Re: [PATCH v2 4/4] promisor-remote: teach lazy-fetch in any repo

>
> This is one step towards supporting partial clone submodules.
>
> Even after this patch, we will still lack partial clone submodules
> support, primarily because a lot of Git code that accesses submodule
> objects does so by adding their object stores as alternates, meaning
> that any lazy fetches that would occur in the submodule would be done
> based on the config of the superproject, not of the submodule. This also
> prevents testing of the functionality in this patch by user-facing
> commands. So for now, test this mechanism using a test helper.

>
> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
> ---
>  Makefile                      |  1 +
>  object-file.c                 |  7 ++----
>  promisor-remote.c             | 14 ++++++++----
>  t/helper/test-partial-clone.c | 43 +++++++++++++++++++++++++++++++++++
>  t/helper/test-tool.c          |  1 +
>  t/helper/test-tool.h          |  1 +
>  t/t0410-partial-clone.sh      | 23 +++++++++++++++++++
>  7 files changed, 80 insertions(+), 10 deletions(-)
>  create mode 100644 t/helper/test-partial-clone.c
>
> diff --git a/Makefile b/Makefile
> index c3565fc0f8..f6653bcd5e 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -725,6 +725,7 @@ TEST_BUILTINS_OBJS += test-oidmap.o
>  TEST_BUILTINS_OBJS += test-online-cpus.o
>  TEST_BUILTINS_OBJS += test-parse-options.o
>  TEST_BUILTINS_OBJS += test-parse-pathspec-file.o
> +TEST_BUILTINS_OBJS += test-partial-clone.o
>  TEST_BUILTINS_OBJS += test-path-utils.o
>  TEST_BUILTINS_OBJS += test-pcre2-config.o
>  TEST_BUILTINS_OBJS += test-pkt-line.o
> diff --git a/object-file.c b/object-file.c
> index f233b440b2..ebf273e9e7 100644
> --- a/object-file.c
> +++ b/object-file.c
> @@ -1570,15 +1570,12 @@ static int do_oid_object_info_extended(struct repository *r,
>                 }
>
>                 /* Check if it is a missing object */
> -               if (fetch_if_missing && has_promisor_remote() &&
> -                   !already_retried && r == the_repository &&
> +               if (fetch_if_missing && repo_has_promisor_remote(r) &&
> +                   !already_retried &&
>                     !(flags & OBJECT_INFO_SKIP_FETCH_OBJECT)) {
>                         /*
>                          * TODO Investigate checking promisor_remote_get_direct()
>                          * TODO return value and stopping on error here.
> -                        * TODO Pass a repository struct through
> -                        * promisor_remote_get_direct(), such that arbitrary
> -                        * repositories work.
>                          */
>                         promisor_remote_get_direct(r, real, 1);
>                         already_retried = 1;
> diff --git a/promisor-remote.c b/promisor-remote.c
> index e1e1f7e93a..1491374d65 100644
> --- a/promisor-remote.c
> +++ b/promisor-remote.c
> @@ -11,7 +11,8 @@ struct promisor_remote_config {
>         struct promisor_remote **promisors_tail;
>  };
>
> -static int fetch_objects(const char *remote_name,
> +static int fetch_objects(struct repository *repo,
> +                        const char *remote_name,
>                          const struct object_id *oids,
>                          int oid_nr)
>  {
> @@ -21,6 +22,11 @@ static int fetch_objects(const char *remote_name,
>
>         child.git_cmd = 1;
>         child.in = -1;
> +       if (repo != the_repository) {
> +               prepare_other_repo_env(&child.env_array);
> +               strvec_pushf(&child.env_array, "%s=%s", GIT_DIR_ENVIRONMENT,
> +                            repo->gitdir);
> +       }
>         strvec_pushl(&child.args, "-c", "fetch.negotiationAlgorithm=noop",
>                      "fetch", remote_name, "--no-tags",
>                      "--no-write-fetch-head", "--recurse-submodules=no",
> @@ -154,7 +160,7 @@ static void promisor_remote_init(struct repository *r)
>                 xcalloc(sizeof(*r->promisor_remote_config), 1);
>         config->promisors_tail = &config->promisors;
>
> -       git_config(promisor_remote_config, config);
> +       repo_config(r, promisor_remote_config, config);
>
>         if (config->repository_format_partial_clone) {
>                 struct promisor_remote *o, *previous;
> @@ -252,10 +258,8 @@ int promisor_remote_get_direct(struct repository *repo,
>
>         promisor_remote_init(repo);
>
> -       if (repo != the_repository)
> -               BUG("only the_repository is supported for now");
>         for (r = repo->promisor_remote_config->promisors; r; r = r->next) {
> -               if (fetch_objects(r->name, remaining_oids, remaining_nr) < 0) {
> +               if (fetch_objects(repo, r->name, remaining_oids, remaining_nr) < 0) {
>                         if (remaining_nr == 1)
>                                 continue;
>                         remaining_nr = remove_fetched_oids(repo, &remaining_oids,
> diff --git a/t/helper/test-partial-clone.c b/t/helper/test-partial-clone.c
> new file mode 100644
> index 0000000000..3f102cfddd
> --- /dev/null
> +++ b/t/helper/test-partial-clone.c
> @@ -0,0 +1,43 @@
> +#include "cache.h"
> +#include "test-tool.h"
> +#include "repository.h"
> +#include "object-store.h"
> +
> +/*
> + * Prints the size of the object corresponding to the given hash in a specific
> + * gitdir. This is similar to "git -C gitdir cat-file -s", except that this
> + * exercises the code that accesses the object of an arbitrary repository that
> + * is not the_repository. ("git -C gitdir" makes it so that the_repository is
> + * the one in gitdir.)
