pack-bitmap: use bitmaps for traversals with '--filter=tree:0'

Hi,

This series contains a handful of patches to make object traversals with '--filter=tree:0' be bitmaps-compatible. They have been kicking around in GitHub's fork for some time, and we use them on every '--filter=tree:0' fetch.

This is a prerequisite for a future series which will introduce configuration in upload-pack to indicate which filter choices are and aren't supported [1]. Since sending [1], GitHub's fork has grown support for

[uploadpack 'filter.tree']
maxDepth = <n>

...and so I figure that we could get this smaller series out for discussion before introducing that option, which doesn't make sense without having some faster variant of the 'tree' filter for certain values of 'n'.

Thanks,
Taylor

[1]: https://lore.kernel.org/git/[email protected]/

Jeff King (2):
list-objects-filter: treat NULL filter_options as "disabled"
pack-bitmap: pass object filter to fill-in traversal

Taylor Blau (2):
pack-bitmap.c: make object filtering functions generic pack-bitmap.c: support 'tree:0' filtering

 list-objects-filter.c              |  3 ++
 pack-bitmap.c                      | 72 +++++++++++++++++++++++-------
 t/perf/p5310-pack-bitmaps.sh       | 10 +++++
 t/t6113-rev-list-bitmap-filters.sh | 21 +++++++++
 4 files changed, 90 insertions(+), 16 deletions(-)

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2.26.2.112.g65467a058e