* [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state
@ 2025-03-26 5:26 Ayush Chandekar
2025-03-28 13:06 ` shejialuo
` (2 more replies)
0 siblings, 3 replies; 14+ messages in thread
From: Ayush Chandekar @ 2025-03-26 5:26 UTC (permalink / raw)
To: git; +Cc: ps, karthik.188, shejialuo, christian.couder, shyamthakkar001
Hello,
This is my GSoC 2025 proposal for the project "Refactoring in order to reduce Git’s global state".
You can view docs version here:
https://docs.google.com/document/d/1tJrtWxo1UGKChB3hu5eZ-ljm0FtU_fsv0TnIRwu3EKY/edit?usp=sharing
---------
Refactoring in order to reduce git’s state
My Information:
---------------
Name: Ayush Chandekar
Email: ayu.chandekar@gmail•com
Mobile No: (+91) 9372496874
Education: UG Sophomore, IIT Roorkee
Github: https://github.com/ayu-ch
Blog: https://ayu-ch.github.io
About me:
---------
I'm Ayush Chandekar, a UG Sophomore studying at Indian Institute of
Technology, Roorkee. I like participating in various software development
and tech-development endeavors, usually hackathons, CTFs, and projects at
SDSLabs. SDSLabs is a student-run technical group that includes passionate
developers and designers interested in various fields and involved in multiple
software development projects that aim to foster a software development
culture on campus. Being a part of this group has exposed me to different
software development methodologies, tools and frameworks and helped me become
comfortable contributing to an open-source project with multiple contributors.
Some open-source contributions I made here are: [1], [2] & [3]
I see this project as a meaningful opportunity to deepen my involvement in
the Git community and to build a foundation for continued contributions to
open source development in the future.
Overview:
---------
Git currently uses a global object called `the_repository`, which refers to a
single instance of `struct repository`. Many internal functions rely on this
global object rather than accepting a `struct repository` as an explicit
parameter. This design inherently assumes a single active repository,
making it difficult to support multi-repository use cases and obstructing
the long-term goal of libification of Git.
A key architectural limitation is that while `struct repository` encapsulates
some repository-specific information, many important environment variables
and configuration settings that logically belong to a repository are still
stored as global variables, primarily in `environment.c`, not within the
`repository` struct. As a result, even if multiple repositories were to
exist concurrently, they would still share this global state, leading to
incorrect behavior, race conditions, or subtle bugs.
This project aims to refactor Git’s environment handling by relocating
these global variables into appropriate local contexts primarily into
`struct repository` and `struct repo_settings`. This change will not
only make the environment state repository-specific, but also improve the
modularity and maintainability of the codebase. The work involves identifying
environment-related global variables, designing a suitable structure to
house them within the repository context, and updating all affected code
paths accordingly.
The difficulty of this project is medium, and it is estimated to take
175 to 350 hours.
Pre-GSOC:
---------
I started exploring Git’s codebase and documentation around the end of
January, familiarizing myself with its structure and development practices. I
submitted a microproject, which helped me navigate the code and contribution
workflow.
After selecting the project on refactoring Git’s state, I studied the
surrounding code and reviewed past patches ([4], [5], [6], [7], [8] & [9])
to understand the reasoning behind previous changes. To better prepare
for the GSoC timeline, I also submitted a patch related to the project,
gaining hands-on experience with both the implementation details and the
submission process.
Patches:
--------
+ (Microproject) t6423: fix suppression of Git’s exit code in tests
Thread:
https://public-inbox.org/git/20250202120926.322417-1-ayu.chandekar@gmail.com/
Status: Merged into master
Commit Hash: 7c1d34fe5d1229362f2c3ecf2d493167a1f555a2
Description: Instead of executing a Git command as the upstream component of
a pipe, which can result in the exit status being lost, redirect
its output to a file and then process that file in two steps to
ensure the exit status is properly preserved.
+ midx: implement progress reporting for QSORT operation
Thread:
https://public-inbox.org/git/20250210074623.136599-1-ayu.chandekar@gmail.com/
Status: Dropped
Description: Add progress reporting during the QSORT operation in
multi-pack-index verification. While going through the code,
I found this TODO, which I thought was interesting however my
approach assumed that the qsort() operation processes elements
in a structured order, which isn't guaranteed.
+ Stop depending on `the_repository` for core.attributesfile
Thread:
https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
Status: WIP, needs more discussion.
Description: This patch refactors access to the `core.attributesfiles`
configuration by moving it into the `repo_settings` struct.
It eliminates the global variable `git_attributes_file` and
updates relevant code paths to pass the `struct repository`
as a parameter.
Proposed Plan:
--------------
I have been reviewing global variables across the codebase to understand their
dependencies and impact. To do this, I examined `config.c` and cross-referenced
it with `environment.c` to see how these variables are currently managed. The
goal of this project is to eliminate global variables by moving their
configurations into repository-specific settings. This involves:
- Identifying all occurrences of these global variables.
- Removing dependencies on `the_repository`.
- Updating function signatures to pass `struct repository` explicitly.
- Replacing global variable references with repository-scoped configurations.
Instead of adding all variables directly into `repo_settings`, we can group
related variables into specialized structs (e.g., `performance_config`,
`behaviour_config`, `whitespace_config`) and embed these within `repo_settings`.
This approach ensures a more modular and maintainable design while keeping
`repo_settings` manageable.
I have also created a diagram explaining this structure in [10].
With this approach, I can structure the patch series by grouping the refactoring
of related variables within specific structs. This will help maintain a clean and
organized codebase while also making the development and review process more
systematic and efficient.
One key challenge is determining which variables should be part of
`repo_settings` and which should remain separate. While working on the patch to
refactor access to `core.attributesfile`, I received feedback from Junio that not
all global variables should be blindly moved into the `repo_settings` struct.
This reinforced the need to carefully assess which variables belong in `repo_settings`
and which should be handled differently.
This plan is flexible and may be refined through multiple iterations as I receive
feedback from the community and reviewers.
Timeline:
---------
Pre-GSOC:
(Until 8 May)
- Explore the codebase more, focusing on environment-related code paths.
- Document how each global variable is used and how it can be moved to
repository settings.
- Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
----------
Community Bonding:
(May 8 - June 1)
- Engage with mentors to discuss different environment variables, their
dependencies, and the best approach for refactoring.
- Finalize an implementation plan based on discussions.
- Since I will be on summer vacation, I can start coding early and make progress
on the project.
----------
Coding Period:
(June 2 - August 25)
- Refactor global variables, replacing them with repository-scoped
configurations.
- Modify function signatures to pass `struct repository` explicitly instead
of relying on `the_repository`.
- Categorize variables into specialized structs to improve modularity and
maintainability.
- Continuously submit patches for review and incorporate feedback from mentors
and the community.
- I plan to write weekly blogs which will document what I did in the whole
week.
----------
Final Week:
(August 25 - September 1)
- Write a detailed report on the entire project.
- Fix bugs if any.
- Reflect on the project, noting challenges faced and lessons learned.
Blogging:
---------
I have also set up a blogging page at [11]. While reading blogs from previous
GSoC contributors, I found them useful in understanding the challenges
they faced and how they approached their projects. Their experiences gave
me a better idea of what to expect and how to navigate the development
process. Inspired by this, I decided to start my own blog to document my
journey throughout GSoC. This will not only help me track my own progress but
also serve as a resource for future contributors who might work on similar
projects. I plan to share updates on my work, challenges encountered and
insights gained from discussions with mentors and the community.
Additionally, I hope my blog encourages more people to contribute to open
source by providing a transparent look into the development process. Writing
about my experience will also help me reflect on my work and improve my
ability to communicate technical ideas effectively.
I liked the format and structure of Chandra's blog, so I decided to use the
same template for my own blogging page.
Availability:
-------------
As a college student, I intend to utilise my summer breaks from May to July
to work on the project. After completing my University exams in April, I can
start working in May. I can dedicate 40 hours a week from May to July, while
in August after the classes commence, I can dedicate about 25 hours a week.
There are no exams or planned vacations throughout the coding period. Besides
this project, I have no commitments/vacations planned for the summer. I shall
keep my status posted to all the community members and maintain transparency
in the project.
Post-GSOC:
----------
Beyond contributing code, I strongly believe in giving back to the community
and helping others grow. Open source thrives on mentorship, knowledge sharing,
and long-term involvement, and I would love to continue contributing even
after GSoC ends.
I have always valued mentorship, both as a mentee and as someone who enjoys
guiding others. If given the opportunity, I would be more than happy to
mentor/co-mentor future GSoC contributors. By staying involved in the
community, whether through contributing, reviewing patches, or mentoring,
I hope to help sustain and expand the project’s reach. I look at GSoC as not
just as a one-time contribution but as a step toward a longer-term relationship
with open source.
I will continue to be involved with Git even after GSoC by contributing patches,
reviewing code, and participating in discussions. My work on refactoring Git’s
state aligns with long-term improvements to the codebase, and I plan to keep
refining it beyond the program. I see GSoC as just the beginning of my journey
with Git.
Appreciation:
-------------
I appreciate the Git community for its excellent documentation, which made it
much easier for me to understand Git in depth. The well-structured resources
helped me navigate the codebase and gain a deeper understanding of how Git
works internally.
Beyond the documentation, I am also grateful for how welcoming and supportive
the community has been. Whether through discussions on the mailing list or
feedback on my patches, the information and guidance I received made my
experience even better.
Additionally, I read the blogs and proposals of Chandra, Jialuo, and Ghanashyam,
which provided valuable insights into their journeys and helped me shape my
own approach to contributing.
Thanks for reviewing this proposal.
References:
-----------
[1] https://github.com/sdslabs/beast/pull/374
[2] https://github.com/sdslabs/beast/tree/add-teams-with-hint
[3] https://github.com/sdslabs/playCTF/pull/177
[4] https://public-inbox.org/git/pull.1826.git.git.1730926082.gitgitgadget@gmail.com/
[5] https://public-inbox.org/git/20250303-b4-pks-objects-without-the-repository-v1-0-c5dd43f2476e@pks.im/
[6] https://public-inbox.org/git/20250206-b4-pks-path-drop-the-repository-v1-0-4e77f0313206@pks.im/
[7] https://public-inbox.org/git/pull.1829.git.1731653548549.gitgitgadget@gmail.com/#t
[8] https://public-inbox.org/git/cover.1733236936.git.karthik.188@gmail.com/
[9] https://public-inbox.org/git/cover.1724923648.git.ps@pks.im/
[10] https://www.mermaidchart.com/raw/327324ea-af1d-4a98-8bff-254479b3a79c?theme=light&version=v0.1&format=svg
[11] https://ayu-ch.github.io
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state
2025-03-26 5:26 [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state Ayush Chandekar
@ 2025-03-28 13:06 ` shejialuo
2025-03-29 9:54 ` Ayush Chandekar
2025-04-04 8:51 ` [GSOC] [PROPOSAL v2]: " Ayush Chandekar
2025-04-08 12:52 ` [GSOC] [PROPOSAL v3]: " Ayush Chandekar
2 siblings, 1 reply; 14+ messages in thread
From: shejialuo @ 2025-03-28 13:06 UTC (permalink / raw)
To: Ayush Chandekar; +Cc: git, ps, karthik.188, christian.couder, shyamthakkar001
On Wed, Mar 26, 2025 at 10:56:00AM +0530, Ayush Chandekar wrote:
> Hello,
> This is my GSoC 2025 proposal for the project "Refactoring in order to reduce Git’s global state".
> You can view docs version here:
> https://docs.google.com/document/d/1tJrtWxo1UGKChB3hu5eZ-ljm0FtU_fsv0TnIRwu3EKY/edit?usp=sharing
>
> ---------
>
> Refactoring in order to reduce git’s state
>
> My Information:
> ---------------
>
> Name: Ayush Chandekar
> Email: ayu.chandekar@gmail•com
> Mobile No: (+91) 9372496874
> Education: UG Sophomore, IIT Roorkee
> Github: https://github.com/ayu-ch
> Blog: https://ayu-ch.github.io
>
>
> About me:
> ---------
>
> I'm Ayush Chandekar, a UG Sophomore studying at Indian Institute of
> Technology, Roorkee. I like participating in various software development
> and tech-development endeavors, usually hackathons, CTFs, and projects at
> SDSLabs. SDSLabs is a student-run technical group that includes passionate
> developers and designers interested in various fields and involved in multiple
> software development projects that aim to foster a software development
> culture on campus. Being a part of this group has exposed me to different
> software development methodologies, tools and frameworks and helped me become
> comfortable contributing to an open-source project with multiple contributors.
> Some open-source contributions I made here are: [1], [2] & [3]
>
> I see this project as a meaningful opportunity to deepen my involvement in
> the Git community and to build a foundation for continued contributions to
> open source development in the future.
>
>
> Overview:
> ---------
>
> Git currently uses a global object called `the_repository`, which refers to a
> single instance of `struct repository`. Many internal functions rely on this
> global object rather than accepting a `struct repository` as an explicit
> parameter. This design inherently assumes a single active repository,
> making it difficult to support multi-repository use cases and obstructing
> the long-term goal of libification of Git.
>
> A key architectural limitation is that while `struct repository` encapsulates
> some repository-specific information, many important environment variables
> and configuration settings that logically belong to a repository are still
> stored as global variables, primarily in `environment.c`, not within the
> `repository` struct. As a result, even if multiple repositories were to
> exist concurrently, they would still share this global state, leading to
> incorrect behavior, race conditions, or subtle bugs.
>
> This project aims to refactor Git’s environment handling by relocating
> these global variables into appropriate local contexts primarily into
> `struct repository` and `struct repo_settings`. This change will not
I think we could just improve this statement better. Some global
variables may only apply to one subsystem or two subsystems. In such
situations, we may just put the global variable into their own context
but not the "struct repository" or "struct repo_settings".
> only make the environment state repository-specific, but also improve the
> modularity and maintainability of the codebase. The work involves identifying
> environment-related global variables, designing a suitable structure to
> house them within the repository context, and updating all affected code
> paths accordingly.
>
> The difficulty of this project is medium, and it is estimated to take
> 175 to 350 hours.
>
>
> Pre-GSOC:
> ---------
>
> I started exploring Git’s codebase and documentation around the end of
> January, familiarizing myself with its structure and development practices. I
> submitted a microproject, which helped me navigate the code and contribution
> workflow.
>
> After selecting the project on refactoring Git’s state, I studied the
> surrounding code and reviewed past patches ([4], [5], [6], [7], [8] & [9])
> to understand the reasoning behind previous changes. To better prepare
> for the GSoC timeline, I also submitted a patch related to the project,
> gaining hands-on experience with both the implementation details and the
> submission process.
