git/t/t4216-log-bloom.sh

#!/bin/sh

test_description='git log for a path with Bloom filters'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME

. ./test-lib.sh
. "$TEST_DIRECTORY"/lib-chunk.sh

GIT_TEST_COMMIT_GRAPH=0
GIT_TEST_COMMIT_GRAPH_CHANGED_PATHS=0

test_expect_success 'setup test - repo, commits, commit graph, log outputs' '
	git init &&
	mkdir A A/B A/B/C &&
	test_commit c1 A/file1 &&
	test_commit c2 A/B/file2 &&
	test_commit c3 A/B/C/file3 &&
	test_commit c4 A/file1 &&
	test_commit c5 A/B/file2 &&
	test_commit c6 A/B/C/file3 &&
	test_commit c7 A/file1 &&
	test_commit c8 A/B/file2 &&
	test_commit c9 A/B/C/file3 &&
	test_commit c10 file_to_be_deleted &&
	git checkout -b side HEAD~4 &&
	test_commit side-1 file4 &&
	git checkout main &&
	git merge side &&
	test_commit c11 file5 &&
	mv file5 file5_renamed &&
	git add file5_renamed &&
	git commit -m "rename" &&
	rm file_to_be_deleted &&
	git add . &&
	git commit -m "file removed" &&
	git commit --allow-empty -m "empty" &&
	git commit-graph write --reachable --changed-paths &&

	test_oid_cache <<-EOF
	oid_version sha1:1
	oid_version sha256:2
	EOF
'

graph_read_expect () {
	NUM_CHUNKS=6
	cat >expect <<- EOF
	header: 43475048 1 $(test_oid oid_version) $NUM_CHUNKS 0
	num_commits: $1
	chunks: oid_fanout oid_lookup commit_metadata generation_data bloom_indexes bloom_data
	options: bloom(1,10,7) read_generation_data
	EOF
	test-tool read-graph >actual &&
	test_cmp expect actual
}

test_expect_success 'commit-graph write wrote out the bloom chunks' '
	graph_read_expect 16
'

# Turn off any inherited trace2 settings for this test.
sane_unset GIT_TRACE2 GIT_TRACE2_PERF GIT_TRACE2_EVENT
sane_unset GIT_TRACE2_PERF_BRIEF
sane_unset GIT_TRACE2_CONFIG_PARAMS

setup () {
	rm -f "$TRASH_DIRECTORY/trace.perf" &&
	git -c core.commitGraph=false log --pretty="format:%s" $1 >log_wo_bloom &&
	GIT_TRACE2_PERF="$TRASH_DIRECTORY/trace.perf" git -c core.commitGraph=true log --pretty="format:%s" $1 >log_w_bloom
}

test_bloom_filters_used () {
	log_args=$1
	bloom_trace_prefix="statistics:{\"filter_not_present\":${2:-0},\"maybe\""
	setup "$log_args" &&
	grep -q "$bloom_trace_prefix" "$TRASH_DIRECTORY/trace.perf" &&
	test_cmp log_wo_bloom log_w_bloom &&
    test_path_is_file "$TRASH_DIRECTORY/trace.perf"
}

test_bloom_filters_not_used () {
	log_args=$1
	setup "$log_args" &&

	if grep -q "statistics:{\"filter_not_present\":" "$TRASH_DIRECTORY/trace.perf"
	then
		# if the Bloom filter system is initialized, ensure that no
		# filters were used
		data="statistics:{"
		# unusable filters (e.g., those computed with a
		# different value of commitGraph.changedPathsVersion)
		# are counted in the filter_not_present bucket, so any
		# value is OK there.
		data="$data\"filter_not_present\":[0-9][0-9]*,"
		data="$data\"maybe\":0,"
		data="$data\"definitely_not\":0,"
		data="$data\"false_positive\":0}"

		grep -q "$data" "$TRASH_DIRECTORY/trace.perf"
	fi &&
	test_cmp log_wo_bloom log_w_bloom
}

