Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

53 files changed, 9367 insertions, 0 deletions

diff --git a/third_party/rust/mio/src/event/event.rs b/third_party/rust/mio/src/event/event.rs
new file mode 100644
index 0000000000..1b4f7b7fbc
--- /dev/null
+++ b/third_party/rust/mio/src/event/event.rs
@@ -0,0 +1,230 @@
+use crate::{sys, Token};
+
+use std::fmt;
+
+/// A readiness event.
+///
+/// `Event` is a readiness state paired with a [`Token`]. It is returned by
+/// [`Poll::poll`].
+///
+/// For more documentation on polling and events, see [`Poll`].
+///
+/// [`Poll::poll`]: ../struct.Poll.html#method.poll
+/// [`Poll`]: ../struct.Poll.html
+/// [`Token`]: ../struct.Token.html
+#[derive(Clone)]
+#[repr(transparent)]
+pub struct Event {
+    inner: sys::Event,
+}
+
+impl Event {
+    /// Returns the event's token.
+    pub fn token(&self) -> Token {
+        sys::event::token(&self.inner)
+    }
+
+    /// Returns true if the event contains readable readiness.
+    ///
+    /// # Notes
+    ///
+    /// Out-of-band (OOB) data also triggers readable events. But must
+    /// application don't actually read OOB data, this could leave an
+    /// application open to a Denial-of-Service (Dos) attack, see
+    /// <https://github.com/sandstorm-io/sandstorm-website/blob/58f93346028c0576e8147627667328eaaf4be9fa/_posts/2015-04-08-osx-security-bug.md>.
+    /// However because Mio uses edge-triggers it will not result in an infinite
+    /// loop as described in the article above.
+    pub fn is_readable(&self) -> bool {
+        sys::event::is_readable(&self.inner)
+    }
+
+    /// Returns true if the event contains writable readiness.
+    pub fn is_writable(&self) -> bool {
+        sys::event::is_writable(&self.inner)
+    }
+
+    /// Returns true if the event contains error readiness.
+    ///
+    /// Error events occur when the socket enters an error state. In this case,
+    /// the socket will also receive a readable or writable event. Reading or
+    /// writing to the socket will result in an error.
+    ///
+    /// # Notes
+    ///
+    /// Method is available on all platforms, but not all platforms trigger the
+    /// error event.
+    ///
+    /// The table below shows what flags are checked on what OS.
+    ///
+    /// | [OS selector] | Flag(s) checked |
+    /// |---------------|-----------------|
+    /// | [epoll]       | `EPOLLERR`      |
+    /// | [kqueue]      | `EV_ERROR` and `EV_EOF` with `fflags` set to `0`. |
+    ///
+    /// [OS selector]: ../struct.Poll.html#implementation-notes
+    /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+    /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+    pub fn is_error(&self) -> bool {
+        sys::event::is_error(&self.inner)
+    }
+
+    /// Returns true if the event contains read closed readiness.
+    ///
+    /// # Notes
+    ///
+    /// Read closed readiness can be expected after any of the following have
+    /// occurred:
+    /// * The local stream has shutdown the read half of its socket
+    /// * The local stream has shutdown both the read half and the write half
+    ///   of its socket
+    /// * The peer stream has shutdown the write half its socket; this sends a
+    ///   `FIN` packet that has been received by the local stream
+    ///
+    /// Method is a best effort implementation. While some platforms may not
+    /// return readiness when read half is closed, it is guaranteed that
+    /// false-positives will not occur.
+    ///
+    /// The table below shows what flags are checked on what OS.
+    ///
+    /// | [OS selector] | Flag(s) checked |
+    /// |---------------|-----------------|
+    /// | [epoll]       | `EPOLLHUP`, or  |
+    /// |               | `EPOLLIN` and `EPOLLRDHUP` |
+    /// | [kqueue]      | `EV_EOF`        |
+    ///
+    /// [OS selector]: ../struct.Poll.html#implementation-notes
+    /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+    /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+    pub fn is_read_closed(&self) -> bool {
+        sys::event::is_read_closed(&self.inner)
+    }
+
+    /// Returns true if the event contains write closed readiness.
+    ///
+    /// # Notes
+    ///
+    /// On [epoll] this is essentially a check for `EPOLLHUP` flag as the
+    /// local stream shutting down its write half does not trigger this event.
+    ///
+    /// On [kqueue] the local stream shutting down the write half of its
+    /// socket will trigger this event.
+    ///
+    /// Method is a best effort implementation. While some platforms may not
+    /// return readiness when write half is closed, it is guaranteed that
+    /// false-positives will not occur.
+    ///
+    /// The table below shows what flags are checked on what OS.
+    ///
+    /// | [OS selector] | Flag(s) checked |
+    /// |---------------|-----------------|
+    /// | [epoll]       | `EPOLLHUP`, or  |
+    /// |               | only `EPOLLERR`, or |
+    /// |               | `EPOLLOUT` and `EPOLLERR` |
+    /// | [kqueue]      | `EV_EOF`        |
+    ///
+    /// [OS selector]: ../struct.Poll.html#implementation-notes
+    /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+    /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+    pub fn is_write_closed(&self) -> bool {
+        sys::event::is_write_closed(&self.inner)
+    }
+
+    /// Returns true if the event contains priority readiness.
+    ///
+    /// # Notes
+    ///
+    /// Method is available on all platforms, but not all platforms trigger the
+    /// priority event.
+    ///
+    /// The table below shows what flags are checked on what OS.
+    ///
+    /// | [OS selector] | Flag(s) checked |
+    /// |---------------|-----------------|
+    /// | [epoll]       | `EPOLLPRI`      |
+    /// | [kqueue]      | *Not supported* |
+    ///
+    /// [OS selector]: ../struct.Poll.html#implementation-notes
+    /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+    /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+    #[inline]
+    pub fn is_priority(&self) -> bool {
+        sys::event::is_priority(&self.inner)
+    }
+
+    /// Returns true if the event contains AIO readiness.
+    ///
+    /// # Notes
+    ///
+    /// Method is available on all platforms, but not all platforms support AIO.
+    ///
+    /// The table below shows what flags are checked on what OS.
+    ///
+    /// | [OS selector] | Flag(s) checked |
+    /// |---------------|-----------------|
+    /// | [epoll]       | *Not supported* |
+    /// | [kqueue]<sup>1</sup> | `EVFILT_AIO` |
+    ///
+    /// 1: Only supported on DragonFly BSD, FreeBSD, iOS and macOS.
+    ///
+    /// [OS selector]: ../struct.Poll.html#implementation-notes
+    /// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+    /// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+    pub fn is_aio(&self) -> bool {
+        sys::event::is_aio(&self.inner)
+    }
+
+    /// Returns true if the event contains LIO readiness.
+    ///
+    /// # Notes
+    ///
+    /// Method is available on all platforms, but only FreeBSD supports LIO. On
+    /// FreeBSD this method checks the `EVFILT_LIO` flag.
+    pub fn is_lio(&self) -> bool {
+        sys::event::is_lio(&self.inner)
+    }
+
+    /// Create a reference to an `Event` from a platform specific event.
+    pub(crate) fn from_sys_event_ref(sys_event: &sys::Event) -> &Event {
+        unsafe {
+            // This is safe because the memory layout of `Event` is
+            // the same as `sys::Event` due to the `repr(transparent)` attribute.
+            &*(sys_event as *const sys::Event as *const Event)
+        }
+    }
+}
+
+/// When the [alternate] flag is enabled this will print platform specific
+/// details, for example the fields of the `kevent` structure on platforms that
+/// use `kqueue(2)`. Note however that the output of this implementation is
+/// **not** consider a part of the stable API.
+///
+/// [alternate]: fmt::Formatter::alternate
+impl fmt::Debug for Event {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let alternate = f.alternate();
+        let mut d = f.debug_struct("Event");
+        d.field("token", &self.token())
+            .field("readable", &self.is_readable())
+            .field("writable", &self.is_writable())
+            .field("error", &self.is_error())
+            .field("read_closed", &self.is_read_closed())
+            .field("write_closed", &self.is_write_closed())
+            .field("priority", &self.is_priority())
+            .field("aio", &self.is_aio())
+            .field("lio", &self.is_lio());
+
+        if alternate {
+            struct EventDetails<'a>(&'a sys::Event);
+
+            impl<'a> fmt::Debug for EventDetails<'a> {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    sys::event::debug_details(f, self.0)
+                }
+            }
+
+            d.field("details", &EventDetails(&self.inner)).finish()
+        } else {
+            d.finish()
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/event/events.rs b/third_party/rust/mio/src/event/events.rs
new file mode 100644
index 0000000000..f3c5a2f02f
--- /dev/null
+++ b/third_party/rust/mio/src/event/events.rs
@@ -0,0 +1,230 @@
+use crate::event::Event;
+use crate::sys;
+
+use std::fmt;
+
+/// A collection of readiness events.
+///
+/// `Events` is passed as an argument to [`Poll::poll`] and will be used to
+/// receive any new readiness events received since the last poll. Usually, a
+/// single `Events` instance is created at the same time as a [`Poll`] and
+/// reused on each call to [`Poll::poll`].
+///
+/// See [`Poll`] for more documentation on polling.
+///
+/// [`Poll::poll`]: ../struct.Poll.html#method.poll
+/// [`Poll`]: ../struct.Poll.html
+///
+/// # Examples
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Events, Poll};
+/// use std::time::Duration;
+///
+/// let mut events = Events::with_capacity(1024);
+/// let mut poll = Poll::new()?;
+/// #
+/// # assert!(events.is_empty());
+///
+/// // Register `event::Source`s with `poll`.
+///
+/// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+///
+/// for event in events.iter() {
+///     println!("Got an event for {:?}", event.token());
+/// }
+/// #     Ok(())
+/// # }
+/// ```
+pub struct Events {
+    inner: sys::Events,
+}
+
+/// [`Events`] iterator.
+///
+/// This struct is created by the [`iter`] method on [`Events`].
+///
+/// [`Events`]: struct.Events.html
+/// [`iter`]: struct.Events.html#method.iter
+///
+/// # Examples
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Events, Poll};
+/// use std::time::Duration;
+///
+/// let mut events = Events::with_capacity(1024);
+/// let mut poll = Poll::new()?;
+///
+/// // Register handles with `poll`.
+///
+/// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+///
+/// for event in events.iter() {
+///     println!("Got an event for {:?}", event.token());
+/// }
+/// #     Ok(())
+/// # }
+/// ```
+#[derive(Debug, Clone)]
+pub struct Iter<'a> {
+    inner: &'a Events,
+    pos: usize,
+}
+
+impl Events {
+    /// Return a new `Events` capable of holding up to `capacity` events.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use mio::Events;
+    ///
+    /// let events = Events::with_capacity(1024);
+    /// assert_eq!(1024, events.capacity());
+    /// ```
+    pub fn with_capacity(capacity: usize) -> Events {
+        Events {
+            inner: sys::Events::with_capacity(capacity),
+        }
+    }
+
+    /// Returns the number of `Event` values that `self` can hold.
+    ///
+    /// ```
+    /// use mio::Events;
+    ///
+    /// let events = Events::with_capacity(1024);
+    /// assert_eq!(1024, events.capacity());
+    /// ```
+    pub fn capacity(&self) -> usize {
+        self.inner.capacity()
+    }
+
+    /// Returns `true` if `self` contains no `Event` values.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use mio::Events;
+    ///
+    /// let events = Events::with_capacity(1024);
+    /// assert!(events.is_empty());
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    /// Returns an iterator over the `Event` values.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Events, Poll};
+    /// use std::time::Duration;
+    ///
+    /// let mut events = Events::with_capacity(1024);
+    /// let mut poll = Poll::new()?;
+    ///
+    /// // Register handles with `poll`.
+    ///
+    /// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+    ///
+    /// for event in events.iter() {
+    ///     println!("Got an event for {:?}", event.token());
+    /// }
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn iter(&self) -> Iter<'_> {
+        Iter {
+            inner: self,
+            pos: 0,
+        }
+    }
+
+    /// Clearing all `Event` values from container explicitly.
+    ///
+    /// # Notes
+    ///
+    /// Events are cleared before every `poll`, so it is not required to call
+    /// this manually.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Events, Poll};
+    /// use std::time::Duration;
+    ///
+    /// let mut events = Events::with_capacity(1024);
+    /// let mut poll = Poll::new()?;
+    ///
+    /// // Register handles with `poll`.
+    ///
+    /// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+    ///
+    /// // Clear all events.
+    /// events.clear();
+    /// assert!(events.is_empty());
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn clear(&mut self) {
+        self.inner.clear();
+    }
+
+    /// Returns the inner `sys::Events`.
+    pub(crate) fn sys(&mut self) -> &mut sys::Events {
+        &mut self.inner
+    }
+}
+
+impl<'a> IntoIterator for &'a Events {
+    type Item = &'a Event;
+    type IntoIter = Iter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = &'a Event;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let ret = self
+            .inner
+            .inner
+            .get(self.pos)
+            .map(Event::from_sys_event_ref);
+        self.pos += 1;
+        ret
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        let size = self.inner.inner.len();
+        (size, Some(size))
+    }
+
+    fn count(self) -> usize {
+        self.inner.inner.len()
+    }
+}
+
+impl fmt::Debug for Events {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_list().entries(self).finish()
+    }
+}
diff --git a/third_party/rust/mio/src/event/mod.rs b/third_party/rust/mio/src/event/mod.rs
new file mode 100644
index 0000000000..8e17f82ee5
--- /dev/null
+++ b/third_party/rust/mio/src/event/mod.rs
@@ -0,0 +1,10 @@
+//! Readiness event types and utilities.
+
+#[allow(clippy::module_inception)]
+mod event;
+mod events;
+mod source;
+
+pub use self::event::Event;
+pub use self::events::{Events, Iter};
+pub use self::source::Source;
diff --git a/third_party/rust/mio/src/event/source.rs b/third_party/rust/mio/src/event/source.rs
new file mode 100644
index 0000000000..4f9c6635a1
--- /dev/null
+++ b/third_party/rust/mio/src/event/source.rs
@@ -0,0 +1,139 @@
+use crate::{Interest, Registry, Token};
+
+use std::io;
+
+/// An event source that may be registered with [`Registry`].
+///
+/// Types that implement `event::Source` can be registered with
+/// `Registry`. Users of Mio **should not** use the `event::Source` trait
+/// functions directly. Instead, the equivalent functions on `Registry` should
+/// be used.
+///
+/// See [`Registry`] for more details.
+///
+/// [`Registry`]: ../struct.Registry.html
+///
+/// # Implementing `event::Source`
+///
+/// Event sources are always backed by system handles, such as sockets or other
+/// system handles. These `event::Source`s will be monitored by the system
+/// selector. An implementation of `Source` will almost always delegates to a
+/// lower level handle. Examples of this are [`TcpStream`]s, or the *unix only*
+/// [`SourceFd`].
+///
+/// [`TcpStream`]: ../net/struct.TcpStream.html
+/// [`SourceFd`]: ../unix/struct.SourceFd.html
+///
+/// # Dropping `event::Source`s
+///
+/// All `event::Source`s, unless otherwise specified, need to be [deregistered]
+/// before being dropped for them to not leak resources. This goes against the
+/// normal drop behaviour of types in Rust which cleanup after themselves, e.g.
+/// a `File` will close itself. However since deregistering needs access to
+/// [`Registry`] this cannot be done while being dropped.
+///
+/// [deregistered]: ../struct.Registry.html#method.deregister
+///
+/// # Examples
+///
+/// Implementing `Source` on a struct containing a socket:
+///
+#[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+#[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+/// use mio::{Interest, Registry, Token};
+/// use mio::event::Source;
+/// use mio::net::TcpStream;
+///
+/// use std::io;
+///
+/// # #[allow(dead_code)]
+/// pub struct MySource {
+///     socket: TcpStream,
+/// }
+///
+/// impl Source for MySource {
+///     fn register(&mut self, registry: &Registry, token: Token, interests: Interest)
+///         -> io::Result<()>
+///     {
+///         // Delegate the `register` call to `socket`
+///         self.socket.register(registry, token, interests)
+///     }
+///
+///     fn reregister(&mut self, registry: &Registry, token: Token, interests: Interest)
+///         -> io::Result<()>
+///     {
+///         // Delegate the `reregister` call to `socket`
+///         self.socket.reregister(registry, token, interests)
+///     }
+///
+///     fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+///         // Delegate the `deregister` call to `socket`
+///         self.socket.deregister(registry)
+///     }
+/// }
+/// ```
+pub trait Source {
+    /// Register `self` with the given `Registry` instance.
+    ///
+    /// This function should not be called directly. Use [`Registry::register`]
+    /// instead. Implementors should handle registration by delegating the call
+    /// to another `Source` type.
+    ///
+    /// [`Registry::register`]: ../struct.Registry.html#method.register
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()>;
+
+    /// Re-register `self` with the given `Registry` instance.
+    ///
+    /// This function should not be called directly. Use
+    /// [`Registry::reregister`] instead. Implementors should handle
+    /// re-registration by either delegating the call to another `Source` type.
+    ///
+    /// [`Registry::reregister`]: ../struct.Registry.html#method.reregister
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()>;
+
+    /// Deregister `self` from the given `Registry` instance.
+    ///
+    /// This function should not be called directly. Use
+    /// [`Registry::deregister`] instead. Implementors should handle
+    /// deregistration by delegating the call to another `Source` type.
+    ///
+    /// [`Registry::deregister`]: ../struct.Registry.html#method.deregister
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()>;
+}
+
+impl<T> Source for Box<T>
+where
+    T: Source + ?Sized,
+{
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        (&mut **self).register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        (&mut **self).reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        (&mut **self).deregister(registry)
+    }
+}
diff --git a/third_party/rust/mio/src/interest.rs b/third_party/rust/mio/src/interest.rs
new file mode 100644
index 0000000000..0aa0bda895
--- /dev/null
+++ b/third_party/rust/mio/src/interest.rs
@@ -0,0 +1,179 @@
+use std::num::NonZeroU8;
+use std::{fmt, ops};
+
+/// Interest used in registering.
+///
+/// Interest are used in [registering] [`event::Source`]s with [`Poll`], they
+/// indicate what readiness should be monitored for. For example if a socket is
+/// registered with [readable] interests and the socket becomes writable, no
+/// event will be returned from a call to [`poll`].
+///
+/// [registering]: struct.Registry.html#method.register
+/// [`event::Source`]: ./event/trait.Source.html
+/// [`Poll`]: struct.Poll.html
+/// [readable]: struct.Interest.html#associatedconstant.READABLE
+/// [`poll`]: struct.Poll.html#method.poll
+#[derive(Copy, PartialEq, Eq, Clone, PartialOrd, Ord)]
+pub struct Interest(NonZeroU8);
+
+// These must be unique.
+const READABLE: u8 = 0b0001;
+const WRITABLE: u8 = 0b0010;
+// The following are not available on all platforms.
+#[cfg_attr(
+    not(any(
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "ios",
+        target_os = "macos"
+    )),
+    allow(dead_code)
+)]
+const AIO: u8 = 0b0100;
+#[cfg_attr(not(target_os = "freebsd"), allow(dead_code))]
+const LIO: u8 = 0b1000;
+
+impl Interest {
+    /// Returns a `Interest` set representing readable interests.
+    pub const READABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(READABLE) });
+
+    /// Returns a `Interest` set representing writable interests.
+    pub const WRITABLE: Interest = Interest(unsafe { NonZeroU8::new_unchecked(WRITABLE) });
+
+    /// Returns a `Interest` set representing AIO completion interests.
+    #[cfg(any(
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "ios",
+        target_os = "macos"
+    ))]
+    pub const AIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(AIO) });
+
+    /// Returns a `Interest` set representing LIO completion interests.
+    #[cfg(target_os = "freebsd")]
+    pub const LIO: Interest = Interest(unsafe { NonZeroU8::new_unchecked(LIO) });
+
+    /// Add together two `Interest`.
+    ///
+    /// This does the same thing as the `BitOr` implementation, but is a
+    /// constant function.
+    ///
+    /// ```
+    /// use mio::Interest;
+    ///
+    /// const INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
+    /// # fn silent_dead_code_warning(_: Interest) { }
+    /// # silent_dead_code_warning(INTERESTS)
+    /// ```
+    #[allow(clippy::should_implement_trait)]
+    pub const fn add(self, other: Interest) -> Interest {
+        Interest(unsafe { NonZeroU8::new_unchecked(self.0.get() | other.0.get()) })
+    }
+
+    /// Removes `other` `Interest` from `self`.
+    ///
+    /// Returns `None` if the set would be empty after removing `other`.
+    ///
+    /// ```
+    /// use mio::Interest;
+    ///
+    /// const RW_INTERESTS: Interest = Interest::READABLE.add(Interest::WRITABLE);
+    ///
+    /// // As long a one interest remain this will return `Some`.
+    /// let w_interest = RW_INTERESTS.remove(Interest::READABLE).unwrap();
+    /// assert!(!w_interest.is_readable());
+    /// assert!(w_interest.is_writable());
+    ///
+    /// // Removing all interests from the set will return `None`.
+    /// assert_eq!(w_interest.remove(Interest::WRITABLE), None);
+    ///
+    /// // Its also possible to remove multiple interests at once.
