Fix leak on txn abort

KissMeme/Sources/KissDB.swift

@@ -134,12 +134,16 @@ public class KissDB: NSObject {
     
     // TODO: impl. more
     public func insertData(from: @escaping ((Int)->DataItem?), count: Int) throws {
+        throw KissDBError.general(-99, "unimplemented")
+        
+        #if false
         let obj = InsertDataItemCallbackObject(insertCallback: from, maxCount: count)
         let userPtr = Unmanaged.passUnretained(obj).toOpaque()
 
         guard kiss_db_insert_from(cPtr, false, InsertDataItemCallbackObject.insertCallback, userPtr, cError) else {
             throw KissDBError.general(cError.code, cError.message)
         }
+        #endif
     }
     
     public func delete(key: String) throws {

kissdb/Sources/kissdb/kissdb.c

@@ -77,6 +77,9 @@ void kiss_db_destroy(kiss_db_ptr ptr)
     if (ptr == NULL) {
         return;
     }
+    if (ptr->txn) {
+        mdb_txn_abort(ptr->txn);
+    }
     mdb_dbi_close(ptr->env, ptr->dbi);
     mdb_env_close(ptr->env);
     free(ptr);
@@ -102,6 +105,7 @@ kiss_bool kiss_db_commit(kiss_db_ptr ptr, kiss_db_error_t* error)
 {
     _kiss_db_update_count(ptr);
     mdb_txn_commit(ptr->txn);
+    ptr->txn = NULL;
     return true;
 }
 
@@ -110,7 +114,7 @@ kiss_bool kiss_db_rollback(kiss_db_ptr ptr, kiss_db_error_t* error)
 {
     _kiss_db_update_count(ptr);
     mdb_txn_abort(ptr->txn);
-
+    ptr->txn = NULL;
     return true;
 }