for path in A A/B A/B/C A/file1 A/B/file2 A/B/C/file3 file4 file5 file5_renamed file_to_be_deleted
do
	for option in "" \
	      "--all" \
		      "--full-history" \
		      "--full-history --simplify-merges" \
		      "--simplify-merges" \
		      "--simplify-by-decoration" \
		      "--follow" \
		      "--first-parent" \
		      "--topo-order" \
		      "--date-order" \
		      "--author-date-order" \
		      "--ancestry-path side..main"
	do
		test_expect_success "git log option: $option for path: $path" '
			test_bloom_filters_used "$option -- $path" &&
			test_config commitgraph.readChangedPaths false &&
			test_bloom_filters_not_used "$option -- $path"
		'
	done
done

test_expect_success 'git log -- folder works with and without the trailing slash' '
	test_bloom_filters_used "-- A" &&
	test_bloom_filters_used "-- A/"
'

test_expect_success 'git log for path that does not exist. ' '
	test_bloom_filters_used "-- path_does_not_exist"
'

test_expect_success 'git log with --walk-reflogs does not use Bloom filters' '
	test_bloom_filters_not_used "--walk-reflogs -- A"
'

test_expect_success 'git log -- multiple path specs does not use Bloom filters' '
	test_bloom_filters_not_used "-- file4 A/file1"
'

test_expect_success 'git log -- "." pathspec at root does not use Bloom filters' '
	test_bloom_filters_not_used "-- ."
'

test_expect_success 'git log with wildcard that resolves to a single path uses Bloom filters' '
	test_bloom_filters_used "-- *4" &&
	test_bloom_filters_used "-- *renamed"
'

test_expect_success 'git log with wildcard that resolves to a multiple paths does not uses Bloom filters' '
	test_bloom_filters_not_used "-- *" &&
	test_bloom_filters_not_used "-- file*"
'

test_expect_success 'setup - add commit-graph to the chain without Bloom filters' '
	test_commit c14 A/anotherFile2 &&
	test_commit c15 A/B/anotherFile2 &&
	test_commit c16 A/B/C/anotherFile2 &&
	git commit-graph write --reachable --split --no-changed-paths &&
	test_line_count = 2 .git/objects/info/commit-graphs/commit-graph-chain
'

test_expect_success 'use Bloom filters even if the latest graph does not have Bloom filters' '
	# Ensure that the number of empty filters is equal to the number of
	# filters in the latest graph layer to prove that they are loaded (and
	# ignored).
	test_bloom_filters_used "-- A/B" 3
'

test_expect_success 'setup - add commit-graph to the chain with Bloom filters' '
	test_commit c17 A/anotherFile3 &&
	git commit-graph write --reachable --changed-paths --split &&
	test_line_count = 3 .git/objects/info/commit-graphs/commit-graph-chain
'

test_bloom_filters_used_when_some_filters_are_missing () {
	log_args=$1
	bloom_trace_prefix="statistics:{\"filter_not_present\":3,\"maybe\":6,\"definitely_not\":10"
	setup "$log_args" &&
	grep -q "$bloom_trace_prefix" "$TRASH_DIRECTORY/trace.perf" &&
	test_cmp log_wo_bloom log_w_bloom
}

test_expect_success 'Use Bloom filters if they exist in the latest but not all commit graphs in the chain.' '
	test_bloom_filters_used_when_some_filters_are_missing "-- A/B"
'

test_expect_success 'persist filter settings' '
	test_when_finished rm -rf .git/objects/info/commit-graph* &&
	rm -rf .git/objects/info/commit-graph* &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		GIT_TEST_BLOOM_SETTINGS_NUM_HASHES=9 \
		GIT_TEST_BLOOM_SETTINGS_BITS_PER_ENTRY=15 \
		git commit-graph write --reachable --changed-paths &&
	grep "{\"hash_version\":1,\"num_hashes\":9,\"bits_per_entry\":15,\"max_changed_paths\":512" trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2-auto.txt" \
		git commit-graph write --reachable --changed-paths &&
	grep "{\"hash_version\":1,\"num_hashes\":9,\"bits_per_entry\":15,\"max_changed_paths\":512" trace2-auto.txt
'