>
>
> Patches:
> --------
>
> + (Microproject) t6423: fix suppression of Git’s exit code in tests
> Thread:
> https://public-inbox.org/git/20250202120926.322417-1-ayu.chandekar@gmail.com/
> Status: Merged into master
> Commit Hash: 7c1d34fe5d1229362f2c3ecf2d493167a1f555a2
> Description: Instead of executing a Git command as the upstream component of
> a pipe, which can result in the exit status being lost, redirect
> its output to a file and then process that file in two steps to
> ensure the exit status is properly preserved.
>
> + midx: implement progress reporting for QSORT operation
> Thread:
> https://public-inbox.org/git/20250210074623.136599-1-ayu.chandekar@gmail.com/
> Status: Dropped
> Description: Add progress reporting during the QSORT operation in
> multi-pack-index verification. While going through the code,
> I found this TODO, which I thought was interesting however my
> approach assumed that the qsort() operation processes elements
> in a structured order, which isn't guaranteed.
>
> + Stop depending on `the_repository` for core.attributesfile
> Thread:
> https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
> Status: WIP, needs more discussion.
> Description: This patch refactors access to the `core.attributesfiles`
> configuration by moving it into the `repo_settings` struct.
> It eliminates the global variable `git_attributes_file` and
> updates relevant code paths to pass the `struct repository`
> as a parameter.
>
>
> Proposed Plan:
> --------------
>
> I have been reviewing global variables across the codebase to understand their
> dependencies and impact. To do this, I examined `config.c` and cross-referenced
> it with `environment.c` to see how these variables are currently managed. The
> goal of this project is to eliminate global variables by moving their
> configurations into repository-specific settings. This involves:
>
> - Identifying all occurrences of these global variables.
>
> - Removing dependencies on `the_repository`.
>
> - Updating function signatures to pass `struct repository` explicitly.
>
When reading this, I feel a little wired because I think in [1], you
have already realized that we should move some global variables to some
specific subsystems.
[1] https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
> - Replacing global variable references with repository-scoped configurations.
>
> Instead of adding all variables directly into `repo_settings`, we can group
> related variables into specialized structs (e.g., `performance_config`,
> `behaviour_config`, `whitespace_config`) and embed these within `repo_settings`.
> This approach ensures a more modular and maintainable design while keeping
> `repo_settings` manageable.
>
> I have also created a diagram explaining this structure in [10].
>
> With this approach, I can structure the patch series by grouping the refactoring
> of related variables within specific structs. This will help maintain a clean and
> organized codebase while also making the development and review process more
> systematic and efficient.
>
Yes, it's a good idea to use sub-structure to make the code be cleaner.
However, from my own experience when being a GSoC student, we should not
consider about this due to that we will over-engineer this.
You need a lot of time and effort to convince the community why the
design is good and why we should put this variable into this
sub-structure.
Instead, you'd better focus on which variables you want to remove
firstly. And how do you try to remove them with some simple steps. This
would make you more concentrate on the jobs you need to do and reduce
the risk.
> One key challenge is determining which variables should be part of
> `repo_settings` and which should remain separate. While working on the patch to
> refactor access to `core.attributesfile`, I received feedback from Junio that not
> all global variables should be blindly moved into the `repo_settings` struct.
> This reinforced the need to carefully assess which variables belong in `repo_settings`
> and which should be handled differently.
>
Yes, this is correct. I somehow think whether we should put this
paragraph into Pre-GSoC part? I think that you have found this when
adding a patch to remove one global variable. And thus by communicating
with the community, you have further understood that the requirement and
the detail of this project.
And in your plan, you should just say that we need to do this. Would
this be better?
> This plan is flexible and may be refined through multiple iterations as I receive
> feedback from the community and reviewers.
>
> Timeline:
> ---------
>
> Pre-GSOC:
> (Until 8 May)
> - Explore the codebase more, focusing on environment-related code paths.
> - Document how each global variable is used and how it can be moved to
> repository settings.
> - Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
>
> ----------
>
> Community Bonding:
> (May 8 - June 1)
> - Engage with mentors to discuss different environment variables, their
> dependencies, and the best approach for refactoring.
> - Finalize an implementation plan based on discussions.
> - Since I will be on summer vacation, I can start coding early and make progress
> on the project.
>
> ----------
>
> Coding Period:
> (June 2 - August 25)
> - Refactor global variables, replacing them with repository-scoped
> configurations.
> - Modify function signatures to pass `struct repository` explicitly instead
> of relying on `the_repository`.
> - Categorize variables into specialized structs to improve modularity and
> maintainability.
As I have said, this is a high-risk task. Categorization needs many
iterations. And we may do this after GSoC.
> - Continuously submit patches for review and incorporate feedback from mentors
> and the community.
> - I plan to write weekly blogs which will document what I did in the whole
> week.
>
> ----------
>
> Final Week:
> (August 25 - September 1)
> - Write a detailed report on the entire project.
> - Fix bugs if any.
> - Reflect on the project, noting challenges faced and lessons learned.
>
>
> Blogging:
> ---------
>
> I have also set up a blogging page at [11]. While reading blogs from previous
> GSoC contributors, I found them useful in understanding the challenges
> they faced and how they approached their projects. Their experiences gave
> me a better idea of what to expect and how to navigate the development
> process. Inspired by this, I decided to start my own blog to document my
> journey throughout GSoC. This will not only help me track my own progress but
> also serve as a resource for future contributors who might work on similar
> projects. I plan to share updates on my work, challenges encountered and
> insights gained from discussions with mentors and the community.
>
> Additionally, I hope my blog encourages more people to contribute to open
> source by providing a transparent look into the development process. Writing
> about my experience will also help me reflect on my work and improve my
> ability to communicate technical ideas effectively.
>
> I liked the format and structure of Chandra's blog, so I decided to use the
> same template for my own blogging page.
>
>
> Availability:
> -------------
>
> As a college student, I intend to utilise my summer breaks from May to July
> to work on the project. After completing my University exams in April, I can
> start working in May. I can dedicate 40 hours a week from May to July, while
> in August after the classes commence, I can dedicate about 25 hours a week.
>
> There are no exams or planned vacations throughout the coding period. Besides
> this project, I have no commitments/vacations planned for the summer. I shall
> keep my status posted to all the community members and maintain transparency
> in the project.
>
>
> Post-GSOC:
> ----------
>
> Beyond contributing code, I strongly believe in giving back to the community
> and helping others grow. Open source thrives on mentorship, knowledge sharing,
> and long-term involvement, and I would love to continue contributing even
> after GSoC ends.
>
> I have always valued mentorship, both as a mentee and as someone who enjoys
> guiding others. If given the opportunity, I would be more than happy to
> mentor/co-mentor future GSoC contributors. By staying involved in the
> community, whether through contributing, reviewing patches, or mentoring,
> I hope to help sustain and expand the project’s reach. I look at GSoC as not
> just as a one-time contribution but as a step toward a longer-term relationship
> with open source.
>
> I will continue to be involved with Git even after GSoC by contributing patches,
> reviewing code, and participating in discussions. My work on refactoring Git’s
> state aligns with long-term improvements to the codebase, and I plan to keep
> refining it beyond the program. I see GSoC as just the beginning of my journey
> with Git.
>
> Appreciation:
> -------------
>
> I appreciate the Git community for its excellent documentation, which made it
> much easier for me to understand Git in depth. The well-structured resources
> helped me navigate the codebase and gain a deeper understanding of how Git
> works internally.
>
> Beyond the documentation, I am also grateful for how welcoming and supportive
> the community has been. Whether through discussions on the mailing list or
> feedback on my patches, the information and guidance I received made my
> experience even better.
>
> Additionally, I read the blogs and proposals of Chandra, Jialuo, and Ghanashyam,
> which provided valuable insights into their journeys and helped me shape my
> own approach to contributing.
I'm happy that my blogs help you.
>
> Thanks for reviewing this proposal.
>
Thanks for your proposal!
> References:
> -----------
>
> [1] https://github.com/sdslabs/beast/pull/374
>
> [2] https://github.com/sdslabs/beast/tree/add-teams-with-hint
>
> [3] https://github.com/sdslabs/playCTF/pull/177
>
> [4] https://public-inbox.org/git/pull.1826.git.git.1730926082.gitgitgadget@gmail.com/
>
> [5] https://public-inbox.org/git/20250303-b4-pks-objects-without-the-repository-v1-0-c5dd43f2476e@pks.im/
>
> [6] https://public-inbox.org/git/20250206-b4-pks-path-drop-the-repository-v1-0-4e77f0313206@pks.im/
>
> [7] https://public-inbox.org/git/pull.1829.git.1731653548549.gitgitgadget@gmail.com/#t
>
> [8] https://public-inbox.org/git/cover.1733236936.git.karthik.188@gmail.com/
>
> [9] https://public-inbox.org/git/cover.1724923648.git.ps@pks.im/
>
> [10] https://www.mermaidchart.com/raw/327324ea-af1d-4a98-8bff-254479b3a79c?theme=light&version=v0.1&format=svg
>
> [11] https://ayu-ch.github.io
Jialuo
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state
2025-03-28 13:06 ` shejialuo
@ 2025-03-29 9:54 ` Ayush Chandekar
2025-03-31 14:17 ` shejialuo
0 siblings, 1 reply; 14+ messages in thread
From: Ayush Chandekar @ 2025-03-29 9:54 UTC (permalink / raw)
To: shejialuo; +Cc: git, ps, karthik.188, christian.couder, shyamthakkar001
> > This project aims to refactor Git’s environment handling by relocating
> > these global variables into appropriate local contexts primarily into
> > `struct repository` and `struct repo_settings`. This change will not
>
> I think we could just improve this statement better. Some global
> variables may only apply to one subsystem or two subsystems. In such
> situations, we may just put the global variable into their own context
> but not the "struct repository" or "struct repo_settings".
Right, I was generalizing in my statement, but I agree that some
global variables
may belong in subsystem-specific contexts rather than `struct repository` or
`struct repo_settings`. I'll make sure to account for that distinction
in my proposal
and implementation.
> >
> > Proposed Plan:
> > --------------
> >
> > I have been reviewing global variables across the codebase to understand their
> > dependencies and impact. To do this, I examined `config.c` and cross-referenced
> > it with `environment.c` to see how these variables are currently managed. The
> > goal of this project is to eliminate global variables by moving their
> > configurations into repository-specific settings. This involves:
> >
> > - Identifying all occurrences of these global variables.
> >
> > - Removing dependencies on `the_repository`.
> >
> > - Updating function signatures to pass `struct repository` explicitly.
> >
>
> When reading this, I feel a little wired because I think in [1], you
> have already realized that we should move some global variables to some
> specific subsystems.
>
> [1] https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
>
I see your point. I was generalizing again, but I’ll make sure to
clarify this distinction
in my proposal. Thanks for pointing it out!
> > - Replacing global variable references with repository-scoped configurations.
> >
> > Instead of adding all variables directly into `repo_settings`, we can group
> > related variables into specialized structs (e.g., `performance_config`,
> > `behaviour_config`, `whitespace_config`) and embed these within `repo_settings`.
> > This approach ensures a more modular and maintainable design while keeping
> > `repo_settings` manageable.
> >
> > I have also created a diagram explaining this structure in [10].
> >
> > With this approach, I can structure the patch series by grouping the refactoring
> > of related variables within specific structs. This will help maintain a clean and
> > organized codebase while also making the development and review process more
> > systematic and efficient.
> >
>
> Yes, it's a good idea to use sub-structure to make the code be cleaner.
> However, from my own experience when being a GSoC student, we should not
> consider about this due to that we will over-engineer this.
>
> You need a lot of time and effort to convince the community why the
> design is good and why we should put this variable into this
> sub-structure.
>
> Instead, you'd better focus on which variables you want to remove
> firstly. And how do you try to remove them with some simple steps. This
> would make you more concentrate on the jobs you need to do and reduce
> the risk.
>
That makes sense. My intent was to provide a structured approach, but
I could see how it
it may introduce unnecessary complexity at this stage. I'll focus on
identifying and managing
the global variables before considering additional structuring. I
think this is something which
can be done at the end of the project. That is, once all the variables
are handled, they can
then be set into specific structures, if needed.
> > One key challenge is determining which variables should be part of
> > `repo_settings` and which should remain separate. While working on the patch to
> > refactor access to `core.attributesfile`, I received feedback from Junio that not
> > all global variables should be blindly moved into the `repo_settings` struct.
> > This reinforced the need to carefully assess which variables belong in `repo_settings`
> > and which should be handled differently.
> >
>
> Yes, this is correct. I somehow think whether we should put this
> paragraph into Pre-GSoC part? I think that you have found this when
> adding a patch to remove one global variable. And thus by communicating
> with the community, you have further understood that the requirement and
> the detail of this project.
Yep, since I encountered this while working on the patch, it fits well
in the Pre-GSoC section.
Moving it there would better show how I learned more about the
project's scope through
community feedback.
>
> And in your plan, you should just say that we need to do this. Would
> this be better?
>
So, I should remove all the categorization stuff and just say that I
would focus on
each variable, discuss in the community whether it should belong in the struct
repo_settings/repo or not while sending patches?
I felt that keeping it general might seem vague, but that's the nature
of the project. Every variable
is unique and would need a different approach and outlining the
approach of each variable
in the proposal is not very feasible, as these decisions need to
happen collaboratively through
discussions in the community.
Should I still mention that once the project is complete, we could
consider structuring related
stuff if the community sees value in it.
> > This plan is flexible and may be refined through multiple iterations as I receive
> > feedback from the community and reviewers.
> >
> > Timeline:
> > ---------
> >
> > Pre-GSOC:
> > (Until 8 May)
> > - Explore the codebase more, focusing on environment-related code paths.
> > - Document how each global variable is used and how it can be moved to
> > repository settings.
> > - Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
> >
> > ----------
> >
> > Community Bonding:
> > (May 8 - June 1)
> > - Engage with mentors to discuss different environment variables, their
> > dependencies, and the best approach for refactoring.
> > - Finalize an implementation plan based on discussions.
> > - Since I will be on summer vacation, I can start coding early and make progress
> > on the project.
> >
> > ----------
> >
> > Coding Period:
> > (June 2 - August 25)
> > - Refactor global variables, replacing them with repository-scoped
> > configurations.
> > - Modify function signatures to pass `struct repository` explicitly instead
> > of relying on `the_repository`.
> > - Categorize variables into specialized structs to improve modularity and
> > maintainability.
>
> As I have said, this is a high-risk task. Categorization needs many
> iterations. And we may do this after GSoC.
Yep, will update that.
