Subject: [PATCH v4 0/2] shallow: handling fetch relative-deepen

From: "Samo Pogačnik via GitGitGadget" <[email-masked]>
Date: Fri, 16 Jan 2026 22:30:59 +0000

When a shallowed repository gets deepened beyond the beginning of a merged
branch, we may endup with some shallows, that are behind the reachable ones.
Added test 'fetching deepen beyond merged branch' exposes that behaviour.

On the other hand, it seems that equivalent absolute depth driven fetches
result in all the correct shallows. That led to this proposal, which unifies
absolute and relative deepening in a way that the same get_shallow_commits()
call is used in both cases. The difference is only that depth is adapted for
relative deepening by measuring equivalent depth of current local shallow
commits in the current remote repo. Thus a new function get_shallows_depth()
has been added and the function get_reachable_list() became redundant /
removed.

The get_shallows_depth() function also shares the logic of the
get_shallow_commits() function, but it focuses on counting depth of each
existing shallow commit. The minimum result is stored as
'data->deepen_relative', which is set not to be zero for relative deepening
anyway. That way we can allways summ 'data->deepen_relative' and 'depth'
values, because 'data->deepen_relative' is always 0 in absolute deepening.

Samo Pogačnik (2):
  shallow: free local object_array allocations
  shallow: handling fetch relative-deepen

 shallow.c             | 45 +++++++++++++++++--------
 shallow.h             |  1 +
 t/t5500-fetch-pack.sh | 23 +++++++++++++
 upload-pack.c         | 76 +++++--------------------------------------
 4 files changed, 64 insertions(+), 81 deletions(-)

base-commit: f0ef5b6d9bcc258e4cbef93839d1b7465d5212b9
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-2121%2Fspog%2Ffix-fetch-deepen-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-2121/spog/fix-fetch-deepen-v4
Pull-Request: https://github.com/git/git/pull/2121

Range-diff vs v3:

 1:  f8a8d077cd = 1:  f8a8d077cd shallow: free local object_array allocations
 2:  e79ab6b740 ! 2:  e9b20ae06f shallow: handling fetch relative-deepen
     @@ Commit message
          get_shallow_commits() function, but it focuses on counting depth of
          each existing shallow commit. The minimum result is stored as
          'data->deepen_relative', which is set not to be zero for relative
     -    deepening anyway. That way we can allways summ 'data->deepen_relative'
     +    deepening anyway. That way we can always sum 'data->deepen_relative'
          and 'depth' values, because 'data->deepen_relative' is always 0 in
          absolute deepening.
     +    To avoid duplicating logic between get_shallows_depth() and
     +    get_shallow_commits(), get_shallow_commits() was modified so that
     +    it is used by get_shallows_depth().
      
          Signed-off-by: Samo Pogačnik <[email-masked]>

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