tokio: Add back poll_* for udp

tokio/src/net/udp/socket.rs

@@ -1,10 +1,11 @@
-use crate::io::PollEvented;
+use crate::io::{PollEvented, ReadBuf};
 use crate::net::{to_socket_addrs, ToSocketAddrs};
 
 use std::convert::TryFrom;
 use std::fmt;
 use std::io;
 use std::net::{self, Ipv4Addr, Ipv6Addr, SocketAddr};
+use std::task::{Context, Poll};
 
 cfg_net! {
     /// A UDP socket
@@ -272,6 +273,42 @@ impl UdpSocket {
             .await
     }
 
+    /// Attempts to send data on the socket to the remote address to which it was previously
+    /// `connect`ed.
+    ///
+    /// The [`connect`] method will connect this socket to a remote address. The future
+    /// will resolve to an error if the socket is not connected.
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the send direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not available to write
+    /// * `Poll::Ready(Ok(n))` `n` is the number of bytes sent
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`connect`]: method@Self::connect
+    pub fn poll_send(&self, cx: &mut Context<'_>, buf: &[u8]) -> Poll<io::Result<usize>> {
+        loop {
+            let ev = ready!(self.io.poll_write_ready(cx))?;
+
+            match self.io.get_ref().send(buf) {
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.clear_readiness(ev);
+                }
+                x => return Poll::Ready(x),
+            }
+        }
+    }
+
     /// Try to send data on the socket to the remote address to which it is
     /// connected.
     ///
@@ -304,6 +341,55 @@ impl UdpSocket {
             .await
     }
 
+    /// Attempts to receive a single datagram message on the socket from the remote
+    /// address to which it is `connect`ed.
+    ///
+    /// The [`connect`] method will connect this socket to a remote address. The future
+    /// will resolve to an error if the socket is not connected.
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the recv direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready to read
+    /// * `Poll::Ready(Ok(()))` reads data `ReadBuf` if the socket is ready
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    ///
+    /// [`connect`]: method@Self::connect
+    pub fn poll_recv(&self, cx: &mut Context<'_>, buf: &mut ReadBuf<'_>) -> Poll<io::Result<()>> {
+        loop {
+            let ev = ready!(self.io.poll_read_ready(cx))?;
+
+            // Safety: will not read the maybe uinitialized bytes.
+            let b = unsafe {
+                &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8])
+            };
+            match self.io.get_ref().recv(b) {
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.clear_readiness(ev);
+                }
+                Err(e) => return Poll::Ready(Err(e)),
+                Ok(n) => {
+                    // Safety: We trust `recv` to have filled up `n` bytes
+                    // in the buffer.
+                    unsafe {
+                        buf.assume_init(n);
+                    }
+                    buf.advance(n);
+                    return Poll::Ready(Ok(()));
+                }
+            }
+        }
+    }
+
     /// Returns a future that sends data on the socket to the given address.
     /// On success, the future will resolve to the number of bytes written.
     ///
@@ -337,6 +423,41 @@ impl UdpSocket {
         }
     }
 
+    /// Attempts to send data on the socket to a given address.
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the send direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready to write
+    /// * `Poll::Ready(Ok(n))` `n` is the number of bytes sent.
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    pub fn poll_send_to(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+        target: &SocketAddr,
+    ) -> Poll<io::Result<usize>> {
+        loop {
+            let ev = ready!(self.io.poll_write_ready(cx))?;
+
+            match self.io.get_ref().send_to(buf, *target) {
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.clear_readiness(ev);
+                }
+                x => return Poll::Ready(x),
+            }
+        }
+    }
+
     /// Try to send data on the socket to the given address, but if the send is blocked
     /// this will return right away.
     ///
@@ -403,6 +524,142 @@ impl UdpSocket {
             .await
     }
 
