# 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/codeberg.org/lindenii/furgit.svg)](https://pkg.go.dev/codeberg.org/lindenii/furgit) Furgit is a fast Git library in pure Go (and a little bit of optional Go Assembly). ## Project status * Initial development * Frequent breaking changes * Do not use in production * Will likely use [Semantic Versioning 2.0.0](https://semver.org/spec/v2.0.0.html) later ## Current features * SHA-256 and SHA-1\ (runtime supports both; tests are SHA-256 by default, but the `sha1` build tag makes it test SHA-1) * Reading loose objects * Writing loose objects * Reading packfiles * Writing packfiles (no thin packs yet) * General support for blobs, trees, commits, and tags ## Future features * Compression algorithm agility * Multi pack indexes * Repack * [commit-graph](https://git-scm.com/docs/commit-graph) * Network protocols * And much more ## General goals Furgit intends to be a general-purpose Git library. For now, Furgit primarily prioritize APIs and optimizations that are likely to be used by software development forges and other server-side usages; in particular, Furgit follows the needs of [Villosa](https://villosa.lindenii.org/villosa//repos/villosa/) and to some extent [tangled](https://tangled.org/@tangled.org/core). ## Performance optimizations * Aggressive pooling of byte buffers * Aggressive pooling of custom zlib readers * Minor SIMD optimizations for Adler-32 * Memory-mapping packfiles and their indexes ## Performance See [gitbench](https://git.sr.ht/~runxiyu/gitbench) for details on methods. All tests below were run on `linux.git` with `HEAD` at `6da43bbeb6918164` on a `Intel(R) Core(TM) i5-10210U CPU @ 1.60GHz`. | Task | [git](https://git-scm.com) | Furgit | [libgit2](https://libgit2.org) | [go-git](https://github.com/go-git/go-git) | | - | - | - | - | - | | Traversing all trees | 0.1s | 9s | 19s | 122s | | Traversing the root tree | 4ms | 1ms | 11ms | 1800ms | **Note:** go-git is expected to perform much better after [storage: filesystem/mmap, Add PackScanner to handle large repos](https://github.com/go-git/go-git/pull/1776). ## Architectural considerations It is important to realize that Furgit, and performant Git implementations in general, heavily rely on using memory mappings of packfiles, and assume relatively predictable fault handling behavior. Therefore, in distributed systems, we strongly advise *not* using Furgit on top of distributed network filesystems such as CephFS or NFS; instead, consider solutions where redundancy and distributions belong *above* the Git layer, such as using a set of Git nodes each running Furgit/etc. on local repositories, then using an RPC protocol over it. ## Dependencies * The standard library * Some things from `golang.org/x` It is unlikely that other dependencies will be introduced. Occasionally, external code is introduced but maintained in-tree. ## Environment requirements 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. ## Repos and mirrors * [Codeberg](https://codeberg.org/lindenii/furgit) (with the canonical issue tracker) * [SourceHut mirror](https://git.sr.ht/~runxiyu/furgit) * [tangled mirror](https://tangled.org/@runxiyu.tngl.sh/furgit) * [GitHub mirror](https://github.com/runxiyu/furgit) ## Community * [#lindenii](https://webirc.runxiyu.org/kiwiirc/#lindenii) on [irc.runxiyu.org](https://irc.runxiyu.org) * [#lindenii](https://web.libera.chat/#lindenii) on [Libera.Chat](https://libera.chat) ## History and lineage * I wrote Lindenii Forge * I wrote [hare-git](https://codeberg.org/lindenii/hare-git) * I wanted a faster Git library for [Lindenii Villosa](https://codeberg.org/lindenii/villosa) the next generation of Lindenii Forge * I translated hare-git and put it into `internal/common/git` in Villosa * I extracted it out into a general-purpose library, which is what we have now * I was thinking of names and I accidentally typed "git" as "fur" (i.e., left shifted one key on my QWERTY keyboard), so, "Furgit" ## 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. ```