Re: [PATCH] Remove StGit patch detection from vcs_info

[Daniel Shahaf <d.s@daniel.shahaf.name>]

Mikael Magnusson wrote on Mon, Nov 14, 2022 at 06:17:02 +0100:
> On 11/14/22, Peter Grayson <pete@jpgrayson.net> wrote:
> > On Sat, Nov 12, 2022, at 11:30 PM, Daniel Shahaf wrote:
> >> Peter Grayson wrote on Sat, Nov 12, 2022 at 09:46:02 -0500:
> >>> On Fri, Nov 11, 2022, at 6:49 AM, Daniel Shahaf wrote:
> >>> > [re #2]: It sounds like StGit 2.x support can be implemented at the
> >>> > cost
> >>> > of one fork(2) for those who don't use StGit and under a microsecond
> >>> > for
> >>> > those who do.  That doesn't sound like a deal breaker at all.
> >>>
> >>> Running `stg series` with StGit 2.0 takes about 12ms in my environment.
> >>> StGit 1.5 it is about 32ms. Not a microsecond, but perhaps acceptable
> >>> nonetheless.
> >>>
> >>
> >> To be clear, are these figures the duration of the «stg series
> >> --noprefix --applied» invocation?
> >
> > Yes.
> >
> >> What's the impact on people who don't have stg(1) installed, or who have
> >> stg(1) installed but are currently in a worktree that doesn't use StGit?
> >> I.e., are those figures immediately after `git init`, or in a worktree
> >> that has a StGit patch stack, or?
> >
> > Without stg(1) installed, the cost would be however long it takes zsh to
> > determine that the executable is not available in $path, which is
> > ostensibly very fast (microseconds?).
> >
> > If stg(1) is installed, but run in a repo with a branch that has not been
> > initialized with `stg init`, it's still about 12ms. Almost all that time
> > is taken just to initialize a libgit2 Repository structure, which is
> > used to interrogate the object database to determine whether a StGit
> > stack is initialized.
> 
> fwiw, vcs_info lets you configure which vcs systems it looks for,
> whether or not you have them installed. eg, I use:
>   zstyle ':vcs_info:*:*' enable git hg svn

Right, but this just determines whether VCS_INFO_get_data_(git|hg|svn)
may ever run at all.  The situation we're talking about is that someone
has «git» in the «enable» style but doesn't use StGit, so would want
VCS_INFO_get_data_git to (1) run, but (2) not look for StGit patch
stacks.  There's no way to selectively disable just that one «elif» in
the middle of VCS_INFO_get_data_git.

> although these days i could surely set that to just git...