magit + libgit2
reddit / emacs

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zsome · 2022-08-24 10:34

Hi,

Do you use magit + libgit2 ?

Can I ask you to write a short  comment how to set it up ?

thanks !

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nnreddit-user · 2022-08-24 11:00

It can't be done, at least not at a level that's useful (I've tried).
There are still things raw git can do that libgit2 cannot (and that
set continues to grow).

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wyuenho · 2022-08-24 19:39

It can be "done", I just don't notice any difference lol, not even
purported speedups because creating a process from emacs is actually
quite fast already.

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jimehgeek · 2022-08-25 01:44

If you’re talking about the `magit-libgit`, there’s no real difference
compared to without it, cause only one thing is implemented:
https://github.com/magit/magit/blob/712be4632b0ddc7899ca90db8f9be20d90
b4326f/lisp/magit-libgit.el

So the rest of magic still won’t use libgit2… lol

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zsome · 2022-08-26 04:36

Thanks, I saw it but I saw this one as well:
[https://github.com/magit/libegit2](https://github.com/magit/libegit2)

I have problem with magit in the win10 system only , but the git gui
and gitk can work well ...

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jimehgeek · 2022-08-26 08:09

Ah, I’ve not seen that repo. Though it looks to be a wrapper module
around libgit2, so I’m not sure the module alone would make magit
automatically use it if available 🤔

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nnreddit-user · 2022-08-26 09:18

In March, I started by trying to get magit-status (C-x g) to use
libgit2 exclusively.  Two weeks of effort resulted in 200 files
changed and a 100 ms shaved off `C-x g` on an ubuntu system.

As much as I hate name-dropping urls (because no one wants to click
out of reddit), I do so here for the court as Exhibits A and B.

https://github.com/dickmao/magit/tree/libgit2-el (magit)
https://github.com/dickmao/libgit2-el (libegit2)

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zsome · 2022-08-27 05:07

Thanks!

I'll give a try to this!

I intended to use it on win10 ... that is where it's a pain :(

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nnreddit-user · 2022-08-27 07:19

> I'll give a try to this!

That would be a mistake.  I can already tell you're not going to get
very far.

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arthurno1 · 2022-08-27 11:12

> It can't be done, at least not at a level that's useful (I've
tried).

Depends on what you tried and how you use Git maybe? "Can't be done"
anyway sounds a bit too presumptuous to me.

There are things where libgit2 is faster than git, and there are
things libgit2 can't do. Here is a brief note from [another
discussion](https://gitlab.com/gitlab-org/gitaly/-/issues/2011):

> There are areas where libgit2 offers major performance benefits,
mostly for batch operations. We recently talked about running git
blame on multiple files: with git, to blame N files you must start N
git blame processes. Spawning a process is relatively expensive.
Another good example is "last commit for path", where for each path,
we must spawn a git log -1 foo/bar process.
Apart from reducing process spawn overhead, libgit2 is also cheaper
for looking up Git objects. The status quo in Gitaly is that we use a
git cat-file process. For each object lookup we must do a write and a
read syscall on the stdin and stdout pipes of git cat-file,
respectively. A process that uses libgit2 is just doing memory-mapped
IO so syscalls get amortized into page faults, and repeat lookups of
the same Git object sometimes don't require context switches at all.

So it seems that mixed libgit2 + git process in Magit, or Emacs in
general, could benefit heavy git users.

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nnreddit-user · 2022-08-27 13:37

> sounds a bit too presumptuous to me

In your case there's almost no limit to what I can presume.

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arthurno1 · 2022-08-27 15:10

> In your case there's almost no limit to what I can presume.

Why limiting yourself to presumptions? The only limit is the
imagination, as they say ...