pragma once and minor change in transactions

src/base.h

@@ -16,8 +16,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef LMDBAL_BASE_H
-#define LMDBAL_BASE_H
+#pragma once
 
 #include <map>
 #include <set>
@@ -106,7 +105,7 @@ private:
     uint16_t size;                                              /**<\brief lmdb map size in MiB*/
     MDB_env* environment;                                       /**<\brief lmdb environment handle*/
     Storages storages;                                          /**<\brief Registered storages and caches*/
-    Transactions* transactions;                                 /**<\brief Active public transactions*/
+    mutable Transactions transactions;                          /**<\brief Active public transactions*/
 
     inline static const std::string emptyName = "";             /**<\brief Empty string for general fallback purposes*/
 };
@@ -215,5 +214,3 @@ template <class K, class V>
 LMDBAL::Cache<K, V>* LMDBAL::Base::getCache(const std::string& storageName) {
     return static_cast<Cache<K, V>*>(storages.at(storageName));
 }
-
-#endif //LMDBAL_BASE_H