Subject: [PATCH v7 0/9] packfile: avoid using the 'the_repository' global variable

From: Karthik Nayak <[email-masked]>
Date: Mon, 11 Nov 2024 12:14:00 +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 last two patches deal with global config values. These values are
localized.

For v5 onwards, I've rebased the series off the new 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 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

 builtin/cat-file.c       |   7 +-
 builtin/count-objects.c  |   2 +-
 builtin/fast-import.c    |  15 ++--
 builtin/fsck.c           |  20 +++---
 builtin/gc.c             |   8 ++-
 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                   |   1 +
 packfile.c               | 148 +++++++++++++++++++++++----------------
 packfile.h               |  18 +++--
 promisor-remote.c        |   2 +-
 prune-packed.c           |   2 +-
 reachable.c              |   4 +-
 repo-settings.c          |  14 ++++
 repo-settings.h          |   5 ++
 revision.c               |  13 ++--
 tag.c                    |   2 +-
 36 files changed, 268 insertions(+), 190 deletions(-)

Range-diff against v6:
 -:  ---------- >  1:  6c00e25c86 packfile: add repository to struct `packed_git`
 -:  ---------- >  2:  70fc8a79af packfile: use `repository` from `packed_git` directly
 -:  ---------- >  3:  167a1f3a11 packfile: pass `repository` to static function in the file
 -:  ---------- >  4:  b7cfe78217 packfile: pass down repository to `odb_pack_name`
 -:  ---------- >  5:  5566f5554c packfile: pass down repository to `has_object[_kept]_pack`
 -:  ---------- >  6:  1b26e45a9b packfile: pass down repository to `for_each_packed_object`
 1:  89313cfed4 !  7:  1bdc34f4d8 config: make `delta_base_cache_limit` a non-global variable
    @@ builtin/gc.c: static void gc_config(struct gc_config *cfg)
      {
      	const char *value;
      	char *owned = NULL;
    -+	unsigned long longval;
    ++	unsigned long ulongval;
      
      	if (!git_config_get_value("gc.packrefs", &value)) {
      		if (value && !strcmp(value, "notbare"))
    @@ builtin/gc.c: static void gc_config(struct gc_config *cfg)
      	git_config_get_ulong("gc.bigpackthreshold", &cfg->big_pack_threshold);
      	git_config_get_ulong("pack.deltacachesize", &cfg->max_delta_cache_size);
      
    -+	if(!git_config_get_ulong("core.deltabasecachelimit", &longval))
    -+		cfg->delta_base_cache_limit = longval;
    ++	if (!git_config_get_ulong("core.deltabasecachelimit", &ulongval))
    ++		cfg->delta_base_cache_limit = ulongval;
     +
      	if (!git_config_get_string("gc.repackfilter", &owned)) {
      		free(cfg->repack_filter);
 2:  3a8e3b88df !  8:  7b6baa89ac config: make `packed_git_(limit|window_size)` non-global variables
    @@ Commit message
         this file, let's change it from being a global config variable to a
         local variable for the subsystem.
     
    -    We do this by introducing a new local `packfile_config` struct in
    -    `packfile.c` and also adding the required function to parse the said
    -    config. We then use this within `packfile.c` to obtain the variables.
    -
         With this, we rid `packfile.c` from all global variable usage and this
         means we can also remove the `USE_THE_REPOSITORY_VARIABLE` guard from
         the file.
    @@ packfile.c: unsigned char *use_pack(struct packed_git *p,
      			off_t len;
     +			struct repo_settings *settings;
     +
    -+			/* lazy load the settings incase it hasn't been setup */
    ++			/* lazy load the settings in case it hasn't been setup */
     +			prepare_repo_settings(p->repo);
     +			settings = &p->repo->settings;
     +
 3:  2f9a146978 =  9:  a3667d87ec midx: add repository to `multi_pack_index` struct
-- 
2.47.0