Implemented mysql_hostgroup_attributes.multiplex

If mysql_hostgroup_attributes.multiplex:
- 0 : multiplexing is always disabled
- 1 : multiplexing is enabled for the hostgroup, but other criteria can disable multiplexing (transaction, temp tables, query rules, etc)

include/mysql_connection.h

@@ -17,7 +17,7 @@ using json = nlohmann::json;
 #define STATUS_MYSQL_CONNECTION_NO_MULTIPLEX         0x00000080
 #define STATUS_MYSQL_CONNECTION_SQL_LOG_BIN0         0x00000100
 #define STATUS_MYSQL_CONNECTION_FOUND_ROWS           0x00000200
-//#define STATUS_MYSQL_CONNECTION_NO_BACKSLASH_ESCAPES 0x00000400
+#define STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG      0x00000400
 #define STATUS_MYSQL_CONNECTION_HAS_SAVEPOINT        0x00000800
 
 class Variable {

lib/MySQL_HostGroups_Manager.cpp

@@ -3114,6 +3114,8 @@ MySQL_Connection * MySrvConnList::get_random_MyConn(MySQL_Session *sess, bool ff
 						// we must create a new connection
 						conn = new MySQL_Connection();
 						conn->parent=mysrvc;
+						// if attributes.multiplex == true , STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG is set to false. And vice-versa
+						conn->set_status(!conn->parent->myhgc->attributes.multiplex, STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 						__sync_fetch_and_add(&MyHGM->status.server_connections_created, 1);
 						proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 7, "Returning MySQL Connection %p, server %s:%d\n", conn, conn->parent->address, conn->parent->port);
 					}
@@ -3126,6 +3128,8 @@ MySQL_Connection * MySrvConnList::get_random_MyConn(MySQL_Session *sess, bool ff
 					if ((conns_used > conns_free) && (mysrvc->max_connections > (conns_free/2 + conns_used/2)) ) {
 						conn = new MySQL_Connection();
 						conn->parent=mysrvc;
+						// if attributes.multiplex == true , STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG is set to false. And vice-versa
+						conn->set_status(!conn->parent->myhgc->attributes.multiplex, STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 						__sync_fetch_and_add(&MyHGM->status.server_connections_created, 1);
 						proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 7, "Returning MySQL Connection %p, server %s:%d\n", conn, conn->parent->address, conn->parent->port);
 					} else {
@@ -3164,6 +3168,8 @@ MySQL_Connection * MySrvConnList::get_random_MyConn(MySQL_Session *sess, bool ff
 		} else {
 			conn = new MySQL_Connection();
 			conn->parent=mysrvc;
+			// if attributes.multiplex == true , STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG is set to false. And vice-versa
+			conn->set_status(!conn->parent->myhgc->attributes.multiplex, STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 			__sync_fetch_and_add(&MyHGM->status.server_connections_created, 1);
 			proxy_debug(PROXY_DEBUG_MYSQL_CONNPOOL, 7, "Returning MySQL Connection %p, server %s:%d\n", conn, conn->parent->address, conn->parent->port);
 			return  conn;

lib/MySQL_Session.cpp

@@ -1214,6 +1214,7 @@ void MySQL_Session::generate_proxysql_internal_session_json(json &j) {
 				j["backends"][i]["conn"]["status"]["user_variable"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_USER_VARIABLE);
 				j["backends"][i]["conn"]["status"]["found_rows"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_FOUND_ROWS);
 				j["backends"][i]["conn"]["status"]["no_multiplex"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_NO_MULTIPLEX);
+				j["backends"][i]["conn"]["status"]["no_multiplex_HG"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 				j["backends"][i]["conn"]["status"]["compression"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_COMPRESSION);
 				j["backends"][i]["conn"]["status"]["prepared_statement"] = _myconn->get_status(STATUS_MYSQL_CONNECTION_PREPARED_STATEMENT);
 				j["backends"][i]["conn"]["MultiplexDisabled"] = _myconn->MultiplexDisabled();

lib/mysql_connection.cpp

@@ -2428,7 +2428,7 @@ bool MySQL_Connection::MultiplexDisabled(bool check_delay_token) {
 // status_flags stores information about the status of the connection
 // can be used to determine if multiplexing can be enabled or not
 	bool ret=false;
-	if (status_flags & (STATUS_MYSQL_CONNECTION_TRANSACTION|STATUS_MYSQL_CONNECTION_USER_VARIABLE|STATUS_MYSQL_CONNECTION_PREPARED_STATEMENT|STATUS_MYSQL_CONNECTION_LOCK_TABLES|STATUS_MYSQL_CONNECTION_TEMPORARY_TABLE|STATUS_MYSQL_CONNECTION_GET_LOCK|STATUS_MYSQL_CONNECTION_NO_MULTIPLEX|STATUS_MYSQL_CONNECTION_SQL_LOG_BIN0|STATUS_MYSQL_CONNECTION_FOUND_ROWS|STATUS_MYSQL_CONNECTION_HAS_SAVEPOINT) ) {
+	if (status_flags & (STATUS_MYSQL_CONNECTION_TRANSACTION|STATUS_MYSQL_CONNECTION_USER_VARIABLE|STATUS_MYSQL_CONNECTION_PREPARED_STATEMENT|STATUS_MYSQL_CONNECTION_LOCK_TABLES|STATUS_MYSQL_CONNECTION_TEMPORARY_TABLE|STATUS_MYSQL_CONNECTION_GET_LOCK|STATUS_MYSQL_CONNECTION_NO_MULTIPLEX|STATUS_MYSQL_CONNECTION_SQL_LOG_BIN0|STATUS_MYSQL_CONNECTION_FOUND_ROWS|STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG|STATUS_MYSQL_CONNECTION_HAS_SAVEPOINT) ) {
 		ret=true;
 	}
 	if (check_delay_token && auto_increment_delay_token) return true;
@@ -2768,7 +2768,10 @@ int MySQL_Connection::async_send_simple_command(short event, char *stmt, unsigne
 }
 
 void MySQL_Connection::reset() {
+	bool old_no_multiplex_hg = get_status(STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 	status_flags=0;
+	// reconfigure STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG
+	set_status(old_no_multiplex_hg,STATUS_MYSQL_CONNECTION_NO_MULTIPLEX_HG);
 	reusable=true;
 	options.last_set_autocommit=-1; // never sent