query the state of a connection

[kristjanvalur]

Is your feature request related to a problem? Please describe.
Client logic that works with connects and reconnects may knot always know what the state of the connection is.
It is convenient to be able to check if a namespace is connected or disconnected. The javascript version of the library has a connected property on the connection.

Describe the solution you'd like
a function querying the status of a connection would be useful. Namespaces shoudld be supported.
so:

def get_state(self.namespace=""):
   # return "connected", "disconnected", "reconnecting" based on internal logic.

Such a method should also exist on the namespace class.

[miguelgrinberg]

The sio.connected attribute can be used to determine if the client is connected or disconnected/reconnecting. There is currently no distinction between a disconnected client and a client that is attempting to reconnect after the connection dropped. The sio.namespaces set contains the connected namespaces.

[kristjanvalur]

Thanks. I guess I can determine the local reconnect state from whether the sio.wait() has returned or not.

Incidentally, I have an outer loop for the initial connect, performing the same kind of retry/backoff logic as the documented behaviour of the internal reconnect. I find that the internal reconnect sometimes failes (and sio.wait() exits) if a server responds with a 404 during a re-connection attempt, which can happen for example during a server update cycle.

[miguelgrinberg]

There are a couple of issues related to the reconnect not working in certain conditions: #485 and miguelgrinberg/python-engineio#254. Currently working on these.