From 8dc517f50090a8375b59e2f0349bf93dd99521be Mon Sep 17 00:00:00 2001 From: Melody Horn Date: Tue, 23 Feb 2021 02:20:52 -0700 Subject: test some git alternatives, and grumble a lot --- _posts/2021-02-22-can-we-please-move-past-git.md | 190 +++++++++++++++++++++++ 1 file changed, 190 insertions(+) create mode 100644 _posts/2021-02-22-can-we-please-move-past-git.md diff --git a/_posts/2021-02-22-can-we-please-move-past-git.md b/_posts/2021-02-22-can-we-please-move-past-git.md new file mode 100644 index 0000000..56b8fb0 --- /dev/null +++ b/_posts/2021-02-22-can-we-please-move-past-git.md @@ -0,0 +1,190 @@ +--- +title: Can We Please Move Past Git? +--- + +> Git is fundamentally a content-addressable filesystem with a VCS user interface written on top of it. +> +> — [Pro Git §10.1](https://git-scm.com/book/en/v2/Git-Internals-Plumbing-and-Porcelain) + +Most software development is not like the Linux kernel's development; as such, Git is not designed for most software development. +Like Samuel Hayden tapping the forces of Hell itself to generate electricity, the foundations on which Git is built are overkill on the largest scale, and when the interface concealing all that complexity cracks, the nightmares which emerge can only be dealt with by the Doom Slayer that is [Oh Shit Git](https://ohshitgit.com/). +Of course, the far more common error handling method is [start over from scratch](https://xkcd.com/1597/). + +Git is bad. +But are version control systems like operating systems in that they're all various kinds of bad, or is an actually good VCS possible? +I don't know, but I can test some things and see what comes up. + +## Mercurial + +[Mercurial](https://www.mercurial-scm.org/) is a distributed VCS that's around the same age as Git, and I've seen it called the Betamax to Git's VHS, which my boomer friends tell me is an apt analogy, but I'm too young for that to carry meaning. +So let me see what all the fuss is about. + +Well, I have some bad news. +From the [download page](https://www.mercurial-scm.org/downloads), under "Requirements": + +> Mercurial uses Python (version **2.7**). Most ready-to-run Mercurial distributions include Python or use the Python that comes with your operating system. + +Emphasis theirs, but I'd have added it myself otherwise. +Python 2 has been dead for a very long time now, and saying you require Python 2 makes me stop caring faster than referring to "GNU/Linux". +If you've updated it to Python 3, cool, don't say it uses Python 2. +Saying it uses Python 2 makes me think you don't have your shit together, and in fairness, that makes two of us, but I'm not asking people to use my version control system (so far, at least). + +You can't be better than Git if you're that outdated. (Although you can totally be better than Git by developing a reputation for having a better UI than Git; word of mouth helps a lot.) + +## Subversion + +I am a fan of subverting things, and I have to respect wordplay. +So let's take a look at [Subversion](https://subversion.apache.org/) (sorry, "Apache® Subversion®"). + +There are no official binaries at all, and the most-plausible-looking blessed unofficial binary for Windows is TortoiseSVN. +I'm looking through the [manual](https://tortoisesvn.net/docs/release/TortoiseSVN_en/tsvn-repository.html#tsvn-repository-layout), and I must say, the fact that branches and tags aren't actually part of the VCS, but instead conventions on top of it, isn't good. +When I want to make a new branch, it's usually "I want to try an experiment, and I want to make it easy to give up on this experiment." +Also, I'm not married to the idea of distributed VCSes, but I do tend to start a project well before I've set up server-side infrastructure for it, and Subversion is not designed for that sort of thing at all. +So I think I'll pass. + +You can't be better than Git if the server setup precedes the client setup when you're starting a new project. +(Although you can totally be better than Git by having monotonically-ish increasing revision numbers.) + +## Fossil + +[Fossil](https://fossil-scm.org/) is kinda nifty: it handles not just code but also issue tracking, documentation authoring, and a bunch of the other things that services like GitHub staple on after the fact. +Where Git was designed for the Linux kernel, which has a fuckton of contributors and needs to scale absurdly widely, Fossil was designed for SQLite, which has a very small number of contributors and does not solicit patches. +My projects tend to only have