* Added comments

* Few issues fixed

lib/MySQL_HostGroups_Manager.cpp

@@ -1842,6 +1842,13 @@ void MySQL_HostGroups_Manager::commit_update_checksums_from_tables() {
 	CUCFT1("mysql_hostgroup_attributes","hostgroup_id", table_resultset_checksum[HGM_TABLES::MYSQL_HOSTGROUP_ATTRIBUTES]);
 }
 
+/**
+ * @brief This code updates the 'hostgroup_server_mapping' table with the most recent mysql_servers and mysql_replication_hostgroups 
+ *	  records while utilizing checksums to prevent unnecessary updates.
+ * 
+ * IMPORTANT: Make sure wrlock() is called before calling this method.
+ * 
+*/
 void MySQL_HostGroups_Manager::update_hostgroup_manager_mappings() {
 
 	if (hgsm_mysql_servers_checksum != table_resultset_checksum[HGM_TABLES::MYSQL_SERVERS] ||
@@ -1912,6 +1919,11 @@ bool MySQL_HostGroups_Manager::commit(
 	bool only_commit_runtime_mysql_servers
 ) {
 	// if only_commit_runtime_mysql_servers is true, mysql_servers_incoming resultset will not be entertained and will cause memory leak.
+	if (only_commit_runtime_mysql_servers) {
+		proxy_info("Generating runtime mysql servers records only");
+	} else {
+		proxy_info("Generating runtime mysql servers and mysql servers incoming records");
+	}
 
 	unsigned long long curtime1=monotonic_time();
 	wrlock();
@@ -2120,9 +2132,6 @@ bool MySQL_HostGroups_Manager::commit(
 		has_gtid_port = false;
 	}
 	if (resultset) { delete resultset; resultset=NULL; }
-	proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 4, "DELETE FROM mysql_servers_incoming\n");
-	mydb->execute("DELETE FROM mysql_servers_incoming");
-
 
 	uint64_t mysql_servers_incoming_checksum = 0;
 
@@ -2165,6 +2174,10 @@ bool MySQL_HostGroups_Manager::commit(
 		mysql_servers_incoming_checksum = get_mysql_servers_incoming_checksum(mysql_servers_incoming, false);
 	}
 
+	proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 4, "DELETE FROM mysql_servers_incoming\n");
+	mydb->execute("DELETE FROM mysql_servers_incoming");
+	
+	// regenerating mysql_servers records
 	mydb->execute("DELETE FROM mysql_servers");
 	generate_mysql_servers_table();
 

lib/ProxySQL_Admin.cpp

@@ -3705,7 +3705,22 @@ void admin_session_handler(MySQL_Session *sess, void *_pa, PtrSize_t *pkt) {
 			GloAdmin->mysql_servers_wrunlock();
 
 			if (resultset == nullptr) {
-				resultset=MyHGM->dump_table_mysql(tn);
+
+				// fetching mysql_servers records from admin table as HGM mysql_servers records might be different.
+				if (tn == "mysql_servers_incoming") {
+					char *error=NULL;
+					int cols=0;
+					int affected_rows=0;
+					const char* query = "SELECT hostgroup_id,hostname,port,gtid_port,status,weight,compression,max_connections,max_replication_lag,use_ssl,max_latency_ms,comment FROM main.mysql_servers ORDER BY hostgroup_id, hostname, port";
+					proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 4, "%s\n", query);
+					
+					GloAdmin->mysql_servers_wrlock();
+					GloAdmin->admindb->execute_statement(query, &error , &cols , &affected_rows , &resultset);
+					GloAdmin->mysql_servers_wrunlock();
+				} else {
+					resultset = MyHGM->dump_table_mysql(tn);
+				}
+
 				if (resultset) {
 					sess->SQLite3_to_MySQL(resultset, error, affected_rows, &sess->client_myds->myprot);
 					delete resultset;

lib/ProxySQL_Cluster.cpp

@@ -1731,13 +1731,13 @@ void ProxySQL_Cluster::pull_runtime_mysql_servers_from_peer(const runtime_mysql_
 					proxy_info("Cluster: Computed checksum for MySQL Servers from peer %s:%d : %s\n", hostname, port, computed_checksum.c_str());
 
 					if (computed_checksum == peer_checksum) {
-						MyHGM->wrlock();
+						GloAdmin->mysql_servers_wrlock();
 						std::unique_ptr<SQLite3_result> runtime_mysql_servers_resultset = get_SQLite3_resulset(result);
 						proxy_debug(PROXY_DEBUG_CLUSTER, 5, "Loading runtime_mysql_servers from peer %s:%d into mysql_servers_incoming", hostname, port);
 						MyHGM->servers_add(runtime_mysql_servers_resultset.get());
 						proxy_debug(PROXY_DEBUG_CLUSTER, 5, "Updating runtime_mysql_servers from peer %s:%d", hostname, port);
 						MyHGM->commit(runtime_mysql_servers_resultset.release(), peer_runtime_mysql_server, nullptr, {}, true);
-						MyHGM->wrunlock();
+						GloAdmin->mysql_servers_wrunlock();
 
 						// free result
 						mysql_free_result(result);