uds: update to std-future (#1227)

tokio-uds/src/send.rs

@@ -0,0 +1,30 @@
+use crate::UnixDatagram;
+use std::future::Future;
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+/// A future that sends a datagram to the connected address.
+///
+/// This `struct` is created by [`send`](crate::UnixDatagram::send).
+#[must_use = "futures do nothing unless polled"]
+#[derive(Debug)]
+pub struct Send<'a, 'b> {
+    socket: &'a UnixDatagram,
+    buf: &'b [u8],
+}
+
+impl<'a, 'b> Send<'a, 'b> {
+    pub(crate) fn new(socket: &'a UnixDatagram, buf: &'b [u8]) -> Self {
+        Self { socket, buf }
+    }
+}
+
+impl<'a, 'b> Future for Send<'a, 'b> {
+    type Output = io::Result<usize>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let Send { socket, buf } = self.get_mut();
+        socket.poll_send_priv(cx, buf)
+    }
+}