On Fri, Oct 29, 2021 at 6:56 AM Victoria Dye via GitGitGadget
<gitgitgadget@xxxxxxxxx> wrote:
>
> From: Victoria Dye <vdye@xxxxxxxxxx>
>
> If `command_requires_full_index` is false, ensure correct in-core index
> sparsity on read by calling `ensure_correct_sparsity`. This change is meant
> to update the how the index is read in a command after sparse index-related
s/update the how/update how/ ?
> repository settings are modified. Previously, for example, if `index.sparse`
> were changed from `true` to `false`, the in-core index on the next command
> would be sparse. The index would only be expanded to full when it was next
> written to disk.
>
> By adding a call to `ensure_correct_sparsity`, the in-core index now matches
> the sparsity dictated by the relevant repository settings as soon as it is
> read into memory, rather than when it is later written to disk.
I split up reading this series across different days, and when I got
here, my first reaction was "Okay, but why would you want that?
Sounds like extra work for no gain." I went and looked up the cover
letter and saw you mentioned that this "introduces the ability to
enable/disable the sparse index on a command-by-command basis (e.g.,
allowing a user to troubleshoot a sparse-aware command with '-c
index.sparse=false' [1]). That seems like a good reason to me, and
sounds like it belongs in this commit message. But it sounds like you
had other reasons in mind. If so, could you share them; I'm having
difficulty understanding how this would make a difference other than
in the troubleshooting scenario.
>
> Helped-by: Junio C Hamano <gitster@xxxxxxxxx>
> Co-authored-by: Derrick Stolee <dstolee@xxxxxxxxxxxxx>
> Signed-off-by: Victoria Dye <vdye@xxxxxxxxxx>
> ---
> read-cache.c | 8 ++++++
> t/t1092-sparse-checkout-compatibility.sh | 31 ++++++++++++++++++++++++
> 2 files changed, 39 insertions(+)
>
> diff --git a/read-cache.c b/read-cache.c
> index a78b88a41bf..b3772ba70a1 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -2337,9 +2337,17 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
>
> if (!istate->repo)
> istate->repo = the_repository;
> +
> + /*
> + * If the command explicitly requires a full index, force it
> + * to be full. Otherwise, correct the sparsity based on repository
> + * settings and other properties of the index (if necessary).
> + */
> prepare_repo_settings(istate->repo);
> if (istate->repo->settings.command_requires_full_index)
> ensure_full_index(istate);
> + else
> + ensure_correct_sparsity(istate);
>
> return istate->cache_nr;
>
> diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
> index ca91c6a67f8..59accde1fa3 100755
> --- a/t/t1092-sparse-checkout-compatibility.sh
> +++ b/t/t1092-sparse-checkout-compatibility.sh
> @@ -694,6 +694,37 @@ test_expect_success 'sparse-index is expanded and converted back' '
> test_region index ensure_full_index trace2.txt
> '
>
> +test_expect_success 'index.sparse disabled inline uses full index' '
> + init_repos &&
> +
> + # When index.sparse is disabled inline with `git status`, the
> + # index is expanded at the beginning of the execution then never
> + # converted back to sparse. It is then written to disk as a full index.
> + rm -f trace2.txt &&
> + GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
> + git -C sparse-index -c index.sparse=false status &&
> + ! test_region index convert_to_sparse trace2.txt &&
> + test_region index ensure_full_index trace2.txt &&
> +
> + # Since index.sparse is set to true at a repo level, the index
> + # is converted from full to sparse when read, then never expanded
> + # over the course of `git status`. It is written to disk as a sparse
> + # index.
> + rm -f trace2.txt &&
> + GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
> + git -C sparse-index status &&
> + test_region index convert_to_sparse trace2.txt &&
> + ! test_region index ensure_full_index trace2.txt &&
> +
> + # Now that the index has been written to disk as sparse, it is not
> + # converted to sparse (or expanded to full) when read by `git status`.
> + rm -f trace2.txt &&
> + GIT_TRACE2_EVENT="$(pwd)/trace2.txt" GIT_TRACE2_EVENT_NESTING=10 \
> + git -C sparse-index status &&
> + ! test_region index convert_to_sparse trace2.txt &&
> + ! test_region index ensure_full_index trace2.txt
> +'
> +
> ensure_not_expanded () {
> rm -f trace2.txt &&
> echo >>sparse-index/untracked.txt &&
> --
> gitgitgadget
The rest of the patch looks fine.
