[PATCH v2 0/6] builtin/repo: introduce stats subcommand

Greetings,

The shape of a repository's history can have huge impacts on the performance and health of the repository itself. Currently, Git lacks a means to surface key stats/information regarding the shape of a repository via a single command. Acquiring this information requires users to be fairly knowledgeable about the structure of a Git repository and how to identify the relevant data points. To fill this gap, supplemental tools such as git-sizer(1) have been developed.

To allow users to more readily identify potential issues for a repository, introduce the "stats" subcommand in git-repo(1) to output stats for the repository that may be of interest to users. The goal of this subcommand is to eventually provide similar functionality to git-sizer(1), but in Git natively.

In this initial version, the "stats" subcommand only surfaces counts of the various reference and object types in a repository. In a follow-up series, I would like to introduce additional data points that are present in git-sizer(1) such as largest objects, combined object sizes by type, and other general repository shape information.

Some other general features that would be nice to introduce eventually:

- A "level of concern" meter for reported stats. This could indicate to
  users which stats may be worth looking into further.
- Links to OIDs of interesting objects that correspond to certain stats.
- Options to limit which references to use when evaluating the
  repository.

Changes since V1:

- Translatable terms displayed in the table have formatting separated
  out.
- Squashed the `keyvalue` and `nul` output format patches into one.
- Added a progress meter to provide users with more feedback.
- Updated docs to outline to outline reported data in a bulleted list.
- Combined similar tests together to reduce repetitive setup.
- Added patch to improve ref-filter interface so we don't have to create
  a dummy patterns array.
- Many other renames and cleanups to improve patch clarity.

Thanks, -Justin

Justin Tobler (6):
  builtin/repo: rename repo_info() to cmd_repo_info()
  ref-filter: allow NULL filter pattern
  builtin/repo: introduce stats subcommand
  builtin/repo: add object counts in stats output
  builtin/repo: add keyvalue and nul format for stats
  builtin/repo: add progress meter for stats

 Documentation/git-repo.adoc |  30 +++
 builtin/repo.c              | 354 +++++++++++++++++++++++++++++++++++-
 ref-filter.c                |   4 +-
 t/meson.build               |   1 +
 t/t1901-repo-stats.sh       | 109 +++++++++++
 5 files changed, 493 insertions(+), 5 deletions(-)
 create mode 100755 t/t1901-repo-stats.sh

base-commit: ca2559c1d630eb4f04cdee2328aaf1c768907a9e