Subject: [PATCH v9 00/10] packfile: avoid using the 'the_repository' global variable

From: Karthik Nayak <[email-masked]>
Date: Tue, 26 Nov 2024 11:57:31 +0100

The `packfile.c` file uses the global variable 'the_repository' extensively
throughout the code. Let's remove all usecases of this, by modifying the
required functions to accept a 'struct repository' instead. This is to clean up
usage of global state.

The first 3 patches are mostly internal to `packfile.c`, we add the repository
field to the `packed_git` struct and this is used to clear up some useages of
the global variables.

The next 3 patches are more disruptive, they modify the function definition of
`odb_pack_name`, `has_object[_kept]_pack` and `for_each_packed_object` to receive
a repository, helping remove other usages of 'the_repository' variable.

Finally, the next two patches deal with global config values. These values are
localized. The last patch is removal of an unecessary call to `prepare_packed_git()`.
For v5 onwards, I've rebased the series off the master: 8f8d6eee53 (The
seventh batch, 2024-11-01), as a dependency for this series 'jk/dumb-http-finalize'
was merged to master. I've found no conflicts while merging with seen & next. But
since this series does touch multiple files, there could be future conflicts.

Changes in v9:
- Added a comment in gc_config to indicate that eventually the
  `delta_base_cache_limit` variable should be used through repo_settings. 

Changes in v8:
- Fix typos in comments
- For packfile.c use delta_base_cache_limit from the repository
settings, this avoids loading the config in hot paths.
- Rename `longval` to `ulongval` to better signify the type.

Changes in v7:
- Cleanup stale commit message.
- Add missing space in `if` statement.
- Fix typo s/incase/in case/.

Changes in v6:
- Lazy load repository settings in packfile.c. This ensures that the settings are
available for sure and we do not rely on callees setting it.
- Use `size_t` for `delta_base_cache_limit`.

Changes in v5:
- Move packed_git* settings to repo_settings to ensure we don't keep reparsing the
settings in `use_pack`.

Changes in v4:
- Renamed the repository field within `packed_git` and `multi_pack_index` from
`r` to `repo`, while keeping function parameters to be `r`.
- Fixed bad braces.

Changes in v3:
- Improved commit messages. In the first commit to talk about how packed_git
struct could also be part of the alternates of a repository. In the 7th commit
to talk about the motive behind removing the global variable.
- Changed 'packed_git->repo' to 'packed_git->r' to keep it consistent with the
rest of the code base.
- Replaced 'the_repository' with locally available access to the repository
struct in multiple regions.
- Removed unecessary inclusion of the 'repository.h' header file by forward
declaring the 'repository' struct.
- Replace memcpy with hashcpy.
- Change the logic in the 7th patch to use if else statements.
- Added an extra commit to cleanup `pack-bitmap.c`.

Karthik Nayak (9):
  packfile: add repository to struct `packed_git`
  packfile: use `repository` from `packed_git` directly
  packfile: pass `repository` to static function in the file
  packfile: pass down repository to `odb_pack_name`
  packfile: pass down repository to `has_object[_kept]_pack`
  packfile: pass down repository to `for_each_packed_object`
  config: make `delta_base_cache_limit` a non-global variable
  config: make `packed_git_(limit|window_size)` non-global variables
  midx: add repository to `multi_pack_index` struct

Taylor Blau (1):
  packfile.c: remove unnecessary prepare_packed_git() call

 builtin/cat-file.c       |   7 +-
 builtin/count-objects.c  |   2 +-
 builtin/fast-import.c    |  15 ++--
 builtin/fsck.c           |  20 +++---
 builtin/gc.c             |  12 +++-
 builtin/index-pack.c     |  20 ++++--
 builtin/pack-objects.c   |  11 +--
 builtin/pack-redundant.c |   2 +-
 builtin/repack.c         |   2 +-
 builtin/rev-list.c       |   2 +-
 commit-graph.c           |   4 +-
 config.c                 |  22 ------
 connected.c              |   3 +-
 diff.c                   |   3 +-
 environment.c            |   3 -
 environment.h            |   1 -
 fsck.c                   |   2 +-
 http.c                   |   4 +-
 list-objects.c           |   7 +-
 midx-write.c             |   2 +-
 midx.c                   |   3 +-
 midx.h                   |   3 +
 object-store-ll.h        |   9 ++-
 pack-bitmap.c            |  90 ++++++++++++++----------
 pack-objects.h           |   3 +-
 pack-write.c             |   1 +
 pack.h                   |   2 +
 packfile.c               | 144 ++++++++++++++++++++++-----------------
 packfile.h               |  18 +++--
 promisor-remote.c        |   2 +-
 prune-packed.c           |   2 +-
 reachable.c              |   4 +-
 repo-settings.c          |  18 +++++
 repo-settings.h          |   7 ++
 revision.c               |  13 ++--
 tag.c                    |   2 +-
 36 files changed, 275 insertions(+), 190 deletions(-)

Range-diff against v8:
 -:  ---------- >  1:  d1fdd6996a packfile: add repository to struct `packed_git`
 -:  ---------- >  2:  65c09858ce packfile: use `repository` from `packed_git` directly
 -:  ---------- >  3:  80632934d1 packfile: pass `repository` to static function in the file
 -:  ---------- >  4:  67d71eab83 packfile: pass down repository to `odb_pack_name`
 -:  ---------- >  5:  ee210fa153 packfile: pass down repository to `has_object[_kept]_pack`
 -:  ---------- >  6:  8db7094f4e packfile: pass down repository to `for_each_packed_object`
 1:  d1b6e8801b !  7:  a66494384d config: make `delta_base_cache_limit` a non-global variable
    @@ builtin/gc.c: struct gc_config {
      	char *repack_filter_to;
      	unsigned long big_pack_threshold;
      	unsigned long max_delta_cache_size;
    ++	/*
    ++	 * Remove this member from gc_config once repo_settings is passed
    ++	 * through the callchain.
    ++	 */
     +	size_t delta_base_cache_limit;
      };
      
 2:  30a52f192f =  8:  bce9196f6b config: make `packed_git_(limit|window_size)` non-global variables
 3:  2fe5d2506f =  9:  c7fba8cf6a midx: add repository to `multi_pack_index` struct
 4:  05989c2e27 = 10:  d7f475fbd0 packfile.c: remove unnecessary prepare_packed_git() call
-- 
2.47.0