Thanks for your review, again:)
Ayush
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state
2025-03-29 9:54 ` Ayush Chandekar
@ 2025-03-31 14:17 ` shejialuo
2025-03-31 15:04 ` Ayush Chandekar
0 siblings, 1 reply; 14+ messages in thread
From: shejialuo @ 2025-03-31 14:17 UTC (permalink / raw)
To: Ayush Chandekar; +Cc: git, ps, karthik.188, christian.couder, shyamthakkar001
On Sat, Mar 29, 2025 at 03:24:05PM +0530, Ayush Chandekar wrote:
[snip]
> > > One key challenge is determining which variables should be part of
> > > `repo_settings` and which should remain separate. While working on the patch to
> > > refactor access to `core.attributesfile`, I received feedback from Junio that not
> > > all global variables should be blindly moved into the `repo_settings` struct.
> > > This reinforced the need to carefully assess which variables belong in `repo_settings`
> > > and which should be handled differently.
> > >
> >
> > Yes, this is correct. I somehow think whether we should put this
> > paragraph into Pre-GSoC part? I think that you have found this when
> > adding a patch to remove one global variable. And thus by communicating
> > with the community, you have further understood that the requirement and
> > the detail of this project.
>
> Yep, since I encountered this while working on the patch, it fits well
> in the Pre-GSoC section.
> Moving it there would better show how I learned more about the
> project's scope through
> community feedback.
>
Yes, this is my intention. This represents your ability where you
interact with the community and get feedback. And this is what we want
to see.
> >
> > And in your plan, you should just say that we need to do this. Would
> > this be better?
> >
> So, I should remove all the categorization stuff and just say that I
> would focus on
> each variable, discuss in the community whether it should belong in the struct
> repo_settings/repo or not while sending patches?
I think you should put the categorization stuff into after-GSoC part.
Well, I don't think you could focus on _each_ variable. This is
impossible for you to talk about the way for _each_ variable. I somehow
think that you could just write the proposal about how to handle one or
two global variables.
You already touch one setting "core.attributesfile" right? You may just
elaborate more in the proposal.
> I felt that keeping it general might seem vague, but that's the nature
> of the project. Every variable
> is unique and would need a different approach and outlining the
> approach of each variable
> in the proposal is not very feasible, as these decisions need to
> happen collaboratively through
> discussions in the community.
>
Yes, so you could firstly give how you want to handle the global
variables from top. And give some concrete examples to demonstrate your
idea.
> Should I still mention that once the project is complete, we could
> consider structuring related
> stuff if the community sees value in it.
>
You could, mention this in after GSoC part.
> > > This plan is flexible and may be refined through multiple iterations as I receive
> > > feedback from the community and reviewers.
> > >
> > > Timeline:
> > > ---------
> > >
> > > Pre-GSOC:
> > > (Until 8 May)
> > > - Explore the codebase more, focusing on environment-related code paths.
> > > - Document how each global variable is used and how it can be moved to
> > > repository settings.
> > > - Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
> > >
> > > ----------
> > >
> > > Community Bonding:
> > > (May 8 - June 1)
> > > - Engage with mentors to discuss different environment variables, their
> > > dependencies, and the best approach for refactoring.
> > > - Finalize an implementation plan based on discussions.
> > > - Since I will be on summer vacation, I can start coding early and make progress
> > > on the project.
> > >
> > > ----------
> > >
> > > Coding Period:
> > > (June 2 - August 25)
> > > - Refactor global variables, replacing them with repository-scoped
> > > configurations.
> > > - Modify function signatures to pass `struct repository` explicitly instead
> > > of relying on `the_repository`.
> > > - Categorize variables into specialized structs to improve modularity and
> > > maintainability.
> >
> > As I have said, this is a high-risk task. Categorization needs many
> > iterations. And we may do this after GSoC.
>
> Yep, will update that.
>
> Thanks for your review, again:)
>
> Ayush
Thanks,
Jialuo
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state
2025-03-31 14:17 ` shejialuo
@ 2025-03-31 15:04 ` Ayush Chandekar
2025-03-31 15:18 ` Ayush Chandekar
0 siblings, 1 reply; 14+ messages in thread
From: Ayush Chandekar @ 2025-03-31 15:04 UTC (permalink / raw)
To: shejialuo; +Cc: git, ps, karthik.188, christian.couder, shyamthakkar001
> > Yep, since I encountered this while working on the patch, it fits well
> > in the Pre-GSoC section.
> > Moving it there would better show how I learned more about the
> > project's scope through
> > community feedback.
> >
>
> Yes, this is my intention. This represents your ability where you
> interact with the community and get feedback. And this is what we want
> to see.
>
Got it!
> > So, I should remove all the categorization stuff and just say that I
> > would focus on
> > each variable, discuss in the community whether it should belong in the struct
> > repo_settings/repo or not while sending patches?
>
> I think you should put the categorization stuff into after-GSoC part.
> Well, I don't think you could focus on _each_ variable. This is
> impossible for you to talk about the way for _each_ variable. I somehow
> think that you could just write the proposal about how to handle one or
> two global variables.
>
Right, I can do that.
> You already touch one setting "core.attributesfile" right? You may just
> elaborate more in the proposal.
>
Yep!
> > I felt that keeping it general might seem vague, but that's the nature
> > of the project. Every variable
> > is unique and would need a different approach and outlining the
> > approach of each variable
> > in the proposal is not very feasible, as these decisions need to
> > happen collaboratively through
> > discussions in the community.
> >
>
> Yes, so you could firstly give how you want to handle the global
> variables from top. And give some concrete examples to demonstrate your
> idea.
>
Alright, will do.
I'll send a new iteration of the proposal soon.
Thank you so much for your inputs:)
Ayush
On Mon, Mar 31, 2025 at 7:47 PM shejialuo <shejialuo@gmail•com> wrote:
>
> On Sat, Mar 29, 2025 at 03:24:05PM +0530, Ayush Chandekar wrote:
>
> [snip]
>
> > > > One key challenge is determining which variables should be part of
> > > > `repo_settings` and which should remain separate. While working on the patch to
> > > > refactor access to `core.attributesfile`, I received feedback from Junio that not
> > > > all global variables should be blindly moved into the `repo_settings` struct.
> > > > This reinforced the need to carefully assess which variables belong in `repo_settings`
> > > > and which should be handled differently.
> > > >
> > >
> > > Yes, this is correct. I somehow think whether we should put this
> > > paragraph into Pre-GSoC part? I think that you have found this when
> > > adding a patch to remove one global variable. And thus by communicating
> > > with the community, you have further understood that the requirement and
> > > the detail of this project.
> >
> > Yep, since I encountered this while working on the patch, it fits well
> > in the Pre-GSoC section.
> > Moving it there would better show how I learned more about the
> > project's scope through
> > community feedback.
> >
>
> Yes, this is my intention. This represents your ability where you
> interact with the community and get feedback. And this is what we want
> to see.
>
> > >
> > > And in your plan, you should just say that we need to do this. Would
> > > this be better?
> > >
> > So, I should remove all the categorization stuff and just say that I
> > would focus on
> > each variable, discuss in the community whether it should belong in the struct
> > repo_settings/repo or not while sending patches?
>
> I think you should put the categorization stuff into after-GSoC part.
> Well, I don't think you could focus on _each_ variable. This is
> impossible for you to talk about the way for _each_ variable. I somehow
> think that you could just write the proposal about how to handle one or
> two global variables.
>
> You already touch one setting "core.attributesfile" right? You may just
> elaborate more in the proposal.
>
> > I felt that keeping it general might seem vague, but that's the nature
> > of the project. Every variable
> > is unique and would need a different approach and outlining the
> > approach of each variable
> > in the proposal is not very feasible, as these decisions need to
> > happen collaboratively through
> > discussions in the community.
> >
>
> Yes, so you could firstly give how you want to handle the global
> variables from top. And give some concrete examples to demonstrate your
> idea.
>
> > Should I still mention that once the project is complete, we could
> > consider structuring related
> > stuff if the community sees value in it.
> >
>
> You could, mention this in after GSoC part.
>
> > > > This plan is flexible and may be refined through multiple iterations as I receive
> > > > feedback from the community and reviewers.
> > > >
> > > > Timeline:
> > > > ---------
> > > >
> > > > Pre-GSOC:
> > > > (Until 8 May)
> > > > - Explore the codebase more, focusing on environment-related code paths.
> > > > - Document how each global variable is used and how it can be moved to
> > > > repository settings.
> > > > - Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
> > > >
> > > > ----------
> > > >
> > > > Community Bonding:
> > > > (May 8 - June 1)
> > > > - Engage with mentors to discuss different environment variables, their
> > > > dependencies, and the best approach for refactoring.
> > > > - Finalize an implementation plan based on discussions.
> > > > - Since I will be on summer vacation, I can start coding early and make progress
> > > > on the project.
> > > >
> > > > ----------
> > > >
> > > > Coding Period:
> > > > (June 2 - August 25)
> > > > - Refactor global variables, replacing them with repository-scoped
> > > > configurations.
> > > > - Modify function signatures to pass `struct repository` explicitly instead
> > > > of relying on `the_repository`.
> > > > - Categorize variables into specialized structs to improve modularity and
> > > > maintainability.
> > >
> > > As I have said, this is a high-risk task. Categorization needs many
> > > iterations. And we may do this after GSoC.
> >
> > Yep, will update that.
> >
> > Thanks for your review, again:)
> >
> > Ayush
>
> Thanks,
> Jialuo
^ permalink raw reply [flat|nested] 14+ messages in thread
* [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-03-26 5:26 [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state Ayush Chandekar
2025-03-28 13:06 ` shejialuo
@ 2025-04-04 8:51 ` Ayush Chandekar
2025-04-04 14:45 ` Karthik Nayak
2025-04-07 8:42 ` Ayush Chandekar
2025-04-08 12:52 ` [GSOC] [PROPOSAL v3]: " Ayush Chandekar
2 siblings, 2 replies; 14+ messages in thread
From: Ayush Chandekar @ 2025-04-04 8:51 UTC (permalink / raw)
To: ayu.chandekar
Cc: christian.couder, git, karthik.188, ps, shejialuo,
shyamthakkar001
Hello,
This is my GSoC 2025 proposal for the project "Refactoring in order to reduce Git’s global state".
You can view docs version here:
https://docs.google.com/document/d/1tJrtWxo1UGKChB3hu5eZ-ljm0FtU_fsv0TnIRwu3EKY/edit?usp=sharing
---------
Refactoring in order to reduce git’s state
My Information:
---------------
Name: Ayush Chandekar
Email: ayu.chandekar@gmail•com
Mobile No: (+91) 9372496874
Education: UG Sophomore, IIT Roorkee
Github: https://github.com/ayu-ch
Blog: https://ayu-ch.github.io
About me:
---------
I'm Ayush Chandekar, a UG Sophomore studying at Indian Institute of
Technology, Roorkee. I like participating in various software development
and tech-development endeavors, usually hackathons, CTFs, and projects at
SDSLabs. SDSLabs is a student-run technical group that includes passionate
developers and designers interested in various fields and involved in multiple
software development projects that aim to foster a software development
culture on campus. Being a part of this group has exposed me to different
software development methodologies, tools and frameworks and helped me become
comfortable contributing to an open-source project with multiple contributors.
Some open-source contributions I made here are: [1], [2] & [3]
I see this project as a meaningful opportunity to deepen my involvement in
the Git community and to build a foundation for continued contributions to
open source development in the future.
Overview:
---------
Git currently uses a global object called `the_repository`, which refers to a
single instance of `struct repository`. Many internal functions rely on this
global object rather than accepting a `struct repository` as an explicit
parameter. This design inherently assumes a single active repository,
making it difficult to support multi-repository use cases and obstructing
the long-term goal of libification of Git.
A key architectural limitation is that while `struct repository` encapsulates
some repository-specific information, many important environment variables
and configuration settings that logically belong to a repository are still
stored as global variables, primarily in `environment.c`, not within the
`repository` struct. As a result, even if multiple repositories were to
exist concurrently, they would still share this global state, leading to
incorrect behavior, race conditions, or subtle bugs.
This project aims to refactor Git’s environment handling by relocating global
variables into more appropriate local contexts, primarily within
struct repository and struct repo_settings. However, some global variables may
only apply to specific subsystems. In such cases, rather than placing them in
struct repository or struct repo_settings, they should be moved into a
context that better reflects their scope.
This change will not only make the environment state repository-specific but
also improve the modularity and maintainability of the codebase. The work
involves identifying environment-related global variables, determining the
most suitable structure to house them, and updating all affected code paths
accordingly.
The difficulty of this project is medium, and it is estimated to take
175 to 350 hours.
Pre-GSOC:
---------
I started exploring Git’s codebase and documentation around the end of
January, familiarizing myself with its structure and development practices. I
submitted a microproject, which helped me navigate the code and contribution
workflow.
After selecting the project on refactoring Git’s state, I studied the
surrounding code and reviewed past patches ([4], [5], [6], [7], [8] & [9])
to understand the reasoning behind previous changes.
To better prepare for the GSoC timeline, I submitted a patch related to the
project, to gain hands-on experience with both the implementation details
and the submission process. The patch focused on refactoring access to
`core.attributesfile`.
Through discussions and feedback from the community, I gained a clearer
understanding of a key aspect of the project:
determining whether certain variables should belong to repo_settings/
repository or be part of a separate subsystem.
Junio pointed out in a feedback that not all global variables should
be blindly moved into `repo_settings`.
Specifically, for `git_attributes_file`, adding it to the repository struct
doesn’t make sense. He explained that it’s similar to how index_state is
handled, while index_state knows which repository it belongs to, the
repository struct only holds a pointer to a single index_state instance
and isn’t aware of other instances.
Following this approach, instead of placing `git_attributes_file` in the
repository struct, we can house it within an attribute set and pass a
pointer to that set wherever needed.
This practice patch gave me a clearer understanding of the project.
Patches:
--------
For git:
+ (Microproject) t6423: fix suppression of Git’s exit code in tests
Thread:
https://public-inbox.org/git/20250202120926.322417-1-ayu.chandekar@gmail.com/
Status: Merged into master
Commit Hash: 7c1d34fe5d1229362f2c3ecf2d493167a1f555a2
Description: Instead of executing a Git command as the upstream component of
a pipe, which can result in the exit status being lost, redirect
its output to a file and then process that file in two steps to
ensure the exit status is properly preserved.
+ midx: implement progress reporting for QSORT operation
Thread:
https://public-inbox.org/git/20250210074623.136599-1-ayu.chandekar@gmail.com/
Status: Dropped
Description: Add progress reporting during the QSORT operation in
multi-pack-index verification. While going through the code,
I found this TODO, which I thought was interesting however my
approach assumed that the qsort() operation processes elements
in a structured order, which isn't guaranteed.
+ Stop depending on `the_repository` for core.attributesfile
Thread:
https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
Status: WIP, needs more discussion.
Description: This patch refactors access to the `core.attributesfiles`
configuration by moving it into the `repo_settings` struct.
It eliminates the global variable `git_attributes_file` and
updates relevant code paths to pass the `struct repository`
as a parameter.
