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authorJeff King <peff@peff.net>2017-05-09 02:54:13 (GMT)
committerJunio C Hamano <gitster@pobox.com>2017-05-09 03:07:24 (GMT)
commit9df4a6074a98740b70b980d43dca5203db0ff688 (patch)
tree070b151a1c0a9ce95464d4ebe840e30ec54d5609 /t/t5310-pack-bitmaps.sh
parent3b9e3c2cede15057af3ff8076c45ad5f33829436 (diff)
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pack-objects: disable pack reuse for object-selection options
If certain options like --honor-pack-keep, --local, or --incremental are used with pack-objects, then we need to feed each potential object to want_object_in_pack() to see if it should be filtered out. But when the bitmap reuse_packfile optimization is in effect, we do not call that function at all, and in fact skip adding the objects to the to_pack list entirely. This means we have a bug: for certain requests we will silently ignore those options and include objects in that pack that should not be there. The problem has been present since the inception of the pack-reuse code in 6b8fda2db (pack-objects: use bitmaps when packing objects, 2013-12-21), but it was unlikely to come up in practice. These options are generally used for on-disk packing, not transfer packs (which go to stdout), but we've never allowed pack reuse for non-stdout packs (until 645c432d6, we did not even use bitmaps, which the reuse optimization relies on; after that, we explicitly turned it off when not packing to stdout). We can fix this by just disabling the reuse_packfile optimization when the options are in use. In theory we could teach the pack-reuse code to satisfy these checks, but it's not worth the complexity. The purpose of the optimization is to keep the amount of per-object work we do to a minimum. But these options inherently require us to search for other copies of each object, drowning out any benefit of the pack-reuse optimization. But note that the optimizations from 56dfeb626 (pack-objects: compute local/ignore_pack_keep early, 2016-07-29) happen before pack-reuse, meaning that specifying "--honor-pack-keep" in a repository with no .keep files can still follow the fast path. There are tests in t5310 that check these options with bitmaps and --stdout, but they didn't catch the bug, and it's hard to adapt them to do so. One problem is that they don't use --delta-base-offset; without that option, we always disable the reuse optimization entirely. It would be fine to add it in (it actually makes the test more realistic), but that still isn't quite enough. The other problem is that the reuse code is very picky; it only kicks in when it can reuse most of a pack, starting from the first byte. So we'd have to start from a fully repacked and bitmapped state to trigger it. But the tests for these options use a much more subtle state; they want to be sure that the want_object_in_pack() code is allowing some objects but not others. Doing a full repack runs counter to that. So this patch adds new tests at the end of the script which create the fully-packed state and make sure that each option is not fooled by reusable pack. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 't/t5310-pack-bitmaps.sh')
-rwxr-xr-xt/t5310-pack-bitmaps.sh38
1 files changed, 38 insertions, 0 deletions
diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index 424bec7..c3ddfa2 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -289,4 +289,42 @@ test_expect_success 'splitting packs does not generate bogus bitmaps' '
git -C no-bitmaps.git fetch .. HEAD
'
+test_expect_success 'set up reusable pack' '
+ rm -f .git/objects/pack/*.keep &&
+ git repack -adb &&
+ reusable_pack () {
+ git for-each-ref --format="%(objectname)" |
+ git pack-objects --delta-base-offset --revs --stdout "$@"
+ }
+'
+
+test_expect_success 'pack reuse respects --honor-pack-keep' '
+ test_when_finished "rm -f .git/objects/pack/*.keep" &&
+ for i in .git/objects/pack/*.pack; do
+ >${i%.pack}.keep
+ done &&
+ reusable_pack --honor-pack-keep >empty.pack &&
+ git index-pack empty.pack &&
+ >expect &&
+ git show-index <empty.idx >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'pack reuse respects --local' '
+ mv .git/objects/pack/* alt.git/objects/pack/ &&
+ test_when_finished "mv alt.git/objects/pack/* .git/objects/pack/" &&
+ reusable_pack --local >empty.pack &&
+ git index-pack empty.pack &&
+ >expect &&
+ git show-index <empty.idx >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success 'pack reuse respects --incremental' '
+ reusable_pack --incremental >empty.pack &&
+ git index-pack empty.pack &&
+ >expect &&
+ git show-index <empty.idx >actual &&
+ test_cmp expect actual
+'
test_done