First attempt to track GTID needed for #1208

Putting this on hold, due to https://jira.mariadb.org/browse/CONC-302

include/mysql_backend.h

@@ -10,6 +10,8 @@ class MySQL_Backend
 	void * operator new(size_t);
 	void operator delete(void *);
 	int hostgroup_id;
+	char gtid_uuid[48];
+	uint64_t gtid_trxid;
 	MySQL_Data_Stream *server_myds;
 //  mysql_cp_entry_t *server_mycpe;
   bytes_stats_t server_bytes_at_cmd;

include/mysql_connection.h

@@ -178,5 +178,7 @@ class MySQL_Connection {
 	void set_is_client(); // used for local_stmts
 
 	void reset();
+
+	bool get_gtid(char *buff, uint64_t *trx_id);
 };
 #endif /* __CLASS_MYSQL_CONNECTION_H */

lib/MySQL_Session.cpp

@@ -2621,6 +2621,7 @@ handler_again:
 						(begint.tv_sec*1000000000+begint.tv_nsec);
 				}
 				if (rc==0) {
+					myconn->get_gtid(mybe->gtid_uuid,&mybe->gtid_trxid);
 					// check if multiplexing needs to be disabled
 					char *qdt=CurrentQuery.get_digest_text();
 					if (qdt)

lib/mysql_backend.cpp

@@ -14,6 +14,8 @@ MySQL_Backend::MySQL_Backend() {
 	server_myds=NULL;
 	server_bytes_at_cmd.bytes_recv=0;
 	server_bytes_at_cmd.bytes_sent=0;
+	memset(gtid_uuid,0,sizeof(gtid_uuid));
+	gtid_trxid=0;
 }
 
 MySQL_Backend::~MySQL_Backend() {

lib/mysql_connection.cpp

@@ -1706,3 +1706,22 @@ void MySQL_Connection::reset() {
 	local_stmts=new MySQL_STMTs_local_v14(false);
 #endif
 }
+
+bool MySQL_Connection::get_gtid(char *buff, uint64_t *trx_id) {
+	// note: current implementation for for OWN GTID only!
+	bool ret = false;
+	if (buff==NULL || trx_id == NULL) {
+		return ret;
+	}
+	if (mysql) {
+		const char *data;
+		size_t length;
+		if (mysql_session_track_get_first(mysql, SESSION_TRACK_GTIDS, &data, &length) == 0) {
+			memcpy(buff,data,length);
+			buff[length]=0;
+			fprintf(stderr,"GTID=%s\n",buff);
+			ret = true;
+		}
+	}
+	return ret;
+}