git/pack-bitmap.h, branch v2.40.2

pack-bitmap: prepare to read lookup table extension

2022-08-26T17:13:58Z

Earlier change teaches Git to write bitmap lookup table. But Git does not know how to parse them. Teach Git to parse the existing bitmap lookup table. The older versions of Git are not affected by it. Those versions ignore the lookup table. Mentored-by: Taylor Blau Co-Mentored-by: Kaartic Sivaraam Signed-off-by: Abhradeep Chakraborty Reviewed-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-bitmap-write.c: write lookup table extension

2022-08-26T17:13:50Z

The bitmap lookup table extension was documented by an earlier change, but Git does not yet know how to write that extension. Teach Git to write bitmap lookup table extension. The table contains the list of `N` ` triplets. These triplets are sorted according to their commit pos (ascending order). The meaning of each data in the i'th triplet is given below: - commit_pos stores commit position (in the pack-index or midx). It is a 4 byte network byte order unsigned integer. - offset is the position (in the bitmap file) from which that commit's bitmap can be read. - xor_row is the position of the triplet in the lookup table whose bitmap is used to compress this bitmap, or `0xffffffff` if no such bitmap exists. Mentored-by: Taylor Blau Co-mentored-by: Kaartic Sivaraam Co-authored-by: Taylor Blau Signed-off-by: Abhradeep Chakraborty Reviewed-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-bitmap-write: use const for hashes

2022-07-19T15:38:17Z

The next change will use a const array when calling this method. There is no need for the non-const version, so let's do this cleanup quickly. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

pack-bitmap: drop filter in prepare_bitmap_walk()

2022-03-09T18:25:27Z

Now that all consumers of prepare_bitmap_walk() have populated the 'filter' member of 'struct rev_info', we can drop that extra parameter from the method and access it directly from the 'struct rev_info'. Signed-off-by: Derrick Stolee Signed-off-by: Junio C Hamano

Merge branch 'tb/repack-write-midx'

2021-10-18T22:47:57Z

"git repack" has been taught to generate multi-pack reachability bitmaps. * tb/repack-write-midx: test-read-midx: fix leak of bitmap_index struct builtin/repack.c: pass `--refs-snapshot` when writing bitmaps builtin/repack.c: make largest pack preferred builtin/repack.c: support writing a MIDX while repacking builtin/repack.c: extract showing progress to a variable builtin/repack.c: rename variables that deal with non-kept packs builtin/repack.c: keep track of existing packs unconditionally midx: preliminary support for `--refs-snapshot` builtin/multi-pack-index.c: support `--stdin-packs` mode midx: expose `write_midx_file_only()` publicly

builtin/repack.c: make largest pack preferred

2021-09-29T04:20:56Z

When repacking into a geometric series and writing a multi-pack bitmap, it is beneficial to have the largest resulting pack be the preferred object source in the bitmap's MIDX, since selecting the large packs can lead to fewer broken delta chains and better compression. Teach 'git repack' to identify this pack and pass it to the MIDX write machinery in order to mark it as preferred. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

t/helper/test-bitmap.c: add 'dump-hashes' mode

2021-09-14T23:34:17Z

The pack-bitmap writer code is about to learn how to propagate values from an existing hash-cache. To prepare, teach the test-bitmap helper to dump the values from a bitmap's hash-cache extension in order to test those changes. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-bitmap: drop repository argument from prepare_midx_bitmap_git()

2021-09-10T00:32:37Z

We never look at the repository argument which is passed. This makes sense, since the multi_pack_index struct already tells us everything we need to access the files in its associated object directory. Signed-off-by: Jeff King Reviewed-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-bitmap: read multi-pack bitmaps

2021-09-01T20:56:43Z

This prepares the code in pack-bitmap to interpret the new multi-pack bitmaps described in Documentation/technical/bitmap-format.txt, which mostly involves converting bit positions to accommodate looking them up in a MIDX. Note that there are currently no writers who write multi-pack bitmaps, and that this will be implemented in the subsequent commit. Note also that get_midx_checksum() and get_midx_filename() are made non-static so they can be called from pack-bitmap.c. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano

pack-bitmap.c: introduce 'bitmap_is_preferred_refname()'

2021-09-01T20:56:43Z

In a recent commit, pack-objects learned support for the 'pack.preferBitmapTips' configuration. This patch prepares the multi-pack bitmap code to respect this configuration, too. The yet-to-be implemented code will find that it is more efficient to check whether each reference contains a prefix found in the configured set of values rather than doing an additional traversal. Implement a function 'bitmap_is_preferred_refname()' which will perform that check. Its caller will be added in a subsequent patch. Signed-off-by: Taylor Blau Signed-off-by: Junio C Hamano