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bitmap coverage is out-of-date with the ref tips, we spend more time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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This patch introduces a new test, t5326, which tests the basic
functionality of multi-pack bitmaps.
Some trivial behavior is tested, such as:
- Whether bitmaps can be generated with more than one pack.
- Whether clones can be served with all objects in the bitmap.
- Whether follow-up fetches can be served with some objects outside of
the server's bitmap
These use lib-bitmap's tests (which in turn were pulled from t5310), and
we cover cases where the MIDX represents both a single pack and multiple
packs.
In addition, some non-trivial and MIDX-specific behavior is tested, too,
including:
- Whether multi-pack bitmaps behave correctly with respect to the
pack-reuse machinery when the base for some object is selected from
a different pack than the delta.
- Whether multi-pack bitmaps correctly respect the
pack.preferBitmapTips configuration.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
