Files
git/t/perf/p2000-sparse-operations.sh
Shuqi Liang 48c5fbfb89 diff-tree: integrate with sparse index
The index is read in 'cmd_diff_tree' at two points:

1. The first index read was added in fd66bcc31f (diff-tree: read the
index so attribute checks work in bare repositories, 2017-12-06) to deal
with reading '.gitattributes' content. 77efbb366a (attr: be careful
about sparse directories, 2021-09-08) established that, in a sparse
index, we do _not_ try to load a '.gitattributes' file from within a
sparse directory.

2. The second index access point is involved in rename detection,
specifically when reading from stdin.This was initially added in
f0c6b2a2fd ([PATCH] Optimize diff-tree -[CM]--stdin, 2005-05-27), where
'setup' was set to 'DIFF_SETUP_USE_SIZE_CACHE |DIFF_SETUP_USE_CACHE'.
That assignment was later modified to drop the'DIFF_SETUP_USE_CACHE' in
ff7fe37b05 (diff.c: move read_index() code back to the caller,
2018-08-13).However, 'DIFF_SETUP_USE_SIZE_CACHE' seems to be unused as
of 6e0b8ed6d3 (diff.c: do not use a separate "size cache"., 2007-05-07)
and nothing about 'detect_rename' otherwise indicates index usage.

Hence we can just set the requires-full-index to false for "diff-tree".

Add tests that verify that 'git diff-tree' behaves correctly when the
sparse index is enabled and test to ensure the index is not expanded.

The `p2000` tests demonstrate a ~98% execution time reduction for
'git diff-tree' using a sparse index:

Test                                                before  after
-----------------------------------------------------------------------
2000.94: git diff-tree HEAD (full-v3)                0.05   0.04 -20.0%
2000.95: git diff-tree HEAD (full-v4)                0.06   0.05 -16.7%
2000.96: git diff-tree HEAD (sparse-v3)              0.59   0.01 -98.3%
2000.97: git diff-tree HEAD (sparse-v4)              0.61   0.01 -98.4%
2000.98: git diff-tree HEAD -- f2/f4/a (full-v3)     0.05   0.05 +0.0%
2000.99: git diff-tree HEAD -- f2/f4/a (full-v4)     0.05   0.04 -20.0%
2000.100: git diff-tree HEAD -- f2/f4/a (sparse-v3)  0.58   0.01 -98.3%
2000.101: git diff-tree HEAD -- f2/f4/a (sparse-v4)  0.55   0.01 -98.2%

Helped-by: Victoria Dye <vdye@github.com>
Signed-off-by: Shuqi Liang <cheskaqiqi@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-05-18 10:40:33 -07:00

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#!/bin/sh
test_description="test performance of Git operations using the index"
. ./perf-lib.sh
test_perf_default_repo
SPARSE_CONE=f2/f4
test_expect_success 'setup repo and indexes' '
git reset --hard HEAD &&
# Remove submodules from the example repo, because our
# duplication of the entire repo creates an unlikely data shape.
if git config --file .gitmodules --get-regexp "submodule.*.path" >modules
then
git rm $(awk "{print \$2}" modules) &&
git commit -m "remove submodules" || return 1
fi &&
echo bogus >a &&
cp a b &&
git add a b &&
git commit -m "level 0" &&
BLOB=$(git rev-parse HEAD:a) &&
OLD_COMMIT=$(git rev-parse HEAD) &&
OLD_TREE=$(git rev-parse HEAD^{tree}) &&
for i in $(test_seq 1 3)
do
cat >in <<-EOF &&
100755 blob $BLOB a
040000 tree $OLD_TREE f1
040000 tree $OLD_TREE f2
040000 tree $OLD_TREE f3
040000 tree $OLD_TREE f4
EOF
NEW_TREE=$(git mktree <in) &&
NEW_COMMIT=$(git commit-tree $NEW_TREE -p $OLD_COMMIT -m "level $i") &&
OLD_TREE=$NEW_TREE &&
OLD_COMMIT=$NEW_COMMIT || return 1
done &&
git sparse-checkout init --cone &&
git tag -a v1.0 -m "Final" &&
git sparse-checkout set $SPARSE_CONE &&
git checkout -b wide $OLD_COMMIT &&
for l2 in f1 f2 f3 f4
do
echo more bogus >>$SPARSE_CONE/$l2/a &&
git commit -a -m "edit $SPARSE_CONE/$l2/a" || return 1
done &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . full-v3 &&
(
cd full-v3 &&
git sparse-checkout init --cone &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 3 &&
git update-index --index-version=3 &&
git checkout HEAD~4
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . full-v4 &&
(
cd full-v4 &&
git sparse-checkout init --cone &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 4 &&
git update-index --index-version=4 &&
git checkout HEAD~4
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . sparse-v3 &&
(
cd sparse-v3 &&
git sparse-checkout init --cone --sparse-index &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 3 &&
git update-index --index-version=3 &&
git checkout HEAD~4
) &&
git -c core.sparseCheckoutCone=true clone --branch=wide --sparse . sparse-v4 &&
(
cd sparse-v4 &&
git sparse-checkout init --cone --sparse-index &&
git sparse-checkout set $SPARSE_CONE &&
git config index.version 4 &&
git update-index --index-version=4 &&
git checkout HEAD~4
)
'
test_perf_on_all () {
command="$@"
for repo in full-v3 full-v4 \
sparse-v3 sparse-v4
do
test_perf "$command ($repo)" "
(
cd $repo &&
echo >>$SPARSE_CONE/a &&
$command
)
"
done
}
test_perf_on_all git status
test_perf_on_all 'git stash && git stash pop'
test_perf_on_all 'echo >>new && git stash -u && git stash pop'
test_perf_on_all git add -A
test_perf_on_all git add .
test_perf_on_all git commit -a -m A
test_perf_on_all git checkout -f -
test_perf_on_all "git sparse-checkout add f2/f3/f1 && git sparse-checkout set $SPARSE_CONE"
test_perf_on_all git reset
test_perf_on_all git reset --hard
test_perf_on_all git reset -- does-not-exist
test_perf_on_all git diff
test_perf_on_all git diff --cached
test_perf_on_all git blame $SPARSE_CONE/a
test_perf_on_all git blame $SPARSE_CONE/f3/a
test_perf_on_all git read-tree -mu HEAD
test_perf_on_all git checkout-index -f --all
test_perf_on_all git update-index --add --remove $SPARSE_CONE/a
test_perf_on_all "git rm -f $SPARSE_CONE/a && git checkout HEAD -- $SPARSE_CONE/a"
test_perf_on_all git grep --cached bogus -- "f2/f1/f1/*"
test_perf_on_all git write-tree
test_perf_on_all git describe --dirty
test_perf_on_all 'echo >>new && git describe --dirty'
test_perf_on_all git diff-files
test_perf_on_all git diff-files -- $SPARSE_CONE/a
test_perf_on_all git diff-tree HEAD
test_perf_on_all git diff-tree HEAD -- $SPARSE_CONE/a
test_done