Hi,

by default, git-maintenance(1) uses git-gc(1) to perform repository
housekeeping. This tool has a couple of shortcomings, most importantly
that it regularly does all-into-one repacks. This doesn't really work
all that well in the context of monorepos, where you really want to
avoid repacking all objects regularly.

An alternative maintenance strategy is the "incremental" strategy, but
this strategy has two downsides:

  - Strategies in general only apply to scheduled maintenance. So if you
    run git-maintenance(1), you still end up with git-gc(1).

  - The strategy is designed to not ever delete any data, but a full
    replacment for git-gc(1) needs to also prune reflogs, rereree caches
    and vanished worktrees.

This patch series aims to fix both of these issues.

First, the series introduces a new "geometric" maintenance task, which
makes use of geometric repacking as exposed by git-repack(1) in the
general case. In the case where a geometric repack ends up merging all
packfiles into one we instead do an all-into-one repack with cruft packs
so that we can still phase out objects over time.

Second, the series extends maintenance strategies to also cover normal
maintenance. If the user has configured the "geometric" strategy, we'll
thus use it for both manual and scheduled maintenance. For backwards
compatibility, the "incremental" strategy is changed so that it uses
git-gc(1) for manual maintenance and the other tasks for scheduled
maintenance.

The series is built on top of b660e2dcb9 (Sync with 'maint', 2025-10-14)
with tb/incremental-midx-part-3.1 at c886af90f8 (SQUASH??? play well
with other topics by preemptively including "repository.h", 2025-09-29)
merged into it.

Thanks!

Patrick

---
Patrick Steinhardt (8):
      builtin/gc: remove global `repack` variable
      builtin/gc: make `too_many_loose_objects()` reusable without GC config
      builtin/maintenance: introduce "geometric-repack" task
      builtin/maintenance: don't silently ignore invalid strategy
      builtin/maintenance: run maintenance tasks depending on type
      builtin/maintenance: extend "maintenance.strategy" to manual maintenance
      builtin/maintenance: make "gc" strategy accessible
      builtin/maintenance: introduce "geometric" strategy

 Documentation/config/maintenance.adoc |  44 +++++-
 builtin/gc.c                          | 271 +++++++++++++++++++++++++++-------
 t/t7900-maintenance.sh                | 212 ++++++++++++++++++++++++++
 3 files changed, 469 insertions(+), 58 deletions(-)


---
base-commit: 0bb2c786c2349dd6700727153c13d81cbfb41710
change-id: 20251015-pks-maintenance-geometric-strategy-580c58581b01