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![Derrick Stolee](/assets/img/avatar_default.png)
The trace2 region around the call to lazy_bitmap_for_commit() in
bitmap_for_commit() was added in 28cd730680
(pack-bitmap: prepare to
read lookup table extension, 2022-08-14). While adding trace2 regions is
typically helpful for tracking performance, this method is called
possibly thousands of times as a commit walk explores commit history
looking for a matching bitmap. When trace2 output is enabled, this
region is emitted many times and performance is throttled by that
output.
For now, remove these regions entirely.
This is a critical path, and it would be valuable to measure that the
time spent in bitmap_for_commit() does not increase when using the
commit lookup table. The best way to do that would be to use a mechanism
that sums the time spent in a region and reports a single value at the
end of the process. This technique was introduced but not merged by [1]
so maybe this example presents some justification to revisit that
approach.
[1] https://lore.kernel.org/git/pull.1099.v2.git.1640720202.gitgitgadget@gmail.com/
To help with the 'git blame' output in this region, add a comment that
warns against adding a trace2 region. Delete a test from t5310 that used
that trace output to check that this lookup optimization was activated.
To create this kind of test again in the future, the stopwatch traces
mentioned earlier could be used as a signal that we activated this code
path.
Helpedy-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
472 lines
15 KiB
Bash
Executable file
472 lines
15 KiB
Bash
Executable file
#!/bin/sh
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test_description='exercise basic bitmap functionality'
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. ./test-lib.sh
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. "$TEST_DIRECTORY"/lib-bitmap.sh
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# t5310 deals only with single-pack bitmaps, so don't write MIDX bitmaps in
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# their place.
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GIT_TEST_MULTI_PACK_INDEX_WRITE_BITMAP=0
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objpath () {
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echo ".git/objects/$(echo "$1" | sed -e 's|\(..\)|\1/|')"
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}
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# show objects present in pack ($1 should be associated *.idx)
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list_packed_objects () {
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git show-index <"$1" >object-list &&
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cut -d' ' -f2 object-list
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}
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# has_any pattern-file content-file
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# tests whether content-file has any entry from pattern-file with entries being
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# whole lines.
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has_any () {
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grep -Ff "$1" "$2"
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}
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test_bitmap_cases () {
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writeLookupTable=false
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for i in "$@"
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do
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case "$i" in
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"pack.writeBitmapLookupTable") writeLookupTable=true;;
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esac
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done
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test_expect_success 'setup test repository' '
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rm -fr * .git &&
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git init &&
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git config pack.writeBitmapLookupTable '"$writeLookupTable"'
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'
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setup_bitmap_history
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test_expect_success 'setup writing bitmaps during repack' '
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git config repack.writeBitmaps true
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'
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test_expect_success 'full repack creates bitmaps' '
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GIT_TRACE2_EVENT="$(pwd)/trace" \
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git repack -ad &&
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ls .git/objects/pack/ | grep bitmap >output &&
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test_line_count = 1 output &&
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grep "\"key\":\"num_selected_commits\",\"value\":\"106\"" trace &&
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grep "\"key\":\"num_maximal_commits\",\"value\":\"107\"" trace
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'
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basic_bitmap_tests
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test_expect_success 'pack-objects respects --local (non-local loose)' '
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git init --bare alt.git &&
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echo $(pwd)/alt.git/objects >.git/objects/info/alternates &&
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echo content1 >file1 &&
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# non-local loose object which is not present in bitmapped pack
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altblob=$(GIT_DIR=alt.git git hash-object -w file1) &&
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# non-local loose object which is also present in bitmapped pack
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git cat-file blob $blob | GIT_DIR=alt.git git hash-object -w --stdin &&
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git add file1 &&
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test_tick &&
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git commit -m commit_file1 &&
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echo HEAD | git pack-objects --local --stdout --revs >1.pack &&
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git index-pack 1.pack &&
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list_packed_objects 1.idx >1.objects &&
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printf "%s\n" "$altblob" "$blob" >nonlocal-loose &&
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! has_any nonlocal-loose 1.objects
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'
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test_expect_success 'pack-objects respects --honor-pack-keep (local non-bitmapped pack)' '
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echo content2 >file2 &&
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blob2=$(git hash-object -w file2) &&
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git add file2 &&
