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.
Since we need to call mysql_thread_init(), which can fail, in
the monitor thread, we need to wait for the outcome of that
before we can return from start().
The configuring of the monitor instance is now performed in a
separate function. That is in preparation for the moving of the
start function to maxscale::MonitorInstance.
- All monitors (but MariaDBMon for the time being) inherit
from that.
- All common member variables moved to that class. Still
manipulated in derived classes.
In subsequent commits common functionality will be moved to
that class.
StartMonitor() now takes a MXS_MONITOR_INSTANCE and returns
true, if the monitor could be started and false otherwise.
So, the setup is such that in createInstance(), the instance
data is created and then using startMonitor() and stopMonitor()
the monitor is started/stopped. Finally in destroyInstance(),
the actual instance data is deleted.
The following type name changes
MXS_MONITOR_OBJECT -> MXS_MONITOR_API
MXS_SPECIFIC_MONITOR -> MXS_MONITOR_INSTANCE
Further, the 'handle' instance variable of what used to be
called MXS_MONITOR_OBJECT has been renamed to 'api'.
An example, what used to look like
mon->module->stopMonitor(mon->handle);
now looks like
mon->api->stopMonitor(mon->instance);
which makes it more obvious what is going on.
MonitorDestroy() (renamed to monitor_destroy()) will be used for
actually destroying the monitor instance, that is, execute
destroyInstance() on the loaded module instance and freeing the
the monitor instance.
TODO: monitor_deactivate() could do all the stuff which is currently
done to the monitor in config_runtime(), instead of just
turning off the flag.
Now, all monitor functions but startMonitor takes a
MXS_SPECIFIC_MONITOR instead of MXS_MONITOR. That is, startMonitor
is now like a static factory member returning a new specific
monitor instance and the other functions are like member functions
of that instance.
The old hkheartbeat variable was changed to the mxs_clock() function that
simply wraps an atomic load of the variable. This allows it to be
correctly read by MaxScale as well as opening up the possibility of
converting the value load to a relaxed memory order read.
Renamed the header and associated macros. Removed inclusion of the
heartbeat header from the housekeeper header and added it to the files
that were missing it.
Add missing listener JSON diagnostics call. Check that the
diagnostics_json function exists before calling it.
As the protocol modules don't have diagnostics functions, they aren't
called.
Replace hard-coded strings with constant parameters. This makes it
slightly cleaner.
