[GSoC] [RFC] Project Proposal: Refactoring in order to reduce Git's global state

From: Anthony Wang <anthonywang513@gmail.com>

Hi all,

I'm interested in working with Git over the summer to "Refactor in Order to Reduce Git's Global State." My main motivation for choosing this idea is that improving Git's environment handling will enhance long-term maintainability and scalability, and allow for multiple-repository interactions.

This is the first version of my proposal. I would love to receive feedback on the content or structure, especially on the points pertaining to the actual implementation of the project and planned work. I will also discuss my past experience, and speak on why I believe I will be able to effectively contribute in a sustainable way to this large undertaking. Thanks!

Note - I am still waiting for feedback on my Microproject, and would 
love to discuss how my patch contents or formatting could be improved!
Patch: https://public-inbox.org/git/20250402081545.94784-1-anthonywang03@icloud.com/

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# Refactoring in Order to Reduce Git’s Global State

### Personal Info
Name: Anthony Wang
Timezone: Eastern Time (ET)/UTC -5
GitHub: https://github.com/wang-anthony03
LinkedIn: https://www.linkedin.com/in/anthonywang03/

## About Me

My name is Anthony Wang, and I am a 3rd year Computer Science student at the University of Virginia. I have experience in software engineering and development, particularly in C, Python, and shell scripting. This is my first time working with open source software, and I am incredibly excited to contribute to Git, as I have always wanted to work on developing the tools that I use everyday.

My background includes building scalable automation tools and contributing to infrastructure projects at Verizon. I was able to work with large codebases, and I learned the importance of clean, well-documented code, as well as the challenges of tech-debt leading to difficulties in maintaining code.

## Previous Experience

- Experience using Git extensively in academic and personal projects.
- Experience working with C as the main language for multiple Computer 
Systems courses.
- Developed a text editor in C: https://github.com/wang-anthony03/Quill

## Project Proposal

### Objective This project aims to modernize Git's environment handling by refactoring the environment.c code to reduce the reliance on global state. The goal is to move environment variables and configuration settings from the global scope into appropriate local contexts, primarily within struct repository and struct repository_settings. This architectural improvement will:

- Enhance code maintainability by making dependencies explicit.
- Reduce the risk of unintended side effects from global state 
modifications.
- Improve Git's ability to handle multiple repositories within the same 
process.

### Expected Project Size: 90 Hours

## Key Tasks

1. Identifying Global State Variables
- Analyze environment.c and related files to locate global variables.
- Categorize these variables based on their use cases and potential 
migration targets.
- Write Documentation listing all desired variable migration, allowing 
for community contribution.
- Discuss prioritization with the community and designate priority of 
tasks.

2. Refactoring Process
- Move identified global variables into struct repository or struct 
repository_settings.
- Ensure proper initialization and access mechanisms to maintain 
current behavior.
- Updating Affected Code Paths
- Modify functions and modules that rely on the old global state.
- Ensure all relevant operations correctly pass repository-specific 
context.

3. Testing and Validation
- Run Git's extensive test suite to verify functionality remains intact.
- Update or create new tests as needed to cover refactored components.

4. Documentation
— Document changes in Git's developer notes.
— Provide clear explanations for new structures and access patterns.

5. Challenges and Considerations
- Ensuring backward compatibility and avoiding regressions.
- Handling dependencies between different parts of the codebase that 
rely on global state.
- Keeping performance overhead minimal while introducing structured 
state management.

## Schedule
1. **Now -- May 5th**: Exploration of codebase
- Research and familiarize with environment.c and related code. 
- Identify global variables to refactor. 
- Engage with the Git community for feedback.

2. **May 6th -- June 1st**: Community bonding
- Get in touch with the mentors;
- Present to the community a first list of variable migrations;
- Receive feedback from the community and modify project plans;
- Present potential changes to ensure they align with community goals;

3. **June 2nd -- July 7th**: First coding period
- Eliminate dependencies on “the_repository” following priority;
- Identify possible patterns in refactoring and document for future 
contributors;

4. **July 8th -- August 10th**: Second coding period
- Move other global variables into local repository contexts;
- Identify possible patterns in refactoring and document for future 
contributors;

5. **August 11 -- August 25th**: Documentation period
- Finalize and refine changes;
- Document changes, the process, and outline future work regarding 
reducing the global namespace;

## Availability I will be working over the summer, but regularly code and study outside of work/school hours. I will be dedicating all of this extra time towards this project, but I acknowledge that I will not be able to spend an incredibly large amount of time, thus I have chosen my expected project size to be 90 hours. I will be fully available outside of working hours to this task, and will set up a compatible schedule with my mentor(s) in order to ensure that an effective line of communication is established.

I appreciate your time in reviewing this proposal and look forward to your feedback! Thank you,

Anthony Wang (He/him/his)