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test_tick &&
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git commit -m commit_file2 &&
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printf "%s\n" "$blob2" "$bitmaptip" >keepobjects &&
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pack2=$(git pack-objects pack2 <keepobjects) &&
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mv pack2-$pack2.* .git/objects/pack/ &&
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>.git/objects/pack/pack2-$pack2.keep &&
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rm $(objpath $blob2) &&
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echo HEAD | git pack-objects --honor-pack-keep --stdout --revs >2a.pack &&
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git index-pack 2a.pack &&
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list_packed_objects 2a.idx >2a.objects &&
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! has_any keepobjects 2a.objects
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'
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test_expect_success 'pack-objects respects --local (non-local pack)' '
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mv .git/objects/pack/pack2-$pack2.* alt.git/objects/pack/ &&
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echo HEAD | git pack-objects --local --stdout --revs >2b.pack &&
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git index-pack 2b.pack &&
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list_packed_objects 2b.idx >2b.objects &&
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! has_any keepobjects 2b.objects
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'
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test_expect_success 'pack-objects respects --honor-pack-keep (local bitmapped pack)' '
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ls .git/objects/pack/ | grep bitmap >output &&
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test_line_count = 1 output &&
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packbitmap=$(basename $(cat output) .bitmap) &&
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list_packed_objects .git/objects/pack/$packbitmap.idx >packbitmap.objects &&
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test_when_finished "rm -f .git/objects/pack/$packbitmap.keep" &&
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>.git/objects/pack/$packbitmap.keep &&
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echo HEAD | git pack-objects --honor-pack-keep --stdout --revs >3a.pack &&
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git index-pack 3a.pack &&
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list_packed_objects 3a.idx >3a.objects &&
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! has_any packbitmap.objects 3a.objects
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'
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test_expect_success 'pack-objects respects --local (non-local bitmapped pack)' '
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mv .git/objects/pack/$packbitmap.* alt.git/objects/pack/ &&
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rm -f .git/objects/pack/multi-pack-index &&
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test_when_finished "mv alt.git/objects/pack/$packbitmap.* .git/objects/pack/" &&
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echo HEAD | git pack-objects --local --stdout --revs >3b.pack &&
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git index-pack 3b.pack &&
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list_packed_objects 3b.idx >3b.objects &&
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! has_any packbitmap.objects 3b.objects
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'
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test_expect_success 'pack-objects to file can use bitmap' '
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# make sure we still have 1 bitmap index from previous tests
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ls .git/objects/pack/ | grep bitmap >output &&
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test_line_count = 1 output &&
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# verify equivalent packs are generated with/without using bitmap index
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packasha1=$(git pack-objects --no-use-bitmap-index --all packa </dev/null) &&
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packbsha1=$(git pack-objects --use-bitmap-index --all packb </dev/null) &&
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list_packed_objects packa-$packasha1.idx >packa.objects &&
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list_packed_objects packb-$packbsha1.idx >packb.objects &&
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test_cmp packa.objects packb.objects
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'
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test_expect_success 'full repack, reusing previous bitmaps' '
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git repack -ad &&
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ls .git/objects/pack/ | grep bitmap >output &&
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test_line_count = 1 output
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'
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test_expect_success 'fetch (full bitmap)' '
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git --git-dir=clone.git fetch origin second:second &&
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git rev-parse HEAD >expect &&
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git --git-dir=clone.git rev-parse HEAD >actual &&
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test_cmp expect actual
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'
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test_expect_success 'create objects for missing-HAVE tests' '
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blob=$(echo "missing have" | git hash-object -w --stdin) &&
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tree=$(printf "100644 blob $blob\tfile\n" | git mktree) &&
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parent=$(echo parent | git commit-tree $tree) &&
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commit=$(echo commit | git commit-tree $tree -p $parent) &&
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cat >revs <<-EOF
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HEAD
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^HEAD^
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^$commit
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EOF
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'
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test_expect_success 'pack-objects respects --incremental' '
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cat >revs2 <<-EOF &&
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HEAD
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$commit
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EOF
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git pack-objects --incremental --stdout --revs <revs2 >4.pack &&
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git index-pack 4.pack &&