test_max_changed_paths () {
	grep "\"max_changed_paths\":$1" $2
}

test_filter_not_computed () {
	grep "\"key\":\"filter-not-computed\",\"value\":\"$1\"" $2
}

test_filter_computed () {
	grep "\"key\":\"filter-computed\",\"value\":\"$1\"" $2
}

test_filter_trunc_empty () {
	grep "\"key\":\"filter-trunc-empty\",\"value\":\"$1\"" $2
}

test_filter_trunc_large () {
	grep "\"key\":\"filter-trunc-large\",\"value\":\"$1\"" $2
}

test_filter_upgraded () {
	grep "\"key\":\"filter-upgraded\",\"value\":\"$1\"" $2
}

test_expect_success 'correctly report changes over limit' '
	git init limits &&
	(
		cd limits &&
		mkdir d &&
		mkdir d/e &&

		for i in $(test_seq 1 2)
		do
			printf $i >d/file$i.txt &&
			printf $i >d/e/file$i.txt || return 1
		done &&

		mkdir mode &&
		printf bash >mode/script.sh &&

		mkdir foo &&
		touch foo/bar &&
		touch foo.txt &&

		git add d foo foo.txt mode &&
		git commit -m "files" &&

		# Commit has 7 file and 4 directory adds
		GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS=10 \
			GIT_TRACE2_EVENT="$(pwd)/trace" \
			git commit-graph write --reachable --changed-paths &&
		test_max_changed_paths 10 trace &&
		test_filter_computed 1 trace &&
		test_filter_trunc_large 1 trace &&

		for path in $(git ls-tree -r --name-only HEAD)
		do
			git -c commitGraph.readChangedPaths=false log \
				-- $path >expect &&
			git log -- $path >actual &&
			test_cmp expect actual || return 1
		done &&

		# Make a variety of path changes
		printf new1 >d/e/file1.txt &&
		printf new2 >d/file2.txt &&
		rm d/e/file2.txt &&
		rm -r foo &&
		printf text >foo &&
		mkdir f &&
		printf new1 >f/file1.txt &&

		# including a mode-only change (counts as modified)
		git update-index --chmod=+x mode/script.sh &&

		git add foo d f &&
		git commit -m "complicated" &&

		# start from scratch and rebuild
		rm -f .git/objects/info/commit-graph &&
		GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS=10 \
			GIT_TRACE2_EVENT="$(pwd)/trace-edit" \
			git commit-graph write --reachable --changed-paths &&
		test_max_changed_paths 10 trace-edit &&
		test_filter_computed 2 trace-edit &&
		test_filter_trunc_large 2 trace-edit &&

		for path in $(git ls-tree -r --name-only HEAD)
		do
			git -c commitGraph.readChangedPaths=false log \
				-- $path >expect &&
			git log -- $path >actual &&
			test_cmp expect actual || return 1
		done &&

		# start from scratch and rebuild
		rm -f .git/objects/info/commit-graph &&
		GIT_TEST_BLOOM_SETTINGS_MAX_CHANGED_PATHS=11 \
			GIT_TRACE2_EVENT="$(pwd)/trace-update" \
			git commit-graph write --reachable --changed-paths &&
		test_max_changed_paths 11 trace-update &&
		test_filter_computed 2 trace-update &&
		test_filter_trunc_large 0 trace-update &&

		for path in $(git ls-tree -r --name-only HEAD)
		do
			git -c commitGraph.readChangedPaths=false log \
				-- $path >expect &&
			git log -- $path >actual &&
			test_cmp expect actual || return 1
		done
	)
'

test_expect_success 'correctly report commits with no changed paths' '
	git init empty &&
	test_when_finished "rm -fr empty" &&
	(
		cd empty &&

		git commit --allow-empty -m "initial commit" &&

		GIT_TRACE2_EVENT="$(pwd)/trace.event" \
			git commit-graph write --reachable --changed-paths &&
		test_filter_computed 1 trace.event &&
		test_filter_not_computed 0 trace.event &&
		test_filter_trunc_empty 1 trace.event &&
		test_filter_trunc_large 0 trace.event
	)
'

