git/t/t5310-pack-bitmaps.sh
Taylor Blau 3f267a1128 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 <peff@peff.net>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-03-31 23:14:03 -07:00

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#!/bin/sh
test_description='exercise basic bitmap functionality'
GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=master
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
. ./test-lib.sh
. "$TEST_DIRECTORY"/lib-bundle.sh
. "$TEST_DIRECTORY"/lib-bitmap.sh
objpath () {
echo ".git/objects/$(echo "$1" | sed -e 's|\(..\)|\1/|')"
}
# show objects present in pack ($1 should be associated *.idx)
list_packed_objects () {
git show-index <"$1" >object-list &&
cut -d' ' -f2 object-list
}
# has_any pattern-file content-file
# tests whether content-file has any entry from pattern-file with entries being
# whole lines.
has_any () {
grep -Ff "$1" "$2"
}
# To ensure the logic for "maximal commits" is exercised, make
# the repository a bit more complicated.
#
# other second
# * *
# (99 commits) (99 commits)
# * *
# |\ /|
# | * octo-other octo-second * |
# |/|\_________ ____________/|\|
# | \ \/ __________/ |
# | | ________/\ / |
# * |/ * merge-right *
# | _|__________/ \____________ |
# |/ | \|
# (l1) * * merge-left * (r1)
# | / \________________________ |
# |/ \|
# (l2) * * (r2)
# \___________________________ |
# \|
# * (base)
#
# We only push bits down the first-parent history, which
# makes some of these commits unimportant!
#
# The important part for the maximal commit algorithm is how
# the bitmasks are extended. Assuming starting bit positions
# for second (bit 0) and other (bit 1), the bitmasks at the
# end should be:
#
# second: 1 (maximal, selected)
# other: 01 (maximal, selected)
# (base): 11 (maximal)
#
# This complicated history was important for a previous
# version of the walk that guarantees never walking a
# commit multiple times. That goal might be important
# again, so preserve this complicated case. For now, this
# test will guarantee that the bitmaps are computed
# correctly, even with the repeat calculations.
test_expect_success 'setup repo with moderate-sized history' '
test_commit_bulk --id=file 10 &&
git branch -M second &&
git checkout -b other HEAD~5 &&
test_commit_bulk --id=side 10 &&
# add complicated history setup, including merges and
# ambiguous merge-bases
git checkout -b merge-left other~2 &&
git merge second~2 -m "merge-left" &&
git checkout -b merge-right second~1 &&
git merge other~1 -m "merge-right" &&
git checkout -b octo-second second &&
git merge merge-left merge-right -m "octopus-second" &&
git checkout -b octo-other other &&
git merge merge-left merge-right -m "octopus-other" &&
git checkout other &&
git merge octo-other -m "pull octopus" &&
git checkout second &&
git merge octo-second -m "pull octopus" &&
# Remove these branches so they are not selected
# as bitmap tips
git branch -D merge-left &&
git branch -D merge-right &&
git branch -D octo-other &&
git branch -D octo-second &&
# add padding to make these merges less interesting
# and avoid having them selected for bitmaps
test_commit_bulk --id=file 100 &&
git checkout other &&
test_commit_bulk --id=side 100 &&
git checkout second &&
bitmaptip=$(git rev-parse second) &&
blob=$(echo tagged-blob | git hash-object -w --stdin) &&
git tag tagged-blob $blob &&
git config repack.writebitmaps true
'
test_expect_success 'full repack creates bitmaps' '
