Currently the state change explanations are only added to mariadbmon. They
are less relevant for Galera clusters as they themselves explain why they
change their states but should still be added to make them easier to
analyze.
The event that isn't explained and is most often encountered is the loss
of a Slave status. Most often the loss of a Slave status happens because
either the IO thread or the SQL thread has stopped. Printing the states of
the threads as well as the latest error should hint at what caused the
outage.
The information can be added to the REST API in 2.5 where the monitors can
add extra information to the server JSON.
During switchover/failover, server events are altered. The ALTER
EVENT command automatically modifies the event charset and collation
to the values of the connetion running the query. This may cause
the event to become invalid.
Fixed this by changing connection charset and collation to the ones
in the event description just before altering it.
The mon_ping_or_connect_to_db resets the MYSQL handle which caused the
loss of the error message. Returning a new enumeration value for
authentication errors solves this problem.
The password values are now masked with asterisks. This tells whether a
password is set or not but it does not expose any information about the
password itself.
name_lookup() now returns all results given by getnameinfo(). When searching
for a server, finding one matching address in the lookup-results is enough for
a match.
Also, added a test for name_lookup(). The test is minimal on its own, as hardcoded
test cases are not generally valid.
When matching hostnames between MaxScale server configuration and the
SHOW SLAVE STATUS-output, use DNS-resolution if a simple string comparison
doesn't find an answer. Results of the resolution are saved to avoid
repeating the operation for the same address.
The settings are different from the other fields in that they should not change
on their own. Most manipulation functions only require the settings.
Also takes into use a class for host and port data.
The slave connection I/O-tread stays running if replication credentials are
wrong when connecting to master. This causes a switchover/failover timeout.
When this happens, print the error in the slave connection status as this
clarifies the problem to the user.
