Re: [PATCH 2/4] show: integrate with the sparse index

> From: Derrick Stolee <dstolee@microsoft.com>
> 
> The 'git show' command can take an input to request the state of an
> object in the index. This can lead to parsing the index in order to load
> a specific file entry. Without the change presented here, a sparse index
> would expand to a full one, taking much longer than usual to access a
> simple file.
> 
> There is one behavioral change that happens here, though: we now can
> find a sparse directory entry within the index! Commands that previously
> failed because we could not find an entry in the worktree or index now
> succeed because we _do_ find an entry in the index.

> There might be more work to do to make other situations succeed when
> looking for an indexed tree, perhaps by looking at or updating the
> cache-tree extension as needed. These situations include having a full
> index or asking for a directory that is within the sparse-checkout cone
> (and hence is not a sparse directory entry in the index).
> 
> For now, we demonstrate how the sparse index integration is extremely
> simple for files outside of the cone as well as directories within the
> cone. A later change will resolve this behavior around sparse
> directories.
> 
> Signed-off-by: Derrick Stolee <derrickstolee@github.com>
> ---
>  builtin/log.c                            |  5 +++++
>  t/t1092-sparse-checkout-compatibility.sh | 23 +++++++++++++++++++----
>  2 files changed, 24 insertions(+), 4 deletions(-)
> 
> diff --git a/builtin/log.c b/builtin/log.c
> index c211d66d1d0..8e2e9912ab9 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -661,6 +661,11 @@ int cmd_show(int argc, const char **argv, const char *prefix)
>  	init_log_defaults();
>  	git_config(git_log_config, NULL);
>  
> +	if (the_repository->gitdir) {
> +		prepare_repo_settings(the_repository);
> +		the_repository->settings.command_requires_full_index = 0;
> +	}
> +
>  	memset(&match_all, 0, sizeof(match_all));
>  	repo_init_revisions(the_repository, &rev, prefix);
>  	git_config(grep_config, &rev.grep_filter);
> diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
> index 74792b5ebbc..f6a14e08b81 100755
> --- a/t/t1092-sparse-checkout-compatibility.sh
> +++ b/t/t1092-sparse-checkout-compatibility.sh
> @@ -1159,12 +1159,20 @@ test_expect_success 'show (cached blobs/trees)' '
>  	test_sparse_match git show :folder1/a &&
>  
>  	# Asking "git show" for directories in the index
> -	# does not work as implemented. The error message is
> -	# different for a full checkout and a sparse checkout
> -	# when the directory is outside of the cone.
> +	# changes depending on the existence of a sparse index.

>  	test_all_match test_must_fail git show :deep/ &&
>  	test_must_fail git -C full-checkout show :folder1/ &&
> -	test_sparse_match test_must_fail git show :folder1/
> +	test_must_fail git -C sparse-checkout show :folder1/ &&
> +
> +	git -C sparse-index show :folder1/ >actual &&
> +	git -C full-checkout show HEAD:folder1 >expect &&
> +
> +	# The output of "git show" includes the way we referenced the
> +	# objects, so strip that out.
> +	test_line_count = 4 actual &&
> +	tail -n 2 actual >actual-trunc &&
> +	tail -n 2 expect >expect-trunc &&
> +	test_cmp expect-trunc actual-trunc
>  '

>  test_expect_success 'submodule handling' '
> @@ -1388,6 +1396,13 @@ test_expect_success 'sparse index is not expanded: diff' '
>  	ensure_not_expanded diff --cached
>  '
>  
> +test_expect_success 'sparse index is not expanded: show' '
> +	init_repos &&
> +
> +	ensure_not_expanded show :a &&
> +	ensure_not_expanded show :deep/a
> +'
> +
>  test_expect_success 'sparse index is not expanded: update-index' '
>  	init_repos &&
>  
> -- 
> gitgitgadget
>