For git.github.io:
+ GSoC-participants: add GSoC 2024 participants to the list #762
Status: Merged into master
Description: Adding GSoC 2024 participants will help new
contributors understand their journey, making it easier for them
to navigate the program and the project.
Proposed Plan:
--------------
I have been reviewing global variables across the codebase to understand their
dependencies and impact. To do this, I examined `config.c` and cross-referenced
it with `environment.c` to see how these variables are currently managed. The
goal of this project is to eliminate global variables by moving their
configurations into their local contexts.
The general approach for handling a global variable begins with understanding
its purpose. This involves tracing its usage across the codebase and identifying
the subsystem it should belong to. If the variable is closely tied to
repository-related functionality, it may belong in struct repository or
struct repo_settings. Otherwise, it should be placed in a more suitable
context based on its scope.
Additionally, it's important to review previous attempts or related patches
to understand past design decisions and ensure consistency with ongoing efforts.
Finally, the global instance is eliminated by relocating the variable into the
appropriate context and passing it through the relevant code paths.
Example: Handling `is_bare_repository_cfg`
The variable `is_bare_repository_cfg` determines whether a repository is bare,
meaning it lacks a working directory. Since this property is fundamental to
how a repository functions, it should be placed in struct repository.
I have also gone through the code paths and analyzed how this variable is
initialized. We can initialize it similarly to how hash_algo is set through
the repository format. The repository format already contains an `is_bare`
field, which we can use to set this variable inside struct repository.
However, I still have some questions regarding why the is_bare_repository()
function checks for `repo->worktree` and why the `worktree struct` itself has
an `is_bare` variable. If a repository is considered bare when !repo->worktree
is true, the role of `worktree->is_bare` needs further clarification. I believe
that by engaging with the community, my understanding will become clearer.
I also went through [4] to see how John Cai's approach was.
This is how we can also approach for other global variables.
Through multiple iterations, this approach will be refined based on feedback,
edge cases, and community input.
Timeline:
---------
Pre-GSOC:
(Until 8 May)
- Explore the codebase more, focusing on environment-related code paths.
- Document how each global variable is used and how it can be moved to
repository settings.
- Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
----------
Community Bonding:
(May 8 - June 1)
- Engage with mentors to discuss different environment variables, their
dependencies, and the best approach for refactoring.
- Finalize an implementation plan based on discussions.
- Since I will be on summer vacation, I can start coding early and make progress
on the project.
----------
Coding Period:
(June 2 - August 25)
- Identify the appropriate subsystem for each global variable and relocate it
into struct repository, struct repo_settings, or other suitable contexts.
- Modify function signatures to pass the new contexts explicitly, replacing
reliance on global variables.
- Continuously submit patches for review and incorporate feedback from mentors
and the community.
- I plan to write weekly blogs which will document what I did in the whole
week.
----------
Final Week:
(August 25 - September 1)
- Write a detailed report on the entire project.
- Fix bugs if any.
- Reflect on the project, noting challenges faced and lessons learned.
Blogging:
---------
I have also set up a blogging page at [10]. While reading blogs from previous
GSoC contributors, I found them useful in understanding the challenges
they faced and how they approached their projects. Their experiences gave
me a better idea of what to expect and how to navigate the development
process. Inspired by this, I decided to start my own blog to document my
journey throughout GSoC. This will not only help me track my own progress but
also serve as a resource for future contributors who might work on similar
projects. I plan to share updates on my work, challenges encountered and
insights gained from discussions with mentors and the community.
Additionally, I hope my blog encourages more people to contribute to open
source by providing a transparent look into the development process. Writing
about my experience will also help me reflect on my work and improve my
ability to communicate technical ideas effectively.
I liked the format and structure of Chandra's blog, so I decided to use the
same template for my own blogging page.
Availability:
-------------
As a college student, I intend to utilise my summer breaks from May to July
to work on the project. After completing my University exams in April, I can
start working in May. I can dedicate 40 hours a week from May to July, while
in August after the classes commence, I can dedicate about 25 hours a week.
There are no exams or planned vacations throughout the coding period. Besides
this project, I have no commitments/vacations planned for the summer. I shall
keep my status posted to all the community members and maintain transparency
in the project.
Post-GSOC:
----------
Beyond contributing code, I strongly believe in giving back to the community
and helping others grow. Open source thrives on mentorship, knowledge sharing,
and long-term involvement, and I would love to continue contributing even
after GSoC ends.
I have always valued mentorship, both as a mentee and as someone who enjoys
guiding others. If given the opportunity, I would be more than happy to
mentor/co-mentor future GSoC contributors. By staying involved in the
community, whether through contributing, reviewing patches, or mentoring,
I hope to help sustain and expand the project’s reach. I look at GSoC as not
just as a one-time contribution but as a step toward a longer-term relationship
with open source.
I will continue to be involved with Git even after GSoC by contributing patches,
reviewing code, and participating in discussions. My work on refactoring Git’s
state aligns with long-term improvements to the codebase, and I plan to keep
refining it beyond the program. I see GSoC as just the beginning of my journey
with Git.
Appreciation:
-------------
I appreciate the Git community for its excellent documentation, which made it
much easier for me to understand Git in depth. The well-structured resources
helped me navigate the codebase and gain a deeper understanding of how Git
works internally.
Beyond the documentation, I am also grateful for how welcoming and supportive
the community has been. Whether through discussions on the mailing list or
feedback on my patches, the information and guidance I received made my
experience even better.
Additionally, I read the blogs and proposals of Chandra, Jialuo, and Ghanashyam,
which provided valuable insights into their journeys and helped me shape my
own approach to contributing.
Thanks for reviewing this proposal.
References:
-----------
[1] https://github.com/sdslabs/beast/pull/374
[2] https://github.com/sdslabs/beast/tree/add-teams-with-hint
[3] https://github.com/sdslabs/playCTF/pull/177
[4] https://public-inbox.org/git/pull.1826.git.git.1730926082.gitgitgadget@gmail.com/
[5] https://public-inbox.org/git/20250303-b4-pks-objects-without-the-repository-v1-0-c5dd43f2476e@pks.im/
[6] https://public-inbox.org/git/20250206-b4-pks-path-drop-the-repository-v1-0-4e77f0313206@pks.im/
[7] https://public-inbox.org/git/pull.1829.git.1731653548549.gitgitgadget@gmail.com/#t
[8] https://public-inbox.org/git/cover.1733236936.git.karthik.188@gmail.com/
[9] https://public-inbox.org/git/cover.1724923648.git.ps@pks.im/
[10] https://ayu-ch.github.io
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-04-04 8:51 ` [GSOC] [PROPOSAL v2]: " Ayush Chandekar
@ 2025-04-04 14:45 ` Karthik Nayak
2025-04-06 10:44 ` Ayush Chandekar
2025-04-07 8:42 ` Ayush Chandekar
1 sibling, 1 reply; 14+ messages in thread
From: Karthik Nayak @ 2025-04-04 14:45 UTC (permalink / raw)
To: Ayush Chandekar; +Cc: christian.couder, git, ps, shejialuo, shyamthakkar001
[-- Attachment #1: Type: text/plain, Size: 3243 bytes --]
Ayush Chandekar <ayu.chandekar@gmail•com> writes:
[snip]
> Proposed Plan:
> --------------
>
> I have been reviewing global variables across the codebase to understand their
> dependencies and impact. To do this, I examined `config.c` and cross-referenced
> it with `environment.c` to see how these variables are currently managed. The
> goal of this project is to eliminate global variables by moving their
> configurations into their local contexts.
>
> The general approach for handling a global variable begins with understanding
> its purpose. This involves tracing its usage across the codebase and identifying
> the subsystem it should belong to. If the variable is closely tied to
> repository-related functionality, it may belong in struct repository or
> struct repo_settings. Otherwise, it should be placed in a more suitable
> context based on its scope.
>
> Additionally, it's important to review previous attempts or related patches
> to understand past design decisions and ensure consistency with ongoing efforts.
> Finally, the global instance is eliminated by relocating the variable into the
> appropriate context and passing it through the relevant code paths.
>
> Example: Handling `is_bare_repository_cfg`
> The variable `is_bare_repository_cfg` determines whether a repository is bare,
> meaning it lacks a working directory. Since this property is fundamental to
> how a repository functions, it should be placed in struct repository.
>
> I have also gone through the code paths and analyzed how this variable is
> initialized. We can initialize it similarly to how hash_algo is set through
> the repository format. The repository format already contains an `is_bare`
> field, which we can use to set this variable inside struct repository.
>
> However, I still have some questions regarding why the is_bare_repository()
> function checks for `repo->worktree` and why the `worktree struct` itself has
> an `is_bare` variable. If a repository is considered bare when !repo->worktree
> is true, the role of `worktree->is_bare` needs further clarification. I believe
> that by engaging with the community, my understanding will become clearer.
> I also went through [4] to see how John Cai's approach was.
>
> This is how we can also approach for other global variables.
> Through multiple iterations, this approach will be refined based on feedback,
> edge cases, and community input.
>
So the approach you suggest is to comb through the global variables and
config and find new locations for them to be stored. While this is
definitely a bunch chunk of the problem, shouldn't we also talk about
how we can reduce usage of some of these variables?
In particular, I'm wondering how you'd want to tackle 'the_repository'
usage. There is some previous work done here, where Patrick added the
'#define USE_THE_REPOSITORY_VARIABLE' definition which tracks usage of
global variable and usage of them in different files.
A possible approach which has been followed is to simply go from the
bottom layers of the code upwards, cleaning up usage of global variables
and ensuring we can remove '#define USE_THE_REPOSITORY_VARIABLE' from
files. This is also the approach taken in some of the patches that
you've linked.
[snip]
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^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-04-04 14:45 ` Karthik Nayak
@ 2025-04-06 10:44 ` Ayush Chandekar
2025-04-07 9:06 ` Christian Couder
0 siblings, 1 reply; 14+ messages in thread
From: Ayush Chandekar @ 2025-04-06 10:44 UTC (permalink / raw)
To: Karthik Nayak; +Cc: christian.couder, git, ps, shejialuo, shyamthakkar001
>
> So the approach you suggest is to comb through the global variables and
> config and find new locations for them to be stored. While this is
> definitely a bunch chunk of the problem, shouldn't we also talk about
> how we can reduce usage of some of these variables?
>
> In particular, I'm wondering how you'd want to tackle 'the_repository'
> usage. There is some previous work done here, where Patrick added the
> '#define USE_THE_REPOSITORY_VARIABLE' definition which tracks usage of
> global variable and usage of them in different files.
>
> A possible approach which has been followed is to simply go from the
> bottom layers of the code upwards, cleaning up usage of global variables
> and ensuring we can remove '#define USE_THE_REPOSITORY_VARIABLE' from
> files. This is also the approach taken in some of the patches that
> you've linked.
>
Your approach makes a lot of sense to me, that is, picking a specific
subsystem or file and aiming to remove the `#define USE_THE_REPOSITORY_VARIABLE`
definition and thus 'the_repository' eventually. This was the method
used by Patrick to tackle
the object subsystem in [1] and the path subsystem in [2] and you to
tackle the packfile in [3].
This approach also helps in removing some of the global variables used
within that particular
subsystem, which is a nice bonus.
However, this approach might not be feasible for the global variables that
arent tightly tied to a single subsystem. So what I can do is, for removing
`the_repository`, I can follow the approach you mentioned, and for relocating
the more general global variables, I can use the approach which I
talked about in the
proposal.
What do you think?
[1]: https://public-inbox.org/git/20250303-b4-pks-objects-without-the-repository-v1-0-c5dd43f2476e@pks.im/
[2]: https://public-inbox.org/git/20250206-b4-pks-path-drop-the-repository-v1-0-4e77f0313206@pks.im/
[3]: https://public-inbox.org/git/cover.1733236936.git.karthik.188@gmail.com/
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-04-06 10:44 ` Ayush Chandekar
@ 2025-04-07 9:06 ` Christian Couder
2025-04-07 10:07 ` Ayush Chandekar
0 siblings, 1 reply; 14+ messages in thread
From: Christian Couder @ 2025-04-07 9:06 UTC (permalink / raw)
To: Ayush Chandekar; +Cc: Karthik Nayak, git, ps, shejialuo, shyamthakkar001
On Sun, Apr 6, 2025 at 12:44 PM Ayush Chandekar <ayu.chandekar@gmail•com> wrote:
>
> >
> > So the approach you suggest is to comb through the global variables and
> > config and find new locations for them to be stored. While this is
> > definitely a bunch chunk of the problem, shouldn't we also talk about
> > how we can reduce usage of some of these variables?
> >
> > In particular, I'm wondering how you'd want to tackle 'the_repository'
> > usage. There is some previous work done here, where Patrick added the
> > '#define USE_THE_REPOSITORY_VARIABLE' definition which tracks usage of
> > global variable and usage of them in different files.
> >
> > A possible approach which has been followed is to simply go from the
> > bottom layers of the code upwards, cleaning up usage of global variables
> > and ensuring we can remove '#define USE_THE_REPOSITORY_VARIABLE' from
> > files. This is also the approach taken in some of the patches that
> > you've linked.
> >
>
> Your approach makes a lot of sense to me, that is, picking a specific
> subsystem or file and aiming to remove the `#define USE_THE_REPOSITORY_VARIABLE`
> definition and thus 'the_repository' eventually. This was the method
> used by Patrick to tackle
> the object subsystem in [1] and the path subsystem in [2] and you to
> tackle the packfile in [3].
> This approach also helps in removing some of the global variables used
> within that particular
> subsystem, which is a nice bonus.
>
> However, this approach might not be feasible for the global variables that
> arent tightly tied to a single subsystem.
Well, initially 'the_repository' wasn't tightly tied to a single
subsystem and even now I am not sure we could say it's tightly tied to
a single subsystem. Or maybe I don't understand what you mean.
Do you mean that it's tightly tied because it needs `#define
USE_THE_REPOSITORY_VARIABLE`?
But for other global variables it could be possible to define and use
similar macros. This way it might be possible to remove those
variables step by step only in some files.
> So what I can do is, for removing
> `the_repository`, I can follow the approach you mentioned, and for relocating
> the more general global variables, I can use the approach which I
> talked about in the
> proposal.
>
> What do you think?
If removing `the_repository` is part of your proposal, then yeah,
describing the approach you will use to remove is a good idea.
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-04-07 9:06 ` Christian Couder
@ 2025-04-07 10:07 ` Ayush Chandekar
0 siblings, 0 replies; 14+ messages in thread
From: Ayush Chandekar @ 2025-04-07 10:07 UTC (permalink / raw)
To: Christian Couder; +Cc: Karthik Nayak, git, ps, shejialuo, shyamthakkar001
>
> Well, initially 'the_repository' wasn't tightly tied to a single
> subsystem and even now I am not sure we could say it's tightly tied to
> a single subsystem. Or maybe I don't understand what you mean.