GIT_TRACE2_EVENT_NESTING=4 GIT_TRACE2_EVENT="$(pwd)/trace" \
git repack -ad &&
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output &&
grep "\"key\":\"num_selected_commits\",\"value\":\"106\"" trace &&
grep "\"key\":\"num_maximal_commits\",\"value\":\"107\"" trace
'
test_expect_success 'rev-list --test-bitmap verifies bitmaps' '
git rev-list --test-bitmap HEAD
'
rev_list_tests_head () {
test_expect_success "counting commits via bitmap ($state, $branch)" '
git rev-list --count $branch >expect &&
git rev-list --use-bitmap-index --count $branch >actual &&
test_cmp expect actual
'
test_expect_success "counting partial commits via bitmap ($state, $branch)" '
git rev-list --count $branch~5..$branch >expect &&
git rev-list --use-bitmap-index --count $branch~5..$branch >actual &&
test_cmp expect actual
'
test_expect_success "counting commits with limit ($state, $branch)" '
git rev-list --count -n 1 $branch >expect &&
git rev-list --use-bitmap-index --count -n 1 $branch >actual &&
test_cmp expect actual
'
test_expect_success "counting non-linear history ($state, $branch)" '
git rev-list --count other...second >expect &&
git rev-list --use-bitmap-index --count other...second >actual &&
test_cmp expect actual
'
test_expect_success "counting commits with limiting ($state, $branch)" '
git rev-list --count $branch -- 1.t >expect &&
git rev-list --use-bitmap-index --count $branch -- 1.t >actual &&
test_cmp expect actual
'
test_expect_success "counting objects via bitmap ($state, $branch)" '
git rev-list --count --objects $branch >expect &&
git rev-list --use-bitmap-index --count --objects $branch >actual &&
test_cmp expect actual
'
test_expect_success "enumerate commits ($state, $branch)" '
git rev-list --use-bitmap-index $branch >actual &&
git rev-list $branch >expect &&
test_bitmap_traversal --no-confirm-bitmaps expect actual
'
test_expect_success "enumerate --objects ($state, $branch)" '
git rev-list --objects --use-bitmap-index $branch >actual &&
git rev-list --objects $branch >expect &&
test_bitmap_traversal expect actual
'
test_expect_success "bitmap --objects handles non-commit objects ($state, $branch)" '
git rev-list --objects --use-bitmap-index $branch tagged-blob >actual &&
grep $blob actual
'
}
rev_list_tests () {
state=$1
for branch in "second" "other"
do
rev_list_tests_head
done
}
rev_list_tests 'full bitmap'
test_expect_success 'clone from bitmapped repository' '
git clone --no-local --bare . clone.git &&
git rev-parse HEAD >expect &&
git --git-dir=clone.git rev-parse HEAD >actual &&
test_cmp expect actual
'
test_expect_success 'partial clone from bitmapped repository' '
test_config uploadpack.allowfilter true &&
git clone --no-local --bare --filter=blob:none . partial-clone.git &&
(
cd partial-clone.git &&
pack=$(echo objects/pack/*.pack) &&
git verify-pack -v "$pack" >have &&
awk "/blob/ { print \$1 }" <have >blobs &&
# we expect this single blob because of the direct ref
git rev-parse refs/tags/tagged-blob >expect &&
test_cmp expect blobs
)
'
test_expect_success 'setup further non-bitmapped commits' '
test_commit_bulk --id=further 10
'
rev_list_tests 'partial bitmap'
test_expect_success 'fetch (partial bitmap)' '
git --git-dir=clone.git fetch origin second:second &&
git rev-parse HEAD >expect &&
git --git-dir=clone.git rev-parse HEAD >actual &&
test_cmp expect actual
'
test_expect_success 'incremental repack fails when bitmaps are requested' '
test_commit more-1 &&
test_must_fail git repack -d 2>err &&
