The purpose of this template class is to provide the
implementation of the monitor C-api. It's to be instantiated
with the class that actually provides the monitor behaviour.
A separate class maxscale::MonitorInstance will be provided
that then in turn implements the behaviour common to most
monitors. So, the structure will be like:
class SomeMonitor : public maxscale::MonitorInstance {...}
extern "C" MXS_MODULE* MXS_CREATE_MODULE()
{
static MXS_MODULE info =
{
...
&maxscale::MonitorApi<SomeMonitor>::s_api,
...
};
return &info;
}
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.
CreateInstance() (renamed from initMonitor()) and destroyInstance()
(renamed from finishMonitor()) have now tentatively been
implemented for all monitors.
Next step is to
1) change the prototype of startMonitor() to
bool (*startMonitor)(MXS_SPECIFIC_MONITOR*,
const MXS_MONITOR_PARAMETER*);
and assume that mon->handle will always contain the
instance,
2) not delete any data in stopMonitor(),
3) add monitorCreateAll() that calls createInstance() for all
monitors (and call that in main()), and
4) add monitorDestroyAll() that calls destroyInstance() for
all monitors (and call that in main()).
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.
Instead of using void there's now a MXS_SPECIFIC_MONITOR struct
from which monitor specific types can be derived. This change
does not bring about other benefits than a bit of clarity but
this is the first step in clearing up the monitor API.
Returning the length of the value instead of a boolean allows the user to
know when the parameter value exceeded the buffer size passed as the
parameter.
To support a wider range of client connectors, MaxScale should respond
with an AuthSwitchRequest packet to all COM_CHANGE_USER commands. Only
MariaDB connectors understand the OK packet as the only response to a
COM_CHANGE_USER but all connectors understand the AuthSwitchRequest
packet.
The mysql_create_standard_error function accepted a packet number as a
parameter but did not use it as the actual packet number. As the value it
used happened to coincide with 50% of the use-cases, it went unnoticed.
The remaining 50% occurred when a KILL command was executed with an
unknown connection ID.
The individual servers were missing a statistic that would give an
estimated query count. As there is no simple way to count queries for all
modules, counting the number of routed protocol packets is a suitable
substitute.
Session commands that span multiple packets are now allowed and will
work. However, if one is executed the session command history is disabled
as no interface for appending to session commands exists.
The backend protocol modules now also correctly track the current
command. This was a pre-requisite for large session commands as they
needed to be gathered into a single buffer and to do this the current
command had to be accurate.
Updated tests to expect success instead of failure for large prepared
statements.
Readwritesplit had redundant parameter values in the
`router_diagnostics`. All module parameters with their current values are
already displayed in the `parameters` member of the resource.