>
> Do you mean that it's tightly tied because it needs `#define
> USE_THE_REPOSITORY_VARIABLE`?
>
Sorry if I was not clear earlier. I wasn't referring to
'the_repository' being tied, it was about other
global variables being tied to a subsystem.
What I meant is that the approach of picking a subsystem and removing the
`#define USE_THE_REPOSITORY_VARIABLE` is really effective for removing
'the_repository.'
It also helps in localizing the global variables from environment.h
that are specific to that subsystem,
either into the subsystem itself or into struct repository / repo_settings.
But let's say if a global variable is common to 2-3 different subsystems, then
this approach would not be feasible for that variable. For that, I
would require to individually
tackle that variable. This is an approach which I mentioned in my proposal.
So using these two approaches according to different needs, I can move forward.
> But for other global variables it could be possible to define and use
> similar macros. This way it might be possible to remove those
> variables step by step only in some files.
>
Yes, I still need to think through how that would align with the
approach I mentioned.
Defining a single macro like `#define USE_GLOBAL_VARIABLES` is
something I can look into.
> > So what I can do is, for removing
> > `the_repository`, I can follow the approach you mentioned, and for relocating
> > the more general global variables, I can use the approach which I
> > talked about in the
> > proposal.
> >
> > What do you think?
>
> If removing `the_repository` is part of your proposal, then yeah,
> describing the approach you will use to remove is a good idea.
Yes, it is a part of the project but I haven't added this specific
approach in the proposal yet and was hence asking if I can.
Thanks:)
^ permalink raw reply [flat|nested] 14+ messages in thread
* Re: [GSOC] [PROPOSAL v2]: Refactoring in order to reduce Git’s global state
2025-04-04 8:51 ` [GSOC] [PROPOSAL v2]: " Ayush Chandekar
2025-04-04 14:45 ` Karthik Nayak
@ 2025-04-07 8:42 ` Ayush Chandekar
1 sibling, 0 replies; 14+ messages in thread
From: Ayush Chandekar @ 2025-04-07 8:42 UTC (permalink / raw)
To: Ayush Chandekar, Patrick Steinhardt
Cc: christian.couder, git, karthik nayak, shejialuo,
Ghanshyam Thakkar
Hey Patrick,
It would be great if you could take a look at my proposal, especially since
you've worked on this area before. Any feedback would be really appreciated!
Thanks!
Ayush
^ permalink raw reply [flat|nested] 14+ messages in thread
* [GSOC] [PROPOSAL v3]: Refactoring in order to reduce Git’s global state
2025-03-26 5:26 [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state Ayush Chandekar
2025-03-28 13:06 ` shejialuo
2025-04-04 8:51 ` [GSOC] [PROPOSAL v2]: " Ayush Chandekar
@ 2025-04-08 12:52 ` Ayush Chandekar
2 siblings, 0 replies; 14+ messages in thread
From: Ayush Chandekar @ 2025-04-08 12:52 UTC (permalink / raw)
To: ayu.chandekar
Cc: christian.couder, git, karthik.188, ps, shejialuo,
shyamthakkar001
Hello,
This is the third version of my GSoC 2025 proposal for the project
"Refactoring in order to reduce Git’s global state".
The key change from v2 to this v3 is that I’ve added how I plan to tackle
the 'the_repository' global object.
You can view docs version here:
https://docs.google.com/document/d/1tJrtWxo1UGKChB3hu5eZ-ljm0FtU_fsv0TnIRwu3EKY/edit?usp=sharing
---------
Refactoring in order to reduce git’s state
My Information:
---------------
Name: Ayush Chandekar
Email: ayu.chandekar@gmail•com
Mobile No: (+91) 9372496874
Education: UG Sophomore, IIT Roorkee
Github: https://github.com/ayu-ch
Blog: https://ayu-ch.github.io
About me:
---------
I'm Ayush Chandekar, a UG Sophomore studying at Indian Institute of
Technology, Roorkee. I like participating in various software development
and tech-development endeavors, usually hackathons, CTFs, and projects at
SDSLabs. SDSLabs is a student-run technical group that includes passionate
developers and designers interested in various fields and involved in multiple
software development projects that aim to foster a software development
culture on campus. Being a part of this group has exposed me to different
software development methodologies, tools and frameworks and helped me become
comfortable contributing to an open-source project with multiple contributors.
Some open-source contributions I made here are: [1], [2] & [3]
I see this project as a meaningful opportunity to deepen my involvement in
the Git community and to build a foundation for continued contributions to
open source development in the future.
Overview:
---------
Git currently uses a global object called `the_repository`, which refers to a
single instance of `struct repository`. Many internal functions rely on this
global object rather than accepting a `struct repository` as an explicit
parameter. This design inherently assumes a single active repository,
making it difficult to support multi-repository use cases and obstructing
the long-term goal of libification of Git.
A key architectural limitation is that while `struct repository` encapsulates
some repository-specific information, many important environment variables
and configuration settings that logically belong to a repository are still
stored as global variables, primarily in `environment.c`, not within the
`repository` struct. As a result, even if multiple repositories were to
exist concurrently, they would still share this global state, leading to
incorrect behavior, race conditions, or subtle bugs.
This project aims to refactor Git’s environment handling by relocating global
variables into more appropriate local contexts, primarily within
struct repository and struct repo_settings. However, some global variables may
only apply to specific subsystems. In such cases, rather than placing them in
struct repository or struct repo_settings, they should be moved into a
context that better reflects their scope.
This change will not only make the environment state repository-specific but
also improve the modularity and maintainability of the codebase. The work
involves identifying environment-related global variables, determining the
most suitable structure to house them, and updating all affected code paths
accordingly.
The difficulty of this project is medium, and it is estimated to take
175 to 350 hours.
Pre-GSOC:
---------
I started exploring Git’s codebase and documentation around the end of
January, familiarizing myself with its structure and development practices. I
submitted a microproject, which helped me navigate the code and contribution
workflow.
After selecting the project on refactoring Git’s state, I studied the
surrounding code and reviewed past patches ([4], [5], [6], [7], [8] & [9])
to understand the reasoning behind previous changes.
To better prepare for the GSoC timeline, I submitted a patch related to the
project, to gain hands-on experience with both the implementation details
and the submission process. The patch focused on refactoring access to
`core.attributesfile`.
Through discussions and feedback from the community, I gained a clearer
understanding of a key aspect of the project:
determining whether certain variables should belong to repo_settings/
repository or be part of a separate subsystem.
Junio pointed out in a feedback that not all global variables should
be blindly moved into `repo_settings`.
Specifically, for `git_attributes_file`, adding it to the repository struct
doesn’t make sense. He explained that it’s similar to how index_state is
handled, while index_state knows which repository it belongs to, the
repository struct only holds a pointer to a single index_state instance
and isn’t aware of other instances.
Following this approach, instead of placing `git_attributes_file` in the
repository struct, we can house it within an attribute set and pass a
pointer to that set wherever needed.
This practice patch gave me a clearer understanding of the project.
Patches:
--------
For git:
+ (Microproject) t6423: fix suppression of Git’s exit code in tests
Thread:
https://public-inbox.org/git/20250202120926.322417-1-ayu.chandekar@gmail.com/
Status: Merged into master
Commit Hash: 7c1d34fe5d1229362f2c3ecf2d493167a1f555a2
Description: Instead of executing a Git command as the upstream component of
a pipe, which can result in the exit status being lost, redirect
its output to a file and then process that file in two steps to
ensure the exit status is properly preserved.
+ midx: implement progress reporting for QSORT operation
Thread:
https://public-inbox.org/git/20250210074623.136599-1-ayu.chandekar@gmail.com/
Status: Dropped
Description: Add progress reporting during the QSORT operation in
multi-pack-index verification. While going through the code,
I found this TODO, which I thought was interesting however my
approach assumed that the qsort() operation processes elements
in a structured order, which isn't guaranteed.
+ Stop depending on `the_repository` for core.attributesfile
Thread:
https://public-inbox.org/git/20250310151048.69825-1-ayu.chandekar@gmail.com/
Status: WIP, needs more discussion.
Description: This patch refactors access to the `core.attributesfiles`
configuration by moving it into the `repo_settings` struct.
It eliminates the global variable `git_attributes_file` and
updates relevant code paths to pass the `struct repository`
as a parameter.
For git.github.io:
+ GSoC-participants: add GSoC 2024 participants to the list #762
Status: Merged into master
Description: Adding GSoC 2024 participants will help new
contributors understand their journey, making it easier for them
to navigate the program and the project.
+ Rename references from *.txt to *.adoc in documentation paths. #769
Status: Merged into master
Description: Since the documentation in git is changed from *.txt to *.adoc
format. Update references to reflect that change.
+ Rename references from *.txt to *.adoc in Rev News editions. #770
Status: Merged into master
Description: Since the documentation in git is changed from *.txt to *.adoc
format. Update references in previous editions to reflect that change.
Proposed Plan:
--------------
I have been reviewing global variables across the codebase to understand their
dependencies and impact. To do this, I examined `config.c` and cross-referenced
it with `environment.c` to see how these variables are currently managed. The
goal of this project is to eliminate global variables by moving their
configurations into their local contexts.
The general approach for handling a global variable begins with understanding
its purpose. This involves tracing its usage across the codebase and identifying
the subsystem it should belong to. If the variable is closely tied to
repository-related functionality, it may belong in struct repository or
struct repo_settings. Otherwise, it should be placed in a more suitable
context based on its scope.
Additionally, it's important to review previous attempts or related patches
to understand past design decisions and ensure consistency with ongoing efforts.
Finally, the global instance is eliminated by relocating the variable into the
appropriate context and passing it through the relevant code paths.
Example: Handling `is_bare_repository_cfg`
The variable `is_bare_repository_cfg` determines whether a repository is bare,
meaning it lacks a working directory. Since this property is fundamental to
how a repository functions, it should be placed in struct repository.
I have also gone through the code paths and analyzed how this variable is
initialized. We can initialize it similarly to how hash_algo is set through
the repository format. The repository format already contains an `is_bare`
field, which we can use to set this variable inside struct repository.
However, I still have some questions regarding why the is_bare_repository()
function checks for `repo->worktree` and why the `worktree struct` itself has
an `is_bare` variable. If a repository is considered bare when !repo->worktree
is true, the role of `worktree->is_bare` needs further clarification. I believe
that by engaging with the community, my understanding will become clearer.
I also went through [4] to see how John Cai's approach was.
This is how we can also approach for other global variables.
Through multiple iterations, this approach will be refined based on feedback,
edge cases, and community input.
Other than that, we have a global object 'the_repository'. As an attempt to
remove this globally, Patrick introduced a macro
`#define USE_THE_REPOSITORY_VARIABLE` in this patch: [10]. An approach I can
follow is picking a subsystem or file, and aiming to remove the macro and
hence eliminating the usage of 'the_repository' in that subsystem/file by
passing the `struct repository` explicitly through the call chain.
This approach also helps in removing some of the global variables in that
particular subsystem.
This is also followed in the patches by Patrick in
[5] and [6] to tackle the object and path subsystem respectively and Karthik
in [8] to tackle the packfile subsystem.
Timeline:
---------
Pre-GSOC:
(Until 8 May)
- Explore the codebase more, focusing on environment-related code paths.
- Document how each global variable is used and how it can be moved to
repository settings.
- Study Git’s Coding Guidelines and the Pro Git Book to align with best practices.
----------
Community Bonding:
(May 8 - June 1)
- Engage with mentors to discuss different environment variables, their
dependencies, and the best approach for refactoring.
- Finalize an implementation plan based on discussions.
- Since I will be on summer vacation, I can start coding early and make progress
on the project.
----------
Coding Period:
(June 2 - August 25)
- Identify the appropriate subsystem for each global variable and relocate it
into struct repository, struct repo_settings, or other suitable contexts.
- Modify function signatures to pass the new contexts explicitly, replacing
reliance on global variables.
- Pick subsystems and remove the macro
#define USE_THE_REPOSITORY_VARIABLE and thereby eliminating usage
of the global variable ‘the_repository’.
- Continuously submit patches for review and incorporate feedback from mentors
and the community.
- I plan to write weekly blogs which will document what I did in the whole
week.
----------
Final Week:
(August 25 - September 1)
- Write a detailed report on the entire project.
- Fix bugs if any.
- Reflect on the project, noting challenges faced and lessons learned.
Blogging:
---------
I have also set up a blogging page at [11]. While reading blogs from previous
GSoC contributors, I found them useful in understanding the challenges
they faced and how they approached their projects. Their experiences gave
me a better idea of what to expect and how to navigate the development
process. Inspired by this, I decided to start my own blog to document my
journey throughout GSoC. This will not only help me track my own progress but
also serve as a resource for future contributors who might work on similar
projects. I plan to share updates on my work, challenges encountered and
insights gained from discussions with mentors and the community.
Additionally, I hope my blog encourages more people to contribute to open
source by providing a transparent look into the development process. Writing
about my experience will also help me reflect on my work and improve my
ability to communicate technical ideas effectively.
I liked the format and structure of Chandra's blog, so I decided to use the
same template for my own blogging page.
Availability:
-------------
As a college student, I intend to utilise my summer breaks from May to July
to work on the project. After completing my University exams in April, I can
start working in May. I can dedicate 40 hours a week from May to July, while
in August after the classes commence, I can dedicate about 25 hours a week.
There are no exams or planned vacations throughout the coding period. Besides
this project, I have no commitments/vacations planned for the summer. I shall
keep my status posted to all the community members and maintain transparency
in the project.
Post-GSOC:
----------
Beyond contributing code, I strongly believe in giving back to the community
and helping others grow. Open source thrives on mentorship, knowledge sharing,
and long-term involvement, and I would love to continue contributing even
after GSoC ends.
I have always valued mentorship, both as a mentee and as someone who enjoys
guiding others. If given the opportunity, I would be more than happy to
mentor/co-mentor future GSoC contributors. By staying involved in the
community, whether through contributing, reviewing patches, or mentoring,
I hope to help sustain and expand the project’s reach. I look at GSoC as not
just as a one-time contribution but as a step toward a longer-term relationship
with open source.
I will continue to be involved with Git even after GSoC by contributing patches,
reviewing code, and participating in discussions. My work on refactoring Git’s
state aligns with long-term improvements to the codebase, and I plan to keep
refining it beyond the program. I see GSoC as just the beginning of my journey
with Git.
Appreciation:
-------------
I appreciate the Git community for its excellent documentation, which made it
much easier for me to understand Git in depth. The well-structured resources
helped me navigate the codebase and gain a deeper understanding of how Git
works internally.
Beyond the documentation, I am also grateful for how welcoming and supportive
the community has been. Whether through discussions on the mailing list or
feedback on my patches, the information and guidance I received made my
experience even better.
