Move tokio::net module into tokio tcp/udp crates (#224)

tokio-udp/src/send_dgram.rs

@@ -0,0 +1,61 @@
+use super::socket::UdpSocket;
+
+use std::io;
+use std::net::SocketAddr;
+
+use futures::{Async, Future, Poll};
+
+/// A future used to write the entire contents of some data to a UDP socket.
+///
+/// This is created by the `UdpSocket::send_dgram` method.
+#[must_use = "futures do nothing unless polled"]
+#[derive(Debug)]
+pub struct SendDgram<T> {
+    /// None means future was completed
+    state: Option<SendDgramInner<T>>
+}
+
+/// A struct is used to represent the full info of SendDgram.
+#[derive(Debug)]
+struct SendDgramInner<T> {
+    /// Tx socket
+    socket: UdpSocket,
+    /// The whole buffer will be sent
+    buffer: T,
+    /// Destination addr
+    addr: SocketAddr,
+}
+
+impl<T> SendDgram<T> {
+    /// Create a new future to send UDP Datagram
+    pub(crate) fn new(socket: UdpSocket, buffer: T, addr: SocketAddr) -> SendDgram<T> {
+        let inner = SendDgramInner { socket: socket, buffer: buffer, addr: addr };
+        SendDgram { state: Some(inner) }
+    }
+}
+
+fn incomplete_write(reason: &str) -> io::Error {
+    io::Error::new(io::ErrorKind::Other, reason)
+}
+
+impl<T> Future for SendDgram<T>
+    where T: AsRef<[u8]>,
+{
+    type Item = (UdpSocket, T);
+    type Error = io::Error;
+
+    fn poll(&mut self) -> Poll<(UdpSocket, T), io::Error> {
+        {
+            let ref mut inner =
+                self.state.as_mut().expect("SendDgram polled after completion");
+            let n = try_ready!(inner.socket.poll_send_to(inner.buffer.as_ref(), &inner.addr));
+            if n != inner.buffer.as_ref().len() {
+                return Err(incomplete_write("failed to send entire message \
+                                             in datagram"))
+            }
+        }
+
+        let inner = self.state.take().unwrap();
+        Ok(Async::Ready((inner.socket, inner.buffer)))
+    }
+}