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git/t/t5333-pseudo-merge-bitmaps.sh
Taylor Blau a72dfab8b8 pseudo-merge.c: ensure pseudo-merge groups are closed
When generating pseudo-merge bitmaps, it's possible that concurrent
reference updates may reveal some pseudo-merge candidates which reach
objects that are not contained in the bitmap's pack or pseudo-pack
order (in the case of MIDX bitmaps).

The latter case is relatively easy to demonstrate: if we generate a MIDX
bitmap with only half of the repository packed, then the unpacked
contents are not part of the MIDX's object order.

If we happen to select one or more commit(s) from the unpacked portion
of the repository for inclusion in a pseudo-merge, we'll get the
following message when trying to generate its bitmap:

    $ git multi-pack-index write --bitmap
    [...]
    Selecting pseudo-merge commits: 100% (1/1), done.
    warning: Failed to write bitmap index. Packfile doesn't have full closure (object ... is missing)
    Building bitmaps:  50% (1/2), done.
    error: could not write multi-pack bitmap

, and the attempted bitmap write will fail, leaving the repository
without a current bitmap.

Rectify this by ensuring that the commits which are pseudo-merge
candidates can only be so if they appear somewhere in the packing order.

This is sufficient, since we know that the original packing order is
closed under reachability, so if a commit appears in that list as a
potential pseudo-merge candidate, we know that everything reachable from
it also appears in the list (and thus the candidate is a good one).

Noticed-by: Jeff King <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2024-08-15 11:32:28 -07:00

