Detect network failure

[quixoten]

I think it would be nice to have a quick way to detect when the network connection disappears unexpectedly. I'm thinking some kind of inactivity timeout that is renewed every time we receive data from the server. When the inactivity timeout is exceeded, a ping should be sent. If the ping times out the GenServer should be stopped.

Not sure how best to implement. Could it be another process that has something like:

# some other module ?
def activity_monitor
  receive do
    :refresh -> activity_monitor
    after 5_000 -> Gnat.ping_or_stop_async(state.gnat)
  end
end

# Gnat module
def handle_info({:tcp, socket, data}, %{socket: socket, parser: parser}=state) do
  ...
  ActivityMonitor.call(state.activity_monitor, :refresh)
  ...
end

I know that is not a fully fleshed out idea, but I think it's enough to understand how I'm thinking about implementing it.