mmm: lockfile to prevent multiple instances.

eventstore/mmm/lockfile_test.go

@@ -0,0 +1,35 @@
+package mmm
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestLockfile(t *testing.T) {
+	// create a temporary directory for the test
+	tmpDir, err := os.MkdirTemp("", "mmm-lockfile-test-*")
+	require.NoError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	// initialize first MMM instance
+	mmmm1 := &MultiMmapManager{Dir: tmpDir}
+	err = mmmm1.Init()
+	require.NoError(t, err)
+	defer mmmm1.Close()
+
+	// try to initialize second MMM instance on the same directory
+	mmmm2 := &MultiMmapManager{Dir: tmpDir}
+	err = mmmm2.Init()
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "already in use by another instance")
+
+	// close first instance
+	mmmm1.Close()
+
+	// now second instance should be able to open
+	err = mmmm2.Init()
+	require.NoError(t, err)
+	mmmm2.Close()
+}