Re: git-testadd: Execute a command with only the staged changes in Git applied

From: Øyvind A. Holm <sunny@sunbase.org>
Date: Jul 28, 2016, 22:31 UTC
Message-ID: <CAA787rm+qLig6mzHw0NjNDt-6HF_77FOwmg5dBBOdwbqo3wP6A@mail.gmail.com>
In-Reply-To: <579A5D97.7080708@gmail.com>

On 28 July 2016 at 21:31, Jakub Narębski <jnareb@gmail.com> wrote:

Show 19 quoted lines

> W dniu 2016-07-28 o 18:56, Øyvind A. Holm pisze:
> > Øyvind A. Holm <sunny@sunbase.org> writes:
> > > This is a script I created some weeks ago, and I've found it to be
> > > immensely useful. Here is a snippet from git-testadd --help:
> > > [...]
> > >   This script clones the repository to the directory
> > >   ".testadd.tmp" in the current directory and applies the staged
> > >   chenges there (unless -u/--unmodified or -p/--pristine is
> > >   specified), chdirs to the same relative directory in the clone
> > >   and executes the command specified on the command line there.
> >
> > That's correct, the test clone is entirely separated from the
> > working copy, and you can keep working while the tests are running
> > in the clone. Combined with git-gui and/or "git add -p/git reset
> > -p", it's easy to tweak the staged changes until things are ok.
>
> I wonder if using `git worktree` instead of `git clone` (well, local
> clone uses hardlinks, so it is not that costly as it looks like) would
> be a better solution.

That's an interesting idea. Have to test it out. This is the result from the current master in linux.git:

With clone:

  $ time git testadd pwd
  git-testadd: Using ".testadd.tmp" as destination directory
  Cloning into '.testadd.tmp'...
  done.
  Checking out files: 100% (55256/55256), done.
  git-testadd: Applying staged changes

  git-testadd: Executing "pwd" in /home/sunny/src/test-wt/.testadd.tmp
  /home/sunny/src/test-wt/.testadd.tmp

  real    0m10.464s
  user    0m5.983s
  sys     0m2.790s
  $

With worktree:

  $ time git worktree add testaddtmp
  Preparing testaddtmp (identifier testaddtmp)
  Checking out files: 100% (55256/55256), done.
  HEAD is now at 194dc87 Add braces to avoid "ambiguous ‘else’" compiler
  warnings

  real    0m10.343s
  user    0m6.010s
  sys     0m2.523s
  $

Both tests were run with cold cache ("echo 3 >/proc/sys/vm/drop_caches" as root). It seems as there's no difference, and that git clone is as fast as it can get without breaking physical laws. And we probably shouldn't do that. :)

Z poważaniem, Øyvind