one contributor, so this should in principle work fine for me. + +However, a few things about Fossil fail to spark joy. +The fact that repository metadata is stored as an independent file separate from the working directory, for example, is a design decision that doesn't merge well with my existing setup. +If I were to move my website into Fossil, I would need somewhere to put `boringcactus.com.fossil` outside of `D:\Melody\Projects\boringcactus.com` where the working directory currently resides. +The [documentation](https://fossil-scm.org/home/doc/trunk/www/whyusefossil.wiki#definitions) suggests `~/Fossils` as a folder in which repository metadata can be stored, but that makes my directory structure more ugly. +The rationale for doing it this way instead of having `.fossil` in the working directory like `.git` etc. is that multiple checkouts of the same repository are simpler when repository metadata is outside each of them. +Presumably the SQLite developers do that sort of thing a lot, but I don't, and I don't know anyone who does, and I've only ever done it once (back in the days when the only way to use GitHub Pages was to make a separate `gh-pages` branch). +Cluttering up my filesystem just so you can support a weird edge case that I don't need isn't a great pitch. + +But sure, let's check this out. +The [docs](https://fossil-scm.org/home/doc/trunk/www/inout.wiki) have instructions for importing a Git repo to Fossil, so let's follow them: + +```text +PS D:\Melody\Projects\boringcactus.com> git fast-export --all | fossil import --git D:\Melody\Projects\misc\boringcactus.com.fossil +]ad fast-import line: [S IN THE +``` + +Well, then. +You can't be better than Git if your instructions for importing from Git don't actually work. +(Although you can totally be better than Git if you can keep track of issues etc. alongside the code.) + +## Darcs + +[Darcs](http://darcs.net/) is a distributed VCS that's a little different to Git etc. +Git etc. have the *commit* as the fundamental unit on which all else is built, whereas Darcs has the *patch* as its fundamental unit. +This means that a branch in Darcs refers to a set of patches, not a commit. +As such, Darcs can be more flexible with its history than Git can: a Git commit depends on its temporal ancestor ("parent"), whereas a Darcs patch depends only on its logical ancestor (e.g. creating a file before adding text to it). +This approach also improves the way that [some types of merge](https://tahoe-lafs.org/~zooko/badmerge/simple.html) are handled; I'm not sure how often this sort of thing actually comes up, but the fact that it could is definitely suboptimal. + +So that's pretty cool; let's take a look for ourselves. +Oh. +Well, then. +The [download page](http://darcs.net/Binaries) is only served over plain HTTP - there's just nothing listening on that server over HTTPS - and the downloaded binaries are also served over plain HTTP. +That's not a good idea. +I'll pass, thanks. + +You can't be better than Git while serving binaries over plain HTTP. +(Although you can totally be better than Git by having nonlinear history and doing interesting things with patches.) + +## Pijul + +[Pijul](https://pijul.org/) is (per [the manual](https://pijul.org/manual/why_pijul.html)) + +> the first distributed version control system to be based on a sound mathematical theory of changes. It is inspired by Darcs, but aims at solving the soundness and performance issues of Darcs. + +Inspired by Darcs but better, you say? +You have my attention. +Also of note is that the developers are also building their own GitHub clone, which they use to [host pijul itself](https://nest.pijul.com/pijul/pijul), which gives a really nice view of how a GitHub clone built on top of pijul would work, and also offers free hosting. + +The manual gives [installation instructions](https://pijul.org/manual/installing.html) for a couple Linuces and OS X, but not Windows, and not Alpine Linux, which is the only WSL distro I have installed. +However, someone involved in the project [showed up in my mentions to say that it works on Windows](https://twitter.com/nuempe/status/1359614145415548939), so we'll just follow the generic instructions and see what happens: + +```text +PS D:\Melody\Projects> cargo install pijul --version "~1.0.0-alpha" + Updating crates.io index + Installing pijul v1.0.0-alpha.38 + Downloaded + Compiling +error: linking with `link.exe` failed: exit code: 1181 + | + = note: "C:\\Program Files (x86)\\Microsoft Visual Studio\\2019\\BuildTools\\VC\\Tools\\MSVC\\14.27.29110\\bin\\HostX64\\x64\\link.exe" + = note: LINK : fatal error LNK1181: cannot open input file 'zstd.lib' + + +error: aborting due to previous error +``` + +So it doesn't work for me on Windows. +(There's a chance that instructions would help, but in the absence of those, I will simply give up.) +Let's try it over on Linux: + +```text +UberPC-V3:~$ cargo install pijul --version "~1.0.0-alpha" + +error: linking with `cc` failed: exit code: 1 + | + = note: "cc" + = note: /usr/lib/gcc/x86_64-alpine-linux-musl/9.