+    /// assert_eq!(RW_INTERESTS.remove(RW_INTERESTS), None);
+    /// ```
+    pub fn remove(self, other: Interest) -> Option<Interest> {
+        NonZeroU8::new(self.0.get() & !other.0.get()).map(Interest)
+    }
+
+    /// Returns true if the value includes readable readiness.
+    pub const fn is_readable(self) -> bool {
+        (self.0.get() & READABLE) != 0
+    }
+
+    /// Returns true if the value includes writable readiness.
+    pub const fn is_writable(self) -> bool {
+        (self.0.get() & WRITABLE) != 0
+    }
+
+    /// Returns true if `Interest` contains AIO readiness
+    pub const fn is_aio(self) -> bool {
+        (self.0.get() & AIO) != 0
+    }
+
+    /// Returns true if `Interest` contains LIO readiness
+    pub const fn is_lio(self) -> bool {
+        (self.0.get() & LIO) != 0
+    }
+}
+
+impl ops::BitOr for Interest {
+    type Output = Self;
+
+    #[inline]
+    fn bitor(self, other: Self) -> Self {
+        self.add(other)
+    }
+}
+
+impl ops::BitOrAssign for Interest {
+    #[inline]
+    fn bitor_assign(&mut self, other: Self) {
+        self.0 = (*self | other).0;
+    }
+}
+
+impl fmt::Debug for Interest {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut one = false;
+        if self.is_readable() {
+            if one {
+                write!(fmt, " | ")?
+            }
+            write!(fmt, "READABLE")?;
+            one = true
+        }
+        if self.is_writable() {
+            if one {
+                write!(fmt, " | ")?
+            }
+            write!(fmt, "WRITABLE")?;
+            one = true
+        }
+        #[cfg(any(
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "ios",
+            target_os = "macos"
+        ))]
+        {
+            if self.is_aio() {
+                if one {
+                    write!(fmt, " | ")?
+                }
+                write!(fmt, "AIO")?;
+                one = true
+            }
+        }
+        #[cfg(any(target_os = "freebsd"))]
+        {
+            if self.is_lio() {
+                if one {
+                    write!(fmt, " | ")?
+                }
+                write!(fmt, "LIO")?;
+                one = true
+            }
+        }
+        debug_assert!(one, "printing empty interests");
+        Ok(())
+    }
+}
diff --git a/third_party/rust/mio/src/io_source.rs b/third_party/rust/mio/src/io_source.rs
new file mode 100644
index 0000000000..ae1cbf3767
--- /dev/null
+++ b/third_party/rust/mio/src/io_source.rs
@@ -0,0 +1,294 @@
+use std::ops::{Deref, DerefMut};
+#[cfg(unix)]
+use std::os::unix::io::AsRawFd;
+#[cfg(windows)]
+use std::os::windows::io::AsRawSocket;
+#[cfg(debug_assertions)]
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::{fmt, io};
+
+use crate::sys::IoSourceState;
+use crate::{event, Interest, Registry, Token};
+
+/// Adapter for a [`RawFd`] or [`RawSocket`] providing an [`event::Source`]
+/// implementation.
+///
+/// `IoSource` enables registering any FD or socket wrapper with [`Poll`].
+///
+/// While only implementations for TCP, UDP, and UDS (Unix only) are provided,
+/// Mio supports registering any FD or socket that can be registered with the
+/// underlying OS selector. `IoSource` provides the necessary bridge.
+///
+/// [`RawFd`]: std::os::unix::io::RawFd
+/// [`RawSocket`]: std::os::windows::io::RawSocket
+///
+/// # Notes
+///
+/// To handle the registrations and events properly **all** I/O operations (such
+/// as `read`, `write`, etc.) must go through the [`do_io`] method to ensure the
+/// internal state is updated accordingly.
+///
+/// [`Poll`]: crate::Poll
+/// [`do_io`]: IoSource::do_io
+/*
+///
+/// # Examples
+///
+/// Basic usage.
+///
+/// ```
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Interest, Poll, Token};
+/// use mio::IoSource;
+///
+/// use std::net;
+///
+/// let poll = Poll::new()?;
+///
+/// // Bind a std TCP listener.
+/// let listener = net::TcpListener::bind("127.0.0.1:0")?;
+/// // Wrap it in the `IoSource` type.
+/// let mut listener = IoSource::new(listener);
+///
+/// // Register the listener.
+/// poll.registry().register(&mut listener, Token(0), Interest::READABLE)?;
+/// #     Ok(())
+/// # }
+/// ```
+*/
+pub struct IoSource<T> {
+    state: IoSourceState,
+    inner: T,
+    #[cfg(debug_assertions)]
+    selector_id: SelectorId,
+}
+
+impl<T> IoSource<T> {
+    /// Create a new `IoSource`.
+    pub fn new(io: T) -> IoSource<T> {
+        IoSource {
+            state: IoSourceState::new(),
+            inner: io,
+            #[cfg(debug_assertions)]
+            selector_id: SelectorId::new(),
+        }
+    }
+
+    /// Execute an I/O operations ensuring that the socket receives more events
+    /// if it hits a [`WouldBlock`] error.
+    ///
+    /// # Notes
+    ///
+    /// This method is required to be called for **all** I/O operations to
+    /// ensure the user will receive events once the socket is ready again after
+    /// returning a [`WouldBlock`] error.
+    ///
+    /// [`WouldBlock`]: io::ErrorKind::WouldBlock
+    pub fn do_io<F, R>(&self, f: F) -> io::Result<R>
+    where
+        F: FnOnce(&T) -> io::Result<R>,
+    {
+        self.state.do_io(f, &self.inner)
+    }
+
+    /// Returns the I/O source, dropping the state.
+    ///
+    /// # Notes
+    ///
+    /// To ensure no more events are to be received for this I/O source first
+    /// [`deregister`] it.
+    ///
+    /// [`deregister`]: Registry::deregister
+    pub fn into_inner(self) -> T {
+        self.inner
+    }
+}
+
+/// Be careful when using this method. All I/O operations that may block must go
+/// through the [`do_io`] method.
+///
+/// [`do_io`]: IoSource::do_io
+impl<T> Deref for IoSource<T> {
+    type Target = T;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+/// Be careful when using this method. All I/O operations that may block must go
+/// through the [`do_io`] method.
+///
+/// [`do_io`]: IoSource::do_io
+impl<T> DerefMut for IoSource<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.inner
+    }
+}
+
+#[cfg(unix)]
+impl<T> event::Source for IoSource<T>
+where
+    T: AsRawFd,
+{
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.associate(registry)?;
+        registry
+            .selector()
+            .register(self.inner.as_raw_fd(), token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.check_association(registry)?;
+        registry
+            .selector()
+            .reregister(self.inner.as_raw_fd(), token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.remove_association(registry)?;
+        registry.selector().deregister(self.inner.as_raw_fd())
+    }
+}
+
+#[cfg(windows)]
+impl<T> event::Source for IoSource<T>
+where
+    T: AsRawSocket,
+{
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.associate(registry)?;
+        self.state
+            .register(registry, token, interests, self.inner.as_raw_socket())
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.check_association(registry)?;
+        self.state.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, _registry: &Registry) -> io::Result<()> {
+        #[cfg(debug_assertions)]
+        self.selector_id.remove_association(_registry)?;
+        self.state.deregister()
+    }
+}
+
+impl<T> fmt::Debug for IoSource<T>
+where
+    T: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+/// Used to associate an `IoSource` with a `sys::Selector`.
+#[cfg(debug_assertions)]
+#[derive(Debug)]
+struct SelectorId {
+    id: AtomicUsize,
+}
+
+#[cfg(debug_assertions)]
+impl SelectorId {
+    /// Value of `id` if `SelectorId` is not associated with any
+    /// `sys::Selector`. Valid selector ids start at 1.
+    const UNASSOCIATED: usize = 0;
+
+    /// Create a new `SelectorId`.
+    const fn new() -> SelectorId {
+        SelectorId {
+            id: AtomicUsize::new(Self::UNASSOCIATED),
+        }
+    }
+
+    /// Associate an I/O source with `registry`, returning an error if its
+    /// already registered.
+    fn associate(&self, registry: &Registry) -> io::Result<()> {
+        let registry_id = registry.selector().id();
+        let previous_id = self.id.swap(registry_id, Ordering::AcqRel);
+
+        if previous_id == Self::UNASSOCIATED {
+            Ok(())
+        } else {
+            Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                "I/O source already registered with a `Registry`",
+            ))
+        }
+    }
+
+    /// Check the association of an I/O source with `registry`, returning an
+    /// error if its registered with a different `Registry` or not registered at
+    /// all.
+    fn check_association(&self, registry: &Registry) -> io::Result<()> {
+        let registry_id = registry.selector().id();
+        let id = self.id.load(Ordering::Acquire);
+
+        if id == registry_id {
+            Ok(())
+        } else if id == Self::UNASSOCIATED {
+            Err(io::Error::new(
+                io::ErrorKind::NotFound,
+                "I/O source not registered with `Registry`",
+            ))
+        } else {
+            Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                "I/O source already registered with a different `Registry`",
+            ))
+        }
+    }
+
+    /// Remove a previously made association from `registry`, returns an error
+    /// if it was not previously associated with `registry`.
+    fn remove_association(&self, registry: &Registry) -> io::Result<()> {
+        let registry_id = registry.selector().id();
+        let previous_id = self.id.swap(Self::UNASSOCIATED, Ordering::AcqRel);
+
+        if previous_id == registry_id {
+            Ok(())
+        } else {
+            Err(io::Error::new(
+                io::ErrorKind::NotFound,
+                "I/O source not registered with `Registry`",
+            ))
+        }
+    }
+}
+
+#[cfg(debug_assertions)]
+impl Clone for SelectorId {
+    fn clone(&self) -> SelectorId {
+        SelectorId {
+            id: AtomicUsize::new(self.id.load(Ordering::Acquire)),
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/lib.rs b/third_party/rust/mio/src/lib.rs
new file mode 100644
index 0000000000..7a0797c77f
--- /dev/null
+++ b/third_party/rust/mio/src/lib.rs
@@ -0,0 +1,264 @@
+#![deny(
+    missing_docs,
+    missing_debug_implementations,
+    rust_2018_idioms,
+    unused_imports,
+    dead_code
+)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+// Disallow warnings when running tests.
+#![cfg_attr(test, deny(warnings))]
+// Disallow warnings in examples.
+#![doc(test(attr(deny(warnings))))]
+
+//! Mio is a fast, low-level I/O library for Rust focusing on non-blocking APIs
+//! and event notification for building high performance I/O apps with as little
+//! overhead as possible over the OS abstractions.
+//!
+//! # Usage
+//!
+//! Using Mio starts by creating a [`Poll`], which reads events from the OS and
+//! puts them into [`Events`]. You can handle I/O events from the OS with it.
+//!
+//! For more detail, see [`Poll`].
+//!
+//! [`Poll`]: ../mio/struct.Poll.html
+//! [`Events`]: ../mio/event/struct.Events.html
+//!
+//! ## Examples
+//!
+//! Examples can found in the `examples` directory of the source code, or [on
+//! GitHub].
+//!
+//! [on GitHub]: https://github.com/tokio-rs/mio/tree/master/examples
+//!
+//! ## Guide
+//!
+//! A getting started guide is available in the [`guide`] module.
+//!
+//! ## Available features
+//!
+//! The available features are described in the [`features`] module.
+
+// macros used internally
+#[macro_use]
+mod macros;
+
+mod interest;
+mod poll;
+mod sys;
+mod token;
+mod waker;
+
+pub mod event;
+
+cfg_io_source! {
+    mod io_source;
+}
+
+cfg_net! {
+    pub mod net;
+}
+
+#[doc(no_inline)]
+pub use event::Events;
+pub use interest::Interest;
+pub use poll::{Poll, Registry};
+pub use token::Token;
+pub use waker::Waker;
+
+#[cfg(all(unix, feature = "os-ext"))]
+#[cfg_attr(docsrs, doc(cfg(all(unix, feature = "os-ext"))))]
+pub mod unix {
+    //! Unix only extensions.
+
+    pub mod pipe {
+        //! Unix pipe.
+        //!
+        //! See the [`new`] function for documentation.
+
+        pub use crate::sys::pipe::{new, Receiver, Sender};
+    }
+
+    pub use crate::sys::SourceFd;
+}
+
+#[cfg(all(windows, feature = "os-ext"))]
+#[cfg_attr(docsrs, doc(cfg(all(windows, feature = "os-ext"))))]
+pub mod windows {
+    //! Windows only extensions.
+
+    pub use crate::sys::named_pipe::NamedPipe;
+}
+
+pub mod features {
+    //! # Mio's optional features.
+    //!
+    //! This document describes the available features in Mio.
+    //!
+    #![cfg_attr(feature = "os-poll", doc = "## `os-poll` (enabled)")]
+    #![cfg_attr(not(feature = "os-poll"), doc = "## `os-poll` (disabled)")]
+    //!
+    //! Mio by default provides only a shell implementation, that `panic!`s the
+    //! moment it is actually run. To run it requires OS support, this is
+    //! enabled by activating the `os-poll` feature.
+    //!
+    //! This makes `Poll`, `Registry` and `Waker` functional.
+    //!
+    #![cfg_attr(feature = "os-ext", doc = "## `os-ext` (enabled)")]
+    #![cfg_attr(not(feature = "os-ext"), doc = "## `os-ext` (disabled)")]
+    //!
+    //! `os-ext` enables additional OS specific facilities. These facilities can
+    //! be found in the `unix` and `windows` module.
+    //!
+    #![cfg_attr(feature = "net", doc = "## Network types (enabled)")]
+    #![cfg_attr(not(feature = "net"), doc = "## Network types (disabled)")]
+    //!
+    //! The `net` feature enables networking primitives in the `net` module.
+}
+
+pub mod guide {
+    //! # Getting started guide.
+    //!
+    //! In this guide we'll do the following:
+    //!
+    //! 1. Create a [`Poll`] instance (and learn what it is).
+    //! 2. Register an [event source].
+    //! 3. Create an event loop.
+    //!
+    //! At the end you'll have a very small (but quick) TCP server that accepts
+    //! connections and then drops (disconnects) them.
+    //!
+    //! ## 1. Creating a `Poll` instance
+    //!
+    //! Using Mio starts by creating a [`Poll`] instance, which monitors events
+    //! from the OS and puts them into [`Events`]. This allows us to execute I/O
+    //! operations based on what operations are ready.
+    //!
+    //! [`Poll`]: ../struct.Poll.html
+    //! [`Events`]: ../event/struct.Events.html
+    //!
+    #![cfg_attr(feature = "os-poll", doc = "```")]
+    #![cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    //! # use mio::{Poll, Events};
+    //! # fn main() -> std::io::Result<()> {
+    //! // `Poll` allows for polling of readiness events.
+    //! let poll = Poll::new()?;
+    //! // `Events` is collection of readiness `Event`s and can be filled by
+    //! // calling `Poll::poll`.
+    //! let events = Events::with_capacity(128);
+    //! # drop((poll, events));
+    //! # Ok(())
+    //! # }
+    //! ```
+    //!
+    //! For example if we're using a [`TcpListener`],  we'll only want to
+    //! attempt to accept an incoming connection *iff* any connections are
+    //! queued and ready to be accepted. We don't want to waste our time if no
+    //! connections are ready.
+    //!
+    //! [`TcpListener`]: ../net/struct.TcpListener.html
+    //!
+    //! ## 2. Registering event source
+    //!
+    //! After we've created a [`Poll`] instance that monitors events from the OS
+    //! for us, we need to provide it with a source of events. This is done by
+    //! registering an [event source]. As the name “event source” suggests it is
+    //! a source of events which can be polled using a `Poll` instance. On Unix
+    //! systems this is usually a file descriptor, or a socket/handle on
+    //! Windows.
+    //!
+    //! In the example below we'll use a [`TcpListener`] for which we'll receive
+    //! an event (from [`Poll`]) once a connection is ready to be accepted.
+    //!
+    //! [event source]: ../event/trait.Source.html
+    //!
+    #![cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #![cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    //! # use mio::net::TcpListener;
+    //! # use mio::{Poll, Token, Interest};
+    //! # fn main() -> std::io::Result<()> {
+    //! # let poll = Poll::new()?;
+    //! # let address = "127.0.0.1:0".parse().unwrap();
+    //! // Create a `TcpListener`, binding it to `address`.
+    //! let mut listener = TcpListener::bind(address)?;
+    //!
+    //! // Next we register it with `Poll` to receive events for it. The `SERVER`
+    //! // `Token` is used to determine that we received an event for the listener
+    //! // later on.
+    //! const SERVER: Token = Token(0);
+    //! poll.registry().register(&mut listener, SERVER, Interest::READABLE)?;
+    //! # Ok(())
+    //! # }
+    //! ```
+    //!
+    //! Multiple event sources can be [registered] (concurrently), so we can
+    //! monitor multiple sources at a time.
+    //!
+    //! [registered]: ../struct.Registry.html#method.register
+    //!
+    //! ## 3. Creating the event loop
+    //!
+    //! After we've created a [`Poll`] instance and registered one or more
+    //! [event sources] with it, we can [poll] it for events. Polling for events
+    //! is simple, we need a container to store the events: [`Events`] and need
+    //! to do something based on the polled events (this part is up to you, we
+    //! can't do it all!). If we do this in a loop we've got ourselves an event
+    //! loop.
+    //!
+    //! The example below shows the event loop in action, completing our small
+    //! TCP server.
+    //!
+    //! [poll]: ../struct.Poll.html#method.poll
+    //! [event sources]: ../event/trait.Source.html
+    //!
+    #![cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #![cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    //! # use std::io;
+    //! # use std::time::Duration;
+    //! # use mio::net::TcpListener;
+    //! # use mio::{Poll, Token, Interest, Events};
+    //! # fn main() -> io::Result<()> {
+    //! # let mut poll = Poll::new()?;
+    //! # let mut events = Events::with_capacity(128);
+    //! # let address = "127.0.0.1:0".parse().unwrap();
+    //! # let mut listener = TcpListener::bind(address)?;
+    //! # const SERVER: Token = Token(0);
+    //! # poll.registry().register(&mut listener, SERVER, Interest::READABLE)?;
+    //! // Start our event loop.
+    //! loop {
+    //!     // Poll the OS for events, waiting at most 100 milliseconds.
+    //!     poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+    //!
+    //!     // Process each event.
+    //!     for event in events.iter() {
+    //!         // We can use the token we previously provided to `register` to
+    //!         // determine for which type the event is.
+    //!         match event.token() {
+    //!             SERVER => loop {
+    //!                 // One or more connections are ready, so we'll attempt to
+    //!                 // accept them (in a loop).
+    //!                 match listener.accept() {
+    //!                     Ok((connection, address)) => {
+    //!                         println!("Got a connection from: {}", address);
+    //! #                       drop(connection);
+    //!                     },
+    //!                     // A "would block error" is returned if the operation
+    //!                     // is not ready, so we'll stop trying to accept
+    //!                     // connections.
+    //!                     Err(ref err) if would_block(err) => break,
+    //!                     Err(err) => return Err(err),
+    //!                 }
+    //!             }
+    //! #           _ => unreachable!(),
+    //!         }
+    //!     }
+    //! #   return Ok(());
+    //! }
+    //!
+    //! fn would_block(err: &io::Error) -> bool {
+    //!     err.kind() == io::ErrorKind::WouldBlock
+    //! }
+    //! # }
+    //! ```
+}
diff --git a/third_party/rust/mio/src/macros.rs b/third_party/rust/mio/src/macros.rs
new file mode 100644
index 0000000000..f97f90911f
--- /dev/null
+++ b/third_party/rust/mio/src/macros.rs
@@ -0,0 +1,70 @@
+//! Macros to ease conditional code based on enabled features.
+
+// Depending on the features not all macros are used.
+#![allow(unused_macros)]
+
+/// The `os-poll` feature is enabled.
+macro_rules! cfg_os_poll {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "os-poll")]
+            #[cfg_attr(docsrs, doc(cfg(feature = "os-poll")))]
+            $item
+        )*
+    }
+}
+
+/// The `os-poll` feature is disabled.
+macro_rules! cfg_not_os_poll {
+    ($($item:item)*) => {
+        $(
+            #[cfg(not(feature = "os-poll"))]
+            $item
+        )*
+    }
+}
+
+/// The `os-ext` feature is enabled.
+macro_rules! cfg_os_ext {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "os-ext")]
+            #[cfg_attr(docsrs, doc(cfg(feature = "os-ext")))]
+            $item
+        )*
+    }
+}
+
+/// The `net` feature is enabled.
+macro_rules! cfg_net {
+    ($($item:item)*) => {
+        $(
+            #[cfg(feature = "net")]
+            #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+            $item
+        )*
+    }
+}
+
+/// One of the features enabled that needs `IoSource`. That is `net` or `os-ext`
+/// on Unix (for `pipe`).
+macro_rules! cfg_io_source {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(feature = "net", all(unix, feature = "os-ext")))]
+            #[cfg_attr(docsrs, doc(cfg(any(feature = "net", all(unix, feature = "os-ext")))))]
+            $item
+        )*
+    }
+}
+
+/// The `os-ext` feature is enabled, or one of the features that need `os-ext`.