Additionally, I read the blogs and proposals of Chandra, Jialuo, and Ghanashyam,
which provided valuable insights into their journeys and helped me shape my
own approach to contributing.
Thanks for reviewing this proposal.
References:
-----------
[1] https://github.com/sdslabs/beast/pull/374
[2] https://github.com/sdslabs/beast/tree/add-teams-with-hint
[3] https://github.com/sdslabs/playCTF/pull/177
[4] https://public-inbox.org/git/pull.1826.git.git.1730926082.gitgitgadget@gmail.com/
[5] https://public-inbox.org/git/20250303-b4-pks-objects-without-the-repository-v1-0-c5dd43f2476e@pks.im/
[6] https://public-inbox.org/git/20250206-b4-pks-path-drop-the-repository-v1-0-4e77f0313206@pks.im/
[7] https://public-inbox.org/git/pull.1829.git.1731653548549.gitgitgadget@gmail.com/#t
[8] https://public-inbox.org/git/cover.1733236936.git.karthik.188@gmail.com/
[9] https://public-inbox.org/git/cover.1724923648.git.ps@pks.im/
[10] https://public-inbox.org/git/cover.1718347699.git.ps@pks.im/
[11] https://ayu-ch.github.io
^ permalink raw reply [flat|nested] 14+ messages in thread
* [GSOC][PROPOSAL v2]: Refactoring in order to reduce Git’s global state
@ 2026-03-07 20:04 Shreyansh Paliwal
2026-03-20 18:12 ` [GSOC][PROPOSAL v3]: " Shreyansh Paliwal
0 siblings, 1 reply; 14+ messages in thread
From: Shreyansh Paliwal @ 2026-03-07 20:04 UTC (permalink / raw)
To: git
Cc: christian.couder, karthik.188, jltobler, ayu.chandekar,
siddharthasthana31
Hello,
This is my second draft of GSoC 2026 proposal for the project
'Refactoring in order to reduce Git’s global state'.
Doc version can be read at:
https://docs.google.com/document/d/16MRNUv6dJi6vtNvI5Ro0WmHf20dRRBHjFLpmhAuaUOA/edit?usp=sharing
Any feedback or suggestions would be greatly appreciated.
Thanks for reading.
---
Changes in v2:
- Added links in the 'About Me' section and updated reference numbering.
- Rephrased and revised the 'Pre-GSoC', 'History' and 'Proposed Plan' sections.
- Updated patch statuses and changed some wordings.
---
Refactoring in order to reduce Git's global state
Personal Information:
---------------------
Name: Shreyansh Paliwal
Email: Shreyanshpaliwalcmsmn@gmail•com
Alternate Email: Shreyansh.01014803123@it•mait.ac.in
Mobile No.: +91-9335120023
Education: GGSIPU, New Delhi, India
Year: III / IV
Degree: Bachelor of Technology in Information Technology
Github: https://github.com/shreyp135
Time-zone: UTC +5:30 (IST)
About Me:
---------
I am Shreyansh Paliwal, a pre-final year undergraduate student at Guru
Gobind Singh Indraprastha University, New Delhi, India. I am a technology
enthusiast, who began programming in 2018 with Java as my first language
and later transitioned to C/C++ in 2023 as my primary focus. I enjoy
exploring new technologies and programming languages, and have developed
solid experience building applications such as [1] using TypeScript,
React.js, Node.js, and AWS. I actively participate in technical events and
have organized multiple hackathons [2], tech-fests [3], and related
activities at my college as the SIG-Head of IOSD [4], a tech-focused
student community.
I started using Git in 2023, which is also when I made my first open-source
contribution to the Git project. I was a winner of Augtoberfest 2024 [5],
an open-source competition organized by C4GT India. Over the past several
months, I have been involved with the Git project, studying the codebase,
submitting patches, and incorporating review feedback. I am motivated to
improve the experience of Git for end users, and this project is an
excellent opportunity to continue that work.
Overview:
---------
Git relies heavily on global state for managing environment variables and
configuration data. In particular, many parts of the codebase depend on the
global struct repository instance, the_repository, which represents the
currently active repository. Instead of passing a repository instance
explicitly, several internal functions implicitly rely on this global
object. Additionally, various configuration derived values and
environment-related variables such as the_hash_algo, default_abbrev, and
comment_line_str are stored globally, most of them defined in
environment.c.
This design assumes that only one repository is active within a process at
a time. As a result, the repository state becomes shared across the entire
process, weakening isolation and making behavior implicitly dependent on
global context. Such global dependencies make the code harder to reason
about, test, and maintain, and can introduce subtle bugs when operations
interact with multiple repositories. They also limit long-term goals such
as safely supporting multiple repositories within a single process and
continuing Git’s ongoing libification efforts.
To address these issues, global environment and configuration state should
be refactored into better-scoped contexts. Repository-specific data can be
moved into struct repository or related structures, while
subsystem-specific state should be localized appropriately. Passing
repository instances explicitly through function interfaces will improve
modularity, reduce hidden dependencies, and make the codebase easier to
maintain while moving Git closer to supporting multiple repositories safely
within a single process.
The difficulty of this project is medium, and it is estimated to take 175
to 350 hours.
Pre-GSOC:
---------
I first explored the Git codebase in December 2023, when I submitted a
small patch fixing the wording of an error message that I noticed while
browsing the source code. At that time I had recently started using Git and
GitHub for version control in my projects, which sparked my curiosity about
how Git works internally. A few months ago, when I had some free time
from college, I decided to start contributing to Git more actively. I built
Git from source, read parts of the documentation, and familiarized myself
with the mailing list workflow. While going through the documentation, I
noticed a few inconsistencies in the MyFirstContribution page and submitted
patches to fix them. I also completed a microproject involving a test
cleanup, and later worked on adding a warning for a quiet fallback.
During this process, I attempted to remove the usage of the_repository from
a file. After discussion on the mailing list [23], Phillip directed me
towards wt-status, which led me to explore parts of the codebase such as
the wt-status and worktree subsystems. Through this, I learned that such
refactors are generally more valuable in core library code. Following this
discussion, I shifted my focus toward understanding the broader global
state refactoring effort. To better understand the project area, I studied
previous patches and blog posts by Ayush Chandekar and Olamide Bello,
followed related discussions on the mailing list, and explored the relevant
parts of the codebase. This motivated me to work further in this area and
shaped my interest in this project.
The following is a list of my contributions, ordered from earliest to most
recent:
Patches for Git:
----------------
* test-lib-functions.sh: fix test_grep fail message wording
Status: Released in v2.43.1
Mailing List: https://lore.kernel.org/git/20231203171956.771-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 37e8d795bed7b93d3f12bcdd3fbb86dfe57921e6
Log: This was my first patch to Git in 2023. While browsing the
source code and past issues, I noticed that even after
the test_i18ngrep function was deprecated, an error message
referring to test_i18ngrep was left behind. I updated
the wording to correctly reference test_grep.
* doc: MyFirstContribution: fix missing dependencies and clarify build steps
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260112195625.391821-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 81021871eaa8b16a892b9c8791a0c905ab26e342
Log: While getting familiar with the codebase, I followed the
MyFirstContribution documentation and encountered a few
issues. Some include headers were missing, the synopsis
format was incorrect, and the explanation for -j$(nproc)
was absent. I submitted fixes to improve the clarity and
correctness of the documentation.
* t5500: simplify test implementation and fix git exit code suppression (Microproject)
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260121130012.888299-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: a824421d3644f39bfa8dfc75876db8ed1c7bcdbf
Log: This was completed as a microproject for GSoC. Instead of
constructing the pack protocol using a complex combination
of here-docs and echo commands, the patch captures command
outputs beforehand and uses the test-tool pkt-line pack
helper to construct the protocol input in a temporary file
before feeding it to git upload-pack.
* show-index: add warning and wrap error messages with gettext
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260130153603.290196-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: ea39808a22714b8f61b9472de7ef467ced15efea,
227e2cc4e1415c4aeadceef527dd33e478ad5ec3
Log: While exploring the code, I noticed a TODO comment suggesting
automatic hash detection. After discussion on the mailing
list, it was concluded that there was no future-proof
approach to implement this until a new index file format
came into use. Instead, an explicit warning was added rather
than silently falling back to SHA-1. Additionally, several
error messages were missing gettext wrapping, which was also
fixed.
* wt-status: reduce reliance on global state
Status: Will merge to next
Mailing List: https://lore.kernel.org/git/20260218175654.66004-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: a7cd24de0b3b679c16ae3ee8215af06aeea1e6a3,
9d0d2ba217f3ceefb0315b556f012edb598b9724,
4631e22f925fa2af8d8548af97ee2215be101409
Log: This has been the most significant patch series in my journey
so far. It began with a suggestion from Phillip to clean up
some the_repository usages in wt-status.c. I extended the
effort to remove all usages of the_repository and
the_hash_algo from the file. During review discussions, it
was suggested that some worktree API cleanup should happen
first, particularly regarding the representation of worktrees
as NULL. Some related changes were later moved to a separate
series, after which this refactoring proceeded.
* worktree: change representation and usage of primary worktree
Status: Merged into master after being continued by Phillip Wood [6]
Mailing List: https://lore.kernel.org/git/20260213120529.15475-1-shreyanshpaliwalcmsmn@gmail.com/
Log: This worktree API cleanup series started while I was working
on wt-status. The intention was to modify the representation
of the current worktree so that struct worktree would not be
NULL. During discussion, Phillip clarified that NULL actually
represents the current worktree rather than the primary
worktree. Since Phillip already had a patch based on the right
logic, he continued the series and it was eventually merged
into master.
* tree-diff: remove the usage of the_hash_algo global
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260220175331.1250726-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 1e50d839f8592daf364778298a61670c4b998654
Log: This was a straightforward patch that removed the remaining
usages of the global the_hash_algo in tree-diff.c by using the
repository’s local instance instead.
* send-email: UTF-8 encoding in subject line
Status: Will merge to master
Mailing List: https://lore.kernel.org/git/20260228112210.270273-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: c52f085a477c8eece87821c5bbc035e5a900eb12
Log: This patch was motivated by an issue I personally encountered
while sending a GSoC discussion email [7]. Initially the
change only modified the wording of the prompt, but after
discussion on the mailing list it was extended to include
proper validation to prevent invalid charset encodings from
being used in git send-email and to reduce confusion.
* Remove global state from editor.c
Status: Waiting for further feedback
Mailing List: https://lore.kernel.org/git/20260301105228.1738388-1-shreyanshpaliwalcmsmn@gmail.com/
Log: This originated from a question I had about localizing
editor_program in editor.c [7]. The patch received some
mixed feedback on whether editor_program state should
instead become repository-scoped, since it can also be set
via git config --local. I am currently awaiting further
guidance from mentors on the appropriate direction.
Patches for git.github.io:
--------------------------
* SoC-2026-ideas: Remove an extra backtick
Status: merged into master
PR Link: https://github.com/git/git.github.io/pull/831
Merge Commit: c1e4aa87a54430953eaa7355061139fdf1ff6796
Log: Minor Typo fix.
* rn-132: fixed 2 typos
Status: merged into master
PR Link: https://github.com/git/git.github.io/pull/832
Merge Commit: 92876114d855d472ce2e0e5337e72a4b97b81681
Log: Fixed typos in Git Rev News Edition 132.
I have also been involved in additional discussions on the Git mailing
list [8][9][10][11].
History / Background:
--------------------
Efforts to reduce Git’s reliance on global state began as several
subsystems moved toward libification, enabling Git’s internal functionality
to be reused as a library. Early examples include the libification of git
mailinfo by Junio [12] and git apply by Christian [13], these large patch
series exposed the limitations of relying on global state and highlighted
the need for better encapsulation of repository-related data. A key step
was the introduction of struct repository through refactoring by Stefan
Beller [14] and Brandon Williams [15], which was motivated to centralize
repository-related state instead of relying on scattered global variables,
improving code clarity while laying groundwork for future improvements such
as safer multithreading and handling submodules in the same process. Later
work by Patrick further reduced reliance on the global the_repository in
the config [16] and path [17] subsystems, consolidating several variables
into environment.c so environment-related state could be managed in one
place [18]. The macro #define USE_THE_REPOSITORY_VARIABLE was also
introduced to help transition code away from implicit global repository
access [19].
During GSoC 2025, Ayush Chandekar [20] removed additional usages of
the_repository across the codebase and moved several global configuration
variables (such as core_preload_index and merge_log_config) into
repository-scoped structures. More recently, during Outreachy, Olamide
Bello improved configuration handling by introducing repo_config_values, a
structure linked to struct repository that stores repository-specific
configuration values [21][22]. A supporting private structure,
config_values_private, was added for initialization and internal handling.
Discussions around this work also highlighted an important design
constraint: directly moving globals into repository structures or
introducing lazy loading helpers can cause user experience regressions if
configuration errors are detected later.
These efforts collectively form the foundation of the ongoing work to
gradually remove Git’s reliance on global state and move toward a more
modular, repository-scoped architecture.
Proposed Plan:
-------------
I started exploring the codebase by browsing relevant files and identifying
global variables by temporarily removing the USE_THE_REPOSITORY_VARIABLE
macro. My primary focus was on core library files rather than builtin code
[23]. Through this exploration, I observed that a large number of files still
depend on the_repository.
To tackle this project systematically, I propose classifying these files into
two categories:
1. Files using the_repository or the_hash_algo where a repository
instance already exists: These files rely on global variables even
though a struct repository instance is available somewhere in the
call stack. A simple example is my patch in tree-diff.c, where a
repository instance was already available through struct diff_options
*opt, but the_hash_algo was still used. I replaced it with
opt->repo->hash_algo.
In such cases, the refactor mainly involves passing the repository
instance through the function call stack and replacing the global
usages. If a repository instance is not directly available in the
file, I will trace the callers and propagate it from higher levels in
the call hierarchy.
Examples of such files include alias.c, archive*.c, walker.c, and
xdiff-interface.c. These typically require localized refactoring and
are good candidates for incremental patches.
2. Files relying on other global variables defined in environment.c:
Some files depend on additional global variables that are parsed and
accessed through environment.c. In these cases, there is no existing
repository-scoped instance, making the refactor slightly more involved.
Examples include wt-status.c (default_abbrev, comment_line_str) and
apply.c (has_symlink, ignore_case, trust_executable_bit,
apply_default_whitespace, apply_default_ignorewhitespace).
For such variables, I will evaluate whether they should be moved into
repository-scoped structures (e.g., repo_settings or
repo_config_values), or instead be localized and passed explicitly
where needed. The appropriate approach will depend on how widely the
variable is used and whether it logically belongs in a
multi-repository standpoint.
I plan to begin with the first category, addressing straightforward
refactors file by file. In parallel, I will analyze and work on specific
groups of global variables from the second category, designing
appropriate repository-scoped replacements while preserving the
original parsing timing and availability of those variables.
