# Furgit

[![builds.sr.ht status](https://builds.sr.ht/~runxiyu/furgit.svg)](https://builds.sr.ht/~runxiyu/furgit?)
[![Go Reference](https://pkg.go.dev/badge/git.sr.ht/~runxiyu/furgit.svg)](https://pkg.go.dev/git.sr.ht/~runxiyu/furgit)

Furgit is a fast implementation of Git in pure Go, extracted from
[an internal package of Lindenii Villosa](https://codeberg.org/lindenii/villosa/src/branch/master/villosad/internal/common/git).

Furgit is in initial development, does not have tagged releases yet, and we can
guarantee that the API will break every now and then. Do not use in
production.

We do not focus on command-line utilities; in particular, Furgit does not
intend to replace [upstream git](https://git-scm.com). It is intended to be
used as a library.

## Features

Currently, furgit is very basic; it supports reading and writing loose objects
and reading from packfiles. There is some infrastructure for writing packfiles
in the tests but they need to be refactored.

We intend for repository objects to be freely usable across goroutines, which
may enable long-running applications such as forges to keep a pool of recently
used repos (including their `.idx` and `.pack` cache) for rapid access.

We currently do not intend to support flexible storage backends such as
[storers in go-git](https://pkg.go.dev/github.com/go-git/go-git/v5/plumbing/storer);
a standard UNIX-like filesystem with
[syscall.Mmap](https://pkg.go.dev/syscall#Mmap) is expected.

## Performance

Furgit is aggressively optimized for performance.
[As of November 2025](https://git.sr.ht/~runxiyu/gitbench),
for the task of `git ls-tree --long HEAD` on large repos such as
[Linux](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git),
it is:

* approximately the same performance as [upstream git](https://git-scm.com),
* approximately 10 times faster than [libgit2](https://libgit2.org), and
* approximately 1000 times faster than [go-git](https://github.com/go-git/go-git).

## Hash algorithm

Furgit uses SHA-256 by default. To switch to SHA-1, use the `sha1` build tag.

There will be future research to investigate potentially supporting both
algorithms in one build of the library (likely heavily using generics).

## Development

* [Main SourceHut repository](https://git.sr.ht/~runxiyu/furgit)
  and [public inbox](https://lists.sr.ht/~runxiyu/public-inbox)
  for [patches](https://git-send-email.io/) and discussions
* [Codeberg](https://codeberg.org/runxiyu/furgit)
  (issues and pulls are welcome here too)
* [tangled](https://tangled.org/@runxiyu.tngl.sh/furgit)
  (issues and pulls are welcome here too)
* [GitHub](https://github.com/runxiyu/furgit)
  (issues and PRs are welcome here too)
* `#chat` on [irc.runxiyu.org](https://irc.runxiyu.org)
  ([web chat](https://webirc.runxiyu.org/kiwiirc/#chat))

## Etymology

I was thinking of names and I accidentally typed "git" as "fur" (i.e., left
shifted one key on my QWERTY keyboard).

## License

This project is licensed under the GNU Affero General Public License,
Version 3.0 only.

Pursuant to Section 14 of the GNU Affero General Public License, Version 3.0,
[Runxi Yu](https://runxiyu.org) is hereby designated as the proxy who is
authorized to issue a public statement accepting any future version of the
GNU Affero General Public License for use with this Program.

Therefore, notwithstanding the specification that this Program is licensed
under the GNU Affero General Public License, Version 3.0 only, a public
acceptance by the Designated Proxy of any subsequent version of the GNU Affero
General Public License shall permanently authorize the use of that accepted
version for this Program.

For the purposes of the Developer Certificate of Origin, the "open source
license" refers to the GNU Affero General Public License, Version 3.0, with the
above proxy designation pursuant to Section 14.

All contributors are required to "sign-off" their commits (using `git commit
-s`) to indicate that they have agreed to the [Developer Certificate of
Origin](https://developercertificate.org), reproduced below.

```
Developer Certificate of Origin
Version 1.1

Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
1 Letterman Drive
Suite D4700
San Francisco, CA, 94129

Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.


Developer's Certificate of Origin 1.1

By making a contribution to this project, I certify that:

(a) The contribution was created in whole or in part by me and I
    have the right to submit it under the open source license
    indicated in the file; or

(b) The contribution is based upon previous work that, to the best
    of my knowledge, is covered under an appropriate open source
    license and I have the right under that license to submit that
    work with modifications, whether created in whole or in part
    by me, under the same open source license (unless I am
    permitted to submit under a different license), as indicated
    in the file; or

(c) The contribution was provided directly to me by some other
    person who certified (a), (b) or (c) and I have not modified
    it.

(d) I understand and agree that this project and the contribution
    are public and that a record of the contribution (including all
    personal information I submit with it, including my sign-off) is
    maintained indefinitely and may be redistributed consistent with
    this project or the open source license(s) involved.
```