[PATCH 0/8] builtin/maintenance: introduce "geometric" strategy

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