🐎 reduced time that Save() needs lock

include/bank.hpp

@@ -97,17 +97,23 @@ public:
         std::ofstream user_save("users.json");
         Json::Value temp;
 
+        std::vector<std::string> temp_names;
+        temp_names.reserve(users.size());
         {
             std::unique_lock<std::shared_mutex> lock{save_lock}; //grabbing it from any busy add/del opperations
             for (const auto &u : users)
             {
-                //we know it contains this key but we call this func to grab mutex
-                users.if_contains(u.first, [&temp, &u](const User &u_val) {
-                    temp[u.first] = u_val.Serialize();
-                });
+                temp_names.push_back(u.first);
             }
         }
 
+        for (const std::string &s : temp_names)
+        {
+            users.if_contains(s, [&temp, &s](const User &u) {
+                temp[s] = u.Serialize();
+            });
+        }
+
         writer->write(temp, &user_save);
         user_save.close();
     }

main.cpp

@@ -7,9 +7,9 @@
 
 int main(int argc, char **argv)
 {
-    if (argc != 4)
+    if (argc != 3)
     {
-        std::cerr << "Usage: sudo ./bank <admin password> <saving frequency in minutes> <threads>\n";
+        std::cerr << "Usage: sudo ./bank <admin password> <saving frequency in minutes>\n";
         return 0;
     }
     if (geteuid() != 0)