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list_packed_objects 4.idx >4.objects &&
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test_line_count = 4 4.objects &&
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git rev-list --objects $commit >revlist &&
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cut -d" " -f1 revlist |sort >objects &&
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test_cmp 4.objects objects
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'
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test_expect_success 'pack with missing blob' '
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rm $(objpath $blob) &&
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git pack-objects --stdout --revs <revs >/dev/null
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'
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test_expect_success 'pack with missing tree' '
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rm $(objpath $tree) &&
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git pack-objects --stdout --revs <revs >/dev/null
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'
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test_expect_success 'pack with missing parent' '
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rm $(objpath $parent) &&
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git pack-objects --stdout --revs <revs >/dev/null
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'
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test_expect_success JGIT,SHA1 'we can read jgit bitmaps' '
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git clone --bare . compat-jgit.git &&
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(
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cd compat-jgit.git &&
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rm -f objects/pack/*.bitmap &&
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jgit gc &&
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git rev-list --test-bitmap HEAD
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)
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'
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test_expect_success JGIT,SHA1 'jgit can read our bitmaps' '
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git clone --bare . compat-us.git &&
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(
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cd compat-us.git &&
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git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
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git repack -adb &&
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# jgit gc will barf if it does not like our bitmaps
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jgit gc
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)
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'
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test_expect_success 'splitting packs does not generate bogus bitmaps' '
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test-tool genrandom foo $((1024 * 1024)) >rand &&
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git add rand &&
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git commit -m "commit with big file" &&
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git -c pack.packSizeLimit=500k repack -adb &&
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git init --bare no-bitmaps.git &&
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git -C no-bitmaps.git fetch .. HEAD
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'
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test_expect_success 'set up reusable pack' '
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rm -f .git/objects/pack/*.keep &&
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git repack -adb &&
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reusable_pack () {
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git for-each-ref --format="%(objectname)" |
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git pack-objects --delta-base-offset --revs --stdout "$@"
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}
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'
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test_expect_success 'pack reuse respects --honor-pack-keep' '
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test_when_finished "rm -f .git/objects/pack/*.keep" &&
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for i in .git/objects/pack/*.pack
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do
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>${i%.pack}.keep || return 1
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done &&
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reusable_pack --honor-pack-keep >empty.pack &&
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git index-pack empty.pack &&
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git show-index <empty.idx >actual &&
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test_must_be_empty actual
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'
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test_expect_success 'pack reuse respects --local' '
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mv .git/objects/pack/* alt.git/objects/pack/ &&
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test_when_finished "mv alt.git/objects/pack/* .git/objects/pack/" &&
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reusable_pack --local >empty.pack &&
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git index-pack empty.pack &&
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git show-index <empty.idx >actual &&
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test_must_be_empty actual
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'
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test_expect_success 'pack reuse respects --incremental' '
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reusable_pack --incremental >empty.pack &&
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git index-pack empty.pack &&
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git show-index <empty.idx >actual &&
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test_must_be_empty actual
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'
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test_expect_success 'truncated bitmap fails gracefully (ewah)' '
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test_config pack.writebitmaphashcache false &&
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test_config pack.writebitmaplookuptable false &&
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git repack -ad &&
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git rev-list --use-bitmap-index --count --all >expect &&
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bitmap=$(ls .git/objects/pack/*.bitmap) &&
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test_when_finished "rm -f $bitmap" &&
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test_copy_bytes 256 <$bitmap >$bitmap.tmp &&
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mv -f $bitmap.tmp $bitmap &&