> + */
> +static void object_info(const char *gitdir, const char *oid_hex)
> +{
> +       struct repository r;
> +       struct object_id oid;
> +       unsigned long size;
> +       struct object_info oi = {.sizep = &size};
> +       const char *p;
> +
> +       if (repo_init(&r, gitdir, NULL))
> +               die("could not init repo");
> +       if (parse_oid_hex(oid_hex, &oid, &p))
> +               die("could not parse oid");
> +       if (oid_object_info_extended(&r, &oid, &oi, 0))
> +               die("could not obtain object info");
> +       printf("%d\n", (int) size);
> +}
> +
> +int cmd__partial_clone(int argc, const char **argv)
> +{
> +       setup_git_directory();
> +
> +       if (argc < 4)
> +               die("too few arguments");
> +
> +       if (!strcmp(argv[1], "object-info"))
> +               object_info(argv[2], argv[3]);
> +       else
> +               die("invalid argument '%s'", argv[1]);
> +
> +       return 0;
> +}
> diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
> index c5bd0c6d4c..b21e8f1519 100644
> --- a/t/helper/test-tool.c
> +++ b/t/helper/test-tool.c
> @@ -46,6 +46,7 @@ static struct test_cmd cmds[] = {
>         { "online-cpus", cmd__online_cpus },
>         { "parse-options", cmd__parse_options },
>         { "parse-pathspec-file", cmd__parse_pathspec_file },
> +       { "partial-clone", cmd__partial_clone },
>         { "path-utils", cmd__path_utils },
>         { "pcre2-config", cmd__pcre2_config },
>         { "pkt-line", cmd__pkt_line },
> diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
> index e8069a3b22..f845ced4b3 100644
> --- a/t/helper/test-tool.h
> +++ b/t/helper/test-tool.h
> @@ -35,6 +35,7 @@ int cmd__oidmap(int argc, const char **argv);
>  int cmd__online_cpus(int argc, const char **argv);
>  int cmd__parse_options(int argc, const char **argv);
>  int cmd__parse_pathspec_file(int argc, const char** argv);
> +int cmd__partial_clone(int argc, const char **argv);
>  int cmd__path_utils(int argc, const char **argv);
>  int cmd__pcre2_config(int argc, const char **argv);
>  int cmd__pkt_line(int argc, const char **argv);
> diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
> index 584a039b85..a211a66c67 100755
> --- a/t/t0410-partial-clone.sh
> +++ b/t/t0410-partial-clone.sh
> @@ -604,6 +604,29 @@ test_expect_success 'do not fetch when checking existence of tree we construct o
>         git -C repo cherry-pick side1
>  '
>
> +test_expect_success 'lazy-fetch when accessing object not in the_repository' '
> +       rm -rf full partial.git &&
> +       test_create_repo full &&
> +       test_commit -C full create-a-file file.txt &&
> +
> +       test_config -C full uploadpack.allowfilter 1 &&
> +       test_config -C full uploadpack.allowanysha1inwant 1 &&
> +       git clone --filter=blob:none --bare "file://$(pwd)/full" partial.git &&
> +       FILE_HASH=$(git -C full rev-parse HEAD:file.txt) &&
> +
> +       # Sanity check that the file is missing
> +       git -C partial.git rev-list --objects --missing=print HEAD >out &&
> +       grep "[?]$FILE_HASH" out &&
> +
> +       git -C full cat-file -s "$FILE_HASH" >expect &&
> +       test-tool partial-clone object-info partial.git "$FILE_HASH" >actual &&
> +       test_cmp expect actual &&
> +
> +       # Sanity check that the file is now present
> +       git -C partial.git rev-list --objects --missing=print HEAD >out &&
> +       ! grep "[?]$FILE_HASH" out
> +'
> +
>  . "$TEST_DIRECTORY"/lib-httpd.sh
>  start_httpd
>
> --
> 2.32.0.rc1.229.g3e70b5a671-goog
>