+macro_rules! cfg_any_os_ext {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(feature = "os-ext", feature = "net"))]
+            #[cfg_attr(docsrs, doc(cfg(any(feature = "os-ext", feature = "net"))))]
+            $item
+        )*
+    }
+}
diff --git a/third_party/rust/mio/src/net/mod.rs b/third_party/rust/mio/src/net/mod.rs
new file mode 100644
index 0000000000..c8cef17e98
--- /dev/null
+++ b/third_party/rust/mio/src/net/mod.rs
@@ -0,0 +1,37 @@
+//! Networking primitives.
+//!
+//! The types provided in this module are non-blocking by default and are
+//! designed to be portable across all supported Mio platforms. As long as the
+//! [portability guidelines] are followed, the behavior should be identical no
+//! matter the target platform.
+//!
+//! [portability guidelines]: ../struct.Poll.html#portability
+//!
+//! # Notes
+//!
+//! When using a datagram based socket, i.e. [`UdpSocket`] or [`UnixDatagram`],
+//! its only possible to receive a packet once. This means that if you provide a
+//! buffer that is too small you won't be able to receive the data anymore. How
+//! OSs deal with this situation is different for each OS:
+//!  * Unixes, such as Linux, FreeBSD and macOS, will simply fill the buffer and
+//!    return the amount of bytes written. This means that if the returned value
+//!    is equal to the size of the buffer it may have only written a part of the
+//!    packet (or the packet has the same size as the buffer).
+//!  * Windows returns an `WSAEMSGSIZE` error.
+//!
+//! Mio does not change the value (either ok or error) returned by the OS, it's
+//! up to the user handle this. How to deal with these difference is still up
+//! for debate, specifically in
+//! <https://github.com/rust-lang/rust/issues/55794>. The best advice we can
+//! give is to always call receive with a large enough buffer.
+
+mod tcp;
+pub use self::tcp::{TcpListener, TcpStream};
+
+mod udp;
+pub use self::udp::UdpSocket;
+
+#[cfg(unix)]
+mod uds;
+#[cfg(unix)]
+pub use self::uds::{SocketAddr, UnixDatagram, UnixListener, UnixStream};
diff --git a/third_party/rust/mio/src/net/tcp/listener.rs b/third_party/rust/mio/src/net/tcp/listener.rs
new file mode 100644
index 0000000000..21bffbaffc
--- /dev/null
+++ b/third_party/rust/mio/src/net/tcp/listener.rs
@@ -0,0 +1,217 @@
+use std::net::{self, SocketAddr};
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+#[cfg(windows)]
+use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+use std::{fmt, io};
+
+use crate::io_source::IoSource;
+use crate::net::TcpStream;
+#[cfg(unix)]
+use crate::sys::tcp::set_reuseaddr;
+use crate::sys::tcp::{bind, listen, new_for_addr};
+use crate::{event, sys, Interest, Registry, Token};
+
+/// A structure representing a socket server
+///
+/// # Examples
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Events, Interest, Poll, Token};
+/// use mio::net::TcpListener;
+/// use std::time::Duration;
+///
+/// let mut listener = TcpListener::bind("127.0.0.1:34255".parse()?)?;
+///
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(128);
+///
+/// // Register the socket with `Poll`
+/// poll.registry().register(&mut listener, Token(0), Interest::READABLE)?;
+///
+/// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+///
+/// // There may be a socket ready to be accepted
+/// #     Ok(())
+/// # }
+/// ```
+pub struct TcpListener {
+    inner: IoSource<net::TcpListener>,
+}
+
+impl TcpListener {
+    /// Convenience method to bind a new TCP listener to the specified address
+    /// to receive new connections.
+    ///
+    /// This function will take the following steps:
+    ///
+    /// 1. Create a new TCP socket.
+    /// 2. Set the `SO_REUSEADDR` option on the socket on Unix.
+    /// 3. Bind the socket to the specified address.
+    /// 4. Calls `listen` on the socket to prepare it to receive new connections.
+    pub fn bind(addr: SocketAddr) -> io::Result<TcpListener> {
+        let socket = new_for_addr(addr)?;
+        #[cfg(unix)]
+        let listener = unsafe { TcpListener::from_raw_fd(socket) };
+        #[cfg(windows)]
+        let listener = unsafe { TcpListener::from_raw_socket(socket as _) };
+
+        // On platforms with Berkeley-derived sockets, this allows to quickly
+        // rebind a socket, without needing to wait for the OS to clean up the
+        // previous one.
+        //
+        // On Windows, this allows rebinding sockets which are actively in use,
+        // which allows “socket hijacking”, so we explicitly don't set it here.
+        // https://docs.microsoft.com/en-us/windows/win32/winsock/using-so-reuseaddr-and-so-exclusiveaddruse
+        #[cfg(not(windows))]
+        set_reuseaddr(&listener.inner, true)?;
+
+        bind(&listener.inner, addr)?;
+        listen(&listener.inner, 1024)?;
+        Ok(listener)
+    }
+
+    /// Creates a new `TcpListener` from a standard `net::TcpListener`.
+    ///
+    /// This function is intended to be used to wrap a TCP listener from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying listener; ; it is left up to the user to set it
+    /// in non-blocking mode.
+    pub fn from_std(listener: net::TcpListener) -> TcpListener {
+        TcpListener {
+            inner: IoSource::new(listener),
+        }
+    }
+
+    /// Accepts a new `TcpStream`.
+    ///
+    /// This may return an `Err(e)` where `e.kind()` is
+    /// `io::ErrorKind::WouldBlock`. This means a stream may be ready at a later
+    /// point and one should wait for an event before calling `accept` again.
+    ///
+    /// If an accepted stream is returned, the remote address of the peer is
+    /// returned along with it.
+    pub fn accept(&self) -> io::Result<(TcpStream, SocketAddr)> {
+        self.inner.do_io(|inner| {
+            sys::tcp::accept(inner).map(|(stream, addr)| (TcpStream::from_std(stream), addr))
+        })
+    }
+
+    /// Returns the local socket address of this listener.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
+
+    /// Sets the value for the `IP_TTL` option on this socket.
+    ///
+    /// This value sets the time-to-live field that is used in every packet sent
+    /// from this socket.
+    pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
+        self.inner.set_ttl(ttl)
+    }
+
+    /// Gets the value of the `IP_TTL` option for this socket.
+    ///
+    /// For more information about this option, see [`set_ttl`][link].
+    ///
+    /// [link]: #method.set_ttl
+    pub fn ttl(&self) -> io::Result<u32> {
+        self.inner.ttl()
+    }
+
+    /// Get the value of the `SO_ERROR` option on this socket.
+    ///
+    /// This will retrieve the stored error in the underlying socket, clearing
+    /// the field in the process. This can be useful for checking errors between
+    /// calls.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+}
+
+impl event::Source for TcpListener {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for TcpListener {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+#[cfg(unix)]
+impl IntoRawFd for TcpListener {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for TcpListener {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl FromRawFd for TcpListener {
+    /// Converts a `RawFd` to a `TcpListener`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> TcpListener {
+        TcpListener::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
+
+#[cfg(windows)]
+impl IntoRawSocket for TcpListener {
+    fn into_raw_socket(self) -> RawSocket {
+        self.inner.into_inner().into_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl AsRawSocket for TcpListener {
+    fn as_raw_socket(&self) -> RawSocket {
+        self.inner.as_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl FromRawSocket for TcpListener {
+    /// Converts a `RawSocket` to a `TcpListener`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_socket(socket: RawSocket) -> TcpListener {
+        TcpListener::from_std(FromRawSocket::from_raw_socket(socket))
+    }
+}
diff --git a/third_party/rust/mio/src/net/tcp/mod.rs b/third_party/rust/mio/src/net/tcp/mod.rs
new file mode 100644
index 0000000000..94af5c10e8
--- /dev/null
+++ b/third_party/rust/mio/src/net/tcp/mod.rs
@@ -0,0 +1,5 @@
+mod listener;
+pub use self::listener::TcpListener;
+
+mod stream;
+pub use self::stream::TcpStream;
diff --git a/third_party/rust/mio/src/net/tcp/stream.rs b/third_party/rust/mio/src/net/tcp/stream.rs
new file mode 100644
index 0000000000..029f186b42
--- /dev/null
+++ b/third_party/rust/mio/src/net/tcp/stream.rs
@@ -0,0 +1,334 @@
+use std::fmt;
+use std::io::{self, IoSlice, IoSliceMut, Read, Write};
+use std::net::{self, Shutdown, SocketAddr};
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+#[cfg(windows)]
+use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+
+use crate::io_source::IoSource;
+use crate::sys::tcp::{connect, new_for_addr};
+use crate::{event, Interest, Registry, Token};
+
+/// A non-blocking TCP stream between a local socket and a remote socket.
+///
+/// The socket will be closed when the value is dropped.
+///
+/// # Examples
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # use std::net::{TcpListener, SocketAddr};
+/// # use std::error::Error;
+/// #
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// let address: SocketAddr = "127.0.0.1:0".parse()?;
+/// let listener = TcpListener::bind(address)?;
+/// use mio::{Events, Interest, Poll, Token};
+/// use mio::net::TcpStream;
+/// use std::time::Duration;
+///
+/// let mut stream = TcpStream::connect(listener.local_addr()?)?;
+///
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(128);
+///
+/// // Register the socket with `Poll`
+/// poll.registry().register(&mut stream, Token(0), Interest::WRITABLE)?;
+///
+/// poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+///
+/// // The socket might be ready at this point
+/// #     Ok(())
+/// # }
+/// ```
+pub struct TcpStream {
+    inner: IoSource<net::TcpStream>,
+}
+
+impl TcpStream {
+    /// Create a new TCP stream and issue a non-blocking connect to the
+    /// specified address.
+    ///
+    /// # Notes
+    ///
+    /// The returned `TcpStream` may not be connected (and thus usable), unlike
+    /// the API found in `std::net::TcpStream`. Because Mio issues a
+    /// *non-blocking* connect it will not block the thread and instead return
+    /// an unconnected `TcpStream`.
+    ///
+    /// Ensuring the returned stream is connected is surprisingly complex when
+    /// considering cross-platform support. Doing this properly should follow
+    /// the steps below, an example implementation can be found
+    /// [here](https://github.com/Thomasdezeeuw/heph/blob/0c4f1ab3eaf08bea1d65776528bfd6114c9f8374/src/net/tcp/stream.rs#L560-L622).
+    ///
+    ///  1. Call `TcpStream::connect`
+    ///  2. Register the returned stream with at least [read interest].
+    ///  3. Wait for a (readable) event.
+    ///  4. Check `TcpStream::peer_addr`. If it returns `libc::EINPROGRESS` or
+    ///     `ErrorKind::NotConnected` it means the stream is not yet connected,
+    ///     go back to step 3. If it returns an address it means the stream is
+    ///     connected, go to step 5. If another error is returned something
+    ///     whent wrong.
+    ///  5. Now the stream can be used.
+    ///
+    /// [read interest]: Interest::READABLE
+    pub fn connect(addr: SocketAddr) -> io::Result<TcpStream> {
+        let socket = new_for_addr(addr)?;
+        #[cfg(unix)]
+        let stream = unsafe { TcpStream::from_raw_fd(socket) };
+        #[cfg(windows)]
+        let stream = unsafe { TcpStream::from_raw_socket(socket as _) };
+        connect(&stream.inner, addr)?;
+        Ok(stream)
+    }
+
+    /// Creates a new `TcpStream` from a standard `net::TcpStream`.
+    ///
+    /// This function is intended to be used to wrap a TCP stream from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying stream; it is left up to the user to set it in
+    /// non-blocking mode.
+    ///
+    /// # Note
+    ///
+    /// The TCP stream here will not have `connect` called on it, so it
+    /// should already be connected via some other means (be it manually, or
+    /// the standard library).
+    pub fn from_std(stream: net::TcpStream) -> TcpStream {
+        TcpStream {
+            inner: IoSource::new(stream),
+        }
+    }
+
+    /// Returns the socket address of the remote peer of this TCP connection.
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Returns the socket address of the local half of this TCP connection.
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
+
+    /// Shuts down the read, write, or both halves of this connection.
+    ///
+    /// This function will cause all pending and future I/O on the specified
+    /// portions to return immediately with an appropriate value (see the
+    /// documentation of `Shutdown`).
+    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
+        self.inner.shutdown(how)
+    }
+
+    /// Sets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// If set, this option disables the Nagle algorithm. This means that
+    /// segments are always sent as soon as possible, even if there is only a
+    /// small amount of data. When not set, data is buffered until there is a
+    /// sufficient amount to send out, thereby avoiding the frequent sending of
+    /// small packets.
+    ///
+    /// # Notes
+    ///
+    /// On Windows make sure the stream is connected before calling this method,
+    /// by receiving an (writable) event. Trying to set `nodelay` on an
+    /// unconnected `TcpStream` is unspecified behavior.
+    pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
+        self.inner.set_nodelay(nodelay)
+    }
+
+    /// Gets the value of the `TCP_NODELAY` option on this socket.
+    ///
+    /// For more information about this option, see [`set_nodelay`][link].
+    ///
+    /// [link]: #method.set_nodelay
+    ///
+    /// # Notes
+    ///
+    /// On Windows make sure the stream is connected before calling this method,
+    /// by receiving an (writable) event. Trying to get `nodelay` on an
+    /// unconnected `TcpStream` is unspecified behavior.
+    pub fn nodelay(&self) -> io::Result<bool> {
+        self.inner.nodelay()
+    }
+
+    /// Sets the value for the `IP_TTL` option on this socket.
+    ///
+    /// This value sets the time-to-live field that is used in every packet sent
+    /// from this socket.
+    ///
+    /// # Notes
+    ///
+    /// On Windows make sure the stream is connected before calling this method,
+    /// by receiving an (writable) event. Trying to set `ttl` on an
+    /// unconnected `TcpStream` is unspecified behavior.
+    pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
+        self.inner.set_ttl(ttl)
+    }
+
+    /// Gets the value of the `IP_TTL` option for this socket.
+    ///
+    /// For more information about this option, see [`set_ttl`][link].
+    ///
+    /// # Notes
+    ///
+    /// On Windows make sure the stream is connected before calling this method,
+    /// by receiving an (writable) event. Trying to get `ttl` on an
+    /// unconnected `TcpStream` is unspecified behavior.
+    ///
+    /// [link]: #method.set_ttl
+    pub fn ttl(&self) -> io::Result<u32> {
+        self.inner.ttl()
+    }
+
+    /// Get the value of the `SO_ERROR` option on this socket.
+    ///
+    /// This will retrieve the stored error in the underlying socket, clearing
+    /// the field in the process. This can be useful for checking errors between
+    /// calls.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+
+    /// Receives data on the socket from the remote address to which it is
+    /// connected, without removing that data from the queue. On success,
+    /// returns the number of bytes peeked.
+    ///
+    /// Successive calls return the same data. This is accomplished by passing
+    /// `MSG_PEEK` as a flag to the underlying recv system call.
+    pub fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.peek(buf)
+    }
+}
+
+impl Read for TcpStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read_vectored(bufs))
+    }
+}
+
+impl<'a> Read for &'a TcpStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read_vectored(bufs))
+    }
+}
+
+impl Write for TcpStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|inner| (&*inner).flush())
+    }
+}
+
+impl<'a> Write for &'a TcpStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|inner| (&*inner).flush())
+    }
+}
+
+impl event::Source for TcpStream {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for TcpStream {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+#[cfg(unix)]
+impl IntoRawFd for TcpStream {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for TcpStream {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl FromRawFd for TcpStream {
+    /// Converts a `RawFd` to a `TcpStream`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> TcpStream {
+        TcpStream::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
+
+#[cfg(windows)]
+impl IntoRawSocket for TcpStream {
+    fn into_raw_socket(self) -> RawSocket {
+        self.inner.into_inner().into_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl AsRawSocket for TcpStream {
+    fn as_raw_socket(&self) -> RawSocket {
+        self.inner.as_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl FromRawSocket for TcpStream {
+    /// Converts a `RawSocket` to a `TcpStream`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_socket(socket: RawSocket) -> TcpStream {
+        TcpStream::from_std(FromRawSocket::from_raw_socket(socket))
+    }
+}
diff --git a/third_party/rust/mio/src/net/udp.rs b/third_party/rust/mio/src/net/udp.rs
new file mode 100644
index 0000000000..8cfe4e456c
--- /dev/null
+++ b/third_party/rust/mio/src/net/udp.rs
@@ -0,0 +1,635 @@
+//! Primitives for working with UDP.
+//!
+//! The types provided in this module are non-blocking by default and are
+//! designed to be portable across all supported Mio platforms. As long as the
+//! [portability guidelines] are followed, the behavior should be identical no
+//! matter the target platform.
+//!
+//! [portability guidelines]: ../struct.Poll.html#portability
+
+use crate::io_source::IoSource;
+use crate::{event, sys, Interest, Registry, Token};
+
+use std::fmt;
+use std::io;
+use std::net;
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr};
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+#[cfg(windows)]
+use std::os::windows::io::{AsRawSocket, FromRawSocket, IntoRawSocket, RawSocket};
+
+/// A User Datagram Protocol socket.
+///
+/// This is an implementation of a bound UDP socket. This supports both IPv4 and
+/// IPv6 addresses, and there is no corresponding notion of a server because UDP
+/// is a datagram protocol.
+///
+/// # Examples
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # use std::error::Error;
+/// #
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// // An Echo program:
+/// // SENDER -> sends a message.
+/// // ECHOER -> listens and prints the message received.
+///
+/// use mio::net::UdpSocket;
+/// use mio::{Events, Interest, Poll, Token};
+/// use std::time::Duration;
+///
+/// const SENDER: Token = Token(0);
+/// const ECHOER: Token = Token(1);
+///
+/// // This operation will fail if the address is in use, so we select different ports for each
+/// // socket.
+/// let mut sender_socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+/// let mut echoer_socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+///
+/// // If we do not use connect here, SENDER and ECHOER would need to call send_to and recv_from
+/// // respectively.
+/// sender_socket.connect(echoer_socket.local_addr()?)?;
+///
+/// // We need a Poll to check if SENDER is ready to be written into, and if ECHOER is ready to be
+/// // read from.
+/// let mut poll = Poll::new()?;
+///
+/// // We register our sockets here so that we can check if they are ready to be written/read.
+/// poll.registry().register(&mut sender_socket, SENDER, Interest::WRITABLE)?;
+/// poll.registry().register(&mut echoer_socket, ECHOER, Interest::READABLE)?;
+///
+/// let msg_to_send = [9; 9];
+/// let mut buffer = [0; 9];
+///
+/// let mut events = Events::with_capacity(128);
+/// loop {
+///     poll.poll(&mut events, Some(Duration::from_millis(100)))?;
+///     for event in events.iter() {
+///         match event.token() {
+///             // Our SENDER is ready to be written into.
+///             SENDER => {
+///                 let bytes_sent = sender_socket.send(&msg_to_send)?;
+///                 assert_eq!(bytes_sent, 9);
+///                 println!("sent {:?} -> {:?} bytes", msg_to_send, bytes_sent);
+///             },
+///             // Our ECHOER is ready to be read from.
+///             ECHOER => {
+///                 let num_recv = echoer_socket.recv(&mut buffer)?;
+///                 println!("echo {:?} -> {:?}", buffer, num_recv);
+///                 buffer = [0; 9];
+///                 # drop(buffer); // Silence unused assignment warning.
+///                 # return Ok(());
+///             }
+///             _ => unreachable!()
+///         }
+///     }
+/// }
+/// # }
+/// ```
+pub struct UdpSocket {
+    inner: IoSource<net::UdpSocket>,
+}
+
+impl UdpSocket {
+    /// Creates a UDP socket from the given address.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// // We must bind it to an open address.
+    /// let socket = match UdpSocket::bind("127.0.0.1:0".parse()?) {
+    ///     Ok(new_socket) => new_socket,
+    ///     Err(fail) => {
+    ///         // We panic! here, but you could try to bind it again on another address.
+    ///         panic!("Failed to bind socket. {:?}", fail);
+    ///     }
+    /// };
+    ///
+    /// // Our socket was created, but we should not use it before checking it's readiness.
+    /// #    drop(socket); // Silence unused variable warning.
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn bind(addr: SocketAddr) -> io::Result<UdpSocket> {
+        sys::udp::bind(addr).map(UdpSocket::from_std)
+    }
+
+    /// Creates a new `UdpSocket` from a standard `net::UdpSocket`.
+    ///
+    /// This function is intended to be used to wrap a UDP socket from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying socket; it is left up to the user to set it in
+    /// non-blocking mode.
+    pub fn from_std(socket: net::UdpSocket) -> UdpSocket {
+        UdpSocket {
+            inner: IoSource::new(socket),
+        }
+    }
+
+    /// Returns the socket address that this socket was created from.
+    ///
+    /// # Examples
+    ///
+    // This assertion is almost, but not quite, universal.  It fails on
+    // shared-IP FreeBSD jails.  It's hard for mio to know whether we're jailed,
+    // so simply disable the test on FreeBSD.
+    #[cfg_attr(all(feature = "os-poll", not(target_os = "freebsd")), doc = "```")]
+    #[cfg_attr(
+        any(not(feature = "os-poll"), target_os = "freebsd"),
+        doc = "```ignore"
+    )]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let addr = "127.0.0.1:0".parse()?;
+    /// let socket = UdpSocket::bind(addr)?;
+    /// assert_eq!(socket.local_addr()?.ip(), addr.ip());
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn local_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.local_addr()
+    }
+
+    /// Returns the socket address of the remote peer this socket was connected to.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let addr = "127.0.0.1:0".parse()?;
+    /// let peer_addr = "127.0.0.1:11100".parse()?;
+    /// let socket = UdpSocket::bind(addr)?;
+    /// socket.connect(peer_addr)?;
+    /// assert_eq!(socket.peer_addr()?.ip(), peer_addr.ip());
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn peer_addr(&self) -> io::Result<SocketAddr> {
+        self.inner.peer_addr()
+    }
+
+    /// Sends data on the socket to the given address. On success, returns the
+    /// number of bytes written.
