1 files changed, 74 insertions, 0 deletions
diff --git a/third_party/rust/tokio-0.1.22/examples/echo-udp.rs b/third_party/rust/tokio-0.1.22/examples/echo-udp.rs
new file mode 100644
index 0000000000..93ebca799d
--- /dev/null
+++ b/third_party/rust/tokio-0.1.22/examples/echo-udp.rs
@@ -0,0 +1,74 @@
+//! An UDP echo server that just sends back everything that it receives.
+//!
+//! If you're on Unix you can test this out by in one terminal executing:
+//!
+//!     cargo run --example echo-udp
+//!
+//! and in another terminal you can run:
+//!
+//!     cargo run --example connect -- --udp 127.0.0.1:8080
+//!
+//! Each line you type in to the `nc` terminal should be echo'd back to you!
+
+#![deny(warnings)]
+
+#[macro_use]
+extern crate futures;
+extern crate tokio;
+
+use std::net::SocketAddr;
+use std::{env, io};
+
+use tokio::net::UdpSocket;
+use tokio::prelude::*;
+
+struct Server {
+    socket: UdpSocket,
+    buf: Vec<u8>,
+    to_send: Option<(usize, SocketAddr)>,
+}
+
+impl Future for Server {
+    type Item = ();
+    type Error = io::Error;
+
+    fn poll(&mut self) -> Poll<(), io::Error> {
+        loop {
+            // First we check to see if there's a message we need to echo back.
+            // If so then we try to send it back to the original source, waiting
+            // until it's writable and we're able to do so.
+            if let Some((size, peer)) = self.to_send {
+                let amt = try_ready!(self.socket.poll_send_to(&self.buf[..size], &peer));
+                println!("Echoed {}/{} bytes to {}", amt, size, peer);
+                self.to_send = None;
+            }
+
+            // If we're here then `to_send` is `None`, so we take a look for the
+            // next message we're going to echo back.
+            self.to_send = Some(try_ready!(self.socket.poll_recv_from(&mut self.buf)));
+        }
+    }
+}
+
+fn main() -> Result<(), Box<std::error::Error>> {
+    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
+    let addr = addr.parse::<SocketAddr>()?;
+
+    let socket = UdpSocket::bind(&addr)?;
+    println!("Listening on: {}", socket.local_addr()?);
+
+    let server = Server {
+        socket: socket,
+        buf: vec![0; 1024],
+        to_send: None,
+    };
+
+    // This starts the server task.
+    //
+    // `map_err` handles the error by logging it and maps the future to a type
+    // that can be spawned.
+    //
+    // `tokio::run` spawns the task on the Tokio runtime and starts running.
+    tokio::run(server.map_err(|e| println!("server error = {:?}", e)));
+    Ok(())
+}