this, I believe that there will be a great deal of interest in the club +for a variety of reasons. Currently, there is another club called Blueprint +that provides a valuable opportunity for real-world development experience +through developing software products for charities. However, the entry process +for this club is extremely competitive. By contrast, I think that an open source +club would offer a similar experience but with a lower barrier to entry, thus +making it accessible to more motivated students. Additionally, given the +widespread use and vibrant community of Git, I plan to direct students to this +community and am confident that many will be interested in contributing to its +open source projects. + +# Some Credits to Myself + +I’ve previously completed three software developer internships and worked +with small startups to large sized companies. I am currently interning +with Morgan Stanley and am on the architecture team, working on a large +scale equity management software. + +I'm interested in open source development as a way to give back to the +community while also growing as a developer. My background in C programming +language has made me particularly interested in contributing to Git, which +is primarily written in C. I am also comfortable with concepts like memory +allocation, thanks to my experience with C programming. Furthermore, I have +studied shell scripting as part of my coursework, which makes me well-equipped +to handle the project's language requirements. Another personal motivation +for contributing to this project is that I have worked with monorepos before, +and given that it is used by many of the larger tech companies, I want to +learn more about it and help improve the user experience with it. + +Victoria mentioned that I was the first person to express interest in the +project this year, either directly or via the mailing list. In my spare time, +I've been contributing and reading documents while also working a full-time +job (internship) and taking one course at my university. I expect to have a +lot more time next term, so you can expect even more from me ;). Nonetheless, +I became familiar and comfortable with the contribution process by writing, +responding to, and auditing various types of patches in the community. + +With the patches I have submitted so far, I have been able to develop a deeper +understanding of Git internals, project structures, commonly used APIs, test +suites, required tech stacks, and coding guidelines. To further enhance my +comprehension of Git, I have either read or skimmed through several relevant +documents, including 'Submitting patches', 'Coding guidelines', +'Myfirstcontribution.txt', 'Git tutorial', 'Git everyday', 'readme', +'Hacking Git', drawing upon my prior knowledge where applicable. Additionally, +I have been referring to the book 'Pro Git' on an as-needed basis. Furthermore, +I have thoroughly read and referenced blogs such as 'Make your monorepo feel +small with Git's sparse index [12]', 'Bring your monorepo down to size with +sparse-checkout [13]', and 'Commits are snapshots, not diffs [14]'. The +advantage of having prior knowledge and experience with my proposed project +idea is that I am well-prepared to tackle any upcoming challenges. + +[12]: https://github.blog/2021-11-10-make-your-monorepo-feel-small-with-gits-sparse-index/ +[13]: https://github.blog/2020-01-17-bring-your-monorepo-down-to-size-with-sparse-checkout/ +[14]: https://github.blog/2020-12-17-commits-are-snapshots-not-diffs/ + +# Closing remarks + +I am very motivated for this project because I have previously worked with +monorepos and will most likely have to work with them again in my future +internships. As a result, I intend to continue working on remaining c +ommands after GSOC whenever I have free time. + +I'd like to state that I'm a genuinely enthusiastic open-source newcomer +who is very much looking forward to this opportunity. I am grateful for +the opportunity to contribute to Git's development, and I am committed to +working diligently to strengthen the open-source ecosystem. My ultimate goal +is to use this opportunity to bring new energy and ideas to the table, and to +make meaningful contributions that benefit the entire community. + +I am grateful for the community's support, especially Victoria's guidance +and feedback. She promptly replied to my inquiries and provided me with +several resources that were instrumental in helping me get started on the +project. I am truly humbled by the dedication and hard work that the +community puts in to nurture and enhance this ecosystem, and I feel +fortunate to have received such warm and welcoming support as a new +contributor. It is an honor to be a part of this community and to +work towards advancing its mission. + +Thank you so much for reading through my proposal! + +Kind Regards, +Vivan Garg + -- 2.37.0 (Apple Git-136)
