Add a test showing that ls-files times grow exponentially in the face of some pathological globs, whereas refglobs via for-each-ref don't in practice suffer from the same issue.
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 The pathological git-ls-files globbing is done by wildmatch() in wildmatch.c. The for-each-ref codepath also uses wildmatch(), but will always match against e.g. "refs/tags/aaa...", not "aaa.." as git-ls-files will. I'm unsure why the pathological case isn't triggered by for-each-ref, but in any case, now we have a performance test for it. Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]> --- t/perf/p0100-globbing.sh | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100755 t/perf/p0100-globbing.sh diff --git a/t/perf/p0100-globbing.sh b/t/perf/p0100-globbing.sh new file mode 100755 index 0000000000..e98fd7ce4b --- /dev/null +++ b/t/perf/p0100-globbing.sh @@ -0,0 +1,48 @@ +#!/bin/sh + +test_description="Tests pathalogical globbing performance + +Shows how Git's globbing performance performs when given the sort of +pathalogical 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 $(cat refname) && + for i in $(test_seq 1 100) + do + echo git tag $(cat refname)-$i + done && + test_commit hello +' + +for i in $test_globs_big +do + test_perf "refglob((a*)^nb) against tag a^100; 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 -- 2.11.0
