Subject: Re: [RFC/PATCH 3/5] ls-files: add and use a new --sparse option

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Wed, 17 Mar 2021 19:27:09 +0100

On Wed, Mar 17 2021, Elijah Newren wrote:

> On Wed, Mar 17, 2021 at 6:28 AM Ævar Arnfjörð Bjarmason
> <[email-masked]> wrote:
>>
>> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
>> ---
>>  Documentation/git-ls-files.txt           |  4 ++
>>  builtin/ls-files.c                       | 10 ++++-
>>  t/t1091-sparse-checkout-builtin.sh       |  9 ++--
>>  t/t1092-sparse-checkout-compatibility.sh | 57 ++++++++++++++++--------
>>  4 files changed, 56 insertions(+), 24 deletions(-)
>>
>> diff --git a/Documentation/git-ls-files.txt b/Documentation/git-ls-files.txt
>> index 6d11ab506b..1145e960a4 100644
>> --- a/Documentation/git-ls-files.txt
>> +++ b/Documentation/git-ls-files.txt
>> @@ -71,6 +71,10 @@ OPTIONS
>>  --unmerged::
>>         Show unmerged files in the output (forces --stage)
>>
>> +--sparse::
>> +       Show sparse directories in the output instead of expanding
>> +       them (forces --stage)
>> +
>>  -k::
>>  --killed::
>>         Show files on the filesystem that need to be removed due
>> diff --git a/builtin/ls-files.c b/builtin/ls-files.c
>> index 4db75351f2..1ebbb63c10 100644
>> --- a/builtin/ls-files.c
>> +++ b/builtin/ls-files.c
>> @@ -26,6 +26,7 @@ static int show_deleted;
>>  static int show_cached;
>>  static int show_others;
>>  static int show_stage;
>> +static int show_sparse;
>>  static int show_unmerged;
>>  static int show_resolve_undo;
>>  static int show_modified;
>> @@ -639,6 +640,8 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
>>                         DIR_SHOW_IGNORED),
>>                 OPT_BOOL('s', "stage", &show_stage,
>>                         N_("show staged contents' object name in the output")),
>> +               OPT_BOOL(0, "sparse", &show_sparse,
>> +                       N_("show unexpanded sparse directories in the output")),
>>                 OPT_BOOL('k', "killed", &show_killed,
>>                         N_("show files on the filesystem that need to be removed")),
>>                 OPT_BIT(0, "directory", &dir.flags,
>> @@ -705,12 +708,17 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
>>                 tag_skip_worktree = "S ";
>>                 tag_resolve_undo = "U ";
>>         }
>> +       if (show_sparse) {
>> +               prepare_repo_settings(the_repository);
>> +               the_repository->settings.command_requires_full_index = 0;
>> +       }
>>         if (show_modified || show_others || show_deleted || (dir.flags & DIR_SHOW_IGNORED) || show_killed)
>>                 require_work_tree = 1;
>> -       if (show_unmerged)
>> +       if (show_unmerged || show_sparse)
>>                 /*
>>                  * There's no point in showing unmerged unless
>>                  * you also show the stage information.
>> +                * The same goes for the --sparse option.
>
> Yuck, haven't you just made --sparse an alias for --stage?  Why does
> it need an alias?

It doesn't, but --unmerged, the one other option which purely modifies
--stage output implies --stage.

So it's in line with existing UI convention in the command, it's
probably better to keep following that than have new options behave
differently.

But yeah, we could spell out --stage --sparse in the tests.

> Was the goal just to get a quick way to make the command run under
> repo->settings.command_requires_full_index = 0 without auditing the
> codepaths?  It seems to rely on them having been audited anyway, since
> it just falls back to the code used for --stage, so I don't see how it
> helps.  It also suggests the command might do unexpected or weird
> things if run without the --sparse option?  If people manually
> configure a sparse-checkout and cone mode AND a sparse-index (it's
> annoying how they have to specify all three instead of having to just
> pass one flag somewhere), then now we also need to force them to
> remember to pass extra flags to random various commands for them to
> operate in a sane manner in their environment??
>
> I think this is a bad path to go down.

Those are probably good points, I don't have enough overview of the
whole sparse thing yet to say.

I just thought it didn't make sense to have a series changing the nature
of the index without corresponding tooling changes to interrogate the
state of the index.

> However, if you want to write the necessary tests to make it so that
> ls-files can operate with command_requires_full_index = 0, then I
> think that's useful.  If you want to add a special flag so that folks
> in a sparse-checkout-with-cone-mode-with-sparse-index setup want to
> operate densely (i.e. to show what files would be in the index if it
> were fully populated), then I think that's useful.  But having
> sparse-yes-with-cone-yes-very-sparse folks need to specify an extra
> flag to commands to get sparse behavior just seems wrong to me.

Maybe, but what else do you suggest for getting this information out of
the index?