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lzstd + /usr/lib/gcc/x86_64-alpine-linux-musl/9.3.0/../../../../x86_64-alpine-linux-musl/bin/ld: cannot find -lxxhash + collect2: error: ld returned 1 exit status + + +error: aborting due to previous error +UberPC-V3:~$ sudo apk add zstd-dev xxhash-dev +UberPC-V3:~$ cargo install pijul --version "~1.0.0-alpha" + + Installed package `pijul v1.0.0-alpha.38` (executable `pijul`) +``` + +Oh hey, would you look at that, it actually worked, and all I had to do was wait six months for each compile to finish (and make an educated guess about what packages to install). +So for the sake of giving back, let's add those instructions to the manual, so nobody else has to bang their head against the wall like I'd done the past few times I tried to get Pijul working for myself. + +First, clone the [repository for the manual](https://nest.pijul.com/pijul/manual): + +```text +UberPC-V3:~$ pijul clone https://nest.pijul.com/pijul/manual +Segmentation fault +``` + +Oh my god. +That's extremely funny. +Oh fuck that's *hilarious* - I sent that to a friend and her reaction reminded me that Pijul is *written in Rust*. +This VCS so profoundly doesn't work on my machine that it manages to segfault in a language that's supposed to make segfaults impossible. +Presumably the segfault came from C code FFId with `unsafe` preconditions that weren't met, but still, that's just amazing. + +You can't be better than Git if you don't work on the platforms I personally have convenient access to. +(Although you can totally be better than Git by having your own officially-blessed GitHub clone sorted out already.) +(And in fairness, this *is* pretty clearly labeled as still in alpha, so maybe as Pijul matures it'll get more reliable and be worth reevaluating.) + +## what next? + +None of the existing VCSes that I looked at were unreservedly better than Git, but they all had aspects that would help beat Git. + +A tool which is actually better than Git should start by being no worse than Git: + +* allow importing existing Git repositories +* don't require Git users to relearn every single thing - we already had to learn Git, we've been through enough + +Then, to pick and choose the best parts of other VCSes, it should + +* have a UI that's better, or at least perceived as better, than Git's - ideally minimalism and intuitiveness will get you there, but user testing is gonna be the main thing +* avoid opaque hashes as the primary identifier for things - `r62` carries more meaning than `7c7bb33` - but not at the expense of features that are actually important +* go beyond just source code, and cover issues, documentation wikis, and similar items, so that (for at least the easy cases) the entire state of the project is contained within version control +* approach history as not just a linear sequence of facts but a *story* +* offer hosting to other developers who want to use your VCS, so they don't have to figure that out themselves to get started in a robust way + +And just for kicks, a couple of extra features that nobody has but everybody should: + +* the CLI takes a back seat to the GUI (or TUI, I guess) - seeing the state gets easier that way, discovering features gets easier that way, teaching to people who aren't CLI-literate gets easier that way +* contributor names & emails aren't immutable - trans people exist, and `git filter-graph` makes it about as difficult to change my name as the state of Colorado did +* if you build in issue/wiki/whatever tracking, also build in CI in some way +* avoid internal jargon - either say things in plain $LANG or develop a consistent and intuitive metaphor and use it literally everywhere + +I probably don't have the skills, and I certainly don't have the free time, to build an Actually Good VCS myself. +But if you want to, here's what you're aiming for. +Good luck. +If you can pull it off, you'll be a hero. +And if you can't, you'll be in good company. -- cgit v1.2.3