[PATCH v4 4/8] t7300: add testcase showing unnecessary traversal into ignored directory

From: Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>
Date: May 11, 2021, 18:34 UTC
Message-ID: <317abab3571e69394cf0a0dbe971440bca16964b.1620758049.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1020.v4.git.git.1620758049.gitgitgadget@gmail.com>

From: Elijah Newren <newren@gmail.com>

The PNPM package manager is apparently creating deeply nested (but ignored) directory structures; traversing them is costly performance-wise, unnecessary, and in some cases is even throwing warnings/errors because the paths are too long to handle on various platforms. Add a testcase that checks for such unnecessary directory traversal.

Signed-off-by: Elijah Newren <newren@gmail.com>
---
 t/t7300-clean.sh | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/t/t7300-clean.sh b/t/t7300-clean.sh
index a74816ca8b46..07e8ba2d4b85 100755
--- a/t/t7300-clean.sh
+++ b/t/t7300-clean.sh
@@ -746,4 +746,27 @@ test_expect_success 'clean untracked paths by pathspec' '
 	test_must_be_empty actual
 '
 
+test_expect_failure 'avoid traversing into ignored directories' '
+	test_when_finished rm -f output error trace.* &&
+	test_create_repo avoid-traversing-deep-hierarchy &&
+	(
+		cd avoid-traversing-deep-hierarchy &&
+
+		mkdir -p untracked/subdir/with/a &&
+		>untracked/subdir/with/a/random-file.txt &&
+
+		GIT_TRACE2_PERF="$TRASH_DIRECTORY/trace.output" \
+		git clean -ffdxn -e untracked
+	) &&
+
+	# Make sure we only visited into the top-level directory, and did
+	# not traverse into the "untracked" subdirectory since it was excluded
+	grep data.*read_directo.*directories-visited trace.output |
+		cut -d "|" -f 9 >trace.relevant &&
+	cat >trace.expect <<-EOF &&
+	 ..directories-visited:1
+	EOF
+	test_cmp trace.expect trace.relevant
+'
+
 test_done

-- 
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