The end goal is to remove reliance on global state and eventually eliminate
the USE_THE_REPOSITORY_VARIABLE macro from these files.
Project Timeline:
----------------
* Community Bonding (Until May 24):
- Discuss the project direction and design approaches with mentors.
- Identify and prioritize two main areas of work:
+ files that rely on the_repository.
+ global variables defined in environment.c.
- Study the previous patches by Olamide Bello and Ayush Chandekar
in depth, and identify any remaining tasks while discussing
their approaches and challenges with them.
- Interact with all the people involved in this work to better
understand design decisions and potential pitfalls.
- Experiment with small RFC patches, if needed to validate approaches.
* Coding period (May 25 - August 16):
- Send patches for any remaining cleanup or refactoring related to
git_default_config() and repo_config_values [22], as well as
the worktree API [24], if any.
- Identify straightforward refactors to remove usages of the_repository
in files such as xdiff-interface.c, archive*.c, fsmonitor*.c etc.
- Work file by file with the goal of eliminating
#define USE_THE_REPOSITORY_VARIABLE by replacing global usages
with explicit repository instances.
- Concurrently maintain at least two parallel patch series:
+ Small / straightforward refactors and replacements like
the_hash_algo or the_repostitory.
+ Larger structural refactors involving globals such as
DEFAULT_ABBREV, comment_line_str etc.
- Publish weekly or biweekly blog updates documenting progress and design
decisions.
* Final week (August 17 - August 24):
- Address any remaining tasks or pending patches.
- Receive final feedback from mentors and reviewers.
- Prepare a detailed report summarizing the work completed during the project.
Blogging:
---------
I believe blogging is an important part of any open-source project. It
helps others understand the ongoing work and also enables the contributor
to develop a deeper understanding and keep a better track of their own
progress. I experienced this firsthand, early in my journey I was unsure
about various aspects, but reading the blogs of Ayush and Olamide Bello
gave me valuable insight into the contributor perspective and their overall
work.
With the goal of helping future contributors in a similar way, I plan to
document my journey and project progress through regular blog posts. I will
publish updates on a weekly or biweekly basis, depending on the amount of
meaningful progress made. I have set up my blogging area on Medium, and my
posts will be available at [25].
Availability:
-------------
The main coding period runs from June to August. Most of June and July
coincide with my summer vacation, which allows me to dedicate significant
time to the project. My final exams are scheduled for May and will last
approximately one week, but they will be completed before the coding period
begins and should not affect my availability.
During June and July, I will be able to dedicate around 40 hours per week to
the project. In August, when my regular semester resumes, I expect to
contribute approximately 25–30 hours per week.
I do not have any other exams, internships, or planned vacations during the
coding period. Apart from this project, I have no other major commitments
for the summer.
I will keep the community regularly updated on my progress throughout the
project. My primary mode of communication will be email, and I will also be
available for calls or meetings if/when required. My preferred availability
window is 13:00–19:00 UTC.
Post GSoC:
----------
Being part of the Git community and contributing to the codebase has been a
very valuable experience for me. The process of understanding Git’s internals,
submitting patches, and receiving feedback on the mailing list has helped me
grow significantly as a developer. The feeling of working on code that is used
by millions of developers and companies around the world is very rewarding.
I plan to remain involved with the Git community even after GSoC by continuing
to contribute patches, review code, and participate in discussions to help make
Git better for end users. The work on refactoring Git’s global state is part of
a long-term effort, and I would love to continue working on it beyond the GSoC
timeline.
I would also be happy to mentor, co-mentor, or volunteer in the future to help
new and upcoming contributors whenever I get the chance. I see GSoC as the
starting point of a long-term relationship with the Git community.
Closing & Appreciation:
-----------------------
I would like to thank the Git community for the excellent documentation and the
welcoming environment. I am also grateful for the patience and guidance shown
in the feedback and discussions on the mailing list by Junio, Phillip, Karthik,
Ben, and others, which have helped me improve my understanding and contributions.
I also read blogs and proposals by Ayush, Lucas, Kousik Sanagavarapu, and Olamide
Bello, which provided valuable insights and helped shape my approach to contributing.
Thank you for reviewing my proposal :)
References:
-----------
[1]- https://github.com/shreyp135/Alethea
[2]- https://unstop.com/hackathons/hackmait-50-iosd-impulse-2024-maharaja-agrasen-institute-of-technology-mait-new-delhi-941779
[3]- https://cse.mait.ac.in/index.php/academics/9-computer-center/1249-iosd-mait-impulse-25, https://unstop.com/college-fests/impulse-2025-maharaja-agrasen-institute-of-technology-mait-new-delhi-348321
[4]- https://iosd-web.vercel.app/
[5]- https://www.linkedin.com/posts/code-for-goodtech_augtoberfest-c4gt2024-activity-7242923677032312834-XMul
[6]- https://lore.kernel.org/git/cover.1771511192.git.phillip.wood@dunelm.org.uk/
[7]- https://lore.kernel.org/git/20260304145823.189440-1-shreyanshpaliwalcmsmn@gmail.com/T/#m65b9b4547036991a7b7f3c861b9663428891f588
[8]- https://lore.kernel.org/git/20260114143238.536312-1-shreyanshpaliwalcmsmn@gmail.com/
[9]- https://lore.kernel.org/git/20260115211609.17420-1-shreyanshpaliwalcmsmn@gmail.com/
[10]- https://lore.kernel.org/git/20260204111343.71975-1-shreyanshpaliwalcmsmn@gmail.com/
[11]- https://lore.kernel.org/git/20260205131132.44282-1-shreyanshpaliwalcmsmn@gmail.com/
[12]- https://lore.kernel.org/git/1444778207-859-1-git-send-email-gitster@pobox.com/
[13]- https://lore.kernel.org/git/20160511131745.2914-1-chriscool@tuxfamily.org/
[14]- https://lore.kernel.org/git/20180205235508.216277-1-sbeller@google.com/
[15]- https://lore.kernel.org/git/20170531214417.38857-1-bmwill@google.com/
[16]- https://lore.kernel.org/git/cover.1715339393.git.ps@pks.im/
[17]- https://lore.kernel.org/git/20250206-b4-pks-path-drop-the-repository-v1-16-4e77f0313206@pks.im/
[18]- https://lore.kernel.org/git/20250717-pks-config-wo-the-repository-v1-20-d888e4a17de1@pks.im/
[19]- https://lore.kernel.org/git/cover.1718347699.git.ps@pks.im/
[20]- https://ayu-ch.github.io/2025/08/29/gsoc-final-report.html
[21]- https://cloobtech.hashnode.dev/week-5-and-6-design-reviews-rfcs-and-refining-the-path-forward
[22]- https://lore.kernel.org/all/cover.1771258573.git.belkid98@gmail.com/
[23]- https://lore.kernel.org/git/7b5dd0c4-0ca0-458e-89db-621a70dac9ae@gmail.com/
[24]- https://lore.kernel.org/git/20260217163909.55094-1-shreyanshpaliwalcmsmn@gmail.com/
[25]- https://medium.com/@shreyanshpaliwal18
^ permalink raw reply [flat|nested] 14+ messages in thread* [GSOC][PROPOSAL v3]: Refactoring in order to reduce Git’s global state
2026-03-07 20:04 [GSOC][PROPOSAL v2]: " Shreyansh Paliwal
@ 2026-03-20 18:12 ` Shreyansh Paliwal
0 siblings, 0 replies; 14+ messages in thread
From: Shreyansh Paliwal @ 2026-03-20 18:12 UTC (permalink / raw)
To: git
Cc: christian.couder, karthik.188, jltobler, ayu.chandekar,
siddharthasthana31
Hello,
This is my third draft of GSoC 2026 proposal for the project
'Refactoring in order to reduce Git’s global state'.
Doc version can be read at:
https://docs.google.com/document/d/16MRNUv6dJi6vtNvI5Ro0WmHf20dRRBHjFLpmhAuaUOA/edit?usp=sharing
I have also uploaded this draft to the GSoC website. Any
final feedback or suggestions would be greatly appreciated.
Thanks for reading.
---
Changes in v3:
- Updated patch list and their statuses.
- Minor wording and grammar changes.
---
Refactoring in order to reduce Git's global state
Personal Information:
---------------------
Name: Shreyansh Paliwal
Email: Shreyanshpaliwalcmsmn@gmail•com
Alternate Email: Shreyansh.01014803123@it•mait.ac.in
Mobile No.: +91-9335120023
Education: GGSIPU, New Delhi, India
Year: III / IV
Degree: Bachelor of Technology in Information Technology
Github: https://github.com/shreyp135
Time-zone: UTC +5:30 (IST)
About Me:
---------
I am Shreyansh Paliwal, a pre-final year undergraduate student at Guru
Gobind Singh Indraprastha University, New Delhi, India. I began programming
in 2018 with Java as my first language and later transitioned to C/C++ in
2023, and it has been my primary focus since then. I also enjoy exploring
new technologies and building applications such as [1], which I developed
using TypeScript, React.js, and AWS. I have also organized multiple
hackathons and technical fests [2][3] at my college as the SIG-Head of
IOSD [4], a tech-focused student community.
I started using Git in 2023, which is also when I made my first open-source
contribution to the Git project. I was also a winner of Augtoberfest 2024
[5], an open-source competition organized by C4GT India. Over the past
several months, I have been actively contributing to Git by studying the
codebase, becoming familiar with the mailing list workflow, and submitting
multiple patches after incorporating review feedback. I am motivated to
improve the experience of Git for end users, and this project is an
excellent opportunity to continue that work.
Overview:
---------
Git relies heavily on global state for managing environment variables and
configuration data. In particular, many parts of the codebase depend on the
global struct repository instance, the_repository, which represents the
currently active repository. Instead of passing a repository instance
explicitly, several internal functions implicitly rely on this global
object. Additionally, various configuration derived values and
environment-related variables such as the_hash_algo, default_abbrev, and
comment_line_str are stored globally, most of them defined in
environment.c.
This design assumes that only one repository is active within a process at
a time. As a result, the repository state becomes shared across the entire
process, weakening isolation and making behavior implicitly dependent on
global context. Such global dependencies make the code harder to reason
about, test, and maintain, and can introduce subtle bugs when operations
interact with multiple repositories. They also limit long-term goals such
as safely supporting multiple repositories within a single process and
continuing Git’s ongoing libification efforts.
To address these issues, global environment and configuration state should
be refactored into better-scoped contexts. Repository-specific data can be
moved into struct repository or related structures, while
subsystem-specific state should be localized appropriately. Passing
repository instances explicitly through function interfaces will improve
modularity, reduce hidden dependencies, and make the codebase easier to
maintain while moving Git closer to supporting multiple repositories safely
within a single process.
The difficulty of this project is medium, and it is estimated to take 175
to 350 hours.
Pre-GSOC:
---------
I first explored the Git codebase in December 2023, when I submitted a
small patch fixing the wording of an error message that I noticed while
browsing the source code. At that time I had recently started using Git and
GitHub for version control in my projects, which sparked my curiosity about
how Git works internally. A few months ago, when I had some free time
from college, I decided to start contributing to Git more actively. I built
Git from source, read parts of the documentation, and familiarized myself
with the mailing list workflow. While going through the documentation, I
noticed a few inconsistencies in the MyFirstContribution page and submitted
patches to fix them. I also completed a microproject involving a test
cleanup, and later worked on adding a warning for a quiet fallback.
During this process, I attempted to remove the usage of the_repository from
a file. After discussion on the mailing list [23], Phillip directed me
towards wt-status, which led me to explore parts of the codebase such as
the wt-status and worktree subsystems. Through this, I learned that such
refactors are generally more valuable in core library code. Following this
discussion, I shifted my focus toward understanding the broader global
state refactoring effort. To better understand the project area, I studied
previous patches and blog posts by Ayush Chandekar and Olamide Bello,
followed related discussions on the mailing list, and explored the relevant
parts of the codebase. This motivated me to work further in this area and
shaped my interest in this project.
The following is a list of my contributions, ordered from earliest to most
recent:
Patches for Git:
----------------
* test-lib-functions.sh: fix test_grep fail message wording
Status: Released in v2.43.1
Mailing List: https://lore.kernel.org/git/20231203171956.771-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 37e8d795bed7b93d3f12bcdd3fbb86dfe57921e6
Log: This was my first patch to Git in 2023. While browsing the
source code and past issues, I noticed that even after
the test_i18ngrep function was deprecated, an error message
referring to test_i18ngrep was left behind. I updated
the wording to correctly reference test_grep.
* doc: MyFirstContribution: fix missing dependencies and clarify build steps
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260112195625.391821-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 81021871eaa8b16a892b9c8791a0c905ab26e342
Log: While getting familiar with the codebase, I followed the
MyFirstContribution documentation and encountered a few
issues. Some include headers were missing, the synopsis
format was incorrect, and the explanation for -j$(nproc)
was absent. I submitted fixes to improve the clarity and
correctness of the documentation.
* t5500: simplify test implementation and fix git exit code suppression (Microproject)
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260121130012.888299-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: a824421d3644f39bfa8dfc75876db8ed1c7bcdbf
Log: This was completed as a microproject for GSoC. Instead of
constructing the pack protocol using a complex combination
of here-docs and echo commands, the patch captures command
outputs beforehand and uses the test-tool pkt-line pack
helper to construct the protocol input in a temporary file
before feeding it to git upload-pack.
* show-index: add warning and wrap error messages with gettext
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260130153603.290196-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: ea39808a22714b8f61b9472de7ef467ced15efea,
227e2cc4e1415c4aeadceef527dd33e478ad5ec3
Log: While exploring the code, I noticed a TODO comment suggesting
automatic hash detection. After discussion on the mailing
list, it was concluded that there was no future-proof
approach to implement this until a new index file format
came into use. Instead, an explicit warning was added rather
than silently falling back to SHA-1. Additionally, several
error messages were missing gettext wrapping, which was also
fixed.
* wt-status: reduce reliance on global state
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260218175654.66004-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: a7cd24de0b3b679c16ae3ee8215af06aeea1e6a3,
9d0d2ba217f3ceefb0315b556f012edb598b9724,
4631e22f925fa2af8d8548af97ee2215be101409
Log: This has been the most significant patch series in my journey
so far. It began with a suggestion from Phillip to clean up
some the_repository usages in wt-status.c. I extended the
effort to remove all usages of the_repository and
the_hash_algo from the file. During review discussions, it
was suggested that some worktree API cleanup should happen
first, particularly regarding the representation of worktrees
as NULL. Some related changes were later moved to a separate
series, after which this refactoring proceeded.
