These types are only necessary when implementing custom runtimes. If you're only trying to perform IO, then there's no need to bother with any of these types as they will have been implemented for you already.
A future representing the notification that an elapsed duration has occurred.
A stream representing notifications at a fixed interval.
The runtime trait.
A TcpListener for this Runtime
A TcpStream for this Runtime
A UDP socket.
Get the current runtime.
Runs a future inside a runtime and blocks on the result.
Set the current runtime.