+    ///
+    /// Address type can be any implementor of `ToSocketAddrs` trait. See its
+    /// documentation for concrete examples.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// # use std::error::Error;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    ///
+    /// // We must check if the socket is writable before calling send_to,
+    /// // or we could run into a WouldBlock error.
+    ///
+    /// let bytes_sent = socket.send_to(&[9; 9], "127.0.0.1:11100".parse()?)?;
+    /// assert_eq!(bytes_sent, 9);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn send_to(&self, buf: &[u8], target: SocketAddr) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.send_to(buf, target))
+    }
+
+    /// Receives data from the socket. 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 recv_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 std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    ///
+    /// // We must check if the socket is readable before calling recv_from,
+    /// // or we could run into a WouldBlock error.
+    ///
+    /// let mut buf = [0; 9];
+    /// let (num_recv, from_addr) = socket.recv_from(&mut buf)?;
+    /// println!("Received {:?} -> {:?} bytes from {:?}", buf, num_recv, from_addr);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        self.inner.do_io(|inner| inner.recv_from(buf))
+    }
+
+    /// 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 std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    ///
+    /// // We must check if the socket is readable before calling recv_from,
+    /// // or we could run into a WouldBlock error.
+    ///
+    /// let mut buf = [0; 9];
+    /// let (num_recv, from_addr) = socket.peek_from(&mut buf)?;
+    /// println!("Received {:?} -> {:?} bytes from {:?}", buf, num_recv, from_addr);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
+        self.inner.do_io(|inner| inner.peek_from(buf))
+    }
+
+    /// Sends data on the socket to the address previously bound via connect(). On success,
+    /// returns the number of bytes written.
+    pub fn send(&self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.send(buf))
+    }
+
+    /// Receives data from the socket previously bound with connect(). On success, returns
+    /// the number of bytes read.
+    ///
+    /// # Notes
+    ///
+    /// On Windows, if the data is larger than the buffer specified, the buffer
+    /// is filled with the first part of the data, and recv 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.
+    pub fn recv(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.recv(buf))
+    }
+
+    /// Receives data from the socket, without removing it from the input queue.
+    /// On success, returns the number of bytes read.
+    ///
+    /// # 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 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.
+    pub fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.peek(buf))
+    }
+
+    /// Connects the UDP socket setting the default destination for `send()`
+    /// and limiting packets that are read via `recv` from the address specified
+    /// in `addr`.
+    pub fn connect(&self, addr: SocketAddr) -> io::Result<()> {
+        self.inner.connect(addr)
+    }
+
+    /// Sets the value of the `SO_BROADCAST` option for this socket.
+    ///
+    /// When enabled, this socket is allowed to send packets to a broadcast
+    /// address.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let broadcast_socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    /// if broadcast_socket.broadcast()? == false {
+    ///     broadcast_socket.set_broadcast(true)?;
+    /// }
+    ///
+    /// assert_eq!(broadcast_socket.broadcast()?, true);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn set_broadcast(&self, on: bool) -> io::Result<()> {
+        self.inner.set_broadcast(on)
+    }
+
+    /// Gets the value of the `SO_BROADCAST` option for this socket.
+    ///
+    /// For more information about this option, see
+    /// [`set_broadcast`][link].
+    ///
+    /// [link]: #method.set_broadcast
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let broadcast_socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    /// assert_eq!(broadcast_socket.broadcast()?, false);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn broadcast(&self) -> io::Result<bool> {
+        self.inner.broadcast()
+    }
+
+    /// Sets the value of the `IP_MULTICAST_LOOP` option for this socket.
+    ///
+    /// If enabled, multicast packets will be looped back to the local socket.
+    /// Note that this may not have any affect on IPv6 sockets.
+    pub fn set_multicast_loop_v4(&self, on: bool) -> io::Result<()> {
+        self.inner.set_multicast_loop_v4(on)
+    }
+
+    /// Gets the value of the `IP_MULTICAST_LOOP` option for this socket.
+    ///
+    /// For more information about this option, see
+    /// [`set_multicast_loop_v4`][link].
+    ///
+    /// [link]: #method.set_multicast_loop_v4
+    pub fn multicast_loop_v4(&self) -> io::Result<bool> {
+        self.inner.multicast_loop_v4()
+    }
+
+    /// Sets the value of the `IP_MULTICAST_TTL` option for this socket.
+    ///
+    /// Indicates the time-to-live value of outgoing multicast packets for
+    /// this socket. The default value is 1 which means that multicast packets
+    /// don't leave the local network unless explicitly requested.
+    ///
+    /// Note that this may not have any affect on IPv6 sockets.
+    pub fn set_multicast_ttl_v4(&self, ttl: u32) -> io::Result<()> {
+        self.inner.set_multicast_ttl_v4(ttl)
+    }
+
+    /// Gets the value of the `IP_MULTICAST_TTL` option for this socket.
+    ///
+    /// For more information about this option, see
+    /// [`set_multicast_ttl_v4`][link].
+    ///
+    /// [link]: #method.set_multicast_ttl_v4
+    pub fn multicast_ttl_v4(&self) -> io::Result<u32> {
+        self.inner.multicast_ttl_v4()
+    }
+
+    /// Sets the value of the `IPV6_MULTICAST_LOOP` option for this socket.
+    ///
+    /// Controls whether this socket sees the multicast packets it sends itself.
+    /// Note that this may not have any affect on IPv4 sockets.
+    pub fn set_multicast_loop_v6(&self, on: bool) -> io::Result<()> {
+        self.inner.set_multicast_loop_v6(on)
+    }
+
+    /// Gets the value of the `IPV6_MULTICAST_LOOP` option for this socket.
+    ///
+    /// For more information about this option, see
+    /// [`set_multicast_loop_v6`][link].
+    ///
+    /// [link]: #method.set_multicast_loop_v6
+    pub fn multicast_loop_v6(&self) -> io::Result<bool> {
+        self.inner.multicast_loop_v6()
+    }
+
+    /// Sets the value for the `IP_TTL` option on this socket.
+    ///
+    /// This value sets the time-to-live field that is used in every packet sent
+    /// from this socket.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    /// if socket.ttl()? < 255 {
+    ///     socket.set_ttl(255)?;
+    /// }
+    ///
+    /// assert_eq!(socket.ttl()?, 255);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn set_ttl(&self, ttl: u32) -> io::Result<()> {
+        self.inner.set_ttl(ttl)
+    }
+
+    /// Gets the value of the `IP_TTL` option for this socket.
+    ///
+    /// For more information about this option, see [`set_ttl`][link].
+    ///
+    /// [link]: #method.set_ttl
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(feature = "os-poll", doc = "```")]
+    #[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// #
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::net::UdpSocket;
+    ///
+    /// let socket = UdpSocket::bind("127.0.0.1:0".parse()?)?;
+    /// socket.set_ttl(255)?;
+    ///
+    /// assert_eq!(socket.ttl()?, 255);
+    /// #
+    /// #    Ok(())
+    /// # }
+    /// ```
+    pub fn ttl(&self) -> io::Result<u32> {
+        self.inner.ttl()
+    }
+
+    /// Executes an operation of the `IP_ADD_MEMBERSHIP` type.
+    ///
+    /// This function specifies a new multicast group for this socket to join.
+    /// The address must be a valid multicast address, and `interface` is the
+    /// address of the local interface with which the system should join the
+    /// multicast group. If it's equal to `INADDR_ANY` then an appropriate
+    /// interface is chosen by the system.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn join_multicast_v4(&self, multiaddr: &Ipv4Addr, interface: &Ipv4Addr) -> io::Result<()> {
+        self.inner.join_multicast_v4(multiaddr, interface)
+    }
+
+    /// Executes an operation of the `IPV6_ADD_MEMBERSHIP` type.
+    ///
+    /// This function specifies a new multicast group for this socket to join.
+    /// The address must be a valid multicast address, and `interface` is the
+    /// index of the interface to join/leave (or 0 to indicate any interface).
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn join_multicast_v6(&self, multiaddr: &Ipv6Addr, interface: u32) -> io::Result<()> {
+        self.inner.join_multicast_v6(multiaddr, interface)
+    }
+
+    /// Executes an operation of the `IP_DROP_MEMBERSHIP` type.
+    ///
+    /// For more information about this option, see
+    /// [`join_multicast_v4`][link].
+    ///
+    /// [link]: #method.join_multicast_v4
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn leave_multicast_v4(&self, multiaddr: &Ipv4Addr, interface: &Ipv4Addr) -> io::Result<()> {
+        self.inner.leave_multicast_v4(multiaddr, interface)
+    }
+
+    /// Executes an operation of the `IPV6_DROP_MEMBERSHIP` type.
+    ///
+    /// For more information about this option, see
+    /// [`join_multicast_v6`][link].
+    ///
+    /// [link]: #method.join_multicast_v6
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn leave_multicast_v6(&self, multiaddr: &Ipv6Addr, interface: u32) -> io::Result<()> {
+        self.inner.leave_multicast_v6(multiaddr, interface)
+    }
+
+    /// Get the value of the `IPV6_V6ONLY` option on this socket.
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn only_v6(&self) -> io::Result<bool> {
+        sys::udp::only_v6(&self.inner)
+    }
+
+    /// Get the value of the `SO_ERROR` option on this socket.
+    ///
+    /// This will retrieve the stored error in the underlying socket, clearing
+    /// the field in the process. This can be useful for checking errors between
+    /// calls.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+}
+
+impl event::Source for UdpSocket {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for UdpSocket {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+#[cfg(unix)]
+impl IntoRawFd for UdpSocket {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for UdpSocket {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+#[cfg(unix)]
+impl FromRawFd for UdpSocket {
+    /// Converts a `RawFd` to a `UdpSocket`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> UdpSocket {
+        UdpSocket::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
+
+#[cfg(windows)]
+impl IntoRawSocket for UdpSocket {
+    fn into_raw_socket(self) -> RawSocket {
+        self.inner.into_inner().into_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl AsRawSocket for UdpSocket {
+    fn as_raw_socket(&self) -> RawSocket {
+        self.inner.as_raw_socket()
+    }
+}
+
+#[cfg(windows)]
+impl FromRawSocket for UdpSocket {
+    /// Converts a `RawSocket` to a `UdpSocket`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_socket(socket: RawSocket) -> UdpSocket {
+        UdpSocket::from_std(FromRawSocket::from_raw_socket(socket))
+    }
+}
diff --git a/third_party/rust/mio/src/net/uds/datagram.rs b/third_party/rust/mio/src/net/uds/datagram.rs
new file mode 100644
index 0000000000..0c8f5ffa6a
--- /dev/null
+++ b/third_party/rust/mio/src/net/uds/datagram.rs
@@ -0,0 +1,165 @@
+use crate::io_source::IoSource;
+use crate::{event, sys, Interest, Registry, Token};
+
+use std::net::Shutdown;
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::os::unix::net;
+use std::path::Path;
+use std::{fmt, io};
+
+/// A Unix datagram socket.
+pub struct UnixDatagram {
+    inner: IoSource<net::UnixDatagram>,
+}
+
+impl UnixDatagram {
+    /// Creates a Unix datagram socket bound to the given path.
+    pub fn bind<P: AsRef<Path>>(path: P) -> io::Result<UnixDatagram> {
+        sys::uds::datagram::bind(path.as_ref()).map(UnixDatagram::from_std)
+    }
+
+    /// Creates a new `UnixDatagram` from a standard `net::UnixDatagram`.
+    ///
+    /// This function is intended to be used to wrap a Unix datagram from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying datagram; ; it is left up to the user to set it
+    /// in non-blocking mode.
+    pub fn from_std(socket: net::UnixDatagram) -> UnixDatagram {
+        UnixDatagram {
+            inner: IoSource::new(socket),
+        }
+    }
+
+    /// Connects the socket to the specified address.
+    pub fn connect<P: AsRef<Path>>(&self, path: P) -> io::Result<()> {
+        self.inner.connect(path)
+    }
+
+    /// Creates a Unix Datagram socket which is not bound to any address.
+    pub fn unbound() -> io::Result<UnixDatagram> {
+        sys::uds::datagram::unbound().map(UnixDatagram::from_std)
+    }
+
+    /// Create an unnamed pair of connected sockets.
+    pub fn pair() -> io::Result<(UnixDatagram, UnixDatagram)> {
+        sys::uds::datagram::pair().map(|(socket1, socket2)| {
+            (
+                UnixDatagram::from_std(socket1),
+                UnixDatagram::from_std(socket2),
+            )
+        })
+    }
+
+    /// Returns the address of this socket.
+    pub fn local_addr(&self) -> io::Result<sys::SocketAddr> {
+        sys::uds::datagram::local_addr(&self.inner)
+    }
+
+    /// Returns the address of this socket's peer.
+    ///
+    /// The `connect` method will connect the socket to a peer.
+    pub fn peer_addr(&self) -> io::Result<sys::SocketAddr> {
+        sys::uds::datagram::peer_addr(&self.inner)
+    }
+
+    /// Receives data from the socket.
+    ///
+    /// On success, returns the number of bytes read and the address from
+    /// whence the data came.
+    pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, sys::SocketAddr)> {
+        self.inner
+            .do_io(|inner| sys::uds::datagram::recv_from(inner, buf))
+    }
+
+    /// Receives data from the socket.
+    ///
+    /// On success, returns the number of bytes read.
+    pub fn recv(&self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.recv(buf))
+    }
+
+    /// Sends data on the socket to the specified address.
+    ///
+    /// On success, returns the number of bytes written.
+    pub fn send_to<P: AsRef<Path>>(&self, buf: &[u8], path: P) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.send_to(buf, path))
+    }
+
+    /// Sends data on the socket to the socket's peer.
+    ///
+    /// The peer address may be set by the `connect` method, and this method
+    /// will return an error if the socket has not already been connected.
+    ///
+    /// On success, returns the number of bytes written.
+    pub fn send(&self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| inner.send(buf))
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+
+    /// Shut down the read, write, or both halves of this connection.
+    ///
+    /// This function will cause all pending and future I/O calls on the
+    /// specified portions to immediately return with an appropriate value
+    /// (see the documentation of `Shutdown`).
+    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
+        self.inner.shutdown(how)
+    }
+}
+
+impl event::Source for UnixDatagram {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for UnixDatagram {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+impl IntoRawFd for UnixDatagram {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+impl AsRawFd for UnixDatagram {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+impl FromRawFd for UnixDatagram {
+    /// Converts a `RawFd` to a `UnixDatagram`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> UnixDatagram {
+        UnixDatagram::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
diff --git a/third_party/rust/mio/src/net/uds/listener.rs b/third_party/rust/mio/src/net/uds/listener.rs
new file mode 100644
index 0000000000..37e8106d89
--- /dev/null
+++ b/third_party/rust/mio/src/net/uds/listener.rs
@@ -0,0 +1,104 @@
+use crate::io_source::IoSource;
+use crate::net::{SocketAddr, UnixStream};
+use crate::{event, sys, Interest, Registry, Token};
+
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::os::unix::net;
+use std::path::Path;
+use std::{fmt, io};
+
+/// A non-blocking Unix domain socket server.
+pub struct UnixListener {
+    inner: IoSource<net::UnixListener>,
+}
+
+impl UnixListener {
+    /// Creates a new `UnixListener` bound to the specified socket.
+    pub fn bind<P: AsRef<Path>>(path: P) -> io::Result<UnixListener> {
+        sys::uds::listener::bind(path.as_ref()).map(UnixListener::from_std)
+    }
+
+    /// Creates a new `UnixListener` from a standard `net::UnixListener`.
+    ///
+    /// This function is intended to be used to wrap a Unix listener from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying listener; it is left up to the user to set it in
+    /// non-blocking mode.
+    pub fn from_std(listener: net::UnixListener) -> UnixListener {
+        UnixListener {
+            inner: IoSource::new(listener),
+        }
+    }
+
+    /// Accepts a new incoming connection to this listener.
+    ///
+    /// The call is responsible for ensuring that the listening socket is in
+    /// non-blocking mode.
+    pub fn accept(&self) -> io::Result<(UnixStream, SocketAddr)> {
+        sys::uds::listener::accept(&self.inner)
+    }
+
+    /// Returns the local socket address of this listener.
+    pub fn local_addr(&self) -> io::Result<sys::SocketAddr> {
+        sys::uds::listener::local_addr(&self.inner)
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+}
+
+impl event::Source for UnixListener {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for UnixListener {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+impl IntoRawFd for UnixListener {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+impl AsRawFd for UnixListener {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+impl FromRawFd for UnixListener {
+    /// Converts a `RawFd` to a `UnixListener`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> UnixListener {
+        UnixListener::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
diff --git a/third_party/rust/mio/src/net/uds/mod.rs b/third_party/rust/mio/src/net/uds/mod.rs
new file mode 100644
index 0000000000..6b4ffdc430
--- /dev/null
+++ b/third_party/rust/mio/src/net/uds/mod.rs
@@ -0,0 +1,10 @@
+mod datagram;
+pub use self::datagram::UnixDatagram;
+
+mod listener;
+pub use self::listener::UnixListener;
+
+mod stream;
+pub use self::stream::UnixStream;
+
+pub use crate::sys::SocketAddr;
diff --git a/third_party/rust/mio/src/net/uds/stream.rs b/third_party/rust/mio/src/net/uds/stream.rs
new file mode 100644
index 0000000000..f21d9e7ba5
--- /dev/null
+++ b/third_party/rust/mio/src/net/uds/stream.rs
@@ -0,0 +1,174 @@
+use crate::io_source::IoSource;
+use crate::{event, sys, Interest, Registry, Token};
+
+use std::fmt;
+use std::io::{self, IoSlice, IoSliceMut, Read, Write};
+use std::net::Shutdown;
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::os::unix::net;
+use std::path::Path;
+
+/// A non-blocking Unix stream socket.
+pub struct UnixStream {
+    inner: IoSource<net::UnixStream>,
+}
+
+impl UnixStream {
+    /// Connects to the socket named by `path`.
+    pub fn connect<P: AsRef<Path>>(path: P) -> io::Result<UnixStream> {
+        sys::uds::stream::connect(path.as_ref()).map(UnixStream::from_std)
+    }
+
+    /// Creates a new `UnixStream` from a standard `net::UnixStream`.
+    ///
+    /// This function is intended to be used to wrap a Unix stream from the
+    /// standard library in the Mio equivalent. The conversion assumes nothing
+    /// about the underlying stream; it is left up to the user to set it in
+    /// non-blocking mode.
+    ///
+    /// # Note
+    ///
+    /// The Unix stream here will not have `connect` called on it, so it
+    /// should already be connected via some other means (be it manually, or
+    /// the standard library).
+    pub fn from_std(stream: net::UnixStream) -> UnixStream {
+        UnixStream {
+            inner: IoSource::new(stream),
+        }
+    }
+
+    /// Creates an unnamed pair of connected sockets.
+    ///
+    /// Returns two `UnixStream`s which are connected to each other.
+    pub fn pair() -> io::Result<(UnixStream, UnixStream)> {
+        sys::uds::stream::pair().map(|(stream1, stream2)| {
+            (UnixStream::from_std(stream1), UnixStream::from_std(stream2))
+        })
+    }
+
+    /// Returns the socket address of the local half of this connection.
+    pub fn local_addr(&self) -> io::Result<sys::SocketAddr> {
+        sys::uds::stream::local_addr(&self.inner)
+    }
+
+    /// Returns the socket address of the remote half of this connection.
+    pub fn peer_addr(&self) -> io::Result<sys::SocketAddr> {
+        sys::uds::stream::peer_addr(&self.inner)
+    }
+
+    /// Returns the value of the `SO_ERROR` option.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        self.inner.take_error()
+    }
+
+    /// Shuts down the read, write, or both halves of this connection.
+    ///
+    /// This function will cause all pending and future I/O calls on the
+    /// specified portions to immediately return with an appropriate value
+    /// (see the documentation of `Shutdown`).
+    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
+        self.inner.shutdown(how)
+    }
+}
+
+impl Read for UnixStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read_vectored(bufs))
+    }
+}
+
+impl<'a> Read for &'a UnixStream {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).read_vectored(bufs))
+    }
+}
+
+impl Write for UnixStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|inner| (&*inner).flush())
+    }
+}
+
+impl<'a> Write for &'a UnixStream {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|inner| (&*inner).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|inner| (&*inner).flush())
+    }
+}
+
+impl event::Source for UnixStream {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl fmt::Debug for UnixStream {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}
+
+impl IntoRawFd for UnixStream {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+impl AsRawFd for UnixStream {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+impl FromRawFd for UnixStream {
+    /// Converts a `RawFd` to a `UnixStream`.
+    ///
+    /// # Notes
+    ///
+    /// The caller is responsible for ensuring that the socket is in
+    /// non-blocking mode.
