1 files changed, 77 insertions, 0 deletions
diff --git a/third_party/rust/mio/examples/udp_server.rs b/third_party/rust/mio/examples/udp_server.rs
new file mode 100644
index 0000000000..ed6881d99c
--- /dev/null
+++ b/third_party/rust/mio/examples/udp_server.rs
@@ -0,0 +1,77 @@
+// You can run this example from the root of the mio repo:
+// cargo run --example udp_server --features="os-poll net"
+use log::warn;
+use mio::net::UdpSocket;
+use mio::{Events, Interest, Poll, Token};
+use std::io;
+
+// A token to allow us to identify which event is for the `UdpSocket`.
+const UDP_SOCKET: Token = Token(0);
+
+fn main() -> io::Result<()> {
+    env_logger::init();
+
+    // Create a poll instance.
+    let mut poll = Poll::new()?;
+    // Create storage for events. Since we will only register a single socket, a
+    // capacity of 1 will do.
+    let mut events = Events::with_capacity(1);
+
+    // Setup the UDP socket.
+    let addr = "127.0.0.1:9000".parse().unwrap();
+    let mut socket = UdpSocket::bind(addr)?;
+
+    // Register our socket with the token defined above and an interest in being
+    // `READABLE`.
+    poll.registry()
+        .register(&mut socket, UDP_SOCKET, Interest::READABLE)?;
+
+    println!("You can connect to the server using `nc`:");
+    println!(" $ nc -u 127.0.0.1 9000");
+    println!("Anything you type will be echoed back to you.");
+
+    // Initialize a buffer for the UDP packet. We use the maximum size of a UDP
+    // packet, which is the maximum value of 16 a bit integer.
+    let mut buf = [0; 1 << 16];
+
+    // Our event loop.
+    loop {
+        // Poll to check if we have events waiting for us.
+        poll.poll(&mut events, None)?;
+
+        // Process each event.
+        for event in events.iter() {
+            // Validate the token we registered our socket with,
+            // in this example it will only ever be one but we
+            // make sure it's valid none the less.
+            match event.token() {
+                UDP_SOCKET => loop {
+                    // In this loop we receive all packets queued for the socket.
+                    match socket.recv_from(&mut buf) {
+                        Ok((packet_size, source_address)) => {
+                            // Echo the data.
+                            socket.send_to(&buf[..packet_size], source_address)?;
+                        }
+                        Err(e) if e.kind() == io::ErrorKind::WouldBlock => {
+                            // If we get a `WouldBlock` error we know our socket
+                            // has no more packets queued, so we can return to
+                            // polling and wait for some more.
+                            break;
+                        }
+                        Err(e) => {
+                            // If it was any other kind of error, something went
+                            // wrong and we terminate with an error.
+                            return Err(e);
+                        }
+                    }
+                },
+                _ => {
+                    // This should never happen as we only registered our
+                    // `UdpSocket` using the `UDP_SOCKET` token, but if it ever
+                    // does we'll log it.
+                    warn!("Got event for unexpected token: {:?}", event);
+                }
+            }
+        }
+    }
+}