test_i18ngrep "Incremental repacks are incompatible with bitmap" err
'
test_expect_success 'incremental repack can disable bitmaps' '
test_commit more-2 &&
git repack -d --no-write-bitmap-index
'
test_expect_success 'pack-objects respects --local (non-local loose)' '
git init --bare alt.git &&
echo $(pwd)/alt.git/objects >.git/objects/info/alternates &&
echo content1 >file1 &&
# non-local loose object which is not present in bitmapped pack
altblob=$(GIT_DIR=alt.git git hash-object -w file1) &&
# non-local loose object which is also present in bitmapped pack
git cat-file blob $blob | GIT_DIR=alt.git git hash-object -w --stdin &&
git add file1 &&
test_tick &&
git commit -m commit_file1 &&
echo HEAD | git pack-objects --local --stdout --revs >1.pack &&
git index-pack 1.pack &&
list_packed_objects 1.idx >1.objects &&
printf "%s\n" "$altblob" "$blob" >nonlocal-loose &&
! has_any nonlocal-loose 1.objects
'
test_expect_success 'pack-objects respects --honor-pack-keep (local non-bitmapped pack)' '
echo content2 >file2 &&
blob2=$(git hash-object -w file2) &&
git add file2 &&
test_tick &&
git commit -m commit_file2 &&
printf "%s\n" "$blob2" "$bitmaptip" >keepobjects &&
pack2=$(git pack-objects pack2 <keepobjects) &&
mv pack2-$pack2.* .git/objects/pack/ &&
>.git/objects/pack/pack2-$pack2.keep &&
rm $(objpath $blob2) &&
echo HEAD | git pack-objects --honor-pack-keep --stdout --revs >2a.pack &&
git index-pack 2a.pack &&
list_packed_objects 2a.idx >2a.objects &&
! has_any keepobjects 2a.objects
'
test_expect_success 'pack-objects respects --local (non-local pack)' '
mv .git/objects/pack/pack2-$pack2.* alt.git/objects/pack/ &&
echo HEAD | git pack-objects --local --stdout --revs >2b.pack &&
git index-pack 2b.pack &&
list_packed_objects 2b.idx >2b.objects &&
! has_any keepobjects 2b.objects
'
test_expect_success 'pack-objects respects --honor-pack-keep (local bitmapped pack)' '
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output &&
packbitmap=$(basename $(cat output) .bitmap) &&
list_packed_objects .git/objects/pack/$packbitmap.idx >packbitmap.objects &&
test_when_finished "rm -f .git/objects/pack/$packbitmap.keep" &&
>.git/objects/pack/$packbitmap.keep &&
echo HEAD | git pack-objects --honor-pack-keep --stdout --revs >3a.pack &&
git index-pack 3a.pack &&
list_packed_objects 3a.idx >3a.objects &&
! has_any packbitmap.objects 3a.objects
'
test_expect_success 'pack-objects respects --local (non-local bitmapped pack)' '
mv .git/objects/pack/$packbitmap.* alt.git/objects/pack/ &&
rm -f .git/objects/pack/multi-pack-index &&
test_when_finished "mv alt.git/objects/pack/$packbitmap.* .git/objects/pack/" &&
echo HEAD | git pack-objects --local --stdout --revs >3b.pack &&
git index-pack 3b.pack &&
list_packed_objects 3b.idx >3b.objects &&
! has_any packbitmap.objects 3b.objects
'
test_expect_success 'pack-objects to file can use bitmap' '
# make sure we still have 1 bitmap index from previous tests
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output &&
# verify equivalent packs are generated with/without using bitmap index
packasha1=$(git pack-objects --no-use-bitmap-index --all packa </dev/null) &&
packbsha1=$(git pack-objects --use-bitmap-index --all packb </dev/null) &&
list_packed_objects packa-$packasha1.idx >packa.objects &&
list_packed_objects packb-$packbsha1.idx >packb.objects &&
test_cmp packa.objects packb.objects
'
test_expect_success 'full repack, reusing previous bitmaps' '
