Move ipset deletion condition check from DeleteSet to DeleteFromSet. (#602)

npm/ipsm/ipsm.go

@@ -291,7 +291,9 @@ func (ipsMgr *IpsetManager) DeleteFromSet(setName, ip string) error {
 		return err
 	}
 
-	ipsMgr.DeleteSet(setName)
+	if len(ipsMgr.setMap[setName].elements) == 0 {
+		ipsMgr.DeleteSet(setName)
+	}
 
 	return nil
 }

npm/ipsm/ipsm_test.go

@@ -195,9 +195,18 @@ func TestDeleteFromSet(t *testing.T) {
 		t.Errorf("TestDeleteFromSet failed @ ipsMgr.AddToSet")
 	}
 
+	if len(ipsMgr.setMap["test-set"].elements) != 1 {
+		t.Errorf("TestDeleteFromSet failed @ ipsMgr.AddToSet")
+	}
+
 	if err := ipsMgr.DeleteFromSet("test-set", "1.2.3.4"); err != nil {
 		t.Errorf("TestDeleteFromSet failed @ ipsMgr.DeleteFromSet")
 	}
+
+	// After deleting the only entry, "1.2.3.4" from "test-set", "test-set" ipset won't exist
+	if _, exists := ipsMgr.setMap["test-set"]; exists {
+		t.Errorf("TestDeleteFromSet failed @ ipsMgr.DeleteFromSet")
+	}
 }
 
 func TestClean(t *testing.T) {