+    /// Attempts to receive a single datagram on the socket.
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the recv direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready to read
+    /// * `Poll::Ready(Ok(addr))` reads data from `addr` into `ReadBuf` if the socket is ready
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    pub fn poll_recv_from(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<SocketAddr>> {
+        loop {
+            let ev = ready!(self.io.poll_read_ready(cx))?;
+
+            // Safety: will not read the maybe uinitialized bytes.
+            let b = unsafe {
+                &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8])
+            };
+            match self.io.get_ref().recv_from(b) {
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.clear_readiness(ev);
+                }
+                Err(e) => return Poll::Ready(Err(e)),
+                Ok((n, addr)) => {
+                    // Safety: We trust `recv` to have filled up `n` bytes
+                    // in the buffer.
+                    unsafe {
+                        buf.assume_init(n);
+                    }
+                    buf.advance(n);
+                    return Poll::Ready(Ok(addr));
+                }
+            }
+        }
+    }
+
+    /// Receives data from the socket, without removing it from the input queue.
+    /// On success, returns the number of bytes read and the address from whence
+    /// the data came.
+    ///
+    /// # Notes
+    ///
+    /// On Windows, if the data is larger than the buffer specified, the buffer
+    /// is filled with the first part of the data, and peek_from returns the error
+    /// WSAEMSGSIZE(10040). The excess data is lost.
+    /// Make sure to always use a sufficiently large buffer to hold the
+    /// maximum UDP packet size, which can be up to 65536 bytes in size.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use tokio::net::UdpSocket;
+    /// # use std::{io, net::SocketAddr};
+    ///
+    /// # #[tokio::main]
+    /// # async fn main() -> io::Result<()> {
+    /// let sock = UdpSocket::bind("0.0.0.0:8080".parse::<SocketAddr>().unwrap()).await?;
+    /// let mut buf = [0u8; 32];
+    /// let (len, addr) = sock.peek_from(&mut buf).await?;
+    /// println!("peeked {:?} bytes from {:?}", len, addr);
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        self.io
+            .async_io(mio::Interest::READABLE, |sock| sock.peek_from(buf))
+            .await
+    }
+
+    /// Receives data from the socket, without removing it from the input queue.
+    /// On success, returns the number of bytes read.
+    ///
+    /// # Notes
+    ///
+    /// Note that on multiple calls to a `poll_*` method in the recv direction, only the
+    /// `Waker` from the `Context` passed to the most recent call will be scheduled to
+    /// receive a wakeup
+    ///
+    /// On Windows, if the data is larger than the buffer specified, the buffer
+    /// is filled with the first part of the data, and peek returns the error
+    /// WSAEMSGSIZE(10040). The excess data is lost.
+    /// Make sure to always use a sufficiently large buffer to hold the
+    /// maximum UDP packet size, which can be up to 65536 bytes in size.
+    ///
+    /// # Return value
+    ///
+    /// The function returns:
+    ///
+    /// * `Poll::Pending` if the socket is not ready to read
+    /// * `Poll::Ready(Ok(addr))` reads data from `addr` into `ReadBuf` if the socket is ready
+    /// * `Poll::Ready(Err(e))` if an error is encountered.
+    ///
+    /// # Errors
+    ///
+    /// This function may encounter any standard I/O error except `WouldBlock`.
+    pub fn poll_peek_from(
+        &self,
+        cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<SocketAddr>> {
+        loop {
+            let ev = ready!(self.io.poll_read_ready(cx))?;
+
+            // Safety: will not read the maybe uinitialized bytes.
+            let b = unsafe {
+                &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8])
+            };
+            match self.io.get_ref().peek_from(b) {
+                Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+                    self.io.clear_readiness(ev);
+                }
+                Err(e) => return Poll::Ready(Err(e)),
+                Ok((n, addr)) => {
+                    // Safety: We trust `recv` to have filled up `n` bytes
+                    // in the buffer.
+                    unsafe {
+                        buf.assume_init(n);
+                    }
+                    buf.advance(n);
+                    return Poll::Ready(Ok(addr));
+                }
+            }
+        }
+    }
+
     /// Gets the value of the `SO_BROADCAST` option for this socket.
     ///
     /// For more information about this option, see [`set_broadcast`].