git repack -ad &&
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output
'
test_expect_success 'fetch (full bitmap)' '
git --git-dir=clone.git fetch origin second:second &&
git rev-parse HEAD >expect &&
git --git-dir=clone.git rev-parse HEAD >actual &&
test_cmp expect actual
'
test_expect_success 'create objects for missing-HAVE tests' '
blob=$(echo "missing have" | git hash-object -w --stdin) &&
tree=$(printf "100644 blob $blob\tfile\n" | git mktree) &&
parent=$(echo parent | git commit-tree $tree) &&
commit=$(echo commit | git commit-tree $tree -p $parent) &&
cat >revs <<-EOF
HEAD
^HEAD^
^$commit
EOF
'
test_expect_success 'pack-objects respects --incremental' '
cat >revs2 <<-EOF &&
HEAD
$commit
EOF
git pack-objects --incremental --stdout --revs <revs2 >4.pack &&
git index-pack 4.pack &&
list_packed_objects 4.idx >4.objects &&
test_line_count = 4 4.objects &&
git rev-list --objects $commit >revlist &&
cut -d" " -f1 revlist |sort >objects &&
test_cmp 4.objects objects
'
test_expect_success 'pack with missing blob' '
rm $(objpath $blob) &&
git pack-objects --stdout --revs <revs >/dev/null
'
test_expect_success 'pack with missing tree' '
rm $(objpath $tree) &&
git pack-objects --stdout --revs <revs >/dev/null
'
test_expect_success 'pack with missing parent' '
rm $(objpath $parent) &&
git pack-objects --stdout --revs <revs >/dev/null
'
test_expect_success JGIT,SHA1 'we can read jgit bitmaps' '
git clone --bare . compat-jgit.git &&
(
cd compat-jgit.git &&
rm -f objects/pack/*.bitmap &&
jgit gc &&
git rev-list --test-bitmap HEAD
)
'
test_expect_success JGIT,SHA1 'jgit can read our bitmaps' '
git clone --bare . compat-us.git &&
(
cd compat-us.git &&
git repack -adb &&
# jgit gc will barf if it does not like our bitmaps
jgit gc
)
'
test_expect_success 'splitting packs does not generate bogus bitmaps' '
test-tool genrandom foo $((1024 * 1024)) >rand &&
git add rand &&
git commit -m "commit with big file" &&
git -c pack.packSizeLimit=500k repack -adb &&
git init --bare no-bitmaps.git &&
git -C no-bitmaps.git fetch .. HEAD
'
test_expect_success 'set up reusable pack' '
rm -f .git/objects/pack/*.keep &&
git repack -adb &&
reusable_pack () {
git for-each-ref --format="%(objectname)" |
git pack-objects --delta-base-offset --revs --stdout "$@"
}
'
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
>${i%.pack}.keep
done &&
reusable_pack --honor-pack-keep >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'pack reuse respects --local' '
mv .git/objects/pack/* alt.git/objects/pack/ &&
test_when_finished "mv alt.git/objects/pack/* .git/objects/pack/" &&
reusable_pack --local >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'pack reuse respects --incremental' '
reusable_pack --incremental >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'truncated bitmap fails gracefully (ewah)' '
test_config pack.writebitmaphashcache false &&
git repack -ad &&
git rev-list --use-bitmap-index --count --all >expect &&
bitmap=$(ls .git/objects/pack/*.bitmap) &&
test_when_finished "rm -f $bitmap" &&
test_copy_bytes 256 <$bitmap >$bitmap.tmp &&
mv -f $bitmap.tmp $bitmap &&
git rev-list --use-bitmap-index --count --all >actual 2>stderr &&
test_cmp expect actual &&
test_i18ngrep corrupt.ewah.bitmap stderr
'
test_expect_success 'truncated bitmap fails gracefully (cache)' '
git repack -ad &&
git rev-list --use-bitmap-index --count --all >expect &&
bitmap=$(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
'
