Lib.rs

I/O reactor that drives the protocol state machine.

The reactor translates network events into protocol events. This has the added benefit that it's trivial to swap nakamoto's networking code with a different implementation, as the code is fully self-contained.

To illustrate the above, lets trace the behavior of the system when a ping message is received via a peer connection to the client:

1. The Reactor reads from the socket and decodes a NetworkMessage::Ping message.
2. The Reactor wraps this message into a protocol input Input::Received(addr, NetworkMessage::Ping), where addr is the remote address of the socket on which it received this message.
3. The Reactor calls Protocol::step(input, time), where input is the above input, and time is the current local time.
4. The Protocol forwards this message to the PingManager, which constructs a new output Out::Message(addr, NetworkMessage::Pong), and forwards it upstream, to the reactor.
5. The Reactor processes the output, encodes the raw message and writes it to the socket corresponding to the addr address, effectively sending a pong message back to the original sender.

Though simplified, the above steps provide a good mental model of how the reactor and protocol interplay to handle network events.