git/t/perf/p7300-clean.sh
Jeff King a2d5156c2b resolve_gitlink_ref: ignore non-repository paths
When we want to look up a submodule ref, we use
get_ref_cache(path) to find or auto-create its ref cache.
But if we feed a path that isn't actually a git repository,
we blindly create the ref cache, and then may die deeper in
the code when we try to access it. This is a problem because
many callers speculatively feed us a path that looks vaguely
like a repository, and expect us to tell them when it is
not.

This patch teaches resolve_gitlink_ref to reject
non-repository paths without creating a ref_cache. This
avoids the die(), and also performs better if you have a
large number of these faux-submodule directories (because
the ref_cache lookup is linear, under the assumption that
there won't be a large number of submodules).

To accomplish this, we also break get_ref_cache into two
pieces: the lookup and auto-creation (the latter is lumped
into create_ref_cache). This lets us first cheaply ask our
cache "is it a submodule we know about?" If so, we can avoid
repeating our filesystem lookup. So lookups of real
submodules are not penalized; they examine the submodule's
.git directory only once.

The test in t3000 demonstrates a case where this improves
correctness (we used to just die). The new perf case in
p7300 shows off the speed improvement in an admittedly
pathological repository:

Test                  HEAD^               HEAD
----------------------------------------------------------------
7300.4: ls-files -o   66.97(66.15+0.87)   0.33(0.08+0.24) -99.5%

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-01-25 11:42:13 -08:00

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#!/bin/sh
test_description="Test git-clean performance"
. ./perf-lib.sh
test_perf_default_repo
test_checkout_worktree
test_expect_success 'setup untracked directory with many sub dirs' '
rm -rf 500_sub_dirs 100000_sub_dirs clean_test_dir &&
mkdir 500_sub_dirs 100000_sub_dirs clean_test_dir &&
for i in $(test_seq 1 500)
do
mkdir 500_sub_dirs/dir$i || return $?
done &&
for i in $(test_seq 1 200)
do
cp -r 500_sub_dirs 100000_sub_dirs/dir$i || return $?
done
'
test_perf 'clean many untracked sub dirs, check for nested git' '
git clean -n -q -f -d 100000_sub_dirs/
'
test_perf 'clean many untracked sub dirs, ignore nested git' '
git clean -n -q -f -f -d 100000_sub_dirs/
'
test_perf 'ls-files -o' '
git ls-files -o
'
test_done