>>                  */
>>                 show_stage = 1;
>>         if (show_tag || show_stage)
>> diff --git a/t/t1091-sparse-checkout-builtin.sh b/t/t1091-sparse-checkout-builtin.sh
>> index ff1ad570a2..c823df423c 100755
>> --- a/t/t1091-sparse-checkout-builtin.sh
>> +++ b/t/t1091-sparse-checkout-builtin.sh
>> @@ -208,12 +208,13 @@ test_expect_success 'sparse-checkout disable' '
>>  test_expect_success 'sparse-index enabled and disabled' '
>>         git -C repo sparse-checkout init --cone --sparse-index &&
>>         test_cmp_config -C repo true extensions.sparseIndex &&
>> -       test-tool -C repo read-cache --table >cache &&
>> -       grep " tree " cache &&
>> +       git -C repo ls-files --sparse >cache &&
>> +       grep "^040000 " cache >lines &&
>> +       test_line_count = 3 lines &&
>>
>>         git -C repo sparse-checkout disable &&
>> -       test-tool -C repo read-cache --table >cache &&
>> -       ! grep " tree " cache &&
>> +       git -C repo ls-files --sparse >cache &&
>> +       ! grep "^040000 " cache &&
>>         git -C repo config --list >config &&
>>         ! grep extensions.sparseindex config
>>  '
>> diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
>> index d97bf9b645..48d3920490 100755
>> --- a/t/t1092-sparse-checkout-compatibility.sh
>> +++ b/t/t1092-sparse-checkout-compatibility.sh
>> @@ -136,48 +136,67 @@ test_sparse_match () {
>>         test_cmp sparse-checkout-err sparse-index-err
>>  }
>>
>> +test_index_entry_like () {
>> +       dir=$1
>> +       shift
>> +       fmt=$1
>> +       shift
>> +       rev=$1
>> +       shift
>> +       entry=$1
>> +       shift
>> +       file=$1
>> +       shift
>> +       hash=$(git -C "$dir" rev-parse "$rev") &&
>> +       printf "$fmt\n" "$hash" "$entry" >expected &&
>> +       if grep "$entry" "$file" >line
>> +       then
>> +               test_cmp expected line
>> +       else
>> +               cat cache &&
>> +               false
>> +       fi
>> +}
>> +
>>  test_expect_success 'sparse-index contents' '
>>         init_repos &&
>>
>> -       test-tool -C sparse-index read-cache --table >cache &&
>> +       git -C sparse-index ls-files --sparse >cache &&
>>         for dir in folder1 folder2 x
>>         do
>> -               TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
>> -               grep "040000 tree $TREE $dir/" cache \
>> -                       || return 1
>> +               test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
>>         done &&
>>
>>         git -C sparse-index sparse-checkout set folder1 &&
>>
>> -       test-tool -C sparse-index read-cache --table >cache &&
>> +       git -C sparse-index ls-files --sparse >cache &&
>>         for dir in deep folder2 x
>>         do
>> -               TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
>> -               grep "040000 tree $TREE $dir/" cache \
>> -                       || return 1
>> +               test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
>>         done &&
>>
>>         git -C sparse-index sparse-checkout set deep/deeper1 &&
>>
>> -       test-tool -C sparse-index read-cache --table >cache &&
>> +       git -C sparse-index ls-files --sparse >cache &&
>>         for dir in deep/deeper2 folder1 folder2 x
>>         do
>> -               TREE=$(git -C sparse-index rev-parse HEAD:$dir) &&
>> -               grep "040000 tree $TREE $dir/" cache \
>> -                       || return 1
>> +               test_index_entry_like sparse-index "040000 %s 0\t%s" "HEAD:$dir" "$dir/" cache || return 1
>>         done &&
>>
>> +       grep 040000 cache >lines &&
>> +       test_line_count = 4 lines &&
>> +
>>         # Disabling the sparse-index removes tree entries with full ones
>>         git -C sparse-index sparse-checkout init --no-sparse-index &&
>>
>> -       test-tool -C sparse-index read-cache --table >cache &&
>> -       ! grep "040000 tree" cache &&
>> -       test_sparse_match test-tool read-cache --table
>> +       git -C sparse-index ls-files --sparse >cache &&
>> +       ! grep "^040000 " cache >lines &&
>> +       test_sparse_match git ls-tree -r HEAD
>>  '
>>
>>  test_expect_success 'expanded in-memory index matches full index' '
>>         init_repos &&
>> -       test_sparse_match test-tool read-cache --expand --table
>> +       test_sparse_match git ls-tree -r HEAD
>>  '
>>
>>  test_expect_success 'status with options' '
>> @@ -394,9 +413,9 @@ test_expect_success 'submodule handling' '
>>         test_all_match git commit -m "add submodule" &&
>>
>>         # having a submodule prevents "modules" from collapse
>> -       test-tool -C sparse-index read-cache --table >cache &&
>> -       grep "100644 blob .*    modules/a" cache &&
>> -       grep "160000 commit $(git -C initial-repo rev-parse HEAD)       modules/sub" cache
>> +       git -C sparse-index ls-files --sparse >cache &&
>> +       test_index_entry_like sparse-index "100644 %s 0\t%s" "HEAD:modules/a" "modules/a" cache &&
>> +       test_index_entry_like sparse-index "160000 %s 0\t%s" "HEAD:modules/sub" "modules/sub" cache
>>  '
>>
>>  test_expect_success 'sparse-index is expanded and converted back' '
>> --
>> 2.31.0.260.g719c683c1d
>
> I do like the tests and your idea that we can use ls-files to list
> whatever entries are in the index, I just think the tests should use
> --stage to do that.