The two cases are now separated. In switchover, the promotion and
demotion targets can swap connections between each other without worry.
In failover, the two connection lists must be merged semi-intelligently.
The slave connections of the two servers are now saved to the operation
descriptor object at the start of the operation. This allows slave status
updating during the operation.
Several small changes:
Binlog is flushed at the end of old master demotion.
Only new master is required to catch up to old master.
Use the same replication check method as failover.
No longer writes events to the master, as this creates problems if the
promoted server was not the overall master. Instead, the slave status
output is inspected.
In progress, does not yet overwrite existing code.
The new promotion mechanism automatically retries queries which timed out. It also
handles multimaster situations correctly.
Now logs messages explaining what has been done. Scheduled events are
disabled/enabled during the operation. Redirection of slaves is done at
the end similar to failover/switchover.
The 'reset_replication' module command deletes all slave connections and binlogs,
sets gtid to sequence 0 and restarts replication from the given master. Should be
only used if gtid:s are incompatible but the actual data is known to be in sync.
Event handling is now enabled by default. If the monitor cannot query the EVENTS-
table (most likely because of missing credentials), print an error suggesting to
turn the feature off.
When disabling events on a rejoining standalone server (likely a former master),
disable binlog event recording for the session. This prevents the ALTER EVENT
queries from generating binlog events.
Also added documentation and combined similar parts in the code.
See script directory for method. The script to run in the top level
MaxScale directory is called maxscale-uncrustify.sh, which uses
another script, list-src, from the same directory (so you need to set
your PATH). The uncrustify version was 0.66.
Since the servers are not modified before or during the wait, the waiting
can be done in the preparation method. This simplifies the actual failover
somewhat, and allows the monitor to keep running normally while waiting for
the log to clear.
No longer depends on monitor events as the other operations do not
either. The active_event/new_event detection was removed, as these
only protect against a rare situation. A similar feature which
protects all the cluster modifications will be implemented later.
The master validity check now checks if the master is down. This requires
that the slave status is assigned even if no master is available.
The failover precondition is also fulfilled as long as one valid promotion
candidate is found. Previously a slave that didn't use GTID replication
appeared to prevent failover.
