Monitoring number of current connections

[bbqsrc]

Is it possible to monitor the number of connections to a TCP server currently?

I need to be able to detect once the number of connections has dropped to zero to do some cleanup, and I am at a loss to work out how to do that.

[tomusdrw]

We support session counting for WS and IPC servers:
https://paritytech.github.io/jsonrpc/jsonrpc_ws_server/trait.SessionStats.html

It's implemented as Drop of Session object:

jsonrpc/ws/src/session.rs

Line 155 in 786f3e1

self.stats.as_ref().map(|stats| stats.close_session(self.context.session_id));

AFAICT it's not possible currently in TCP server, but I'm open for help in implementing that.
You could possibly have a custom Metadata and count session using this, but you need to ensure that the method implementation is storing the metadata for as long as the session object.