+    unsafe fn from_raw_fd(fd: RawFd) -> UnixStream {
+        UnixStream::from_std(FromRawFd::from_raw_fd(fd))
+    }
+}
diff --git a/third_party/rust/mio/src/poll.rs b/third_party/rust/mio/src/poll.rs
new file mode 100644
index 0000000000..fd643fdd00
--- /dev/null
+++ b/third_party/rust/mio/src/poll.rs
@@ -0,0 +1,682 @@
+use crate::{event, sys, Events, Interest, Token};
+use log::trace;
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, RawFd};
+use std::time::Duration;
+use std::{fmt, io};
+
+/// Polls for readiness events on all registered values.
+///
+/// `Poll` allows a program to monitor a large number of [`event::Source`]s,
+/// waiting until one or more become "ready" for some class of operations; e.g.
+/// reading and writing. An event source is considered ready if it is possible
+/// to immediately perform a corresponding operation; e.g. [`read`] or
+/// [`write`].
+///
+/// To use `Poll`, an `event::Source` must first be registered with the `Poll`
+/// instance using the [`register`] method on its associated `Register`,
+/// supplying readiness interest. The readiness interest tells `Poll` which
+/// specific operations on the handle to monitor for readiness. A `Token` is
+/// also passed to the [`register`] function. When `Poll` returns a readiness
+/// event, it will include this token.  This associates the event with the
+/// event source that generated the event.
+///
+/// [`event::Source`]: ./event/trait.Source.html
+/// [`read`]: ./net/struct.TcpStream.html#method.read
+/// [`write`]: ./net/struct.TcpStream.html#method.write
+/// [`register`]: struct.Registry.html#method.register
+///
+/// # Examples
+///
+/// A basic example -- establishing a `TcpStream` connection.
+///
+#[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+#[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Events, Poll, Interest, Token};
+/// use mio::net::TcpStream;
+///
+/// use std::net::{self, SocketAddr};
+///
+/// // Bind a server socket to connect to.
+/// let addr: SocketAddr = "127.0.0.1:0".parse()?;
+/// let server = net::TcpListener::bind(addr)?;
+///
+/// // Construct a new `Poll` handle as well as the `Events` we'll store into
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(1024);
+///
+/// // Connect the stream
+/// let mut stream = TcpStream::connect(server.local_addr()?)?;
+///
+/// // Register the stream with `Poll`
+/// poll.registry().register(&mut stream, Token(0), Interest::READABLE | Interest::WRITABLE)?;
+///
+/// // Wait for the socket to become ready. This has to happens in a loop to
+/// // handle spurious wakeups.
+/// loop {
+///     poll.poll(&mut events, None)?;
+///
+///     for event in &events {
+///         if event.token() == Token(0) && event.is_writable() {
+///             // The socket connected (probably, it could still be a spurious
+///             // wakeup)
+///             return Ok(());
+///         }
+///     }
+/// }
+/// # }
+/// ```
+///
+/// # Portability
+///
+/// Using `Poll` provides a portable interface across supported platforms as
+/// long as the caller takes the following into consideration:
+///
+/// ### Spurious events
+///
+/// [`Poll::poll`] may return readiness events even if the associated
+/// event source is not actually ready. Given the same code, this may
+/// happen more on some platforms than others. It is important to never assume
+/// that, just because a readiness event was received, that the associated
+/// operation will succeed as well.
+///
+/// If operation fails with [`WouldBlock`], then the caller should not treat
+/// this as an error, but instead should wait until another readiness event is
+/// received.
+///
+/// ### Draining readiness
+///
+/// Once a readiness event is received, the corresponding operation must be
+/// performed repeatedly until it returns [`WouldBlock`]. Unless this is done,
+/// there is no guarantee that another readiness event will be delivered, even
+/// if further data is received for the event source.
+///
+/// [`WouldBlock`]: std::io::ErrorKind::WouldBlock
+///
+/// ### Readiness operations
+///
+/// The only readiness operations that are guaranteed to be present on all
+/// supported platforms are [`readable`] and [`writable`]. All other readiness
+/// operations may have false negatives and as such should be considered
+/// **hints**. This means that if a socket is registered with [`readable`]
+/// interest and either an error or close is received, a readiness event will
+/// be generated for the socket, but it **may** only include `readable`
+/// readiness. Also note that, given the potential for spurious events,
+/// receiving a readiness event with `read_closed`, `write_closed`, or `error`
+/// doesn't actually mean that a `read` on the socket will return a result
+/// matching the readiness event.
+///
+/// In other words, portable programs that explicitly check for [`read_closed`],
+/// [`write_closed`], or [`error`] readiness should be doing so as an
+/// **optimization** and always be able to handle an error or close situation
+/// when performing the actual read operation.
+///
+/// [`readable`]: ./event/struct.Event.html#method.is_readable
+/// [`writable`]: ./event/struct.Event.html#method.is_writable
+/// [`error`]: ./event/struct.Event.html#method.is_error
+/// [`read_closed`]: ./event/struct.Event.html#method.is_read_closed
+/// [`write_closed`]: ./event/struct.Event.html#method.is_write_closed
+///
+/// ### Registering handles
+///
+/// Unless otherwise noted, it should be assumed that types implementing
+/// [`event::Source`] will never become ready unless they are registered with
+/// `Poll`.
+///
+/// For example:
+///
+#[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+#[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+/// # use std::error::Error;
+/// # use std::net;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Poll, Interest, Token};
+/// use mio::net::TcpStream;
+/// use std::net::SocketAddr;
+/// use std::time::Duration;
+/// use std::thread;
+///
+/// let address: SocketAddr = "127.0.0.1:0".parse()?;
+/// let listener = net::TcpListener::bind(address)?;
+/// let mut sock = TcpStream::connect(listener.local_addr()?)?;
+///
+/// thread::sleep(Duration::from_secs(1));
+///
+/// let poll = Poll::new()?;
+///
+/// // The connect is not guaranteed to have started until it is registered at
+/// // this point
+/// poll.registry().register(&mut sock, Token(0), Interest::READABLE | Interest::WRITABLE)?;
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// ### Dropping `Poll`
+///
+/// When the `Poll` instance is dropped it may cancel in-flight operations for
+/// the registered [event sources], meaning that no further events for them may
+/// be received. It also means operations on the registered event sources may no
+/// longer work. It is up to the user to keep the `Poll` instance alive while
+/// registered event sources are being used.
+///
+/// [event sources]: ./event/trait.Source.html
+///
+/// ### Accessing raw fd/socket/handle
+///
+/// Mio makes it possible for many types to be converted into a raw file
+/// descriptor (fd, Unix), socket (Windows) or handle (Windows). This makes it
+/// possible to support more operations on the type than Mio supports, for
+/// example it makes [mio-aio] possible. However accessing the raw fd is not
+/// without it's pitfalls.
+///
+/// Specifically performing I/O operations outside of Mio on these types (via
+/// the raw fd) has unspecified behaviour. It could cause no more events to be
+/// generated for the type even though it returned `WouldBlock` (in an operation
+/// directly accessing the fd). The behaviour is OS specific and Mio can only
+/// guarantee cross-platform behaviour if it can control the I/O.
+///
+/// [mio-aio]: https://github.com/asomers/mio-aio
+///
+/// *The following is **not** guaranteed, just a description of the current
+/// situation!* Mio is allowed to change the following without it being considered
+/// a breaking change, don't depend on this, it's just here to inform the user.
+/// Currently the kqueue and epoll implementation support direct I/O operations
+/// on the fd without Mio's knowledge. Windows however needs **all** I/O
+/// operations to go through Mio otherwise it is not able to update it's
+/// internal state properly and won't generate events.
+///
+/// # Implementation notes
+///
+/// `Poll` is backed by the selector provided by the operating system.
+///
+/// |      OS       |  Selector |
+/// |---------------|-----------|
+/// | Android       | [epoll]   |
+/// | DragonFly BSD | [kqueue]  |
+/// | FreeBSD       | [kqueue]  |
+/// | iOS           | [kqueue]  |
+/// | illumos       | [epoll]   |
+/// | Linux         | [epoll]   |
+/// | NetBSD        | [kqueue]  |
+/// | OpenBSD       | [kqueue]  |
+/// | Windows       | [IOCP]    |
+/// | macOS         | [kqueue]  |
+///
+/// On all supported platforms, socket operations are handled by using the
+/// system selector. Platform specific extensions (e.g. [`SourceFd`]) allow
+/// accessing other features provided by individual system selectors. For
+/// example, Linux's [`signalfd`] feature can be used by registering the FD with
+/// `Poll` via [`SourceFd`].
+///
+/// On all platforms except windows, a call to [`Poll::poll`] is mostly just a
+/// direct call to the system selector. However, [IOCP] uses a completion model
+/// instead of a readiness model. In this case, `Poll` must adapt the completion
+/// model Mio's API. While non-trivial, the bridge layer is still quite
+/// efficient. The most expensive part being calls to `read` and `write` require
+/// data to be copied into an intermediate buffer before it is passed to the
+/// kernel.
+///
+/// [epoll]: http://man7.org/linux/man-pages/man7/epoll.7.html
+/// [kqueue]: https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2
+/// [IOCP]: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365198(v=vs.85).aspx
+/// [`signalfd`]: http://man7.org/linux/man-pages/man2/signalfd.2.html
+/// [`SourceFd`]: unix/struct.SourceFd.html
+/// [`Poll::poll`]: struct.Poll.html#method.poll
+pub struct Poll {
+    registry: Registry,
+}
+
+/// Registers I/O resources.
+pub struct Registry {
+    selector: sys::Selector,
+}
+
+impl Poll {
+    /// Create a separate `Registry` which can be used to register
+    /// `event::Source`s.
+    pub fn registry(&self) -> &Registry {
+        &self.registry
+    }
+
+    /// Wait for readiness events
+    ///
+    /// Blocks the current thread and waits for readiness events for any of the
+    /// [`event::Source`]s that have been registered with this `Poll` instance.
+    /// The function will block until either at least one readiness event has
+    /// been received or `timeout` has elapsed. A `timeout` of `None` means that
+    /// `poll` will block until a readiness event has been received.
+    ///
+    /// The supplied `events` will be cleared and newly received readiness events
+    /// will be pushed onto the end. At most `events.capacity()` events will be
+    /// returned. If there are further pending readiness events, they will be
+    /// returned on the next call to `poll`.
+    ///
+    /// A single call to `poll` may result in multiple readiness events being
+    /// returned for a single event source. For example, if a TCP socket becomes
+    /// both readable and writable, it may be possible for a single readiness
+    /// event to be returned with both [`readable`] and [`writable`] readiness
+    /// **OR** two separate events may be returned, one with [`readable`] set
+    /// and one with [`writable`] set.
+    ///
+    /// Note that the `timeout` will be rounded up to the system clock
+    /// granularity (usually 1ms), and kernel scheduling delays mean that
+    /// the blocking interval may be overrun by a small amount.
+    ///
+    /// See the [struct] level documentation for a higher level discussion of
+    /// polling.
+    ///
+    /// [`event::Source`]: ./event/trait.Source.html
+    /// [`readable`]: struct.Interest.html#associatedconstant.READABLE
+    /// [`writable`]: struct.Interest.html#associatedconstant.WRITABLE
+    /// [struct]: struct.Poll.html
+    /// [`iter`]: ./event/struct.Events.html#method.iter
+    ///
+    /// # Notes
+    ///
+    /// This returns any errors without attempting to retry, previous versions
+    /// of Mio would automatically retry the poll call if it was interrupted
+    /// (if `EINTR` was returned).
+    ///
+    /// # Examples
+    ///
+    /// A basic example -- establishing a `TcpStream` connection.
+    ///
+    #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Events, Poll, Interest, Token};
+    /// use mio::net::TcpStream;
+    ///
+    /// use std::net::{TcpListener, SocketAddr};
+    /// use std::thread;
+    ///
+    /// // Bind a server socket to connect to.
+    /// let addr: SocketAddr = "127.0.0.1:0".parse()?;
+    /// let server = TcpListener::bind(addr)?;
+    /// let addr = server.local_addr()?.clone();
+    ///
+    /// // Spawn a thread to accept the socket
+    /// thread::spawn(move || {
+    ///     let _ = server.accept();
+    /// });
+    ///
+    /// // Construct a new `Poll` handle as well as the `Events` we'll store into
+    /// let mut poll = Poll::new()?;
+    /// let mut events = Events::with_capacity(1024);
+    ///
+    /// // Connect the stream
+    /// let mut stream = TcpStream::connect(addr)?;
+    ///
+    /// // Register the stream with `Poll`
+    /// poll.registry().register(
+    ///     &mut stream,
+    ///     Token(0),
+    ///     Interest::READABLE | Interest::WRITABLE)?;
+    ///
+    /// // Wait for the socket to become ready. This has to happens in a loop to
+    /// // handle spurious wakeups.
+    /// loop {
+    ///     poll.poll(&mut events, None)?;
+    ///
+    ///     for event in &events {
+    ///         if event.token() == Token(0) && event.is_writable() {
+    ///             // The socket connected (probably, it could still be a spurious
+    ///             // wakeup)
+    ///             return Ok(());
+    ///         }
+    ///     }
+    /// }
+    /// # }
+    /// ```
+    ///
+    /// [struct]: #
+    pub fn poll(&mut self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        self.registry.selector.select(events.sys(), timeout)
+    }
+}
+
+cfg_os_poll! {
+    impl Poll {
+        /// Return a new `Poll` handle.
+        ///
+        /// This function will make a syscall to the operating system to create
+        /// the system selector. If this syscall fails, `Poll::new` will return
+        /// with the error.
+        ///
+        /// See [struct] level docs for more details.
+        ///
+        /// [struct]: struct.Poll.html
+        ///
+        /// # Examples
+        ///
+        /// ```
+        /// # use std::error::Error;
+        /// # fn main() -> Result<(), Box<dyn Error>> {
+        /// use mio::{Poll, Events};
+        /// use std::time::Duration;
+        ///
+        /// let mut poll = match Poll::new() {
+        ///     Ok(poll) => poll,
+        ///     Err(e) => panic!("failed to create Poll instance; err={:?}", e),
+        /// };
+        ///
+        /// // Create a structure to receive polled events
+        /// let mut events = Events::with_capacity(1024);
+        ///
+        /// // Wait for events, but none will be received because no
+        /// // `event::Source`s have been registered with this `Poll` instance.
+        /// poll.poll(&mut events, Some(Duration::from_millis(500)))?;
+        /// assert!(events.is_empty());
+        /// #     Ok(())
+        /// # }
+        /// ```
+        pub fn new() -> io::Result<Poll> {
+            sys::Selector::new().map(|selector| Poll {
+                registry: Registry { selector },
+            })
+        }
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for Poll {
+    fn as_raw_fd(&self) -> RawFd {
+        self.registry.as_raw_fd()
+    }
+}
+
+impl fmt::Debug for Poll {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("Poll").finish()
+    }
+}
+
+impl Registry {
+    /// Register an [`event::Source`] with the `Poll` instance.
+    ///
+    /// Once registered, the `Poll` instance will monitor the event source for
+    /// readiness state changes. When it notices a state change, it will return
+    /// a readiness event for the handle the next time [`poll`] is called.
+    ///
+    /// See [`Poll`] docs for a high level overview.
+    ///
+    /// # Arguments
+    ///
+    /// `source: &mut S: event::Source`: This is the source of events that the
+    /// `Poll` instance should monitor for readiness state changes.
+    ///
+    /// `token: Token`: The caller picks a token to associate with the socket.
+    /// When [`poll`] returns an event for the handle, this token is included.
+    /// This allows the caller to map the event to its source. The token
+    /// associated with the `event::Source` can be changed at any time by
+    /// calling [`reregister`].
+    ///
+    /// See documentation on [`Token`] for an example showing how to pick
+    /// [`Token`] values.
+    ///
+    /// `interest: Interest`: Specifies which operations `Poll` should monitor
+    /// for readiness. `Poll` will only return readiness events for operations
+    /// specified by this argument.
+    ///
+    /// If a socket is registered with readable interest and the socket becomes
+    /// writable, no event will be returned from [`poll`].
+    ///
+    /// The readiness interest for an `event::Source` can be changed at any time
+    /// by calling [`reregister`].
+    ///
+    /// # Notes
+    ///
+    /// Callers must ensure that if a source being registered with a `Poll`
+    /// instance was previously registered with that `Poll` instance, then a
+    /// call to [`deregister`] has already occurred. Consecutive calls to
+    /// `register` is unspecified behavior.
+    ///
+    /// Unless otherwise specified, the caller should assume that once an event
+    /// source is registered with a `Poll` instance, it is bound to that `Poll`
+    /// instance for the lifetime of the event source. This remains true even
+    /// if the event source is deregistered from the poll instance using
+    /// [`deregister`].
+    ///
+    /// [`event::Source`]: ./event/trait.Source.html
+    /// [`poll`]: struct.Poll.html#method.poll
+    /// [`reregister`]: struct.Registry.html#method.reregister
+    /// [`deregister`]: struct.Registry.html#method.deregister
+    /// [`Token`]: struct.Token.html
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # use std::net;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Events, Poll, Interest, Token};
+    /// use mio::net::TcpStream;
+    /// use std::net::SocketAddr;
+    /// use std::time::{Duration, Instant};
+    ///
+    /// let mut poll = Poll::new()?;
+    ///
+    /// let address: SocketAddr = "127.0.0.1:0".parse()?;
+    /// let listener = net::TcpListener::bind(address)?;
+    /// let mut socket = TcpStream::connect(listener.local_addr()?)?;
+    ///
+    /// // Register the socket with `poll`
+    /// poll.registry().register(
+    ///     &mut socket,
+    ///     Token(0),
+    ///     Interest::READABLE | Interest::WRITABLE)?;
+    ///
+    /// let mut events = Events::with_capacity(1024);
+    /// let start = Instant::now();
+    /// let timeout = Duration::from_millis(500);
+    ///
+    /// loop {
+    ///     let elapsed = start.elapsed();
+    ///
+    ///     if elapsed >= timeout {
+    ///         // Connection timed out
+    ///         return Ok(());
+    ///     }
+    ///
+    ///     let remaining = timeout - elapsed;
+    ///     poll.poll(&mut events, Some(remaining))?;
+    ///
+    ///     for event in &events {
+    ///         if event.token() == Token(0) {
+    ///             // Something (probably) happened on the socket.
+    ///             return Ok(());
+    ///         }
+    ///     }
+    /// }
+    /// # }
+    /// ```
+    pub fn register<S>(&self, source: &mut S, token: Token, interests: Interest) -> io::Result<()>
+    where
+        S: event::Source + ?Sized,
+    {
+        trace!(
+            "registering event source with poller: token={:?}, interests={:?}",
+            token,
+            interests
+        );
+        source.register(self, token, interests)
+    }
+
+    /// Re-register an [`event::Source`] with the `Poll` instance.
+    ///
+    /// Re-registering an event source allows changing the details of the
+    /// registration. Specifically, it allows updating the associated `token`
+    /// and `interests` specified in previous `register` and `reregister` calls.
+    ///
+    /// The `reregister` arguments fully override the previous values. In other
+    /// words, if a socket is registered with [`readable`] interest and the call
+    /// to `reregister` specifies [`writable`], then read interest is no longer
+    /// requested for the handle.
+    ///
+    /// The event source must have previously been registered with this instance
+    /// of `Poll`, otherwise the behavior is unspecified.
+    ///
+    /// See the [`register`] documentation for details about the function
+    /// arguments and see the [`struct`] docs for a high level overview of
+    /// polling.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # use std::net;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Poll, Interest, Token};
+    /// use mio::net::TcpStream;
+    /// use std::net::SocketAddr;
+    ///
+    /// let poll = Poll::new()?;
+    ///
+    /// let address: SocketAddr = "127.0.0.1:0".parse()?;
+    /// let listener = net::TcpListener::bind(address)?;
+    /// let mut socket = TcpStream::connect(listener.local_addr()?)?;
+    ///
+    /// // Register the socket with `poll`, requesting readable
+    /// poll.registry().register(
+    ///     &mut socket,
+    ///     Token(0),
+    ///     Interest::READABLE)?;
+    ///
+    /// // Reregister the socket specifying write interest instead. Even though
+    /// // the token is the same it must be specified.
+    /// poll.registry().reregister(
+    ///     &mut socket,
+    ///     Token(0),
+    ///     Interest::WRITABLE)?;
+    /// #     Ok(())
+    /// # }
+    /// ```
+    ///
+    /// [`event::Source`]: ./event/trait.Source.html
+    /// [`struct`]: struct.Poll.html
+    /// [`register`]: struct.Registry.html#method.register
+    /// [`readable`]: ./event/struct.Event.html#is_readable
+    /// [`writable`]: ./event/struct.Event.html#is_writable
+    pub fn reregister<S>(&self, source: &mut S, token: Token, interests: Interest) -> io::Result<()>
+    where
+        S: event::Source + ?Sized,
+    {
+        trace!(
+            "reregistering event source with poller: token={:?}, interests={:?}",
+            token,
+            interests
+        );
+        source.reregister(self, token, interests)
+    }
+
+    /// Deregister an [`event::Source`] with the `Poll` instance.
+    ///
+    /// When an event source is deregistered, the `Poll` instance will no longer
+    /// monitor it for readiness state changes. Deregistering clears up any
+    /// internal resources needed to track the handle.  After an explicit call
+    /// to this method completes, it is guaranteed that the token previously
+    /// registered to this handle will not be returned by a future poll, so long
+    /// as a happens-before relationship is established between this call and
+    /// the poll.
