Changed the ROUTER_INSTANCE struct to a class and added functions for
common operations.
Renamed configuration and statistics structures and added constructors.
Moved objects around in readwritesplit.hh to be ready for a split into
multiple headers.
Providing helper functions for the commonly used parts of the server makes
code easier to read. It also removes any possibility for formatting
problems by moving the URI and name string handling inside the Backend
class.
Renamed variables to better represent the types of variables they
represent. Reordered some of the functions so that the functions don't
need to be declared before they are used.
Return values instead of objects. This removes the need to handle cases
where a reference to a "debug value" is returned.
Return SRWBackend values instead of passing output references. This
doubles as a false boolan return value when an empty reference is
returned.
As the session commands are always appended to the end of the list, the
name should reflect that action. For this reason, the function was renamed
to append_session_command.
Readwritesplit supports replacement of slave servers by storing all
executed session commands in a list. To make the copying of this list a
bit cleaner, an overload for a list of session commands was added. This
will allow relatively smooth addition of server replacement to all router
modules that use the Backend class.
This is the first step to taking the Backend class into use. It is now
used in rwsplit_select_backends.cc and readwritesplit.hh. The module is
not yet functional and doesn't even compile.
Added some helper functions to the Backend class to get easier access to
the server referenced by the SERVER_REF and to check the state of the
backend.
Creating duplicate connections using the Backend class allows the
connections and their handling to be tested at the same time that the old
system is in place. This should make it somewhat easier to grasp what
changes and where when the new implementation is taken into use.
