Server side throttling

Since MariaDB and MySQL database server has max_connections Server System Variable, the MaxScale monitor can query this variable

MaxScale Monitor should report the max_connections system variable for each server
At a time MaxScale should not have more than max_connections number of concurrent connections towards a backend server.

When client connection request results in need a new backend server connection, if the number of concurrent connection from MaxScale to the backend server has reached max_connections value for that server

• MaxScale should reject the incoming client connection with a connection error
• MaxScale should not make a connection request to that server