+    ///
+    /// The event source must have previously been registered with this instance
+    /// of `Poll`, otherwise the behavior is unspecified.
+    ///
+    /// A handle can be passed back to `register` after it has been
+    /// deregistered; however, it must be passed back to the **same** `Poll`
+    /// instance, otherwise the behavior is unspecified.
+    ///
+    /// # Examples
+    ///
+    #[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+    #[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+    /// # use std::error::Error;
+    /// # use std::net;
+    /// # fn main() -> Result<(), Box<dyn Error>> {
+    /// use mio::{Events, Poll, Interest, Token};
+    /// use mio::net::TcpStream;
+    /// use std::net::SocketAddr;
+    /// use std::time::Duration;
+    ///
+    /// let mut poll = Poll::new()?;
+    ///
+    /// let address: SocketAddr = "127.0.0.1:0".parse()?;
+    /// let listener = net::TcpListener::bind(address)?;
+    /// let mut socket = TcpStream::connect(listener.local_addr()?)?;
+    ///
+    /// // Register the socket with `poll`
+    /// poll.registry().register(
+    ///     &mut socket,
+    ///     Token(0),
+    ///     Interest::READABLE)?;
+    ///
+    /// poll.registry().deregister(&mut socket)?;
+    ///
+    /// let mut events = Events::with_capacity(1024);
+    ///
+    /// // Set a timeout because this poll should never receive any events.
+    /// poll.poll(&mut events, Some(Duration::from_secs(1)))?;
+    /// assert!(events.is_empty());
+    /// #     Ok(())
+    /// # }
+    /// ```
+    pub fn deregister<S>(&self, source: &mut S) -> io::Result<()>
+    where
+        S: event::Source + ?Sized,
+    {
+        trace!("deregistering event source from poller");
+        source.deregister(self)
+    }
+
+    /// Creates a new independently owned `Registry`.
+    ///
+    /// Event sources registered with this `Registry` will be registered with
+    /// the original `Registry` and `Poll` instance.
+    pub fn try_clone(&self) -> io::Result<Registry> {
+        self.selector
+            .try_clone()
+            .map(|selector| Registry { selector })
+    }
+
+    /// Internal check to ensure only a single `Waker` is active per [`Poll`]
+    /// instance.
+    #[cfg(debug_assertions)]
+    pub(crate) fn register_waker(&self) {
+        assert!(
+            !self.selector.register_waker(),
+            "Only a single `Waker` can be active per `Poll` instance"
+        );
+    }
+
+    /// Get access to the `sys::Selector`.
+    pub(crate) fn selector(&self) -> &sys::Selector {
+        &self.selector
+    }
+}
+
+impl fmt::Debug for Registry {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt.debug_struct("Registry").finish()
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for Registry {
+    fn as_raw_fd(&self) -> RawFd {
+        self.selector.as_raw_fd()
+    }
+}
+
+cfg_os_poll! {
+    #[cfg(unix)]
+    #[test]
+    pub fn as_raw_fd() {
+        let poll = Poll::new().unwrap();
+        assert!(poll.as_raw_fd() > 0);
+    }
+}
diff --git a/third_party/rust/mio/src/sys/mod.rs b/third_party/rust/mio/src/sys/mod.rs
new file mode 100644
index 0000000000..81ae6d2e61
--- /dev/null
+++ b/third_party/rust/mio/src/sys/mod.rs
@@ -0,0 +1,80 @@
+//! Module with system specific types.
+//!
+//! Required types:
+//!
+//! * `Event`: a type alias for the system specific event, e.g. `kevent` or
+//!            `epoll_event`.
+//! * `event`: a module with various helper functions for `Event`, see
+//!            [`crate::event::Event`] for the required functions.
+//! * `Events`: collection of `Event`s, see [`crate::Events`].
+//! * `IoSourceState`: state for the `IoSource` type.
+//! * `Selector`: selector used to register event sources and poll for events,
+//!               see [`crate::Poll`] and [`crate::Registry`] for required
+//!               methods.
+//! * `tcp` and `udp` modules: see the [`crate::net`] module.
+//! * `Waker`: see [`crate::Waker`].
+
+cfg_os_poll! {
+    macro_rules! debug_detail {
+        (
+            $type: ident ($event_type: ty), $test: path,
+            $($(#[$target: meta])* $libc: ident :: $flag: ident),+ $(,)*
+        ) => {
+            struct $type($event_type);
+
+            impl fmt::Debug for $type {
+                fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+                    let mut written_one = false;
+                    $(
+                        $(#[$target])*
+                        #[allow(clippy::bad_bit_mask)] // Apparently some flags are zero.
+                        {
+                            // Windows doesn't use `libc` but the `afd` module.
+                            if $test(&self.0, &$libc :: $flag) {
+                                if !written_one {
+                                    write!(f, "{}", stringify!($flag))?;
+                                    written_one = true;
+                                } else {
+                                    write!(f, "|{}", stringify!($flag))?;
+                                }
+                            }
+                        }
+                    )+
+                    if !written_one {
+                        write!(f, "(empty)")
+                    } else {
+                        Ok(())
+                    }
+                }
+            }
+        };
+    }
+}
+
+#[cfg(unix)]
+cfg_os_poll! {
+    mod unix;
+    pub use self::unix::*;
+}
+
+#[cfg(windows)]
+cfg_os_poll! {
+    mod windows;
+    pub use self::windows::*;
+}
+
+cfg_not_os_poll! {
+    mod shell;
+    pub(crate) use self::shell::*;
+
+    #[cfg(unix)]
+    cfg_any_os_ext! {
+        mod unix;
+        pub use self::unix::SourceFd;
+    }
+
+    #[cfg(unix)]
+    cfg_net! {
+        pub use self::unix::SocketAddr;
+    }
+}
diff --git a/third_party/rust/mio/src/sys/shell/mod.rs b/third_party/rust/mio/src/sys/shell/mod.rs
new file mode 100644
index 0000000000..7e1533f452
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/mod.rs
@@ -0,0 +1,70 @@
+macro_rules! os_required {
+    () => {
+        panic!("mio must be compiled with `os-poll` to run.")
+    };
+}
+
+mod selector;
+pub(crate) use self::selector::{event, Event, Events, Selector};
+
+mod waker;
+pub(crate) use self::waker::Waker;
+
+cfg_net! {
+    pub(crate) mod tcp;
+    pub(crate) mod udp;
+    #[cfg(unix)]
+    pub(crate) mod uds;
+}
+
+cfg_io_source! {
+    use std::io;
+    #[cfg(windows)]
+    use std::os::windows::io::RawSocket;
+
+    #[cfg(windows)]
+    use crate::{Registry, Token, Interest};
+
+    pub(crate) struct IoSourceState;
+
+    impl IoSourceState {
+        pub fn new() -> IoSourceState {
+            IoSourceState
+        }
+
+        pub fn do_io<T, F, R>(&self, f: F, io: &T) -> io::Result<R>
+        where
+            F: FnOnce(&T) -> io::Result<R>,
+        {
+            // We don't hold state, so we can just call the function and
+            // return.
+            f(io)
+        }
+    }
+
+    #[cfg(windows)]
+    impl IoSourceState {
+         pub fn register(
+            &mut self,
+            _: &Registry,
+            _: Token,
+            _: Interest,
+            _: RawSocket,
+        ) -> io::Result<()> {
+            os_required!()
+        }
+
+        pub fn reregister(
+            &mut self,
+            _: &Registry,
+            _: Token,
+            _: Interest,
+        ) -> io::Result<()> {
+           os_required!()
+        }
+
+        pub fn deregister(&mut self) -> io::Result<()> {
+            os_required!()
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/shell/selector.rs b/third_party/rust/mio/src/sys/shell/selector.rs
new file mode 100644
index 0000000000..91fc0bf47c
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/selector.rs
@@ -0,0 +1,108 @@
+use std::io;
+#[cfg(unix)]
+use std::os::unix::io::{AsRawFd, RawFd};
+use std::time::Duration;
+
+pub type Event = usize;
+
+pub type Events = Vec<Event>;
+
+#[derive(Debug)]
+pub struct Selector {}
+
+impl Selector {
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        os_required!();
+    }
+
+    pub fn select(&self, _: &mut Events, _: Option<Duration>) -> io::Result<()> {
+        os_required!();
+    }
+
+    #[cfg(debug_assertions)]
+    pub fn register_waker(&self) -> bool {
+        os_required!();
+    }
+}
+
+#[cfg(unix)]
+cfg_any_os_ext! {
+    use crate::{Interest, Token};
+
+    impl Selector {
+        pub fn register(&self, _: RawFd, _: Token, _: Interest) -> io::Result<()> {
+            os_required!();
+        }
+
+        pub fn reregister(&self, _: RawFd, _: Token, _: Interest) -> io::Result<()> {
+            os_required!();
+        }
+
+        pub fn deregister(&self, _: RawFd) -> io::Result<()> {
+            os_required!();
+        }
+    }
+}
+
+cfg_io_source! {
+    #[cfg(debug_assertions)]
+    impl Selector {
+        pub fn id(&self) -> usize {
+            os_required!();
+        }
+    }
+}
+
+#[cfg(unix)]
+impl AsRawFd for Selector {
+    fn as_raw_fd(&self) -> RawFd {
+        os_required!()
+    }
+}
+
+#[allow(clippy::trivially_copy_pass_by_ref)]
+pub mod event {
+    use crate::sys::Event;
+    use crate::Token;
+    use std::fmt;
+
+    pub fn token(_: &Event) -> Token {
+        os_required!();
+    }
+
+    pub fn is_readable(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_writable(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_error(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_read_closed(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_write_closed(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_priority(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_aio(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn is_lio(_: &Event) -> bool {
+        os_required!();
+    }
+
+    pub fn debug_details(_: &mut fmt::Formatter<'_>, _: &Event) -> fmt::Result {
+        os_required!();
+    }
+}
diff --git a/third_party/rust/mio/src/sys/shell/tcp.rs b/third_party/rust/mio/src/sys/shell/tcp.rs
new file mode 100644
index 0000000000..60dfe70f67
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/tcp.rs
@@ -0,0 +1,27 @@
+use std::io;
+use std::net::{self, SocketAddr};
+
+pub(crate) fn new_for_addr(_: SocketAddr) -> io::Result<i32> {
+    os_required!();
+}
+
+pub(crate) fn bind(_: &net::TcpListener, _: SocketAddr) -> io::Result<()> {
+    os_required!();
+}
+
+pub(crate) fn connect(_: &net::TcpStream, _: SocketAddr) -> io::Result<()> {
+    os_required!();
+}
+
+pub(crate) fn listen(_: &net::TcpListener, _: u32) -> io::Result<()> {
+    os_required!();
+}
+
+#[cfg(unix)]
+pub(crate) fn set_reuseaddr(_: &net::TcpListener, _: bool) -> io::Result<()> {
+    os_required!();
+}
+
+pub(crate) fn accept(_: &net::TcpListener) -> io::Result<(net::TcpStream, SocketAddr)> {
+    os_required!();
+}
diff --git a/third_party/rust/mio/src/sys/shell/udp.rs b/third_party/rust/mio/src/sys/shell/udp.rs
new file mode 100644
index 0000000000..48ccac740f
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/udp.rs
@@ -0,0 +1,10 @@
+use std::io;
+use std::net::{self, SocketAddr};
+
+pub fn bind(_: SocketAddr) -> io::Result<net::UdpSocket> {
+    os_required!()
+}
+
+pub(crate) fn only_v6(_: &net::UdpSocket) -> io::Result<bool> {
+    os_required!()
+}
diff --git a/third_party/rust/mio/src/sys/shell/uds.rs b/third_party/rust/mio/src/sys/shell/uds.rs
new file mode 100644
index 0000000000..c18aca042f
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/uds.rs
@@ -0,0 +1,75 @@
+pub(crate) mod datagram {
+    use crate::net::SocketAddr;
+    use std::io;
+    use std::os::unix::net;
+    use std::path::Path;
+
+    pub(crate) fn bind(_: &Path) -> io::Result<net::UnixDatagram> {
+        os_required!()
+    }
+
+    pub(crate) fn unbound() -> io::Result<net::UnixDatagram> {
+        os_required!()
+    }
+
+    pub(crate) fn pair() -> io::Result<(net::UnixDatagram, net::UnixDatagram)> {
+        os_required!()
+    }
+
+    pub(crate) fn local_addr(_: &net::UnixDatagram) -> io::Result<SocketAddr> {
+        os_required!()
+    }
+
+    pub(crate) fn peer_addr(_: &net::UnixDatagram) -> io::Result<SocketAddr> {
+        os_required!()
+    }
+
+    pub(crate) fn recv_from(
+        _: &net::UnixDatagram,
+        _: &mut [u8],
+    ) -> io::Result<(usize, SocketAddr)> {
+        os_required!()
+    }
+}
+
+pub(crate) mod listener {
+    use crate::net::{SocketAddr, UnixStream};
+    use std::io;
+    use std::os::unix::net;
+    use std::path::Path;
+
+    pub(crate) fn bind(_: &Path) -> io::Result<net::UnixListener> {
+        os_required!()
+    }
+
+    pub(crate) fn accept(_: &net::UnixListener) -> io::Result<(UnixStream, SocketAddr)> {
+        os_required!()
+    }
+
+    pub(crate) fn local_addr(_: &net::UnixListener) -> io::Result<SocketAddr> {
+        os_required!()
+    }
+}
+
+pub(crate) mod stream {
+    use crate::net::SocketAddr;
+    use std::io;
+    use std::os::unix::net;
+    use std::path::Path;
+
+    pub(crate) fn connect(_: &Path) -> io::Result<net::UnixStream> {
+        os_required!()
+    }
+
+    pub(crate) fn pair() -> io::Result<(net::UnixStream, net::UnixStream)> {
+        os_required!()
+    }
+
+    pub(crate) fn local_addr(_: &net::UnixStream) -> io::Result<SocketAddr> {
+        os_required!()
+    }
+
+    pub(crate) fn peer_addr(_: &net::UnixStream) -> io::Result<SocketAddr> {
+        os_required!()
+    }
+}
diff --git a/third_party/rust/mio/src/sys/shell/waker.rs b/third_party/rust/mio/src/sys/shell/waker.rs
new file mode 100644
index 0000000000..bbdd7c33af
--- /dev/null
+++ b/third_party/rust/mio/src/sys/shell/waker.rs
@@ -0,0 +1,16 @@
+use crate::sys::Selector;
+use crate::Token;
+use std::io;
+
+#[derive(Debug)]
+pub struct Waker {}
+
+impl Waker {
+    pub fn new(_: &Selector, _: Token) -> io::Result<Waker> {
+        os_required!();
+    }
+
+    pub fn wake(&self) -> io::Result<()> {
+        os_required!();
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/mod.rs b/third_party/rust/mio/src/sys/unix/mod.rs
new file mode 100644
index 0000000000..231480a5da
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/mod.rs
@@ -0,0 +1,72 @@
+/// Helper macro to execute a system call that returns an `io::Result`.
+//
+// Macro must be defined before any modules that uses them.
+#[allow(unused_macros)]
+macro_rules! syscall {
+    ($fn: ident ( $($arg: expr),* $(,)* ) ) => {{
+        let res = unsafe { libc::$fn($($arg, )*) };
+        if res == -1 {
+            Err(std::io::Error::last_os_error())
+        } else {
+            Ok(res)
+        }
+    }};
+}
+
+cfg_os_poll! {
+    mod selector;
+    pub(crate) use self::selector::{event, Event, Events, Selector};
+
+    mod sourcefd;
+    pub use self::sourcefd::SourceFd;
+
+    mod waker;
+    pub(crate) use self::waker::Waker;
+
+    cfg_net! {
+        mod net;
+
+        pub(crate) mod tcp;
+        pub(crate) mod udp;
+        pub(crate) mod uds;
+        pub use self::uds::SocketAddr;
+    }
+
+    cfg_io_source! {
+        use std::io;
+
+        // Both `kqueue` and `epoll` don't need to hold any user space state.
+        pub(crate) struct IoSourceState;
+
+        impl IoSourceState {
+            pub fn new() -> IoSourceState {
+                IoSourceState
+            }
+
+            pub fn do_io<T, F, R>(&self, f: F, io: &T) -> io::Result<R>
+            where
+                F: FnOnce(&T) -> io::Result<R>,
+            {
+                // We don't hold state, so we can just call the function and
+                // return.
+                f(io)
+            }
+        }
+    }
+
+    cfg_os_ext! {
+        pub(crate) mod pipe;
+    }
+}
+
+cfg_not_os_poll! {
+    cfg_net! {
+        mod uds;
+        pub use self::uds::SocketAddr;
+    }
+
+    cfg_any_os_ext! {
+        mod sourcefd;
+        pub use self::sourcefd::SourceFd;
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/net.rs b/third_party/rust/mio/src/sys/unix/net.rs
new file mode 100644
index 0000000000..78f1387b1f
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/net.rs
@@ -0,0 +1,168 @@
+use std::io;
+use std::mem::size_of;
+use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
+
+pub(crate) fn new_ip_socket(addr: SocketAddr, socket_type: libc::c_int) -> io::Result<libc::c_int> {
+    let domain = match addr {
+        SocketAddr::V4(..) => libc::AF_INET,
+        SocketAddr::V6(..) => libc::AF_INET6,
+    };
+
+    new_socket(domain, socket_type)
+}
+
+/// Create a new non-blocking socket.
+pub(crate) fn new_socket(domain: libc::c_int, socket_type: libc::c_int) -> io::Result<libc::c_int> {
+    #[cfg(any(
+        target_os = "android",
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "illumos",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "openbsd"
+    ))]
+    let socket_type = socket_type | libc::SOCK_NONBLOCK | libc::SOCK_CLOEXEC;
+
+    // Gives a warning for platforms without SOCK_NONBLOCK.
+    #[allow(clippy::let_and_return)]
+    let socket = syscall!(socket(domain, socket_type, 0));
+
+    // Mimick `libstd` and set `SO_NOSIGPIPE` on apple systems.
+    #[cfg(target_vendor = "apple")]
+    let socket = socket.and_then(|socket| {
+        syscall!(setsockopt(
+            socket,
+            libc::SOL_SOCKET,
+            libc::SO_NOSIGPIPE,
+            &1 as *const libc::c_int as *const libc::c_void,
+            size_of::<libc::c_int>() as libc::socklen_t
+        ))
+        .map(|_| socket)
+    });
+
+    // Darwin doesn't have SOCK_NONBLOCK or SOCK_CLOEXEC.
+    #[cfg(any(target_os = "ios", target_os = "macos"))]
+    let socket = socket.and_then(|socket| {
+        // For platforms that don't support flags in socket, we need to
+        // set the flags ourselves.
+        syscall!(fcntl(socket, libc::F_SETFL, libc::O_NONBLOCK))
+            .and_then(|_| syscall!(fcntl(socket, libc::F_SETFD, libc::FD_CLOEXEC)).map(|_| socket))
+            .map_err(|e| {
+                // If either of the `fcntl` calls failed, ensure the socket is
+                // closed and return the error.
+                let _ = syscall!(close(socket));
+                e
+            })
+    });
+
+    socket
+}
+
+/// A type with the same memory layout as `libc::sockaddr`. Used in converting Rust level
+/// SocketAddr* types into their system representation. The benefit of this specific
+/// type over using `libc::sockaddr_storage` is that this type is exactly as large as it
+/// needs to be and not a lot larger. And it can be initialized cleaner from Rust.
+#[repr(C)]
+pub(crate) union SocketAddrCRepr {
+    v4: libc::sockaddr_in,
+    v6: libc::sockaddr_in6,
+}
+
+impl SocketAddrCRepr {
+    pub(crate) fn as_ptr(&self) -> *const libc::sockaddr {
+        self as *const _ as *const libc::sockaddr
+    }
+}
+
+/// Converts a Rust `SocketAddr` into the system representation.
+pub(crate) fn socket_addr(addr: &SocketAddr) -> (SocketAddrCRepr, libc::socklen_t) {
+    match addr {
+        SocketAddr::V4(ref addr) => {
+            // `s_addr` is stored as BE on all machine and the array is in BE order.
+            // So the native endian conversion method is used so that it's never swapped.
+            let sin_addr = libc::in_addr {
+                s_addr: u32::from_ne_bytes(addr.ip().octets()),
+            };
+
+            let sockaddr_in = libc::sockaddr_in {
+                sin_family: libc::AF_INET as libc::sa_family_t,
+                sin_port: addr.port().to_be(),
+                sin_addr,
+                sin_zero: [0; 8],
+                #[cfg(any(
+                    target_os = "dragonfly",
+                    target_os = "freebsd",
+                    target_os = "ios",
+                    target_os = "macos",
+                    target_os = "netbsd",
+                    target_os = "openbsd"
+                ))]
+                sin_len: 0,
+            };
+
+            let sockaddr = SocketAddrCRepr { v4: sockaddr_in };
+            let socklen = size_of::<libc::sockaddr_in>() as libc::socklen_t;
+            (sockaddr, socklen)
+        }
+        SocketAddr::V6(ref addr) => {
+            let sockaddr_in6 = libc::sockaddr_in6 {
+                sin6_family: libc::AF_INET6 as libc::sa_family_t,
+                sin6_port: addr.port().to_be(),
+                sin6_addr: libc::in6_addr {
+                    s6_addr: addr.ip().octets(),
+                },
+                sin6_flowinfo: addr.flowinfo(),
+                sin6_scope_id: addr.scope_id(),
+                #[cfg(any(
+                    target_os = "dragonfly",
+                    target_os = "freebsd",
+                    target_os = "ios",
+                    target_os = "macos",
+                    target_os = "netbsd",
+                    target_os = "openbsd"
+                ))]
+                sin6_len: 0,
+                #[cfg(target_os = "illumos")]
+                __sin6_src_id: 0,
+            };
+
+            let sockaddr = SocketAddrCRepr { v6: sockaddr_in6 };
+            let socklen = size_of::<libc::sockaddr_in6>() as libc::socklen_t;
+            (sockaddr, socklen)
+        }
+    }
+}
+
+/// Converts a `libc::sockaddr` compatible struct into a native Rust `SocketAddr`.
