Re: [PATCH v2] diff: don't read index when --no-index is given

[Eric Sunshine <sunshine@sunshineco.com>]

On Mon, Dec 9, 2013 at 3:40 PM, Thomas Gummerer <t.gummerer@gmail.com> wrote:
> git diff --no-index ... currently reads the index, during setup, when
> calling gitmodules_config().  This results in worse performance when
> the index is not actually needed.  This patch avoids calling
> gitmodules_config() when the --no-index option is given.  The times for
> executing "git diff --no-index" in the WebKit repository are improved as
> follows:
>
> Test                      HEAD~3            HEAD
> ------------------------------------------------------------------
> 4001.1: diff --no-index   0.24(0.15+0.09)   0.01(0.00+0.00) -95.8%
>
> An additional improvement of this patch is that "git diff --no-index" no
> longer breaks when the index file is corrupt, which makes it possible to
> use it for investigating the broken repository.
>
> To improve the possible usage as investigation tool for broken
> repositories, setup_git_directory_gently() is also not called when the
> --no-index option is given.
>
> Also add a test to guard against future breakages, and a performance
> test to show the improvements.
>
> Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
> ---
> diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
> index 979e983..d3dbf6b 100755
> --- a/t/t4053-diff-no-index.sh
> +++ b/t/t4053-diff-no-index.sh
> @@ -29,4 +29,10 @@ test_expect_success 'git diff --no-index relative path outside repo' '
>         )
>  '
>
> +test_expect_success 'git diff --no-index with broken index' '
> +       cd repo &&
> +       echo broken >.git/index &&
> +       git diff --no-index a ../non/git/a &&
> +'

Stray && on the last line of the test.

Also, don't you want to do the 'cd' and subsequent commands inside a
subshell so that tests added after this one won't have to worry about
cd'ing back to the top-level?

> +
>  test_done
> --
> 1.8.5.4.g8639e57