Change conn_pool metrics update functions to use 'const refs'

include/MySQL_HostGroups_Manager.h

@@ -414,8 +414,14 @@ class MySQL_HostGroups_Manager {
 	 */
 	void p_update_mysql_gtid_executed();
 
-	void p_update_connection_pool_update_counter(std::string& endpoint_id, std::map<std::string, std::string> labels, std::map<std::string, prometheus::Counter*>& m_map, unsigned long long value, p_hg_dyn_counter::metric idx);
-	void p_update_connection_pool_update_gauge(std::string& endpoint_id, std::map<std::string, std::string> labels, std::map<std::string, prometheus::Gauge*>& m_map, unsigned long long value, p_hg_dyn_gauge::metric idx);
+	void p_update_connection_pool_update_counter(
+		const std::string& endpoint_id, const std::map<std::string, std::string>& labels,
+		std::map<std::string, prometheus::Counter*>& m_map, unsigned long long value, p_hg_dyn_counter::metric idx
+	);
+	void p_update_connection_pool_update_gauge(
+		const std::string& endpoint_id, const std::map<std::string, std::string>& labels,
+		std::map<std::string, prometheus::Gauge*>& m_map, unsigned long long value, p_hg_dyn_gauge::metric idx
+	);
 
 	void group_replication_lag_action_set_server_status(MyHGC* myhgc, char* address, int port, int lag_count, bool enable);
 

lib/MySQL_HostGroups_Manager.cpp

@@ -3811,7 +3811,10 @@ SQLite3_result * MySQL_HostGroups_Manager::SQL3_Free_Connections() {
 	return result;
 }
 
-void MySQL_HostGroups_Manager::p_update_connection_pool_update_counter(std::string& endpoint_id, std::map<std::string, std::string> labels, std::map<std::string, prometheus::Counter*>& m_map, unsigned long long value, p_hg_dyn_counter::metric idx) {
+void MySQL_HostGroups_Manager::p_update_connection_pool_update_counter(
+	const std::string& endpoint_id, const std::map<std::string, std::string>& labels, std::map<std::string,
+	prometheus::Counter*>& m_map, unsigned long long value, p_hg_dyn_counter::metric idx
+) {
 	const auto& counter_id = m_map.find(endpoint_id);
 	if (counter_id != m_map.end()) {
 		const auto& cur_val = counter_id->second->Value();
@@ -3827,7 +3830,10 @@ void MySQL_HostGroups_Manager::p_update_connection_pool_update_counter(std::stri
 	}
 }
 
-void MySQL_HostGroups_Manager::p_update_connection_pool_update_gauge(std::string& endpoint_id, std::map<std::string, std::string> labels, std::map<std::string, prometheus::Gauge*>& m_map, unsigned long long value, p_hg_dyn_gauge::metric idx) {
+void MySQL_HostGroups_Manager::p_update_connection_pool_update_gauge(
+	const std::string& endpoint_id, const std::map<std::string, std::string>& labels,
+	std::map<std::string, prometheus::Gauge*>& m_map, unsigned long long value, p_hg_dyn_gauge::metric idx
+) {
 	const auto& counter_id = m_map.find(endpoint_id);
 	if (counter_id != m_map.end()) {
 		counter_id->second->Set(value);