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#!/bin/sh
test_description='pseudo-merge bitmaps'
GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0
. ./test-lib.sh
test_pseudo_merges () {
test-tool bitmap dump-pseudo-merges
}
test_pseudo_merge_commits () {
test-tool bitmap dump-pseudo-merge-commits "$1"
}
test_pseudo_merges_satisfied () {
test_trace2_data bitmap pseudo_merges_satisfied "$1"
}
test_pseudo_merges_cascades () {
test_trace2_data bitmap pseudo_merges_cascades "$1"
}
test_pseudo_merges_reused () {
test_trace2_data pack-bitmap-write building_bitmaps_pseudo_merge_reused "$1"
}
tag_everything () {
git rev-list --all --no-object-names >in &&
perl -lne '
print "create refs/tags/" . $. . " " . $1 if /([0-9a-f]+)/
' <in | git update-ref --stdin
}
test_expect_success 'setup' '
test_commit_bulk 512 &&
tag_everything
'
test_expect_success 'bitmap traversal without pseudo-merges' '
git repack -adb &&
git rev-list --count --all --objects >expect &&
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt \
git rev-list --count --all --objects --use-bitmap-index >actual &&
test_pseudo_merges_satisfied 0 <trace2.txt &&
test_pseudo_merges_cascades 0 <trace2.txt &&
test_pseudo_merges >merges &&
test_must_be_empty merges &&
test_cmp expect actual
'
test_expect_success 'pseudo-merges accurately represent their objects' '
test_config bitmapPseudoMerge.test.pattern "refs/tags/" &&
test_config bitmapPseudoMerge.test.maxMerges 8 &&
test_config bitmapPseudoMerge.test.stableThreshold never &&
git repack -adb &&
test_pseudo_merges >merges &&
test_line_count = 8 merges &&
for i in $(test_seq 0 $(($(wc -l <merges)-1)))
do
test-tool bitmap dump-pseudo-merge-commits $i >commits &&
git rev-list --objects --no-object-names --stdin <commits >expect.raw &&
test-tool bitmap dump-pseudo-merge-objects $i >actual.raw &&
sort -u <expect.raw >expect &&
sort -u <actual.raw >actual &&
test_cmp expect actual || return 1
done
'
test_expect_success 'bitmap traversal with pseudo-merges' '
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt \
git rev-list --count --all --objects --use-bitmap-index >actual &&
git rev-list --count --all --objects >expect &&
test_pseudo_merges_satisfied 8 <trace2.txt &&
test_pseudo_merges_cascades 1 <trace2.txt &&
test_cmp expect actual
'
test_expect_success 'stale bitmap traversal with pseudo-merges' '
test_commit other &&
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt \
git rev-list --count --all --objects --use-bitmap-index >actual &&
git rev-list --count --all --objects >expect &&
test_pseudo_merges_satisfied 8 <trace2.txt &&
test_pseudo_merges_cascades 1 <trace2.txt &&
test_cmp expect actual
'
test_expect_success 'bitmapPseudoMerge.sampleRate adjusts commit selection rate' '
test_config bitmapPseudoMerge.test.pattern "refs/tags/" &&
test_config bitmapPseudoMerge.test.maxMerges 1 &&
test_config bitmapPseudoMerge.test.stableThreshold never &&
commits_nr=$(git rev-list --all --count) &&
for rate in 1.0 0.5 0.25
do
git -c bitmapPseudoMerge.test.sampleRate=$rate repack -adb &&
test_pseudo_merges >merges &&
test_line_count = 1 merges &&
test_pseudo_merge_commits 0 >commits &&
test-tool bitmap list-commits >bitmaps &&
bitmaps_nr="$(wc -l <bitmaps)" &&
perl -MPOSIX -e "print ceil(\$ARGV[0]*(\$ARGV[1]-\$ARGV[2]))" \
"$rate" "$commits_nr" "$bitmaps_nr" >expect &&
test $(cat expect) -eq $(wc -l <commits) || return 1
done
'
test_expect_success 'bitmapPseudoMerge.threshold excludes newer commits' '
git init pseudo-merge-threshold &&
(
cd pseudo-merge-threshold &&
new="1672549200" && # 2023-01-01
old="1641013200" && # 2022-01-01
GIT_COMMITTER_DATE="$new +0000" &&
export GIT_COMMITTER_DATE &&
test_commit_bulk --message="new" --notick 128 &&
GIT_COMMITTER_DATE="$old +0000" &&
