Please note that this is my first contribution to git. I've tried to follow
the instructions about how to correctly submit a patch (I'm using
GitGitGadget as getting Outlook to do plain text e-mail correctly seems
impossible), but please let me know if I've missed something.

My motivation for making this change is purely performance. We have a large
repository that we enable the sparse index for, and I am developing a
pre-commit hook that (among other things) uses git cat-file to get the
staged contents of certain files. Without this change, getting the contents
of a single small file from the index can take upwards of 10 seconds due to
the index expansion. After this change, it only takes ~0.3 seconds unless
the file is outside of the sparse index.

Kevin Lyles (2):
  Allow using stdin in run_on_* functions
  Mark 'git cat-file' sparse-index compatible

 builtin/cat-file.c                       |  3 ++
 t/t1092-sparse-checkout-compatibility.sh | 50 +++++++++++++++++++++---
 2 files changed, 48 insertions(+), 5 deletions(-)


base-commit: 4590f2e9412378c61eac95966709c78766d326ba
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1770%2Fklylesatepic%2Fkl%2Fmark-cat-file-sparse-index-compatible-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1770/klylesatepic/kl/mark-cat-file-sparse-index-compatible-v3
Pull-Request: https://github.com/git/git/pull/1770

Range-diff vs v2:

 1:  7067a4c5da2 = 1:  b310593aec2 Allow using stdin in run_on_* functions
 2:  a92825e502f ! 2:  f4d1461b993 Mark 'git cat-file' sparse-index compatible
     @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'advice.sparseInde
      +	test_all_match git cat-file -p :deep/a &&
      +	ensure_not_expanded cat-file -p :deep/a &&
      +	test_all_match git cat-file -p :folder1/a &&
     -+	ensure_expanded cat-file -p :folder1/a'
     ++	ensure_expanded cat-file -p :folder1/a
     ++'
      +
      +test_expect_success 'cat-file --batch' '
      +	init_repos &&
     @@ t/t1092-sparse-checkout-compatibility.sh: test_expect_success 'advice.sparseInde
      +	echo "new content" >>sparse-index/deep/a &&
      +	run_on_all git add deep/a &&
      +
     -+	echo ":deep/a">in &&
     ++	echo ":deep/a" >in &&
      +	test_all_match git cat-file --batch <in &&
      +	ensure_not_expanded cat-file --batch <in &&
      +
     -+	echo ":folder1/a">in &&
     ++	echo ":folder1/a" >in &&
      +	test_all_match git cat-file --batch <in &&
      +	ensure_expanded cat-file --batch <in &&
      +
     -+	cat <<-\EOF >in &&
     ++	cat >in <<-\EOF &&
      +	:deep/a
      +	:folder1/a
      +	EOF
      +	test_all_match git cat-file --batch <in &&
     -+	ensure_expanded cat-file --batch <in'
     ++	ensure_expanded cat-file --batch <in
     ++'
      +
       test_done

-- 
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