Duplicate connections to the Backend class

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.

server/modules/routing/readwritesplit/readwritesplit.hh

@@ -27,6 +27,7 @@
 #include <maxscale/hashtable.h>
 #include <maxscale/router.h>
 #include <maxscale/service.h>
+#include <maxscale/backend.hh>
 #include <maxscale/session_command.hh>
 
 enum bref_state_t
@@ -235,6 +236,39 @@ struct rwsplit_config_t
                                              * been idle for too long */
 };
 
+class RWBackend: public mxs::Backend
+{
+    RWBackend(const RWBackend&);
+    RWBackend& operator=(const RWBackend&);
+
+public:
+    RWBackend(SERVER_REF* ref):
+        mxs::Backend(ref),
+        m_reply_state(REPLY_STATE_DONE)
+    {
+    }
+
+    ~RWBackend()
+    {
+    }
+
+    reply_state_t get_reply_state() const
+    {
+        return m_reply_state;
+    }
+
+    void set_reply_state(reply_state_t state)
+    {
+        m_reply_state = state;
+    }
+
+private:
+    reply_state_t m_reply_state;
+};
+
+typedef std::tr1::shared_ptr<RWBackend> SRWBackend;
+typedef std::list<SRWBackend> SRWBackendList;
+
 typedef std::tr1::unordered_set<std::string> TableSet;
 
 /**
@@ -247,6 +281,9 @@ struct ROUTER_CLIENT_SES
     rses_property_t*          rses_properties[RSES_PROP_TYPE_COUNT]; /**< Properties listed by their type */
     backend_ref_t*            rses_master_ref;
     backend_ref_t*            rses_backend_ref; /**< Pointer to backend reference array */
+    SRWBackendList            backends; /**< List of backend servers */
+    SRWBackend                current_master; /**< Current master server */
+    SRWBackend                target_node; /**< The currently locked target node */
     rwsplit_config_t          rses_config; /**< copied config info from router instance */
     int                       rses_nbackends;
     int                       rses_nsescmd; /**< Number of executed session commands */