diff mbox series

[v3,7/7] t5326: test propagating hashcache values

Message ID bb1612591516bf7e88886d405fc06dd1d2e9a8bb.1631913631.git.me@ttaylorr.com (mailing list archive)
State Accepted
Commit 54156af0d66b64cfa290ffce302af05d256d9b9c
Headers show
Series pack-bitmap: permute existing namehash values | expand

Commit Message

Taylor Blau Sept. 17, 2021, 9:21 p.m. UTC
Now that we both can propagate values from the hashcache, and respect
the configuration to enable the hashcache at all, test that both of
these function correctly by hardening their behavior with a test.

Like the hash-cache in classic single-pack bitmaps, this helps more
proportionally the more up-to-date your bitmap coverage is. When our
bitmap coverage is out-of-date with the ref tips, we spend more time
proportionally traversing, and all of that traversal gets the name-hash
filled in.

But for the up-to-date bitmaps, this helps quite a bit. These numbers
are on git.git, with `pack.threads=1` to help see the difference
reflected in the overall runtime.

    Test                            origin/tb/multi-pack-bitmaps   HEAD
    -------------------------------------------------------------------------------------
    5326.4: simulated clone         1.87(1.80+0.07)                1.46(1.42+0.03) -21.9%
    5326.5: simulated fetch         2.66(2.61+0.04)                1.47(1.43+0.04) -44.7%
    5326.6: pack to file (bitmap)   2.74(2.62+0.12)                1.89(1.82+0.07) -31.0%

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
 t/t5326-multi-pack-bitmaps.sh | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
diff mbox series

Patch

diff --git a/t/t5326-multi-pack-bitmaps.sh b/t/t5326-multi-pack-bitmaps.sh
index 4ad7c2c969..ec4aa89f63 100755
--- a/t/t5326-multi-pack-bitmaps.sh
+++ b/t/t5326-multi-pack-bitmaps.sh
@@ -283,4 +283,34 @@  test_expect_success 'pack.preferBitmapTips' '
 	)
 '
 
+test_expect_success 'hash-cache values are propagated from pack bitmaps' '
+	rm -fr repo &&
+	git init repo &&
+	test_when_finished "rm -fr repo" &&
+	(
+		cd repo &&
+
+		test_commit base &&
+		test_commit base2 &&
+		git repack -adb &&
+
+		test-tool bitmap dump-hashes >pack.raw &&
+		test_file_not_empty pack.raw &&
+		sort pack.raw >pack.hashes &&
+
+		test_commit new &&
+		git repack &&
+		git multi-pack-index write --bitmap &&
+
+		test-tool bitmap dump-hashes >midx.raw &&
+		sort midx.raw >midx.hashes &&
+
+		# ensure that every namehash in the pack bitmap can be found in
+		# the midx bitmap (i.e., that there are no oid-namehash pairs
+		# unique to the pack bitmap).
+		comm -23 pack.hashes midx.hashes >dropped.hashes &&
+		test_must_be_empty dropped.hashes
+	)
+'
+
 test_done