test_expect_success 'Bloom generation is limited by --max-new-filters' '
	(
		cd limits &&
		test_commit c2 filter &&
		test_commit c3 filter &&
		test_commit c4 no-filter &&

		rm -f trace.event &&
		GIT_TRACE2_EVENT="$(pwd)/trace.event" \
			git commit-graph write --reachable --split=replace \
				--changed-paths --max-new-filters=2 &&

		test_filter_computed 2 trace.event &&
		test_filter_not_computed 3 trace.event &&
		test_filter_trunc_empty 0 trace.event &&
		test_filter_trunc_large 0 trace.event
	)
'

test_expect_success 'Bloom generation backfills previously-skipped filters' '
	# Check specifying commitGraph.maxNewFilters over "git config" works.
	test_config -C limits commitGraph.maxNewFilters 1 &&
	(
		cd limits &&

		rm -f trace.event &&
		GIT_TRACE2_EVENT="$(pwd)/trace.event" \
			git commit-graph write --reachable --changed-paths \
				--split=replace &&
		test_filter_computed 1 trace.event &&
		test_filter_not_computed 4 trace.event &&
		test_filter_trunc_empty 0 trace.event &&
		test_filter_trunc_large 0 trace.event
	)
'

test_expect_success '--max-new-filters overrides configuration' '
	git init override &&
	test_when_finished "rm -fr override" &&
	test_config -C override commitGraph.maxNewFilters 2 &&
	(
		cd override &&
		test_commit one &&
		test_commit two &&

		rm -f trace.event &&
		GIT_TRACE2_EVENT="$(pwd)/trace.event" \
			git commit-graph write --reachable --changed-paths \
				--max-new-filters=1 &&
		test_filter_computed 1 trace.event &&
		test_filter_not_computed 1 trace.event &&
		test_filter_trunc_empty 0 trace.event &&
		test_filter_trunc_large 0 trace.event
	)
'

test_expect_success 'Bloom generation backfills empty commits' '
	git init empty &&
	test_when_finished "rm -fr empty" &&
	(
		cd empty &&
		for i in $(test_seq 1 6)
		do
			git commit --allow-empty -m "$i" || return 1
		done &&

		# Generate Bloom filters for empty commits 1-6, two at a time.
		for i in $(test_seq 1 3)
		do
			rm -f trace.event &&
			GIT_TRACE2_EVENT="$(pwd)/trace.event" \
				git commit-graph write --reachable \
					--changed-paths --max-new-filters=2 &&
			test_filter_computed 2 trace.event &&
			test_filter_not_computed 4 trace.event &&
			test_filter_trunc_empty 2 trace.event &&
			test_filter_trunc_large 0 trace.event || return 1
		done &&

		# Finally, make sure that once all commits have filters, that
		# none are subsequently recomputed.
		rm -f trace.event &&
		GIT_TRACE2_EVENT="$(pwd)/trace.event" \
			git commit-graph write --reachable \
				--changed-paths --max-new-filters=2 &&
		test_filter_computed 0 trace.event &&
		test_filter_not_computed 6 trace.event &&
		test_filter_trunc_empty 0 trace.event &&
		test_filter_trunc_large 0 trace.event
	)
'

graph=.git/objects/info/commit-graph
graphdir=.git/objects/info/commit-graphs
chain=$graphdir/commit-graph-chain

test_expect_success 'setup for mixed Bloom setting tests' '
	repo=mixed-bloom-settings &&

	git init $repo &&
	for i in one two three
	do
		test_commit -C $repo $i file || return 1
	done
'

test_expect_success 'ensure Bloom filters with incompatible settings are ignored' '
	# Compute Bloom filters with "unusual" settings.
	git -C $repo rev-parse one >in &&
	GIT_TEST_BLOOM_SETTINGS_NUM_HASHES=3 git -C $repo commit-graph write \
		--stdin-commits --changed-paths --split <in &&
	layer=$(head -n 1 $repo/$chain) &&

	# A commit-graph layer without Bloom filters "hides" the layers
	# below ...
	git -C $repo rev-parse two >in &&
	git -C $repo commit-graph write --stdin-commits --no-changed-paths \
		--split=no-merge <in &&

