git/t/perf/p0100-globbing.sh
Ævar Arnfjörð Bjarmason 62ca75a6b9 perf: add test showing exponential growth in path globbing
Add a test showing that runtimes of the wildmatch() function used for
globbing in git grow exponentially in the face of some pathological
globs.

This issue affects both globs matching filenames via e.g. ls-files,
and globs matching refnames via e.g. for-each-ref.

As noted in the test description this is a test to see whether Git
suffers from the issue noted in an article Russ Cox posted today about
common bugs in various glob implementations:
https://research.swtch.com/glob

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-12 10:07:43 +09:00

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#!/bin/sh
test_description="Tests pathological globbing performance
Shows how Git's globbing performance performs when given the sort of
pathological patterns described in at https://research.swtch.com/glob
"
. ./perf-lib.sh
test_globs_big='10 25 50 75 100'
test_globs_small='1 2 3 4 5 6'
test_perf_fresh_repo
test_expect_success 'setup' '
for i in $(test_seq 1 100)
do
printf "a" >>refname &&
for j in $(test_seq 1 $i)
do
printf "a*" >>refglob.$i
done &&
echo b >>refglob.$i
done &&
test_commit test $(cat refname).t "" $(cat refname).t
'
for i in $test_globs_small
do
test_perf "refglob((a*)^nb) against tag (a^100).t; n = $i" '
git for-each-ref "refs/tags/$(cat refglob.'$i')b"
'
done
for i in $test_globs_small
do
test_perf "fileglob((a*)^nb) against file (a^100).t; n = $i" '
git ls-files "$(cat refglob.'$i')b"
'
done
test_done