# have_delta <obj> <expected_base>
#
# Note that because this relies on cat-file, it might find _any_ copy of an
# object in the repository. The caller is responsible for making sure
# there's only one (e.g., via "repack -ad", or having just fetched a copy).
have_delta () {
echo $2 >expect &&
echo $1 | git cat-file --batch-check="%(deltabase)" >actual &&
test_cmp expect actual
}
# Create a state of history with these properties:
#
# - refs that allow a client to fetch some new history, while sharing some old
# history with the server; we use branches delta-reuse-old and
# delta-reuse-new here
#
# - the new history contains an object that is stored on the server as a delta
# against a base that is in the old history
#
# - the base object is not immediately reachable from the tip of the old
# history; finding it would involve digging down through history we know the
# other side has
#
# This should result in a state where fetching from old->new would not
# traditionally reuse the on-disk delta (because we'd have to dig to realize
# that the client has it), but we will do so if bitmaps can tell us cheaply
# that the other side has it.
test_expect_success 'set up thin delta-reuse parent' '
# This first commit contains the buried base object.
test-tool genrandom delta 16384 >file &&
git add file &&
git commit -m "delta base" &&
base=$(git rev-parse --verify HEAD:file) &&
# These intermediate commits bury the base back in history.
# This becomes the "old" state.
for i in 1 2 3 4 5
do
echo $i >file &&
git commit -am "intermediate $i" || return 1
done &&
git branch delta-reuse-old &&
# And now our new history has a delta against the buried base. Note
# that this must be smaller than the original file, since pack-objects
# prefers to create deltas from smaller objects to larger.
test-tool genrandom delta 16300 >file &&
git commit -am "delta result" &&
delta=$(git rev-parse --verify HEAD:file) &&
git branch delta-reuse-new &&
# Repack with bitmaps and double check that we have the expected delta
# relationship.
git repack -adb &&
have_delta $delta $base
'
# Now we can sanity-check the non-bitmap behavior (that the server is not able
# to reuse the delta). This isn't strictly something we care about, so this
# test could be scrapped in the future. But it makes sure that the next test is
# actually triggering the feature we want.
#
# Note that our tools for working with on-the-wire "thin" packs are limited. So
# we actually perform the fetch, retain the resulting pack, and inspect the
# result.
test_expect_success 'fetch without bitmaps ignores delta against old base' '
test_config pack.usebitmaps false &&
test_when_finished "rm -rf client.git" &&
git init --bare client.git &&
(
cd client.git &&
git config transfer.unpackLimit 1 &&
git fetch .. delta-reuse-old:delta-reuse-old &&
git fetch .. delta-reuse-new:delta-reuse-new &&
have_delta $delta $ZERO_OID
)
'
# And do the same for the bitmap case, where we do expect to find the delta.
test_expect_success 'fetch with bitmaps can reuse old base' '
test_config pack.usebitmaps true &&
test_when_finished "rm -rf client.git" &&
git init --bare client.git &&
(
cd client.git &&
git config transfer.unpackLimit 1 &&
git fetch .. delta-reuse-old:delta-reuse-old &&
git fetch .. delta-reuse-new:delta-reuse-new &&
have_delta $delta $base
)
'
test_expect_success 'pack.preferBitmapTips' '
git init repo &&
test_when_finished "rm -fr repo" &&
(
cd repo &&
# create enough commits that not all are receive bitmap
# coverage even if they are all at the tip of some reference.
test_commit_bulk --message="%s" 103 &&
git rev-list HEAD >commits.raw &&
sort <commits.raw >commits &&
git log --format="create refs/tags/%s %H" HEAD >refs &&
git update-ref --stdin <refs &&
git repack -adb &&
test-tool bitmap list-commits | sort >bitmaps &&
# remember which commits did not receive bitmaps
comm -13 bitmaps commits >before &&
test_file_not_empty before &&
# mark the commits which did not receive bitmaps as preferred,
# and generate the bitmap again
perl -pe "s{^}{create refs/tags/include/$. }" <before |
git update-ref --stdin &&
git -c pack.preferBitmapTips=refs/tags/include repack -adb &&
# finally, check that the commit(s) without bitmap coverage
# are not the same ones as before
test-tool bitmap list-commits | sort >bitmaps &&
comm -13 bitmaps commits >after &&
! test_cmp before after
)
'
test_done