Improve HardlinkDir performance

Makefile

@@ -110,6 +110,10 @@ test-fuzz: export DL_SKIP_SSL_VERIFICATION=1
 test-fuzz: reset-db
 	go run cmd/fuzz-test/main.go --host $(GRPC_HOST) --iterations 1000 --projects 5
 
+bench: export DB_URI = postgres://$(DB_USER):$(DB_PASS)@$(DB_HOST):5432/dl_tests
+bench: migrate
+	cd test && go test -bench . -run=^#
+
 reset-db: migrate
 	psql $(DB_URI) -c "truncate dl.objects; truncate dl.contents; truncate dl.projects; truncate dl.cache_versions;"
 

test/hardlink_dir_benchmark_test.go

@@ -0,0 +1,25 @@
+package test
+
+import (
+	"fmt"
+	"os"
+	"path"
+	"testing"
+
+	"github.com/gadget-inc/dateilager/internal/files"
+)
+
+func BenchmarkHardlinkDir(b *testing.B) {
+	wd, err := os.Getwd()
+	if err != nil {
+		b.Error(err)
+	}
+
+	bigDir := path.Join(wd, "../node_modules")
+	tmpDir := emptyTmpDir(b)
+	defer os.RemoveAll(tmpDir)
+
+	for n := 0; n < b.N; n++ {
+		files.HardlinkDir(bigDir, path.Join(tmpDir, "node_modules", fmt.Sprintf("%d", n)))
+	}
+}

test/shared_test.go

@@ -274,9 +274,11 @@ func writeFile(t *testing.T, dir string, path string, content string) {
 	require.NoError(t, err, "write file %v", path)
 }
 
-func emptyTmpDir(t *testing.T) string {
+func emptyTmpDir(t testing.TB) string {
 	dir, err := os.MkdirTemp("", "dateilager_tests_")
-	require.NoError(t, err, "create temp dir")
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	return dir
 }