Relaced router_options with configuration parameters in the createInstance
router entry point. The same needs to be done for the filter API as barely
any filters use the feature.
Some routers (binlogrouter) still support router_options but using it is
deprecated. This had to be done as their use wasn't deprecated in 2.2.
Added a new router API entry point that allows configuration changes after
the instance has been created. This makes alterations to most service
parameters at runtime possible.
An option to reconfiguration would have been the creation of a new
service and the eventual destruction of the old one. This would be a more
complicated and costly method but from an architectural point of view it
is interesting.
The actual implementation of the configuration change is left to the
router. Currently, only readwritesplit performs reconfiguration as
implementing it with versioned configurations is very easy.
Versioned configurations can be considered an adequate first step but it
is not an optimal solution as it causes a bottleneck in the reference
counting of the shared configuration. Thread-specific configuration
definitions would make for a more efficient solution but the
implementation is more complex.
All routers except the binlogrouter now fully implement the JSON
diagnostic entry point. The binlogrouter needs to be handled in a separate
commit as it produces a large amount of diagnostic output.
Using the class RouterSession and the template Router, a router
module can be defined. The way they are intended to be used are
as follows:
class MyRouterSession : public maxscale::RouterSession
{
...
};
class MyRouter : public maxscale::Router<MyRouter, MyRouterSession>
{
...
}
...
extern "C" MXS_MODULE* MXS_CREATE_MODULE()
{
static MXS_MODULE module =
{
...
&MyRouter::s_object,
...
};
return &module;
}