	# Another commit-graph layer that has Bloom filters, but with
	# standard settings, and is thus incompatible with the base
	# layer written above.
	git -C $repo rev-parse HEAD >in &&
	git -C $repo commit-graph write --stdin-commits --changed-paths \
		--split=no-merge <in &&

	test_line_count = 3 $repo/$chain &&

	# Ensure that incompatible Bloom filters are ignored.
	git -C $repo -c core.commitGraph=false log --oneline --no-decorate -- file \
		>expect 2>err &&
	git -C $repo log --oneline --no-decorate -- file >actual 2>err &&
	test_cmp expect actual &&
	grep "disabling Bloom filters for commit-graph layer .$layer." err
'

test_expect_success 'merge graph layers with incompatible Bloom settings' '
	# Ensure that incompatible Bloom filters are ignored when
	# merging existing layers.
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C $repo commit-graph write --reachable --changed-paths 2>err &&
	grep "disabling Bloom filters for commit-graph layer .$layer." err &&
	grep "{\"hash_version\":1,\"num_hashes\":7,\"bits_per_entry\":10,\"max_changed_paths\":512" trace2.txt &&

	test_path_is_file $repo/$graph &&
	test_dir_is_empty $repo/$graphdir &&

	git -C $repo -c core.commitGraph=false log --oneline --no-decorate -- \
		file >expect &&
	trace_out="$(pwd)/trace.perf" &&
	GIT_TRACE2_PERF="$trace_out" \
		git -C $repo log --oneline --no-decorate -- file >actual 2>err &&

	test_cmp expect actual &&
	grep "statistics:{\"filter_not_present\":0," trace.perf &&
	test_must_be_empty err
'

# chosen to be the same under all Unicode normalization forms
CENT=$(printf "\302\242")

test_expect_success 'ensure Bloom filter with incompatible versions are ignored' '
	rm "$repo/$graph" &&

	git -C $repo log --oneline --no-decorate -- $CENT >expect &&

	# Compute v1 Bloom filters for commits at the bottom.
	git -C $repo rev-parse HEAD^ >in &&
	git -C $repo commit-graph write --stdin-commits --changed-paths \
		--split <in &&

	# Compute v2 Bloomfilters for the rest of the commits at the top.
	git -C $repo rev-parse HEAD >in &&
	git -C $repo -c commitGraph.changedPathsVersion=2 commit-graph write \
		--stdin-commits --changed-paths --split=no-merge <in &&

	test_line_count = 2 $repo/$chain &&

	git -C $repo log --oneline --no-decorate -- $CENT >actual 2>err &&
	test_cmp expect actual &&

	layer="$(head -n 1 $repo/$chain)" &&
	cat >expect.err <<-EOF &&
	warning: disabling Bloom filters for commit-graph layer $SQ$layer$SQ due to incompatible settings
	EOF
	test_cmp expect.err err &&

	# Merge the two layers with incompatible bloom filter versions,
	# ensuring that the v2 filters are used.
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C $repo -c commitGraph.changedPathsVersion=2 commit-graph write --reachable --changed-paths 2>err &&
	grep "disabling Bloom filters for commit-graph layer .$layer." err &&
	grep "{\"hash_version\":2,\"num_hashes\":7,\"bits_per_entry\":10,\"max_changed_paths\":512" trace2.txt
'

get_first_changed_path_filter () {
	test-tool read-graph bloom-filters >filters.dat &&
	head -n 1 filters.dat
}

test_expect_success 'set up repo with high bit path, version 1 changed-path' '
	git init highbit1 &&
	test_commit -C highbit1 c1 "$CENT" &&
	git -C highbit1 commit-graph write --reachable --changed-paths
'

test_expect_success 'setup check value of version 1 changed-path' '
	(
		cd highbit1 &&
		echo "52a9" >expect &&
		get_first_changed_path_filter >actual
	)
'