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git rev-list --use-bitmap-index --count --all >actual 2>stderr &&
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test_cmp expect actual &&
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test_i18ngrep corrupt.ewah.bitmap stderr
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'
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test_expect_success 'truncated bitmap fails gracefully (cache)' '
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git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
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git repack -ad &&
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git rev-list --use-bitmap-index --count --all >expect &&
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bitmap=$(ls .git/objects/pack/*.bitmap) &&
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test_when_finished "rm -f $bitmap" &&
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test_copy_bytes 512 <$bitmap >$bitmap.tmp &&
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mv -f $bitmap.tmp $bitmap &&
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git rev-list --use-bitmap-index --count --all >actual 2>stderr &&
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test_cmp expect actual &&
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test_i18ngrep corrupted.bitmap.index stderr
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'
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# Create a state of history with these properties:
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#
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# - refs that allow a client to fetch some new history, while sharing some old
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# history with the server; we use branches delta-reuse-old and
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# delta-reuse-new here
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#
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# - the new history contains an object that is stored on the server as a delta
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# against a base that is in the old history
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#
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# - the base object is not immediately reachable from the tip of the old
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# history; finding it would involve digging down through history we know the
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# other side has
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#
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# This should result in a state where fetching from old->new would not
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# traditionally reuse the on-disk delta (because we'd have to dig to realize
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# that the client has it), but we will do so if bitmaps can tell us cheaply
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# that the other side has it.
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test_expect_success 'set up thin delta-reuse parent' '
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# This first commit contains the buried base object.
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test-tool genrandom delta 16384 >file &&
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git add file &&
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git commit -m "delta base" &&
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base=$(git rev-parse --verify HEAD:file) &&
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# These intermediate commits bury the base back in history.
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# This becomes the "old" state.
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for i in 1 2 3 4 5
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do
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echo $i >file &&
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git commit -am "intermediate $i" || return 1
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done &&
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git branch delta-reuse-old &&
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# And now our new history has a delta against the buried base. Note
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# that this must be smaller than the original file, since pack-objects
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# prefers to create deltas from smaller objects to larger.
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test-tool genrandom delta 16300 >file &&
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git commit -am "delta result" &&
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delta=$(git rev-parse --verify HEAD:file) &&
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git branch delta-reuse-new &&
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# Repack with bitmaps and double check that we have the expected delta
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# relationship.
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git repack -adb &&
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have_delta $delta $base
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'
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# Now we can sanity-check the non-bitmap behavior (that the server is not able
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# to reuse the delta). This isn't strictly something we care about, so this
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# test could be scrapped in the future. But it makes sure that the next test is
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# actually triggering the feature we want.
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#
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# Note that our tools for working with on-the-wire "thin" packs are limited. So
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# we actually perform the fetch, retain the resulting pack, and inspect the
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# result.
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test_expect_success 'fetch without bitmaps ignores delta against old base' '
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test_config pack.usebitmaps false &&
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test_when_finished "rm -rf client.git" &&
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git init --bare client.git &&
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(
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cd client.git &&
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git config transfer.unpackLimit 1 &&
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git fetch .. delta-reuse-old:delta-reuse-old &&
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git fetch .. delta-reuse-new:delta-reuse-new &&
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have_delta $delta $ZERO_OID
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)
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'
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# And do the same for the bitmap case, where we do expect to find the delta.
