Subject: [PATCH v2 0/3] refs/files: use heuristics to decide whether to repack with `--auto`

From: Patrick Steinhardt <[email-masked]>
Date: Wed, 4 Sep 2024 10:52:58 +0200

Hi,

this is the second version of my patch series that introduces a new
heuristic for packing refs with the "files" backend. This heuristic is
designed to avoid needlessly rewriting the "packed-refs" file when there
are only a small set of loose refs. The number of loose refs required
scales with the size of the "packed-refs" file.

There is only one change compared to v1, namely a deduplication of the
log2 functions we have in our tree.

Thanks!

Patrick

Patrick Steinhardt (3):
  wrapper: introduce `log2u()`
  t0601: merge tests for auto-packing of refs
  refs/files: use heuristic to decide whether to repack with `--auto`

 bisect.c                      |  12 +---
 refs/files-backend.c          |  65 ++++++++++++++++++++++
 refs/packed-backend.c         |  18 ++++++
 refs/packed-backend.h         |   7 +++
 t/t0601-reffiles-pack-refs.sh | 101 ++++++++++++++++++++++++++++------
 wrapper.h                     |  18 ++++++
 6 files changed, 194 insertions(+), 27 deletions(-)

Range-diff against v1:
-:  ----------- > 1:  df8c5dffffe wrapper: introduce `log2u()`
1:  3a8063e8b2c = 2:  4a59cec205d t0601: merge tests for auto-packing of refs
2:  9a63abfe3b8 ! 3:  49f953142b1 refs/files: use heuristic to decide whether to repack with `--auto`
    @@ refs/files-backend.c: static int should_pack_ref(struct files_ref_store *refs,
      	return 0;
      }
      
    -+static size_t fastlog2(size_t sz)
    -+{
    -+	size_t l = 0;
    -+	if (!sz)
    -+		return 0;
    -+	for (; sz; sz /= 2)
    -+		l++;
    -+	return l - 1;
    -+}
    -+
     +static int should_pack_refs(struct files_ref_store *refs,
     +			    struct pack_refs_opts *opts)
     +{
    @@ refs/files-backend.c: static int should_pack_ref(struct files_ref_store *refs,
     +	 * packed refs. This heuristic may be tweaked in the future, but should
     +	 * serve as a sufficiently good first iteration.
     +	 */
    -+	limit = fastlog2(packed_size / 100) * 5;
    ++	limit = log2u(packed_size / 100) * 5;
     +	if (limit < 16)
     +		limit = 16;
     +

base-commit: 4590f2e9412378c61eac95966709c78766d326ba
-- 
2.46.0.519.g2e7b89e038.dirty