lib/fs: Cache user lookups (#8496)

lib/scanner/walk_test.go

@@ -1028,3 +1028,25 @@ func testConfig() (Config, context.CancelFunc) {
 		EventLogger: evLogger,
 	}, cancel
 }
+
+func BenchmarkWalk(b *testing.B) {
+	testFs := fs.NewFilesystem(fs.FilesystemTypeBasic, b.TempDir())
+
+	for i := 0; i < 100; i++ {
+		if err := testFs.Mkdir(fmt.Sprintf("dir%d", i), 0755); err != nil {
+			b.Fatal(err)
+		}
+		for j := 0; j < 100; j++ {
+			if fd, err := testFs.Create(fmt.Sprintf("dir%d/file%d", i, j)); err != nil {
+				b.Fatal(err)
+			} else {
+				fd.Close()
+			}
+		}
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		walkDir(testFs, "/", nil, nil, 0)
+	}
+}