When protocol closes DCB it calls dcb_close instead of dcb->func.close. dcb_close then calls dcb->func.close. This is now changed to all protocols and routers.

Rwsplit handles ERRACT_NEW_CONNECTION by clearing backend reference, removing callbacks and associating backend reference with new backend server. If it succeeds and the router session can continue, handleError returns true. Otherwise false. When ever false is returned it means that session must be closed.

Rwsplit now tolerates backend failures in a way that it searches new backends when monitor, backend, or client operation fails due to backend failure.

server/include/dcb.h

@@ -195,6 +195,7 @@ typedef struct dcb_callback {
 typedef struct dcb {
 #if defined(SS_DEBUG)
         skygw_chk_t     dcb_chk_top;
+        bool            dcb_errhandle_called;
 #endif
         dcb_role_t      dcb_role;
         SPINLOCK        dcb_initlock;