+///
+/// # Safety
+///
+/// `storage` must have the `ss_family` field correctly initialized.
+/// `storage` must be initialised to a `sockaddr_in` or `sockaddr_in6`.
+pub(crate) unsafe fn to_socket_addr(
+    storage: *const libc::sockaddr_storage,
+) -> io::Result<SocketAddr> {
+    match (*storage).ss_family as libc::c_int {
+        libc::AF_INET => {
+            // Safety: if the ss_family field is AF_INET then storage must be a sockaddr_in.
+            let addr: &libc::sockaddr_in = &*(storage as *const libc::sockaddr_in);
+            let ip = Ipv4Addr::from(addr.sin_addr.s_addr.to_ne_bytes());
+            let port = u16::from_be(addr.sin_port);
+            Ok(SocketAddr::V4(SocketAddrV4::new(ip, port)))
+        }
+        libc::AF_INET6 => {
+            // Safety: if the ss_family field is AF_INET6 then storage must be a sockaddr_in6.
+            let addr: &libc::sockaddr_in6 = &*(storage as *const libc::sockaddr_in6);
+            let ip = Ipv6Addr::from(addr.sin6_addr.s6_addr);
+            let port = u16::from_be(addr.sin6_port);
+            Ok(SocketAddr::V6(SocketAddrV6::new(
+                ip,
+                port,
+                addr.sin6_flowinfo,
+                addr.sin6_scope_id,
+            )))
+        }
+        _ => Err(io::ErrorKind::InvalidInput.into()),
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/pipe.rs b/third_party/rust/mio/src/sys/unix/pipe.rs
new file mode 100644
index 0000000000..c899dfb2da
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/pipe.rs
@@ -0,0 +1,431 @@
+//! Unix pipe.
+//!
+//! See the [`new`] function for documentation.
+
+use std::fs::File;
+use std::io::{self, IoSlice, IoSliceMut, Read, Write};
+use std::os::unix::io::{AsRawFd, FromRawFd, IntoRawFd, RawFd};
+use std::process::{ChildStderr, ChildStdin, ChildStdout};
+
+use crate::io_source::IoSource;
+use crate::{event, Interest, Registry, Token};
+
+/// Create a new non-blocking Unix pipe.
+///
+/// This is a wrapper around Unix's [`pipe(2)`] system call and can be used as
+/// inter-process or thread communication channel.
+///
+/// This channel may be created before forking the process and then one end used
+/// in each process, e.g. the parent process has the sending end to send command
+/// to the child process.
+///
+/// [`pipe(2)`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/pipe.html
+///
+/// # Events
+///
+/// The [`Sender`] can be registered with [`WRITABLE`] interest to receive
+/// [writable events], the [`Receiver`] with [`READABLE`] interest. Once data is
+/// written to the `Sender` the `Receiver` will receive an [readable event].
+///
+/// In addition to those events, events will also be generated if the other side
+/// is dropped. To check if the `Sender` is dropped you'll need to check
+/// [`is_read_closed`] on events for the `Receiver`, if it returns true the
+/// `Sender` is dropped. On the `Sender` end check [`is_write_closed`], if it
+/// returns true the `Receiver` was dropped. Also see the second example below.
+///
+/// [`WRITABLE`]: Interest::WRITABLE
+/// [writable events]: event::Event::is_writable
+/// [`READABLE`]: Interest::READABLE
+/// [readable event]: event::Event::is_readable
+/// [`is_read_closed`]: event::Event::is_read_closed
+/// [`is_write_closed`]: event::Event::is_write_closed
+///
+/// # Deregistering
+///
+/// Both `Sender` and `Receiver` will deregister themselves when dropped,
+/// **iff** the file descriptors are not duplicated (via [`dup(2)`]).
+///
+/// [`dup(2)`]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/dup.html
+///
+/// # Examples
+///
+/// Simple example that writes data into the sending end and read it from the
+/// receiving end.
+///
+/// ```
+/// use std::io::{self, Read, Write};
+///
+/// use mio::{Poll, Events, Interest, Token};
+/// use mio::unix::pipe;
+///
+/// // Unique tokens for the two ends of the channel.
+/// const PIPE_RECV: Token = Token(0);
+/// const PIPE_SEND: Token = Token(1);
+///
+/// # fn main() -> io::Result<()> {
+/// // Create our `Poll` instance and the `Events` container.
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(8);
+///
+/// // Create a new pipe.
+/// let (mut sender, mut receiver) = pipe::new()?;
+///
+/// // Register both ends of the channel.
+/// poll.registry().register(&mut receiver, PIPE_RECV, Interest::READABLE)?;
+/// poll.registry().register(&mut sender, PIPE_SEND, Interest::WRITABLE)?;
+///
+/// const MSG: &[u8; 11] = b"Hello world";
+///
+/// loop {
+///     poll.poll(&mut events, None)?;
+///
+///     for event in events.iter() {
+///         match event.token() {
+///             PIPE_SEND => sender.write(MSG)
+///                 .and_then(|n| if n != MSG.len() {
+///                         // We'll consider a short write an error in this
+///                         // example. NOTE: we can't use `write_all` with
+///                         // non-blocking I/O.
+///                         Err(io::ErrorKind::WriteZero.into())
+///                     } else {
+///                         Ok(())
+///                     })?,
+///             PIPE_RECV => {
+///                 let mut buf = [0; 11];
+///                 let n = receiver.read(&mut buf)?;
+///                 println!("received: {:?}", &buf[0..n]);
+///                 assert_eq!(n, MSG.len());
+///                 assert_eq!(&buf, &*MSG);
+///                 return Ok(());
+///             },
+///             _ => unreachable!(),
+///         }
+///     }
+/// }
+/// # }
+/// ```
+///
+/// Example that receives an event once the `Sender` is dropped.
+///
+/// ```
+/// # use std::io;
+/// #
+/// # use mio::{Poll, Events, Interest, Token};
+/// # use mio::unix::pipe;
+/// #
+/// # const PIPE_RECV: Token = Token(0);
+/// # const PIPE_SEND: Token = Token(1);
+/// #
+/// # fn main() -> io::Result<()> {
+/// // Same setup as in the example above.
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(8);
+///
+/// let (mut sender, mut receiver) = pipe::new()?;
+///
+/// poll.registry().register(&mut receiver, PIPE_RECV, Interest::READABLE)?;
+/// poll.registry().register(&mut sender, PIPE_SEND, Interest::WRITABLE)?;
+///
+/// // Drop the sender.
+/// drop(sender);
+///
+/// poll.poll(&mut events, None)?;
+///
+/// for event in events.iter() {
+///     match event.token() {
+///         PIPE_RECV if event.is_read_closed() => {
+///             // Detected that the sender was dropped.
+///             println!("Sender dropped!");
+///             return Ok(());
+///         },
+///         _ => unreachable!(),
+///     }
+/// }
+/// # unreachable!();
+/// # }
+/// ```
+pub fn new() -> io::Result<(Sender, Receiver)> {
+    let mut fds: [RawFd; 2] = [-1, -1];
+
+    #[cfg(any(
+        target_os = "android",
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "illumos",
+    ))]
+    unsafe {
+        if libc::pipe2(fds.as_mut_ptr(), libc::O_CLOEXEC | libc::O_NONBLOCK) != 0 {
+            return Err(io::Error::last_os_error());
+        }
+    }
+
+    #[cfg(any(target_os = "ios", target_os = "macos"))]
+    unsafe {
+        // For platforms that don't have `pipe2(2)` we need to manually set the
+        // correct flags on the file descriptor.
+        if libc::pipe(fds.as_mut_ptr()) != 0 {
+            return Err(io::Error::last_os_error());
+        }
+
+        for fd in &fds {
+            if libc::fcntl(*fd, libc::F_SETFL, libc::O_NONBLOCK) != 0
+                || libc::fcntl(*fd, libc::F_SETFD, libc::FD_CLOEXEC) != 0
+            {
+                let err = io::Error::last_os_error();
+                // Don't leak file descriptors. Can't handle error though.
+                let _ = libc::close(fds[0]);
+                let _ = libc::close(fds[1]);
+                return Err(err);
+            }
+        }
+    }
+
+    #[cfg(not(any(
+        target_os = "android",
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "ios",
+        target_os = "macos",
+        target_os = "illumos",
+    )))]
+    compile_error!("unsupported target for `mio::unix::pipe`");
+
+    // Safety: we just initialised the `fds` above.
+    let r = unsafe { Receiver::from_raw_fd(fds[0]) };
+    let w = unsafe { Sender::from_raw_fd(fds[1]) };
+    Ok((w, r))
+}
+
+/// Sending end of an Unix pipe.
+///
+/// See [`new`] for documentation, including examples.
+#[derive(Debug)]
+pub struct Sender {
+    inner: IoSource<File>,
+}
+
+impl Sender {
+    /// Set the `Sender` into or out of non-blocking mode.
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        set_nonblocking(self.inner.as_raw_fd(), nonblocking)
+    }
+}
+
+impl event::Source for Sender {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl Write for Sender {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|sender| (&*sender).flush())
+    }
+}
+
+impl Write for &Sender {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).write(buf))
+    }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).write_vectored(bufs))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.inner.do_io(|sender| (&*sender).flush())
+    }
+}
+
+/// # Notes
+///
+/// The underlying pipe is **not** set to non-blocking.
+impl From<ChildStdin> for Sender {
+    fn from(stdin: ChildStdin) -> Sender {
+        // Safety: `ChildStdin` is guaranteed to be a valid file descriptor.
+        unsafe { Sender::from_raw_fd(stdin.into_raw_fd()) }
+    }
+}
+
+impl FromRawFd for Sender {
+    unsafe fn from_raw_fd(fd: RawFd) -> Sender {
+        Sender {
+            inner: IoSource::new(File::from_raw_fd(fd)),
+        }
+    }
+}
+
+impl AsRawFd for Sender {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for Sender {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+/// Receiving end of an Unix pipe.
+///
+/// See [`new`] for documentation, including examples.
+#[derive(Debug)]
+pub struct Receiver {
+    inner: IoSource<File>,
+}
+
+impl Receiver {
+    /// Set the `Receiver` into or out of non-blocking mode.
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        set_nonblocking(self.inner.as_raw_fd(), nonblocking)
+    }
+}
+
+impl event::Source for Receiver {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.register(registry, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        self.inner.reregister(registry, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        self.inner.deregister(registry)
+    }
+}
+
+impl Read for Receiver {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).read_vectored(bufs))
+    }
+}
+
+impl Read for &Receiver {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).read(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        self.inner.do_io(|sender| (&*sender).read_vectored(bufs))
+    }
+}
+
+/// # Notes
+///
+/// The underlying pipe is **not** set to non-blocking.
+impl From<ChildStdout> for Receiver {
+    fn from(stdout: ChildStdout) -> Receiver {
+        // Safety: `ChildStdout` is guaranteed to be a valid file descriptor.
+        unsafe { Receiver::from_raw_fd(stdout.into_raw_fd()) }
+    }
+}
+
+/// # Notes
+///
+/// The underlying pipe is **not** set to non-blocking.
+impl From<ChildStderr> for Receiver {
+    fn from(stderr: ChildStderr) -> Receiver {
+        // Safety: `ChildStderr` is guaranteed to be a valid file descriptor.
+        unsafe { Receiver::from_raw_fd(stderr.into_raw_fd()) }
+    }
+}
+
+impl FromRawFd for Receiver {
+    unsafe fn from_raw_fd(fd: RawFd) -> Receiver {
+        Receiver {
+            inner: IoSource::new(File::from_raw_fd(fd)),
+        }
+    }
+}
+
+impl AsRawFd for Receiver {
+    fn as_raw_fd(&self) -> RawFd {
+        self.inner.as_raw_fd()
+    }
+}
+
+impl IntoRawFd for Receiver {
+    fn into_raw_fd(self) -> RawFd {
+        self.inner.into_inner().into_raw_fd()
+    }
+}
+
+#[cfg(not(target_os = "illumos"))]
+fn set_nonblocking(fd: RawFd, nonblocking: bool) -> io::Result<()> {
+    let value = nonblocking as libc::c_int;
+    if unsafe { libc::ioctl(fd, libc::FIONBIO, &value) } == -1 {
+        Err(io::Error::last_os_error())
+    } else {
+        Ok(())
+    }
+}
+
+#[cfg(target_os = "illumos")]
+fn set_nonblocking(fd: RawFd, nonblocking: bool) -> io::Result<()> {
+    let flags = unsafe { libc::fcntl(fd, libc::F_GETFL) };
+    if flags < 0 {
+        return Err(io::Error::last_os_error());
+    }
+
+    let nflags = if nonblocking {
+        flags | libc::O_NONBLOCK
+    } else {
+        flags & !libc::O_NONBLOCK
+    };
+
+    if flags != nflags {
+        if unsafe { libc::fcntl(fd, libc::F_SETFL, nflags) } < 0 {
+            return Err(io::Error::last_os_error());
+        }
+    }
+
+    Ok(())
+}
diff --git a/third_party/rust/mio/src/sys/unix/selector/epoll.rs b/third_party/rust/mio/src/sys/unix/selector/epoll.rs
new file mode 100644
index 0000000000..f4430909b0
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/selector/epoll.rs
@@ -0,0 +1,246 @@
+use crate::{Interest, Token};
+
+use libc::{EPOLLET, EPOLLIN, EPOLLOUT, EPOLLRDHUP};
+use log::error;
+use std::os::unix::io::{AsRawFd, RawFd};
+#[cfg(debug_assertions)]
+use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::time::Duration;
+use std::{cmp, i32, io, ptr};
+
+/// Unique id for use as `SelectorId`.
+#[cfg(debug_assertions)]
+static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+
+#[derive(Debug)]
+pub struct Selector {
+    #[cfg(debug_assertions)]
+    id: usize,
+    ep: RawFd,
+    #[cfg(debug_assertions)]
+    has_waker: AtomicBool,
+}
+
+impl Selector {
+    pub fn new() -> io::Result<Selector> {
+        // According to libuv, `EPOLL_CLOEXEC` is not defined on Android API <
+        // 21. But `EPOLL_CLOEXEC` is an alias for `O_CLOEXEC` on that platform,
+        // so we use it instead.
+        #[cfg(target_os = "android")]
+        let flag = libc::O_CLOEXEC;
+        #[cfg(not(target_os = "android"))]
+        let flag = libc::EPOLL_CLOEXEC;
+
+        syscall!(epoll_create1(flag)).map(|ep| Selector {
+            #[cfg(debug_assertions)]
+            id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
+            ep,
+            #[cfg(debug_assertions)]
+            has_waker: AtomicBool::new(false),
+        })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        syscall!(fcntl(self.ep, libc::F_DUPFD_CLOEXEC, super::LOWEST_FD)).map(|ep| Selector {
+            // It's the same selector, so we use the same id.
+            #[cfg(debug_assertions)]
+            id: self.id,
+            ep,
+            #[cfg(debug_assertions)]
+            has_waker: AtomicBool::new(self.has_waker.load(Ordering::Acquire)),
+        })
+    }
+
+    pub fn select(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        // A bug in kernels < 2.6.37 makes timeouts larger than LONG_MAX / CONFIG_HZ
+        // (approx. 30 minutes with CONFIG_HZ=1200) effectively infinite on 32 bits
+        // architectures. The magic number is the same constant used by libuv.
+        #[cfg(target_pointer_width = "32")]
+        const MAX_SAFE_TIMEOUT: u128 = 1789569;
+        #[cfg(not(target_pointer_width = "32"))]
+        const MAX_SAFE_TIMEOUT: u128 = libc::c_int::max_value() as u128;
+
+        let timeout = timeout
+            .map(|to| cmp::min(to.as_millis(), MAX_SAFE_TIMEOUT) as libc::c_int)
+            .unwrap_or(-1);
+
+        events.clear();
+        syscall!(epoll_wait(
+            self.ep,
+            events.as_mut_ptr(),
+            events.capacity() as i32,
+            timeout,
+        ))
+        .map(|n_events| {
+            // This is safe because `epoll_wait` ensures that `n_events` are
+            // assigned.
+            unsafe { events.set_len(n_events as usize) };
+        })
+    }
+
+    pub fn register(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
+        let mut event = libc::epoll_event {
+            events: interests_to_epoll(interests),
+            u64: usize::from(token) as u64,
+        };
+
+        syscall!(epoll_ctl(self.ep, libc::EPOLL_CTL_ADD, fd, &mut event)).map(|_| ())
+    }
+
+    pub fn reregister(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
+        let mut event = libc::epoll_event {
+            events: interests_to_epoll(interests),
+            u64: usize::from(token) as u64,
+        };
+
+        syscall!(epoll_ctl(self.ep, libc::EPOLL_CTL_MOD, fd, &mut event)).map(|_| ())
+    }
+
+    pub fn deregister(&self, fd: RawFd) -> io::Result<()> {
+        syscall!(epoll_ctl(self.ep, libc::EPOLL_CTL_DEL, fd, ptr::null_mut())).map(|_| ())
+    }
+
+    #[cfg(debug_assertions)]
+    pub fn register_waker(&self) -> bool {
+        self.has_waker.swap(true, Ordering::AcqRel)
+    }
+}
+
+cfg_io_source! {
+    impl Selector {
+        #[cfg(debug_assertions)]
+        pub fn id(&self) -> usize {
+            self.id
+        }
+    }
+}
+
+impl AsRawFd for Selector {
+    fn as_raw_fd(&self) -> RawFd {
+        self.ep
+    }
+}
+
+impl Drop for Selector {
+    fn drop(&mut self) {
+        if let Err(err) = syscall!(close(self.ep)) {
+            error!("error closing epoll: {}", err);
+        }
+    }
+}
+
+fn interests_to_epoll(interests: Interest) -> u32 {
+    let mut kind = EPOLLET;
+
+    if interests.is_readable() {
+        kind = kind | EPOLLIN | EPOLLRDHUP;
+    }
+
+    if interests.is_writable() {
+        kind |= EPOLLOUT;
+    }
+
+    kind as u32
+}
+
+pub type Event = libc::epoll_event;
+pub type Events = Vec<Event>;
+
+pub mod event {
+    use std::fmt;
+
+    use crate::sys::Event;
+    use crate::Token;
+
+    pub fn token(event: &Event) -> Token {
+        Token(event.u64 as usize)
+    }
+
+    pub fn is_readable(event: &Event) -> bool {
+        (event.events as libc::c_int & libc::EPOLLIN) != 0
+            || (event.events as libc::c_int & libc::EPOLLPRI) != 0
+    }
+
+    pub fn is_writable(event: &Event) -> bool {
+        (event.events as libc::c_int & libc::EPOLLOUT) != 0
+    }
+
+    pub fn is_error(event: &Event) -> bool {
+        (event.events as libc::c_int & libc::EPOLLERR) != 0
+    }
+
+    pub fn is_read_closed(event: &Event) -> bool {
+        // Both halves of the socket have closed
+        event.events as libc::c_int & libc::EPOLLHUP != 0
+            // Socket has received FIN or called shutdown(SHUT_RD)
+            || (event.events as libc::c_int & libc::EPOLLIN != 0
+                && event.events as libc::c_int & libc::EPOLLRDHUP != 0)
+    }
+
+    pub fn is_write_closed(event: &Event) -> bool {
+        // Both halves of the socket have closed
+        event.events as libc::c_int & libc::EPOLLHUP != 0
+            // Unix pipe write end has closed
+            || (event.events as libc::c_int & libc::EPOLLOUT != 0
+                && event.events as libc::c_int & libc::EPOLLERR != 0)
+            // The other side (read end) of a Unix pipe has closed.
+            || event.events as libc::c_int == libc::EPOLLERR
+    }
+
+    pub fn is_priority(event: &Event) -> bool {
+        (event.events as libc::c_int & libc::EPOLLPRI) != 0
+    }
+
+    pub fn is_aio(_: &Event) -> bool {
+        // Not supported in the kernel, only in libc.
+        false
+    }
+
+    pub fn is_lio(_: &Event) -> bool {
+        // Not supported.
