The auto_failover is a more reliable solution and should be used instead. Several
unused parameters were removed, although they can still be defined in the config
file. Updated documentation on the relevant parts.
In previously the status bits were assigned only for running servers. Due
to the changes done in the monitoring algorithm, the slave and master
status bits are assigned to servers that are down. This change broke a
number of tests and deviates from previous behavior.
To keep the old behavior and to fix the test, the status bits are not
assigned to servers that are down.
The command is saved in a function object which is read by the monitor
thread. This way, manual and automatic cluster modification commands are
ran in the same step of a monitor cycle.
This update required several modifications in related code.
The monitor now detects when a server has changed such that a replication
graph rebuild is needed and only then rebuilds the graph and detects
cycles and master.
Also, some old code is no longer called in the monitor cycle. It will be
removed in later commits. Refactored some of the related functions.
This also applies to autoselect switchover. The disk space warning has the least
priority, as the other criteria could lead to replication failures. Also, print
the reason the new master was selected over the second best candidate.
Not yet used, as more is needed to replace the old code. The
algorithm is based on counting the total number of slave nodes
a server has, possibly in multiple layers and/or cycles.
MonitorInstanceSimple is intended for simple monitors that
probe servers in a straightforward fashion. More complex monitors
can be derived directly from MonitorInstance.
Tracking how many times the monitor has performed its monitoring allows
the test framework to consistently wait for an event instead of waiting
for a hard-coded time period. The MaxCtrl `api get` command can be used to
easily extract the numeric value.
Start/stop now provided by MonitorInstance. The thread main
function is now virtual and overriden by MariaDBMonitor. Some
additional refactoring is necessary in order to be able to allow
MonitorInstance to handle the main loop.
This makes the code clearer and reduces race conditions, as the monitor
could be writing SERVER->status while a router is reading it. Also,
the time during which the SERVER struct is locked drops to a fraction.