* worktree: change representation and usage of primary worktree
Status: Merged into master after being continued by Phillip Wood [6]
Mailing List: https://lore.kernel.org/git/20260213120529.15475-1-shreyanshpaliwalcmsmn@gmail.com/
Log: This worktree API cleanup series started while I was working
on wt-status. The intention was to modify the representation
of the current worktree so that struct worktree would not be
NULL. During discussion, Phillip clarified that NULL actually
represents the current worktree rather than the primary
worktree. Since Phillip already had a patch based on the right
logic, he continued the series and it was eventually merged
into master.
* tree-diff: remove the usage of the_hash_algo global
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260220175331.1250726-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 1e50d839f8592daf364778298a61670c4b998654
Log: This was a straightforward patch that removed the remaining
usages of the global the_hash_algo in tree-diff.c by using the
repository’s local instance instead.
* send-email: UTF-8 encoding in subject line
Status: Merged into master
Mailing List: https://lore.kernel.org/git/20260228112210.270273-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: c52f085a477c8eece87821c5bbc035e5a900eb12
Log: This patch was motivated by an issue I personally encountered
while sending a GSoC discussion email [7]. Initially the
change only modified the wording of the prompt, but after
discussion on the mailing list it was extended to include
proper validation to prevent invalid charset encodings from
being used in git send-email and to reduce confusion.
* Remove global state from editor.c
Status: Awaiting further feedback / not yet picked up
Mailing List: https://lore.kernel.org/git/20260310174519.676851-1-shreyanshpaliwalcmsmn@gmail.com/
Log: This originated from a question I had about localizing
editor_program in editor.c [7]. The patch had some
discussion on whether editor_program state should become
repository-scoped, since it can also be set via
git config --local. Though it was approved by Karthik it
has not been picked up by Junio yet and may be awaiting
further review.
* add-patch: use repository instance from add_p_state instead of the_repository
Status: Needs Review
Mailing List: https://lore.kernel.org/git/20260318090546.1213077-1-shreyanshpaliwalcmsmn@gmail.com/
Commit: 3cfe355ca74aae5cf90a4eca73a341732b0eb456
Log: This was also a straightforward change where the_repository
was used instead of local instance of struct repo in add-patch
config structs, but it had some changes that overlapped with a
recent patch by Patrik. So I got to know the proper method of
checking any overlapping changing and how to base your changes
on top of them. I have sent the revised version, it needs to be
replaced in the seen branch.
Patches for git.github.io:
--------------------------
* SoC-2026-ideas: Remove an extra backtick
Status: merged into master
PR Link: https://github.com/git/git.github.io/pull/831
Merge Commit: c1e4aa87a54430953eaa7355061139fdf1ff6796
Log: Minor Typo fix.
* rn-132: fixed 2 typos
Status: merged into master
PR Link: https://github.com/git/git.github.io/pull/832
Merge Commit: 92876114d855d472ce2e0e5337e72a4b97b81681
Log: Fixed typos in Git Rev News Edition 132.
* Add Outreachy 2026 participant
Status: merged into master
PR Link: https://github.com/git/git.github.io/pull/836
Merge Commit: 519170970ce7cf29661ee2707aa4e0411cbd2dac
Log: Added Bello Caleb Olamide as Outreachy participant.
I have also been involved in additional discussions on the Git mailing
list [8][9][10][11][26].
History / Background:
--------------------
Efforts to reduce Git’s reliance on global state began as several
subsystems moved toward libification, enabling Git’s internal functionality
to be reused as a library. Early examples include the libification of git
mailinfo [12] and git apply [13], these large patch series exposed the
limitations of relying on global state and highlighted the need for better
encapsulation of repository-related data. A key step was the introduction
of struct repository through refactoring by Stefan Beller [14] and Brandon
Williams [15], which was motivated to centralize repository-related state
instead of relying on scattered global variables, improving code clarity
while laying groundwork for future improvements such as safer
multithreading and handling submodules in the same process. Later work by
Patrick further reduced reliance on the global the_repository in the config
[16] and path [17] subsystems, consolidating several variables into
environment.c so environment-related state could be managed in one place
[18]. The macro #define USE_THE_REPOSITORY_VARIABLE was also introduced to
help transition code away from implicit global repository access [19].
During GSoC 2025, Ayush Chandekar [20] removed additional usages of
the_repository across the codebase and moved several global configuration
variables (such as core_preload_index and merge_log_config) into
repository-scoped structures. More recently, during Outreachy, Olamide
Bello improved configuration handling by introducing repo_config_values, a
structure linked to struct repository that stores repository-specific
configuration values [21][22]. A supporting private structure,
config_values_private, was added for initialization and internal handling.
Discussions around this work also highlighted an important design
constraint: directly moving globals into repository structures or
introducing lazy loading helpers can cause user experience regressions if
configuration errors are detected later.
These efforts collectively form the foundation of the ongoing work to
gradually remove Git’s reliance on global state and move toward a more
modular, repository-scoped architecture.
Proposed Plan:
-------------
I started exploring the codebase by browsing relevant files and identifying
global variables by temporarily removing the USE_THE_REPOSITORY_VARIABLE
macro. My primary focus was on core library files rather than builtin code
[23]. Through this exploration, I observed that a large number of files still
depend on the_repository.
To tackle this project systematically, I propose classifying these files into
two categories:
1. Files using the_repository or the_hash_algo where a repository
instance already exists: These files rely on global variables even
though a struct repository instance is available somewhere in the
call stack. A simple example is my patch in tree-diff.c, where a
repository instance was already available through struct diff_options
*opt, but the_hash_algo was still used. I replaced it with
opt->repo->hash_algo.
In such cases, the refactor mainly involves passing the repository
instance through the function call stack and replacing the global
usages. If a repository instance is not directly available in the
file, I will trace the callers and propagate it from higher levels in
the call hierarchy.
Examples of such files include alias.c, archive*.c, walker.c, and
xdiff-interface.c. These typically require localized refactoring and
are good candidates for incremental patches.
2. Files relying on other global variables defined in environment.c:
Some files depend on additional global variables that are parsed and
accessed through environment.c. In these cases, there is no existing
repository-scoped instance, making the refactor slightly more involved.
Examples include wt-status.c (default_abbrev, comment_line_str) and
apply.c (has_symlink, ignore_case, trust_executable_bit,
apply_default_whitespace, apply_default_ignorewhitespace).
For such variables, I will evaluate whether they should be moved into
repository-scoped structures (e.g., repo_settings or
repo_config_values), or instead be localized and passed explicitly
where needed. The appropriate approach will depend on how widely the
variable is used and whether it logically belongs in a
multi-repository standpoint.
I plan to begin with the first category, addressing straightforward
refactors file by file. In parallel, I will analyze and work on specific
groups of global variables from the second category, designing
appropriate repository-scoped replacements while preserving the
original parsing timing and availability of those variables.
The end goal is to remove reliance on global state and eventually eliminate
the USE_THE_REPOSITORY_VARIABLE macro from these files.
Project Timeline:
----------------
* Community Bonding (Until May 24):
- Discuss the project direction and design approaches with mentors.
- Identify and prioritize two main areas of work:
+ files that rely on the_repository.
+ global variables defined in environment.c.
- Study the previous patches by Olamide Bello and Ayush Chandekar
in depth, and identify any remaining tasks while discussing
their approaches and challenges with them.
- Interact with all the people involved in this work to better
understand design decisions and potential pitfalls.
- Experiment with small RFC patches, if needed to validate approaches.
* Coding period (May 25 - August 16):
- Send patches for any remaining cleanup or refactoring related to
git_default_config() and repo_config_values [22], as well as
the worktree API [24], if any.
- Identify straightforward refactors to remove usages of the_repository
in files such as xdiff-interface.c, archive*.c, fsmonitor*.c etc.
- Work file by file with the goal of eliminating
#define USE_THE_REPOSITORY_VARIABLE by replacing global usages
with explicit repository instances.
- Concurrently maintain at least two parallel patch series:
+ Small / straightforward refactors and replacements like
the_hash_algo or the_repository.
+ Larger structural refactors involving globals such as
DEFAULT_ABBREV, comment_line_str etc.
- Publish weekly or biweekly blog updates documenting progress and design
decisions.
* Final week (August 17 - August 24):
- Address any remaining tasks or pending patches.
- Receive final feedback from mentors and reviewers.
- Prepare a detailed report summarizing the work completed during the project.
Blogging:
---------
I believe blogging is an important part of any open-source project. It
helps others understand the ongoing work and also enables the contributor
to develop a deeper understanding and keep a better track of their own
progress. I experienced this firsthand, early in my journey I was unsure
about various aspects, but reading the blogs of Ayush and Olamide Bello
gave me valuable insight into the contributor perspective and their overall
work.
With the goal of helping future contributors in a similar way, I plan to
document my journey and project progress through regular blog posts. I will
publish updates on a weekly or biweekly basis, depending on the amount of
meaningful progress made. I have set up my blogging area on Medium, and my
posts will be available at [25].
Availability:
-------------
The main coding period runs from June to August. Most of June and July
coincide with my summer vacation, which allows me to dedicate significant
time to the project. My final exams are scheduled for May and will last
approximately one week, but they will be completed before the coding period
begins and should not affect my availability.
During June and July, I will be able to dedicate around 40 hours per week to
the project. In August, when my regular semester resumes, I expect to
contribute approximately 25–30 hours per week.
I do not have any other exams, internships, or planned vacations during the
coding period. Apart from this project, I have no other major commitments
for the summer.
I will keep the community regularly updated on my progress throughout the
project. My primary mode of communication will be email, and I will also be
available for calls or meetings if/when required. My preferred availability
window is 13:00–19:00 UTC.
Post GSoC:
----------
Being part of the Git community and contributing to the codebase has been a
very valuable experience for me. The process of understanding Git’s internals,
submitting patches, and receiving feedback on the mailing list has helped me
grow significantly as a developer. The feeling of working on code that is used
by millions of developers and companies around the world is very rewarding.
I plan to remain involved with the Git community even after GSoC by continuing
to contribute patches, review code, and participate in discussions to help make
Git better for end users. The work on refactoring Git’s global state is part of
a long-term effort, and I would love to continue working on it beyond the GSoC
timeline.
I would also be happy to mentor, co-mentor, or volunteer in the future to help
new and upcoming contributors whenever I get the chance. I see GSoC as the
starting point of a long-term relationship with the Git community.
Closing & Appreciation:
-----------------------
I would like to thank the Git community for the excellent documentation and the
welcoming environment. I am also grateful for the patience and guidance shown
in the feedback and discussions on the mailing list by Junio, Phillip, Karthik,
Ben, and others, which have helped me improve my understanding and contributions.
I also read blogs and proposals by Ayush, Lucas, Kousik Sanagavarapu, and Olamide
Bello, which provided valuable insights and helped shape my approach to contributing.
Thank you for reading my proposal :)
References:
-----------
[1]- https://github.com/shreyp135/Alethea
[2]- https://unstop.com/college-fests/impulse-2025-maharaja-agrasen-institute-of-technology-mait-new-delhi-348321
[3]- https://cse.mait.ac.in/index.php/academics/9-computer-center/1249-iosd-mait-impulse-25
[4]- https://iosd-web.vercel.app/
[5]- https://www.linkedin.com/posts/code-for-goodtech_augtoberfest-c4gt2024-activity-7242923677032312834-XMul
[6]- https://lore.kernel.org/git/cover.1771511192.git.phillip.wood@dunelm.org.uk/
[7]- https://lore.kernel.org/git/20260304145823.189440-1-shreyanshpaliwalcmsmn@gmail.com/T/#m65b9b4547036991a7b7f3c861b9663428891f588
[8]- https://lore.kernel.org/git/20260114143238.536312-1-shreyanshpaliwalcmsmn@gmail.com/
[9]- https://lore.kernel.org/git/20260115211609.17420-1-shreyanshpaliwalcmsmn@gmail.com/
[10]- https://lore.kernel.org/git/20260204111343.71975-1-shreyanshpaliwalcmsmn@gmail.com/
[11]- https://lore.kernel.org/git/20260205131132.44282-1-shreyanshpaliwalcmsmn@gmail.com/
[12]- https://lore.kernel.org/git/1444778207-859-1-git-send-email-gitster@pobox.com/
[13]- https://lore.kernel.org/git/20160511131745.2914-1-chriscool@tuxfamily.org/
[14]- https://lore.kernel.org/git/20180205235508.216277-1-sbeller@google.com/
[15]- https://lore.kernel.org/git/20170531214417.38857-1-bmwill@google.com/
[16]- https://lore.kernel.org/git/cover.1715339393.git.ps@pks.im/
[17]- https://lore.kernel.org/git/20250206-b4-pks-path-drop-the-repository-v1-16-4e77f0313206@pks.im/
[18]- https://lore.kernel.org/git/20250717-pks-config-wo-the-repository-v1-20-d888e4a17de1@pks.im/
[19]- https://lore.kernel.org/git/cover.1718347699.git.ps@pks.im/
[20]- https://ayu-ch.github.io/2025/08/29/gsoc-final-report.html
[21]- https://cloobtech.hashnode.dev/week-5-and-6-design-reviews-rfcs-and-refining-the-path-forward
[22]- https://lore.kernel.org/all/cover.1771258573.git.belkid98@gmail.com/
[23]- https://lore.kernel.org/git/7b5dd0c4-0ca0-458e-89db-621a70dac9ae@gmail.com/
[24]- https://lore.kernel.org/git/20260217163909.55094-1-shreyanshpaliwalcmsmn@gmail.com/
[25]- https://medium.com/@shreyanshpaliwal18
[26]- https://lore.kernel.org/git/20260319092441.1283001-1-shreyanshpaliwalcmsmn@gmail.com/
^ permalink raw reply [flat|nested] 14+ messages in thread
end of thread, other threads:[~2026-03-20 18:17 UTC | newest]
Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-03-26 5:26 [GSOC] [PROPOSAL V1]: Refactoring in order to reduce Git’s global state Ayush Chandekar
2025-03-28 13:06 ` shejialuo
2025-03-29 9:54 ` Ayush Chandekar
2025-03-31 14:17 ` shejialuo
2025-03-31 15:04 ` Ayush Chandekar
2025-03-31 15:18 ` Ayush Chandekar
2025-04-04 8:51 ` [GSOC] [PROPOSAL v2]: " Ayush Chandekar
2025-04-04 14:45 ` Karthik Nayak
2025-04-06 10:44 ` Ayush Chandekar
2025-04-07 9:06 ` Christian Couder
2025-04-07 10:07 ` Ayush Chandekar
2025-04-07 8:42 ` Ayush Chandekar
2025-04-08 12:52 ` [GSOC] [PROPOSAL v3]: " Ayush Chandekar
-- strict thread matches above, loose matches on Subject: below --
2026-03-07 20:04 [GSOC][PROPOSAL v2]: " Shreyansh Paliwal
2026-03-20 18:12 ` [GSOC][PROPOSAL v3]: " Shreyansh Paliwal
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