pub type ConnectionId = u64;Expand description
Unique, monotonically-assigned identifier for a tracked connection.
Connections are keyed by id rather than by peer std::net::SocketAddr so that
(a) a stream can be removed from the pool at drop time without re-querying
the (possibly already-reset) socket, and (b) two connections sharing a peer
address (NAT, rapid address reuse) cannot collide in the tracking map.