export GIT_COMMITTER_DATE &&
test_commit_bulk --message="old" --notick 128 &&
tag_everything &&
git \
-c bitmapPseudoMerge.test.pattern="refs/tags/" \
-c bitmapPseudoMerge.test.maxMerges=1 \
-c bitmapPseudoMerge.test.threshold=$(($new - 1)) \
-c bitmapPseudoMerge.test.stableThreshold=never \
repack -adb &&
test_pseudo_merges >merges &&
test_line_count = 1 merges &&
test_pseudo_merge_commits 0 >oids &&
git cat-file --batch <oids >commits &&
test $(wc -l <oids) = $(grep -c "^committer.*$old +0000$" commits)
)
'
test_expect_success 'bitmapPseudoMerge.stableThreshold creates stable groups' '
(
cd pseudo-merge-threshold &&
new="1672549200" && # 2023-01-01
mid="1654059600" && # 2022-06-01
old="1641013200" && # 2022-01-01
GIT_COMMITTER_DATE="$mid +0000" &&
export GIT_COMMITTER_DATE &&
test_commit_bulk --message="mid" --notick 128 &&
git for-each-ref --format="delete %(refname)" refs/tags >in &&
git update-ref --stdin <in &&
tag_everything &&
git \
-c bitmapPseudoMerge.test.pattern="refs/tags/" \
-c bitmapPseudoMerge.test.maxMerges=1 \
-c bitmapPseudoMerge.test.threshold=$(($new - 1)) \
-c bitmapPseudoMerge.test.stableThreshold=$(($mid - 1)) \
-c bitmapPseudoMerge.test.stableSize=10 \
repack -adb &&
test_pseudo_merges >merges &&
merges_nr="$(wc -l <merges)" &&
for i in $(test_seq $(($merges_nr - 1)))
do
test_pseudo_merge_commits 0 >oids &&
git cat-file --batch <oids >commits &&
expect="$(grep -c "^committer.*$old +0000$" commits)" &&
actual="$(wc -l <oids)" &&
test $expect = $actual || return 1
done &&
test_pseudo_merge_commits $(($merges_nr - 1)) >oids &&
git cat-file --batch <oids >commits &&
test $(wc -l <oids) = $(grep -c "^committer.*$mid +0000$" commits)
)
'
test_expect_success 'out of order thresholds are rejected' '
test_must_fail git \
-c bitmapPseudoMerge.test.pattern="refs/*" \
-c bitmapPseudoMerge.test.threshold=1.month.ago \
-c bitmapPseudoMerge.test.stableThreshold=1.week.ago \
repack -adb 2>err &&
cat >expect <<-EOF &&
fatal: pseudo-merge group ${SQ}test${SQ} has unstable threshold before stable one
EOF
test_cmp expect err
'
test_expect_success 'pseudo-merge pattern with capture groups' '
git init pseudo-merge-captures &&
(
cd pseudo-merge-captures &&
test_commit_bulk 128 &&
tag_everything &&
for r in $(test_seq 8)
do
test_commit_bulk 16 &&
git rev-list HEAD~16.. >in &&
perl -lne "print \"create refs/remotes/$r/tags/\$. \$_\"" <in |
git update-ref --stdin || return 1
done &&
git \
-c bitmapPseudoMerge.tags.pattern="refs/remotes/([0-9]+)/tags/" \
-c bitmapPseudoMerge.tags.maxMerges=1 \
repack -adb &&
git for-each-ref --format="%(objectname) %(refname)" >refs &&
test_pseudo_merges >merges &&
for m in $(test_seq 0 $(($(wc -l <merges) - 1)))
do
test_pseudo_merge_commits $m >oids &&
grep -f oids refs |
perl -lne "print \$1 if /refs\/remotes\/([0-9]+)/" |
sort -u || return 1
done >remotes &&
test $(wc -l <remotes) -eq $(sort -u <remotes | wc -l)
)
'
test_expect_success 'pseudo-merge overlap setup' '
git init pseudo-merge-overlap &&
(
cd pseudo-merge-overlap &&
test_commit_bulk 256 &&
tag_everything &&
git \
-c bitmapPseudoMerge.all.pattern="refs/" \
-c bitmapPseudoMerge.all.maxMerges=1 \
-c bitmapPseudoMerge.all.stableThreshold=never \
-c bitmapPseudoMerge.tags.pattern="refs/tags/" \
-c bitmapPseudoMerge.tags.maxMerges=1 \
-c bitmapPseudoMerge.tags.stableThreshold=never \
repack -adb
)
'
test_expect_success 'pseudo-merge overlap generates overlapping groups' '
(
cd pseudo-merge-overlap &&
test_pseudo_merges >merges &&
test_line_count = 2 merges &&
test_pseudo_merge_commits 0 >commits-0.raw &&
test_pseudo_merge_commits 1 >commits-1.raw &&
sort commits-0.raw >commits-0 &&
sort commits-1.raw >commits-1 &&
comm -12 commits-0 commits-1 >overlap &&
test_line_count -gt 0 overlap
)