# expect will not match actual if char is unsigned by default. Write the test
# in this way, so that a user running this test script can still see if the two
# files match. (It will appear as an ordinary success if they match, and a skip
# if not.)
if test_cmp highbit1/expect highbit1/actual
then
	test_set_prereq SIGNED_CHAR_BY_DEFAULT
fi
test_expect_success SIGNED_CHAR_BY_DEFAULT 'check value of version 1 changed-path' '
	# Only the prereq matters for this test.
	true
'

test_expect_success 'setup make another commit' '
	# "git log" does not use Bloom filters for root commits - see how, in
	# revision.c, rev_compare_tree() (the only code path that eventually calls
	# get_bloom_filter()) is only called by try_to_simplify_commit() when the commit
	# has one parent. Therefore, make another commit so that we perform the tests on
	# a non-root commit.
	test_commit -C highbit1 anotherc1 "another$CENT"
'

test_expect_success 'version 1 changed-path used when version 1 requested' '
	(
		cd highbit1 &&
		test_bloom_filters_used "-- another$CENT"
	)
'

test_expect_success 'version 1 changed-path not used when version 2 requested' '
	(
		cd highbit1 &&
		git config --add commitGraph.changedPathsVersion 2 &&
		test_bloom_filters_not_used "-- another$CENT"
	)
'

test_expect_success 'version 1 changed-path used when autodetect requested' '
	(
		cd highbit1 &&
		git config --add commitGraph.changedPathsVersion -1 &&
		test_bloom_filters_used "-- another$CENT"
	)
'

test_expect_success 'when writing another commit graph, preserve existing version 1 of changed-path' '
	test_commit -C highbit1 c1double "$CENT$CENT" &&
	git -C highbit1 commit-graph write --reachable --changed-paths &&
	(
		cd highbit1 &&
		git config --add commitGraph.changedPathsVersion -1 &&
		echo "options: bloom(1,10,7) read_generation_data" >expect &&
		test-tool read-graph >full &&
		grep options full >actual &&
		test_cmp expect actual
	)
'

test_expect_success 'set up repo with high bit path, version 2 changed-path' '
	git init highbit2 &&
	git -C highbit2 config --add commitGraph.changedPathsVersion 2 &&
	test_commit -C highbit2 c2 "$CENT" &&
	git -C highbit2 commit-graph write --reachable --changed-paths
'

test_expect_success 'check value of version 2 changed-path' '
	(
		cd highbit2 &&
		echo "c01f" >expect &&
		get_first_changed_path_filter >actual &&
		test_cmp expect actual
	)
'

test_expect_success 'setup make another commit' '
	# "git log" does not use Bloom filters for root commits - see how, in
	# revision.c, rev_compare_tree() (the only code path that eventually calls
	# get_bloom_filter()) is only called by try_to_simplify_commit() when the commit
	# has one parent. Therefore, make another commit so that we perform the tests on
	# a non-root commit.
	test_commit -C highbit2 anotherc2 "another$CENT"
'

test_expect_success 'version 2 changed-path used when version 2 requested' '
	(
		cd highbit2 &&
		test_bloom_filters_used "-- another$CENT"
	)
'

test_expect_success 'version 2 changed-path not used when version 1 requested' '
	(
		cd highbit2 &&
		git config --add commitGraph.changedPathsVersion 1 &&
		test_bloom_filters_not_used "-- another$CENT"
	)
'

test_expect_success 'version 2 changed-path used when autodetect requested' '
	(
		cd highbit2 &&
		git config --add commitGraph.changedPathsVersion -1 &&
		test_bloom_filters_used "-- another$CENT"
	)
'

test_expect_success 'when writing another commit graph, preserve existing version 2 of changed-path' '
	test_commit -C highbit2 c2double "$CENT$CENT" &&
	git -C highbit2 commit-graph write --reachable --changed-paths &&
	(
		cd highbit2 &&
		git config --add commitGraph.changedPathsVersion -1 &&
		echo "options: bloom(2,10,7) read_generation_data" >expect &&
		test-tool read-graph >full &&
		grep options full >actual &&
		test_cmp expect actual
	)
'

test_expect_success 'when writing commit graph, do not reuse changed-path of another version' '
	git init doublewrite &&
	test_commit -C doublewrite c "$CENT" &&

