pack-objects: respect --local/--honor-pack-keep/--incremental when bitmap is in use

Since 6b8fda2d (pack-objects: use bitmaps when packing objects) there
are two codepaths in pack-objects: with & without using bitmap
reachability index.

However add_object_entry_from_bitmap(), despite its non-bitmapped
counterpart add_object_entry(), in no way does check for whether --local
or --honor-pack-keep or --incremental should be respected. In
non-bitmapped codepath this is handled in want_object_in_pack(), but
bitmapped codepath has simply no such checking at all.

The bitmapped codepath however was allowing to pass in all those options
and with bitmap indices still being used under such conditions -
potentially giving wrong output (e.g. including objects from non-local or
.keep'ed pack).

We can easily fix this by noting the following: when an object comes to
add_object_entry_from_bitmap() it can come for two reasons:

    1. entries coming from main pack covered by bitmap index, and
    2. object coming from, possibly alternate, loose or other packs.

"2" can be already handled by want_object_in_pack() and to cover
"1" we can teach want_object_in_pack() to expect that *found_pack can be
non-NULL, meaning calling client already found object's pack entry.

In want_object_in_pack() we care to start the checks from already found
pack, if we have one, this way determining the answer right away
in case neither --local nor --honour-pack-keep are active. In
particular, as p5310-pack-bitmaps.sh shows (3 consecutive runs), we do
not do harm to served-with-bitmap clones performance-wise:

    Test                      56dfeb62          this tree
    -----------------------------------------------------------------
    5310.2: repack to disk    9.08(8.20+0.25)   9.09(8.14+0.32) +0.1%
    5310.3: simulated clone   1.92(2.12+0.08)   1.93(2.12+0.09) +0.5%
    5310.4: simulated fetch   0.82(1.07+0.04)   0.82(1.06+0.04) +0.0%
    5310.6: partial bitmap    1.96(2.42+0.13)   1.95(2.40+0.15) -0.5%

    Test                      56dfeb62          this tree
    -----------------------------------------------------------------
    5310.2: repack to disk    9.11(8.16+0.32)   9.11(8.19+0.28) +0.0%
    5310.3: simulated clone   1.93(2.14+0.07)   1.92(2.11+0.10) -0.5%
    5310.4: simulated fetch   0.82(1.06+0.04)   0.82(1.04+0.05) +0.0%
    5310.6: partial bitmap    1.95(2.38+0.16)   1.94(2.39+0.14) -0.5%

    Test                      56dfeb62          this tree
    -----------------------------------------------------------------
    5310.2: repack to disk    9.13(8.17+0.31)   9.07(8.13+0.28) -0.7%
    5310.3: simulated clone   1.92(2.13+0.07)   1.91(2.12+0.06) -0.5%
    5310.4: simulated fetch   0.82(1.08+0.03)   0.82(1.08+0.03) +0.0%
    5310.6: partial bitmap    1.96(2.43+0.14)   1.96(2.42+0.14) +0.0%

with delta timings showing they are all within noise from run to run.

In the general case we do not want to call find_pack_entry_one() more than
once, because it is expensive. This patch splits the loop in
want_object_in_pack() into two parts: finding the object and seeing if it
impacts our choice to include it in the pack. We may call the inexpensive
want_found_object() twice, but we will never call find_pack_entry_one() if we
do not need to.

I appreciate help and discussing this change with Junio C Hamano and
Jeff King.

Signed-off-by: Kirill Smelkov <kirr@nexedi.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 92 insertions, 0 deletions

diff --git a/t/t5310-pack-bitmaps.sh b/t/t5310-pack-bitmaps.sh
index 3893afd687..a278d3032a 100755
--- a/t/t5310-pack-bitmaps.sh
+++ b/t/t5310-pack-bitmaps.sh
@@ -7,6 +7,18 @@ 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" | cut -d' ' -f2
+}
+
+# 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 $i
@@ -16,6 +28,7 @@ test_expect_success 'setup repo with moderate-sized history' '
 		test_commit side-$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 &&
@@ -118,6 +131,71 @@ test_expect_success 'incremental repack can disable bitmaps' '
 	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/$packbitmap.* alt.git/objects/pack/ &&
+	test_when_finished "mv alt.git/objects/pack/$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 'full repack, reusing previous bitmaps' '
 	git repack -ad &&
 	ls .git/objects/pack/ | grep bitmap >output &&
@@ -143,6 +221,20 @@ test_expect_success 'create objects for missing-HAVE tests' '
 	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