[PATCH v5 0/6] odb: make creation of object database pluggable

Hi,

when creating a new repository we create a couple of on-disk data
structures for the object database. This includes the "objects/"
directory hierarchy with "objects/info" and "objects/pack", which are
specific to the backend.

This patch series makes the creation of the on-disk data structures
pluggable. While we continue to always create "objects/" regardless of
the backend (it's required for a repository to be recognized as such),
the other subdirectories are now created by the backend. This will allow
other backends to plug in their own logic.

The series starts with a small detour into the loose-object map. This
detour is required so that we can defer initialization of the object
database itself to a later point in time.

The series is based on 9a0c4701dc (The 7th batch, 2026-07-22).

Changes in v5:
  - Remove a leftover formatting change.
  - Fix a stale comment.
  - Link to v4: https://patch.msgid.link/[email protected]

Changes in v4:
  - Drop `APPLY_REPOSITOY_FORMAT_SKIP_ODB_CREATION` in favor of explicit
    calls to `odb_new()`.
  - Remove a useless call to `xstrdup()`.
  - Mark a string as translatable.
  - Link to v3: https://patch.msgid.link/[email protected]

Changes in v3:
  - Move handling of GIT_OBJECT_DIRECTORY and
    GIT_ALTERNATE_OBJECT_DIRECTORIES into `odb_new()` itself. This
    deduplicates some of the logic and also preps us for a future where
    alternates are handled in the "files" backend itself.
  - Link to v2: https://patch.msgid.link/[email protected]

Changes in v2:
  - Add a testcase that demonstrates the bug fixed with alternate loose
    object maps.
  - Rename the "inmemory" bakcend to "in-memory".
  - Clarify some commit messages.
  - Link to v1: https://patch.msgid.link/[email protected]

Thanks!

Patrick

---
Patrick Steinhardt (6):
      loose: load loose object map for the correct source
      setup: detangle loading of loose object maps
      setup: handle ODB-related environment variables in `odb_new()`
      setup: defer object database creation
      odb/source: introduce function to map source type to name
      odb: make creation of on-disk structures pluggable

 loose.c                       | 25 +++++++++++----------
 loose.h                       |  1 +
 odb.c                         | 21 ++++++++++--------
 odb.h                         | 17 +++++++++++++--
 odb/source-files.c            | 19 ++++++++++++++++
 odb/source-files.h            |  4 +++-
 odb/source-inmemory.h         |  4 +++-
 odb/source-loose.c            |  2 ++
 odb/source-loose.h            |  4 +++-
 odb/source-packed.h           |  4 +++-
 odb/source.c                  | 19 ++++++++++++++++
 odb/source.h                  | 29 ++++++++++++++++++++++++
 repository.c                  |  3 +--
 setup.c                       | 51 +++++++++++++++++++++----------------------
 setup.h                       |  4 ++--
 t/t1016-compatObjectFormat.sh | 18 +++++++++++++++
 t/unit-tests/u-odb-inmemory.c |  2 +-
 17 files changed, 169 insertions(+), 58 deletions(-)

Range-diff versus v4:

1:  40ca0d1345 = 1:  3a0fbf9498 loose: load loose object map for the correct source
2:  d18ddec5dd = 2:  7ba250f4d7 setup: detangle loading of loose object maps
3:  9b6fbc510f = 3:  fbe755388b setup: handle ODB-related environment variables in `odb_new()`
4:  f27f8d45a4 ! 4:  4d7a12e3cb setup: defer object database creation
    @@ setup.c: static int create_default_files(struct repository *repo,
      	baselen = path.len;
      
     @@ setup.c: int init_db(struct repository *repo,
    - 	 */
    - 	read_and_verify_repository_format(&repo_fmt, repo_get_git_dir(repo), NULL);
      	repository_format_configure(&repo_fmt, hash, ref_storage_format);
    --	if (apply_repository_format(repo, &repo_fmt, APPLY_REPOSITORY_FORMAT_HONOR_ENV, &err) < 0)
    -+	if (apply_repository_format(repo, &repo_fmt,
    -+				    APPLY_REPOSITORY_FORMAT_HONOR_ENV, &err) < 0)
    + 	if (apply_repository_format(repo, &repo_fmt, APPLY_REPOSITORY_FORMAT_HONOR_ENV, &err) < 0)
      		die("%s", err.buf);
     -	startup_info->have_repository = 1;
      
    @@ setup.c: int init_db(struct repository *repo,
      
      	if (repo_settings_get_shared_repository(repo)) {
      		char buf[10];
    +
    + ## setup.h ##
    +@@ setup.h: enum apply_repository_format_flags {
    + 
    + /*
    +  * Apply the given repository format to the repo. This initializes extensions
    +- * and basic data structures required for normal operation. Returns 0 on
    +- * success, a negative error code when the format is not valid as determined by
    ++ * required for normal operation. Returns 0 on success, a negative error code
    ++ * when the format is not valid as determined by
    +  * `verify_repository_format()`.
    +  */
    + int apply_repository_format(struct repository *repo,
5:  1c0afb893f = 5:  6bb4ecc76d odb/source: introduce function to map source type to name
6:  387fe6e204 = 6:  806f399c63 odb: make creation of on-disk structures pluggable

---
base-commit: 9a0c4701dcd5725c4184599322b52933ff5005ca
change-id: 20260710-pks-odb-create-on-disk-ae8757861c69