[PATCH 0/7] reftable: memory optimizations for reflog iteration

[Patrick Steinhardt <ps@pks.im>]

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Hi,

this patch series does the same as all the preceding patch series that
optimized how the reftable library iterates through refs, but for
reflogs instead.

The goal of this patch series is to arrive at a constant number of
allocations when iterating refs. This is achieved in mostly the same way
we did it for ref iteration, namely by reusing already-allocated memory.
Overall, this brings us down from 8 allocations per reflog record to
essentially 0 allocations per reflog. Iterating through 1 million
reflogs with `git reflog list` thus goes down from 8.068m allocations to
only around 68.5k.

This series is built on top of "master" at b387623c12 (The third batch,
2024-03-01) with Junio's "ps/reftable-iteration-perf-part2" at
43f70eaea0 (refs/reftable: precompute prefix length, 2024-03-04) merged
into it.

Patrick

Patrick Steinhardt (7):
  refs/reftable: reload correct stack when creating reflog iter
  reftable/record: convert old and new object IDs to arrays
  reftable/record: avoid copying author info
  reftable/record: reuse refnames when decoding log records
  reftable/record: reuse message when decoding log records
  reftable/record: use scratch buffer when decoding records
  refs/reftable: track last log record name via strbuf

 refs/reftable-backend.c    |  52 +++++----------
 reftable/block.c           |   4 +-
 reftable/block.h           |   2 +
 reftable/merged_test.c     |  11 ++--
 reftable/readwrite_test.c  |  62 +++++++-----------
 reftable/record.c          | 129 ++++++++++++++-----------------------
 reftable/record.h          |   5 +-
 reftable/record_test.c     |  68 ++++++++++---------
 reftable/reftable-record.h |   6 +-
 reftable/stack_test.c      |  26 ++++----
 10 files changed, 154 insertions(+), 211 deletions(-)

-- 
2.44.0


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