server.h:added macro SERVER_IS_ROOT_MASTER for finding valid candidate for root master
readwritesplit.c: wrote open three if conditions in get_root_master_bref for clarity
Fix for broken replication has been added to mysql_monitor.
Both Slave_IO and Slave_SQL threads must be running in order to assign
the SERVER_SLAVE status but If only Slave_IO is running let’s assign
the master_id to current server and continue building the replication
tree; if no slaves at all the master will be still available.
The “detect_stale_master” option has been added, its default is 0.
If set to 1 the monitor will keep the last detected master even if the
replication setup is completely not working, i.e. both Slave_IO and
Slave_SQL threads are not running: this applies only to the server that
was master before.
After monitor or MaxScale are restarted and the replication is still
stopped or not configured there will be no master because it’s not
possible to compute the replication topology tree.
Rwsplit handles ERRACT_NEW_CONNECTION by clearing backend reference, removing callbacks and associating backend reference with new backend server. If it succeeds and the router session can continue, handleError returns true. Otherwise false. When ever false is returned it means that session must be closed.
Rwsplit now tolerates backend failures in a way that it searches new backends when monitor, backend, or client operation fails due to backend failure.
Maintenance mode prevents a server from having new connections made
to it and stops MaxScale from monitoring a server. It is designed
to allow a server to be taken out of an active cluster for maintenance.
It prevents new connections and allowsg existing connections to
drain away prior to performaing maintenance on the server.
