feat: transaction implement

internal/processlock/lock_linux_test.go

@@ -0,0 +1,40 @@
+//go:build linux
+
+package processlock
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestLockUsesKernelOwnershipAndLeavesFileInPlace(t *testing.T) {
+	t.Parallel()
+	path := filepath.Join(t.TempDir(), "serve.lock")
+	first, err := Acquire(path)
+	if err != nil {
+		t.Fatalf("acquire first lock: %v", err)
+	}
+	second, err := Acquire(path)
+	if !errors.Is(err, ErrAlreadyLocked) || second != nil {
+		t.Fatalf("expected second acquire to fail with lock ownership, lock=%v err=%v", second, err)
+	}
+	metadata, err := os.ReadFile(path)
+	if err != nil || len(metadata) == 0 {
+		t.Fatalf("read diagnostic PID: data=%q err=%v", metadata, err)
+	}
+	if err := first.Close(); err != nil {
+		t.Fatalf("release first lock: %v", err)
+	}
+	if _, err := os.Stat(path); err != nil {
+		t.Fatalf("lock file should remain after release: %v", err)
+	}
+	third, err := Acquire(path)
+	if err != nil {
+		t.Fatalf("reacquire existing lock file: %v", err)
+	}
+	if err := third.Close(); err != nil {
+		t.Fatalf("release reacquired lock: %v", err)
+	}
+}