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test_expect_success 'fetch with bitmaps can reuse old base' '
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test_config pack.usebitmaps true &&
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test_when_finished "rm -rf client.git" &&
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git init --bare client.git &&
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(
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cd client.git &&
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git config transfer.unpackLimit 1 &&
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git fetch .. delta-reuse-old:delta-reuse-old &&
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git fetch .. delta-reuse-new:delta-reuse-new &&
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have_delta $delta $base
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)
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'
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test_expect_success 'pack.preferBitmapTips' '
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git init repo &&
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test_when_finished "rm -fr repo" &&
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(
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cd repo &&
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git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
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# create enough commits that not all are receive bitmap
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# coverage even if they are all at the tip of some reference.
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test_commit_bulk --message="%s" 103 &&
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git rev-list HEAD >commits.raw &&
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sort <commits.raw >commits &&
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git log --format="create refs/tags/%s %H" HEAD >refs &&
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git update-ref --stdin <refs &&
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git repack -adb &&
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test-tool bitmap list-commits | sort >bitmaps &&
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# remember which commits did not receive bitmaps
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comm -13 bitmaps commits >before &&
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test_file_not_empty before &&
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# mark the commits which did not receive bitmaps as preferred,
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# and generate the bitmap again
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perl -pe "s{^}{create refs/tags/include/$. }" <before |
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git update-ref --stdin &&
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git -c pack.preferBitmapTips=refs/tags/include repack -adb &&
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# finally, check that the commit(s) without bitmap coverage
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# are not the same ones as before
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test-tool bitmap list-commits | sort >bitmaps &&
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comm -13 bitmaps commits >after &&
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! test_cmp before after
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)
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'
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test_expect_success 'complains about multiple pack bitmaps' '
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rm -fr repo &&
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git init repo &&
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test_when_finished "rm -fr repo" &&
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(
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cd repo &&
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git config pack.writeBitmapLookupTable '"$writeLookupTable"' &&
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test_commit base &&
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git repack -adb &&
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bitmap="$(ls .git/objects/pack/pack-*.bitmap)" &&
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mv "$bitmap" "$bitmap.bak" &&
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test_commit other &&
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git repack -ab &&
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mv "$bitmap.bak" "$bitmap" &&
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find .git/objects/pack -type f -name "*.pack" >packs &&
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find .git/objects/pack -type f -name "*.bitmap" >bitmaps &&
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test_line_count = 2 packs &&
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test_line_count = 2 bitmaps &&
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git rev-list --use-bitmap-index HEAD 2>err &&
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grep "ignoring extra bitmap file" err
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)
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'
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}
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test_bitmap_cases
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test_expect_success 'incremental repack fails when bitmaps are requested' '
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test_commit more-1 &&
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test_must_fail git repack -d 2>err &&
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test_i18ngrep "Incremental repacks are incompatible with bitmap" err
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'
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test_expect_success 'incremental repack can disable bitmaps' '
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test_commit more-2 &&
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git repack -d --no-write-bitmap-index
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'
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test_bitmap_cases "pack.writeBitmapLookupTable"
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test_expect_success 'verify writing bitmap lookup table when enabled' '
|
|
GIT_TRACE2_EVENT="$(pwd)/trace2" \
|
|
git repack -ad &&
|
|
grep "\"label\":\"writing_lookup_table\"" trace2
|
|
'
|
|
|
|
test_expect_success 'truncated bitmap fails gracefully (lookup table)' '
|
|
test_config pack.writebitmaphashcache false &&
|
|
git repack -adb &&
|
|
git rev-list --use-bitmap-index --count --all >expect &&
|
|
bitmap=$(ls .git/objects/pack/*.bitmap) &&
|
|
test_when_finished "rm -f $bitmap" &&
|
|
test_copy_bytes 512 <$bitmap >$bitmap.tmp &&
|
|
mv -f $bitmap.tmp $bitmap &&
|
|
git rev-list --use-bitmap-index --count --all >actual 2>stderr &&
|
|
test_cmp expect actual &&
|
|
test_i18ngrep corrupted.bitmap.index stderr
|
|
'
|
|
|
|
test_done
|