git/t/t5310-pack-bitmaps.sh
Jeff King d4316604f8 pack-objects: default to writing bitmap hash-cache
Enabling pack.writebitmaphashcache should always be a performance win.
It costs only 4 bytes per object on disk, and the timings in ae4f07fbcc
(pack-bitmap: implement optional name_hash cache, 2013-12-21) show it
improving fetch and partial-bitmap clone times by 40-50%.

The only reason we didn't enable it by default at the time is that early
versions of JGit's bitmap reader complained about the presence of
optional header bits it didn't understand. But that was changed in
JGit's d2fa3987a (Use bitcheck to check for presence of OPT_FULL option,
2013-10-30), which made it into JGit v3.5.0 in late 2014.

So let's turn this option on by default. It's backwards-compatible with
all versions of Git, and if you are also using JGit on the same
repository, you'd only run into problems using a version that's almost 5
years old.

We'll drop the manual setting from all of our test scripts, including
perf tests. This isn't strictly necessary, but it has two advantages:

  1. If the hash-cache ever stops being enabled by default, our perf
     regression tests will notice.

  2. We can use the modified perf tests to show off the behavior of an
     otherwise unconfigured repo, as shown below.

These are the results of a few of a perf tests against linux.git that
showed interesting results. You can see the expected speedup in 5310.4,
which was noted in ae4f07fbcc. Curiously, 5310.8 did not improve (and
actually got slower), despite seeing the opposite in ae4f07fbcc.
I don't have an explanation for that.

The tests from p5311 did not exist back then, but do show improvements
(a smaller pack due to better deltas, which we found in less time).

  Test                                    HEAD^                HEAD
  -------------------------------------------------------------------------------------
  5310.4: simulated fetch                 7.39(22.70+0.25)     5.64(11.43+0.22) -23.7%
  5310.8: clone (partial bitmap)          18.45(24.83+1.19)    19.94(28.40+1.36) +8.1%
  5311.31: server (128 days)              0.41(1.13+0.05)      0.34(0.72+0.02) -17.1%
  5311.32: size   (128 days)                         7.4M                 7.0M -4.8%
  5311.33: client (128 days)              1.33(1.49+0.06)      1.29(1.37+0.12) -3.0%

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-03-18 14:11:15 +09:00

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#!/bin/sh
test_description='exercise basic bitmap functionality'
. ./test-lib.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"
}
test_expect_success 'setup repo with moderate-sized history' '
for i in $(test_seq 1 10)
do
test_commit $i
done &&
git checkout -b other HEAD~5 &&
for i in $(test_seq 1 10)
do
test_commit side-$i
done &&
git checkout master &&
bitmaptip=$(git rev-parse master) &&
blob=$(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 repack -ad &&
ls .git/objects/pack/ | grep bitmap >output &&
test_line_count = 1 output
'
test_expect_success 'rev-list --test-bitmap verifies bitmaps' '
git rev-list --test-bitmap HEAD
'
rev_list_tests() {
state=$1
test_expect_success "counting commits via bitmap ($state)" '
git rev-list --count HEAD >expect &&
git rev-list --use-bitmap-index --count HEAD >actual &&
test_cmp expect actual
'
test_expect_success "counting partial commits via bitmap ($state)" '
git rev-list --count HEAD~5..HEAD >expect &&
git rev-list --use-bitmap-index --count HEAD~5..HEAD >actual &&
test_cmp expect actual
'
test_expect_success "counting commits with limit ($state)" '
git rev-list --count -n 1 HEAD >expect &&
git rev-list --use-bitmap-index --count -n 1 HEAD >actual &&
test_cmp expect actual
'
test_expect_success "counting non-linear history ($state)" '
git rev-list --count other...master >expect &&
git rev-list --use-bitmap-index --count other...master >actual &&
test_cmp expect actual
'
test_expect_success "counting commits with limiting ($state)" '
git rev-list --count HEAD -- 1.t >expect &&
git rev-list --use-bitmap-index --count HEAD -- 1.t >actual &&
test_cmp expect actual
'
test_expect_success "enumerate --objects ($state)" '
git rev-list --objects --use-bitmap-index HEAD >tmp &&
cut -d" " -f1 <tmp >tmp2 &&
sort <tmp2 >actual &&
git rev-list --objects HEAD >tmp &&
cut -d" " -f1 <tmp >tmp2 &&
sort <tmp2 >expect &&
test_cmp expect actual
'
test_expect_success "bitmap --objects handles non-commit objects ($state)" '
git rev-list --objects --use-bitmap-index HEAD tagged-blob >actual &&
grep $blob actual
'
}
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 'setup further non-bitmapped commits' '
for i in $(test_seq 1 10)
do
test_commit further-$i
done
'
rev_list_tests 'partial bitmap'
test_expect_success 'fetch (partial bitmap)' '
git --git-dir=clone.git fetch origin master:master &&
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 master:master &&
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 '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 '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
>${i%.pack}.keep
done &&
reusable_pack --honor-pack-keep >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'pack reuse respects --local' '
mv .git/objects/pack/* alt.git/objects/pack/ &&
test_when_finished "mv alt.git/objects/pack/* .git/objects/pack/" &&
reusable_pack --local >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'pack reuse respects --incremental' '
reusable_pack --incremental >empty.pack &&
git index-pack empty.pack &&
git show-index <empty.idx >actual &&
test_must_be_empty actual
'
test_expect_success 'truncated bitmap fails gracefully' '
git repack -ad &&
git rev-list --use-bitmap-index --count --all >expect &&
bitmap=$(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 corrupt 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_done