	git -C doublewrite config --add commitGraph.changedPathsVersion 1 &&
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C doublewrite commit-graph write --reachable --changed-paths &&
	test_filter_computed 1 trace2.txt &&
	test_filter_upgraded 0 trace2.txt &&

	git -C doublewrite commit-graph write --reachable --changed-paths &&
	for v in -2 3
	do
		git -C doublewrite config --add commitGraph.changedPathsVersion $v &&
		git -C doublewrite commit-graph write --reachable --changed-paths 2>err &&
		cat >expect <<-EOF &&
		warning: attempting to write a commit-graph, but ${SQ}commitGraph.changedPathsVersion${SQ} ($v) is not supported
		EOF
		test_cmp expect err || return 1
	done &&

	git -C doublewrite config --add commitGraph.changedPathsVersion 2 &&
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C doublewrite commit-graph write --reachable --changed-paths &&
	test_filter_computed 1 trace2.txt &&
	test_filter_upgraded 0 trace2.txt &&

	(
		cd doublewrite &&
		echo "c01f" >expect &&
		get_first_changed_path_filter >actual &&
		test_cmp expect actual
	)
'

test_expect_success 'when writing commit graph, reuse changed-path of another version where possible' '
	git init upgrade &&

	test_commit -C upgrade base no-high-bits &&

	git -C upgrade config --add commitGraph.changedPathsVersion 1 &&
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C upgrade commit-graph write --reachable --changed-paths &&
	test_filter_computed 1 trace2.txt &&
	test_filter_upgraded 0 trace2.txt &&

	git -C upgrade config --add commitGraph.changedPathsVersion 2 &&
	>trace2.txt &&
	GIT_TRACE2_EVENT="$(pwd)/trace2.txt" \
		git -C upgrade commit-graph write --reachable --changed-paths &&
	test_filter_computed 0 trace2.txt &&
	test_filter_upgraded 1 trace2.txt
'

corrupt_graph () {
	test_when_finished "rm -rf $graph" &&
	git commit-graph write --reachable --changed-paths &&
	corrupt_chunk_file $graph "$@"
}

check_corrupt_graph () {
	corrupt_graph "$@" &&
	git -c core.commitGraph=false log -- A/B/file2 >expect.out &&
	git -c core.commitGraph=true log -- A/B/file2 >out 2>err &&
	test_cmp expect.out out
}

test_expect_success PERL_TEST_HELPERS 'Bloom reader notices too-small data chunk' '
	check_corrupt_graph BDAT clear 00000000 &&
	echo "warning: ignoring too-small changed-path chunk" \
		"(4 < 12) in commit-graph file" >expect.err &&
	test_cmp expect.err err
'

test_expect_success PERL_TEST_HELPERS 'Bloom reader notices out-of-bounds filter offsets' '
	check_corrupt_graph BIDX 12 FFFFFFFF &&
	# use grep to avoid depending on exact chunk size
	grep "warning: ignoring out-of-range offset (4294967295) for changed-path filter at pos 3 of .git/objects/info/commit-graph" err
'

test_expect_success PERL_TEST_HELPERS 'Bloom reader notices too-small index chunk' '
	# replace the index with a single entry, making most
	# lookups out-of-bounds
	check_corrupt_graph BIDX clear 00000000 &&
	echo "warning: commit-graph changed-path index chunk" \
		"is too small" >expect.err &&
	test_cmp expect.err err
'

test_expect_success PERL_TEST_HELPERS 'Bloom reader notices out-of-order index offsets' '
	# we do not know any real offsets, but we can pick
	# something plausible; we should not get to the point of
	# actually reading from the bogus offsets anyway.
	corrupt_graph BIDX 4 0000000c00000005 &&
	echo "warning: ignoring decreasing changed-path index offsets" \
		"(12 > 5) for positions 1 and 2 of .git/objects/info/commit-graph" >expect.err &&
	git -c core.commitGraph=false log -- A/B/file2 >expect.out &&
	git -c core.commitGraph=true log -- A/B/file2 >out 2>err &&
	test_cmp expect.out out &&
	test_cmp expect.err err
'

test_done