This crate provides a mechanism for interrupting a Stream.
Any stream can be wrapped in a [Valved], which enables it to be remotely terminated through
an associated [ValveHandle]. This can be useful to implement graceful shutdown on "infinite"
streams like a TcpListener. Once [ValveHandle::close] is called on the handle for a given
stream's [Valved], the stream will yield None to indicate that it has terminated.
```rust extern crate tokio;
use stream_cancel::Valved; use tokio::prelude::*; use std::thread;
let listener = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let (exit, incoming) = Valved::new(listener.incoming());
let server = thread::spawn(move || { // start a tokio echo server tokio::run( incoming .maperr(|e| eprintln!("accept failed = {:?}", e)) .foreach(|sock| { let (reader, writer) = sock.split(); tokio::spawn( tokio::io::copy(reader, writer) .map(|amt| println!("wrote {:?} bytes", amt)) .map_err(|err| eprintln!("IO error {:?}", err)), ) }), ) });
// the server thread will normally never exit, since more connections // can always arrive. however, with a Valved, we can turn off the // stream of incoming connections to initiate a graceful shutdown exit.close(); server.join().unwrap(); ```
You can share the same [ValveHandle] between multiple streams by first creating a [Valve],
and then wrapping multiple streams using [Valve::Wrap]:
```rust extern crate tokio;
use stream_cancel::Valve; use tokio::prelude::*;
let (exit, valve) = Valve::new(); let listener1 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let listener2 = tokio::net::TcpListener::bind(&"0.0.0.0:0".parse().unwrap()).unwrap(); let incoming1 = valve.wrap(listener1.incoming()); let incoming2 = valve.wrap(listener2.incoming());
let mut rt = tokio::runtime::Runtime::new().unwrap(); rt.spawn( incoming1 .select(incoming2) .maperr(|e| eprintln!("accept failed = {:?}", e)) .foreach(|sock| { let (reader, writer) = sock.split(); tokio::spawn( tokio::io::copy(reader, writer) .map(|amt| println!("wrote {:?} bytes", amt)) .map_err(|err| eprintln!("IO error {:?}", err)), ) }), );
// the runtime will not become idle until both incoming1 and incoming2 have stopped (due to // the select). this checks that they are indeed both interrupted when the valve is closed. exit.close(); rt.shutdownonidle().wait().unwrap(); ```