path: root/t/helper/test-tool.c
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authorTaylor Blau <>2021-04-01 01:32:14 (GMT)
committerJunio C Hamano <>2021-04-01 06:14:03 (GMT)
commit3f267a112820f3bdf6b82362680ea6339f0e5f86 (patch)
tree423bb1820ec16deb96e6a68b15a7b38b2077c5b8 /t/helper/test-tool.c
parent483fa7f42d9e7723154aa1baa6e1576cf51cc64b (diff)
builtin/pack-objects.c: respect 'pack.preferBitmapTips'
When writing a new pack with a bitmap, it is sometimes convenient to indicate some reference prefixes which should receive priority when selecting which commits to receive bitmaps. A truly motivated caller could accomplish this by setting 'pack.islandCore', (since all commits in the core island are similarly marked as preferred) but this requires callers to opt into using delta islands, which they may or may not want to do. Introduce a new multi-valued configuration, 'pack.preferBitmapTips' to allow callers to specify a list of reference prefixes. All references which have a prefix contained in 'pack.preferBitmapTips' will mark their tips as "preferred" in the same way as commits are marked as preferred for selection by 'pack.islandCore'. The choice of the verb "prefer" is intentional: marking the NEEDS_BITMAP flag on an object does *not* guarantee that that object will receive a bitmap. It merely guarantees that that commit will receive a bitmap over any *other* commit in the same window by bitmap_writer_select_commits(). The test this patch adds reflects this quirk, too. It only tests that a commit (which didn't receive bitmaps by default) is selected for bitmaps after changing the value of 'pack.preferBitmapTips' to include it. Other commits may lose their bitmaps as a byproduct of how the selection process works (bitmap_writer_select_commits() ignores the remainder of a window after seeing a commit with the NEEDS_BITMAP flag). This configuration will aide in selecting important references for multi-pack bitmaps, since they do not respect the same pack.islandCore configuration. (They could, but doing so may be confusing, since it is packs--not bitmaps--which are influenced by the delta-islands configuration). In a fork network repository (one which lists all forks of a given repository as remotes), for example, it is useful to set pack.preferBitmapTips to 'refs/remotes/<root>/heads' and 'refs/remotes/<root>/tags', where '<root>' is an opaque identifier referring to the repository which is at the base of the fork chain. Suggested-by: Jeff King <> Signed-off-by: Taylor Blau <> Signed-off-by: Junio C Hamano <>
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