'
test_expect_success 'pseudo-merge overlap traversal' '
(
cd pseudo-merge-overlap &&
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt \
git rev-list --count --all --objects --use-bitmap-index >actual &&
git rev-list --count --all --objects >expect &&
test_pseudo_merges_satisfied 2 <trace2.txt &&
test_pseudo_merges_cascades 1 <trace2.txt &&
test_cmp expect actual
)
'
test_expect_success 'pseudo-merge overlap stale traversal' '
(
cd pseudo-merge-overlap &&
test_commit other &&
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt \
git rev-list --count --all --objects --use-bitmap-index >actual &&
git rev-list --count --all --objects >expect &&
test_pseudo_merges_satisfied 2 <trace2.txt &&
test_pseudo_merges_cascades 1 <trace2.txt &&
test_cmp expect actual
)
'
test_expect_success 'pseudo-merge reuse' '
git init pseudo-merge-reuse &&
(
cd pseudo-merge-reuse &&
stable="1641013200" && # 2022-01-01
unstable="1672549200" && # 2023-01-01
GIT_COMMITTER_DATE="$stable +0000" &&
export GIT_COMMITTER_DATE &&
test_commit_bulk --notick 128 &&
GIT_COMMITTER_DATE="$unstable +0000" &&
export GIT_COMMITTER_DATE &&
test_commit_bulk --notick 128 &&
tag_everything &&
git \
-c bitmapPseudoMerge.test.pattern="refs/tags/" \
-c bitmapPseudoMerge.test.maxMerges=1 \
-c bitmapPseudoMerge.test.threshold=now \
-c bitmapPseudoMerge.test.stableThreshold=$(($unstable - 1)) \
-c bitmapPseudoMerge.test.stableSize=512 \
repack -adb &&
test_pseudo_merges >merges &&
test_line_count = 2 merges &&
test_pseudo_merge_commits 0 >stable-oids.before &&
test_pseudo_merge_commits 1 >unstable-oids.before &&
: >trace2.txt &&
GIT_TRACE2_EVENT=$PWD/trace2.txt git \
-c bitmapPseudoMerge.test.pattern="refs/tags/" \
-c bitmapPseudoMerge.test.maxMerges=2 \
-c bitmapPseudoMerge.test.threshold=now \
-c bitmapPseudoMerge.test.stableThreshold=$(($unstable - 1)) \
-c bitmapPseudoMerge.test.stableSize=512 \
repack -adb &&
test_pseudo_merges_reused 1 <trace2.txt &&
test_pseudo_merges >merges &&
test_line_count = 3 merges &&
test_pseudo_merge_commits 0 >stable-oids.after &&
for i in 1 2
do
test_pseudo_merge_commits $i || return 1
done >unstable-oids.after &&
sort -u <stable-oids.before >expect &&
sort -u <stable-oids.after >actual &&
test_cmp expect actual &&
sort -u <unstable-oids.before >expect &&
sort -u <unstable-oids.after >actual &&
test_cmp expect actual
)
'
test_expect_success 'empty pseudo-merge group' '
git init pseudo-merge-empty-group &&
(
cd pseudo-merge-empty-group &&
# Ensure that a pseudo-merge group with no unstable
# commits does not generate an empty pseudo-merge
# bitmap.
git config bitmapPseudoMerge.empty.pattern refs/ &&
test_commit base &&
git repack -adb &&
test-tool bitmap dump-pseudo-merges >merges &&
test_line_count = 1 merges &&
test 0 -eq "$(grep -c commits=0 <merges)"
)
'
test_expect_success 'pseudo-merge closure' '
git init pseudo-merge-closure &&
(
cd pseudo-merge-closure &&
test_commit A &&
git repack -d &&
test_commit B &&
# Note that the contents of A is packed, but B is not. A
# (and the objects reachable from it) are thus visible
# to the MIDX, but the same is not true for B and its
# objects.
#
# Ensure that we do not attempt to create a pseudo-merge
# for B, depsite it matching the below pseudo-merge
# group pattern, as doing so would result in a failure
# to write a non-closed bitmap.
git config bitmapPseudoMerge.test.pattern refs/ &&
git config bitmapPseudoMerge.test.threshold now &&
git multi-pack-index write --bitmap &&
test-tool bitmap dump-pseudo-merges >pseudo-merges &&
test_line_count = 1 pseudo-merges &&
git rev-parse A >expect &&
test-tool bitmap list-commits >actual &&
test_cmp expect actual &&
test-tool bitmap dump-pseudo-merge-commits 0 >actual &&
test_cmp expect actual
)
'
test_done