+        false
+    }
+
+    pub fn debug_details(f: &mut fmt::Formatter<'_>, event: &Event) -> fmt::Result {
+        #[allow(clippy::trivially_copy_pass_by_ref)]
+        fn check_events(got: &u32, want: &libc::c_int) -> bool {
+            (*got as libc::c_int & want) != 0
+        }
+        debug_detail!(
+            EventsDetails(u32),
+            check_events,
+            libc::EPOLLIN,
+            libc::EPOLLPRI,
+            libc::EPOLLOUT,
+            libc::EPOLLRDNORM,
+            libc::EPOLLRDBAND,
+            libc::EPOLLWRNORM,
+            libc::EPOLLWRBAND,
+            libc::EPOLLMSG,
+            libc::EPOLLERR,
+            libc::EPOLLHUP,
+            libc::EPOLLET,
+            libc::EPOLLRDHUP,
+            libc::EPOLLONESHOT,
+            #[cfg(target_os = "linux")]
+            libc::EPOLLEXCLUSIVE,
+            #[cfg(any(target_os = "android", target_os = "linux"))]
+            libc::EPOLLWAKEUP,
+            libc::EPOLL_CLOEXEC,
+        );
+
+        // Can't reference fields in packed structures.
+        let e_u64 = event.u64;
+        f.debug_struct("epoll_event")
+            .field("events", &EventsDetails(event.events))
+            .field("u64", &e_u64)
+            .finish()
+    }
+}
+
+#[cfg(target_os = "android")]
+#[test]
+fn assert_close_on_exec_flag() {
+    // This assertion need to be true for Selector::new.
+    assert_eq!(libc::O_CLOEXEC, libc::EPOLL_CLOEXEC);
+}
diff --git a/third_party/rust/mio/src/sys/unix/selector/kqueue.rs b/third_party/rust/mio/src/sys/unix/selector/kqueue.rs
new file mode 100644
index 0000000000..b7a01a51c6
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/selector/kqueue.rs
@@ -0,0 +1,688 @@
+use crate::{Interest, Token};
+use log::error;
+use std::mem::MaybeUninit;
+use std::ops::{Deref, DerefMut};
+use std::os::unix::io::{AsRawFd, RawFd};
+#[cfg(debug_assertions)]
+use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
+use std::time::Duration;
+use std::{cmp, io, ptr, slice};
+
+/// Unique id for use as `SelectorId`.
+#[cfg(debug_assertions)]
+static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+
+// Type of the `nchanges` and `nevents` parameters in the `kevent` function.
+#[cfg(not(target_os = "netbsd"))]
+type Count = libc::c_int;
+#[cfg(target_os = "netbsd")]
+type Count = libc::size_t;
+
+// Type of the `filter` field in the `kevent` structure.
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
+type Filter = libc::c_short;
+#[cfg(any(target_os = "macos", target_os = "ios"))]
+type Filter = i16;
+#[cfg(target_os = "netbsd")]
+type Filter = u32;
+
+// Type of the `flags` field in the `kevent` structure.
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
+type Flags = libc::c_ushort;
+#[cfg(any(target_os = "macos", target_os = "ios"))]
+type Flags = u16;
+#[cfg(target_os = "netbsd")]
+type Flags = u32;
+
+// Type of the `data` field in the `kevent` structure.
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "macos"
+))]
+type Data = libc::intptr_t;
+#[cfg(any(target_os = "netbsd", target_os = "openbsd"))]
+type Data = i64;
+
+// Type of the `udata` field in the `kevent` structure.
+#[cfg(not(target_os = "netbsd"))]
+type UData = *mut libc::c_void;
+#[cfg(target_os = "netbsd")]
+type UData = libc::intptr_t;
+
+macro_rules! kevent {
+    ($id: expr, $filter: expr, $flags: expr, $data: expr) => {
+        libc::kevent {
+            ident: $id as libc::uintptr_t,
+            filter: $filter as Filter,
+            flags: $flags,
+            fflags: 0,
+            data: 0,
+            udata: $data as UData,
+        }
+    };
+}
+
+#[derive(Debug)]
+pub struct Selector {
+    #[cfg(debug_assertions)]
+    id: usize,
+    kq: RawFd,
+    #[cfg(debug_assertions)]
+    has_waker: AtomicBool,
+}
+
+impl Selector {
+    pub fn new() -> io::Result<Selector> {
+        syscall!(kqueue())
+            .and_then(|kq| syscall!(fcntl(kq, libc::F_SETFD, libc::FD_CLOEXEC)).map(|_| kq))
+            .map(|kq| Selector {
+                #[cfg(debug_assertions)]
+                id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
+                kq,
+                #[cfg(debug_assertions)]
+                has_waker: AtomicBool::new(false),
+            })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        syscall!(fcntl(self.kq, libc::F_DUPFD_CLOEXEC, super::LOWEST_FD)).map(|kq| Selector {
+            // It's the same selector, so we use the same id.
+            #[cfg(debug_assertions)]
+            id: self.id,
+            kq,
+            #[cfg(debug_assertions)]
+            has_waker: AtomicBool::new(self.has_waker.load(Ordering::Acquire)),
+        })
+    }
+
+    pub fn select(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        let timeout = timeout.map(|to| libc::timespec {
+            tv_sec: cmp::min(to.as_secs(), libc::time_t::max_value() as u64) as libc::time_t,
+            // `Duration::subsec_nanos` is guaranteed to be less than one
+            // billion (the number of nanoseconds in a second), making the
+            // cast to i32 safe. The cast itself is needed for platforms
+            // where C's long is only 32 bits.
+            tv_nsec: libc::c_long::from(to.subsec_nanos() as i32),
+        });
+        let timeout = timeout
+            .as_ref()
+            .map(|s| s as *const _)
+            .unwrap_or(ptr::null_mut());
+
+        events.clear();
+        syscall!(kevent(
+            self.kq,
+            ptr::null(),
+            0,
+            events.as_mut_ptr(),
+            events.capacity() as Count,
+            timeout,
+        ))
+        .map(|n_events| {
+            // This is safe because `kevent` ensures that `n_events` are
+            // assigned.
+            unsafe { events.set_len(n_events as usize) };
+        })
+    }
+
+    pub fn register(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
+        let flags = libc::EV_CLEAR | libc::EV_RECEIPT | libc::EV_ADD;
+        // At most we need two changes, but maybe we only need 1.
+        let mut changes: [MaybeUninit<libc::kevent>; 2] =
+            [MaybeUninit::uninit(), MaybeUninit::uninit()];
+        let mut n_changes = 0;
+
+        if interests.is_writable() {
+            let kevent = kevent!(fd, libc::EVFILT_WRITE, flags, token.0);
+            changes[n_changes] = MaybeUninit::new(kevent);
+            n_changes += 1;
+        }
+
+        if interests.is_readable() {
+            let kevent = kevent!(fd, libc::EVFILT_READ, flags, token.0);
+            changes[n_changes] = MaybeUninit::new(kevent);
+            n_changes += 1;
+        }
+
+        // Older versions of macOS (OS X 10.11 and 10.10 have been witnessed)
+        // can return EPIPE when registering a pipe file descriptor where the
+        // other end has already disappeared. For example code that creates a
+        // pipe, closes a file descriptor, and then registers the other end will
+        // see an EPIPE returned from `register`.
+        //
+        // It also turns out that kevent will still report events on the file
+        // descriptor, telling us that it's readable/hup at least after we've
+        // done this registration. As a result we just ignore `EPIPE` here
+        // instead of propagating it.
+        //
+        // More info can be found at tokio-rs/mio#582.
+        let changes = unsafe {
+            // This is safe because we ensure that at least `n_changes` are in
+            // the array.
+            slice::from_raw_parts_mut(changes[0].as_mut_ptr(), n_changes)
+        };
+        kevent_register(self.kq, changes, &[libc::EPIPE as Data])
+    }
+
+    pub fn reregister(&self, fd: RawFd, token: Token, interests: Interest) -> io::Result<()> {
+        let flags = libc::EV_CLEAR | libc::EV_RECEIPT;
+        let write_flags = if interests.is_writable() {
+            flags | libc::EV_ADD
+        } else {
+            flags | libc::EV_DELETE
+        };
+        let read_flags = if interests.is_readable() {
+            flags | libc::EV_ADD
+        } else {
+            flags | libc::EV_DELETE
+        };
+
+        let mut changes: [libc::kevent; 2] = [
+            kevent!(fd, libc::EVFILT_WRITE, write_flags, token.0),
+            kevent!(fd, libc::EVFILT_READ, read_flags, token.0),
+        ];
+
+        // Since there is no way to check with which interests the fd was
+        // registered we modify both readable and write, adding it when required
+        // and removing it otherwise, ignoring the ENOENT error when it comes
+        // up. The ENOENT error informs us that a filter we're trying to remove
+        // wasn't there in first place, but we don't really care since our goal
+        // is accomplished.
+        //
+        // For the explanation of ignoring `EPIPE` see `register`.
+        kevent_register(
+            self.kq,
+            &mut changes,
+            &[libc::ENOENT as Data, libc::EPIPE as Data],
+        )
+    }
+
+    pub fn deregister(&self, fd: RawFd) -> io::Result<()> {
+        let flags = libc::EV_DELETE | libc::EV_RECEIPT;
+        let mut changes: [libc::kevent; 2] = [
+            kevent!(fd, libc::EVFILT_WRITE, flags, 0),
+            kevent!(fd, libc::EVFILT_READ, flags, 0),
+        ];
+
+        // Since there is no way to check with which interests the fd was
+        // registered we remove both filters (readable and writeable) and ignore
+        // the ENOENT error when it comes up. The ENOENT error informs us that
+        // the filter wasn't there in first place, but we don't really care
+        // about that since our goal is to remove it.
+        kevent_register(self.kq, &mut changes, &[libc::ENOENT as Data])
+    }
+
+    #[cfg(debug_assertions)]
+    pub fn register_waker(&self) -> bool {
+        self.has_waker.swap(true, Ordering::AcqRel)
+    }
+
+    // Used by `Waker`.
+    #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+    pub fn setup_waker(&self, token: Token) -> io::Result<()> {
+        // First attempt to accept user space notifications.
+        let mut kevent = kevent!(
+            0,
+            libc::EVFILT_USER,
+            libc::EV_ADD | libc::EV_CLEAR | libc::EV_RECEIPT,
+            token.0
+        );
+
+        syscall!(kevent(self.kq, &kevent, 1, &mut kevent, 1, ptr::null())).and_then(|_| {
+            if (kevent.flags & libc::EV_ERROR) != 0 && kevent.data != 0 {
+                Err(io::Error::from_raw_os_error(kevent.data as i32))
+            } else {
+                Ok(())
+            }
+        })
+    }
+
+    // Used by `Waker`.
+    #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+    pub fn wake(&self, token: Token) -> io::Result<()> {
+        let mut kevent = kevent!(
+            0,
+            libc::EVFILT_USER,
+            libc::EV_ADD | libc::EV_RECEIPT,
+            token.0
+        );
+        kevent.fflags = libc::NOTE_TRIGGER;
+
+        syscall!(kevent(self.kq, &kevent, 1, &mut kevent, 1, ptr::null())).and_then(|_| {
+            if (kevent.flags & libc::EV_ERROR) != 0 && kevent.data != 0 {
+                Err(io::Error::from_raw_os_error(kevent.data as i32))
+            } else {
+                Ok(())
+            }
+        })
+    }
+}
+
+/// Register `changes` with `kq`ueue.
+fn kevent_register(
+    kq: RawFd,
+    changes: &mut [libc::kevent],
+    ignored_errors: &[Data],
+) -> io::Result<()> {
+    syscall!(kevent(
+        kq,
+        changes.as_ptr(),
+        changes.len() as Count,
+        changes.as_mut_ptr(),
+        changes.len() as Count,
+        ptr::null(),
+    ))
+    .map(|_| ())
+    .or_else(|err| {
+        // According to the manual page of FreeBSD: "When kevent() call fails
+        // with EINTR error, all changes in the changelist have been applied",
+        // so we can safely ignore it.
+        if err.raw_os_error() == Some(libc::EINTR) {
+            Ok(())
+        } else {
+            Err(err)
+        }
+    })
+    .and_then(|()| check_errors(changes, ignored_errors))
+}
+
+/// Check all events for possible errors, it returns the first error found.
+fn check_errors(events: &[libc::kevent], ignored_errors: &[Data]) -> io::Result<()> {
+    for event in events {
+        // We can't use references to packed structures (in checking the ignored
+        // errors), so we need copy the data out before use.
+        let data = event.data;
+        // Check for the error flag, the actual error will be in the `data`
+        // field.
+        if (event.flags & libc::EV_ERROR != 0) && data != 0 && !ignored_errors.contains(&data) {
+            return Err(io::Error::from_raw_os_error(data as i32));
+        }
+    }
+    Ok(())
+}
+
+cfg_io_source! {
+    #[cfg(debug_assertions)]
+    impl Selector {
+        pub fn id(&self) -> usize {
+            self.id
+        }
+    }
+}
+
+impl AsRawFd for Selector {
+    fn as_raw_fd(&self) -> RawFd {
+        self.kq
+    }
+}
+
+impl Drop for Selector {
+    fn drop(&mut self) {
+        if let Err(err) = syscall!(close(self.kq)) {
+            error!("error closing kqueue: {}", err);
+        }
+    }
+}
+
+pub type Event = libc::kevent;
+pub struct Events(Vec<libc::kevent>);
+
+impl Events {
+    pub fn with_capacity(capacity: usize) -> Events {
+        Events(Vec::with_capacity(capacity))
+    }
+}
+
+impl Deref for Events {
+    type Target = Vec<libc::kevent>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for Events {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+// `Events` cannot derive `Send` or `Sync` because of the
+// `udata: *mut ::c_void` field in `libc::kevent`. However, `Events`'s public
+// API treats the `udata` field as a `uintptr_t` which is `Send`. `Sync` is
+// safe because with a `events: &Events` value, the only access to the `udata`
+// field is through `fn token(event: &Event)` which cannot mutate the field.
+unsafe impl Send for Events {}
+unsafe impl Sync for Events {}
+
+pub mod event {
+    use std::fmt;
+
+    use crate::sys::Event;
+    use crate::Token;
+
+    use super::{Filter, Flags};
+
+    pub fn token(event: &Event) -> Token {
+        Token(event.udata as usize)
+    }
+
+    pub fn is_readable(event: &Event) -> bool {
+        event.filter == libc::EVFILT_READ || {
+            #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+            // Used by the `Awakener`. On platforms that use `eventfd` or a unix
+            // pipe it will emit a readable event so we'll fake that here as
+            // well.
+            {
+                event.filter == libc::EVFILT_USER
+            }
+            #[cfg(not(any(target_os = "freebsd", target_os = "ios", target_os = "macos")))]
+            {
+                false
+            }
+        }
+    }
+
+    pub fn is_writable(event: &Event) -> bool {
+        event.filter == libc::EVFILT_WRITE
+    }
+
+    pub fn is_error(event: &Event) -> bool {
+        (event.flags & libc::EV_ERROR) != 0 ||
+            // When the read end of the socket is closed, EV_EOF is set on
+            // flags, and fflags contains the error if there is one.
+            (event.flags & libc::EV_EOF) != 0 && event.fflags != 0
+    }
+
+    pub fn is_read_closed(event: &Event) -> bool {
+        event.filter == libc::EVFILT_READ && event.flags & libc::EV_EOF != 0
+    }
+
+    pub fn is_write_closed(event: &Event) -> bool {
+        event.filter == libc::EVFILT_WRITE && event.flags & libc::EV_EOF != 0
+    }
+
+    pub fn is_priority(_: &Event) -> bool {
+        // kqueue doesn't have priority indicators.
+        false
+    }
+
+    #[allow(unused_variables)] // `event` is not used on some platforms.
+    pub fn is_aio(event: &Event) -> bool {
+        #[cfg(any(
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "ios",
+            target_os = "macos"
+        ))]
+        {
+            event.filter == libc::EVFILT_AIO
+        }
+        #[cfg(not(any(
+            target_os = "dragonfly",
+            target_os = "freebsd",
+            target_os = "ios",
+            target_os = "macos"
+        )))]
+        {
+            false
+        }
+    }
+
+    #[allow(unused_variables)] // `event` is only used on FreeBSD.
+    pub fn is_lio(event: &Event) -> bool {
+        #[cfg(target_os = "freebsd")]
+        {
+            event.filter == libc::EVFILT_LIO
+        }
+        #[cfg(not(target_os = "freebsd"))]
+        {
+            false
+        }
+    }
+
+    pub fn debug_details(f: &mut fmt::Formatter<'_>, event: &Event) -> fmt::Result {
+        debug_detail!(
+            FilterDetails(Filter),
+            PartialEq::eq,
+            libc::EVFILT_READ,
+            libc::EVFILT_WRITE,
+            libc::EVFILT_AIO,
+            libc::EVFILT_VNODE,
+            libc::EVFILT_PROC,
+            libc::EVFILT_SIGNAL,
+            libc::EVFILT_TIMER,
+            #[cfg(target_os = "freebsd")]
+            libc::EVFILT_PROCDESC,
+            #[cfg(any(
+                target_os = "freebsd",
+                target_os = "dragonfly",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::EVFILT_FS,
+            #[cfg(target_os = "freebsd")]
+            libc::EVFILT_LIO,
+            #[cfg(any(
+                target_os = "freebsd",
+                target_os = "dragonfly",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::EVFILT_USER,
+            #[cfg(target_os = "freebsd")]
+            libc::EVFILT_SENDFILE,
+            #[cfg(target_os = "freebsd")]
+            libc::EVFILT_EMPTY,
+            #[cfg(target_os = "dragonfly")]
+            libc::EVFILT_EXCEPT,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::EVFILT_MACHPORT,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::EVFILT_VM,
+        );
+
+        #[allow(clippy::trivially_copy_pass_by_ref)]
+        fn check_flag(got: &Flags, want: &Flags) -> bool {
+            (got & want) != 0
+        }
+        debug_detail!(
+            FlagsDetails(Flags),
+            check_flag,
+            libc::EV_ADD,
+            libc::EV_DELETE,
+            libc::EV_ENABLE,
+            libc::EV_DISABLE,
+            libc::EV_ONESHOT,
+            libc::EV_CLEAR,
+            libc::EV_RECEIPT,
+            libc::EV_DISPATCH,
+            #[cfg(target_os = "freebsd")]
+            libc::EV_DROP,
+            libc::EV_FLAG1,
+            libc::EV_ERROR,
+            libc::EV_EOF,
+            libc::EV_SYSFLAGS,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::EV_FLAG0,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::EV_POLL,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::EV_OOBAND,
+            #[cfg(target_os = "dragonfly")]
+            libc::EV_NODATA,
+        );
+
+        #[allow(clippy::trivially_copy_pass_by_ref)]
+        fn check_fflag(got: &u32, want: &u32) -> bool {
+            (got & want) != 0
+        }
+        debug_detail!(
+            FflagsDetails(u32),
+            check_fflag,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_TRIGGER,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFNOP,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFAND,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFOR,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFCOPY,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFCTRLMASK,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "ios",
+                target_os = "macos"
+            ))]
+            libc::NOTE_FFLAGSMASK,
+            libc::NOTE_LOWAT,
+            libc::NOTE_DELETE,
+            libc::NOTE_WRITE,
+            #[cfg(target_os = "dragonfly")]
+            libc::NOTE_OOB,
+            #[cfg(target_os = "openbsd")]
+            libc::NOTE_EOF,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXTEND,
+            libc::NOTE_ATTRIB,
+            libc::NOTE_LINK,
+            libc::NOTE_RENAME,
+            libc::NOTE_REVOKE,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_NONE,
+            #[cfg(any(target_os = "openbsd"))]
+            libc::NOTE_TRUNCATE,
+            libc::NOTE_EXIT,
+            libc::NOTE_FORK,
+            libc::NOTE_EXEC,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_SIGNAL,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXITSTATUS,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXIT_DETAIL,
+            libc::NOTE_PDATAMASK,
+            libc::NOTE_PCTRLMASK,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "netbsd",
+                target_os = "openbsd"
+            ))]
+            libc::NOTE_TRACK,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "netbsd",
+                target_os = "openbsd"
+            ))]
+            libc::NOTE_TRACKERR,
+            #[cfg(any(
+                target_os = "dragonfly",
+                target_os = "freebsd",
+                target_os = "netbsd",
+                target_os = "openbsd"
+            ))]
+            libc::NOTE_CHILD,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXIT_DETAIL_MASK,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXIT_DECRYPTFAIL,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXIT_MEMORY,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_EXIT_CSERROR,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_VM_PRESSURE,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_VM_PRESSURE_TERMINATE,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_VM_PRESSURE_SUDDEN_TERMINATE,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_VM_ERROR,
+            #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+            libc::NOTE_SECONDS,
+            #[cfg(any(target_os = "freebsd"))]
+            libc::NOTE_MSECONDS,
+            #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+            libc::NOTE_USECONDS,
+            #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+            libc::NOTE_NSECONDS,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+            libc::NOTE_ABSOLUTE,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_LEEWAY,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_CRITICAL,
+            #[cfg(any(target_os = "ios", target_os = "macos"))]
+            libc::NOTE_BACKGROUND,
+        );
+
+        // Can't reference fields in packed structures.
+        let ident = event.ident;
+        let data = event.data;
+        let udata = event.udata;
+        f.debug_struct("kevent")
+            .field("ident", &ident)
+            .field("filter", &FilterDetails(event.filter))
+            .field("flags", &FlagsDetails(event.flags))
+            .field("fflags", &FflagsDetails(event.fflags))
+            .field("data", &data)
+            .field("udata", &udata)
+            .finish()
+    }
+}
+
+#[test]
+#[cfg(feature = "os-ext")]
+fn does_not_register_rw() {
+    use crate::unix::SourceFd;
+    use crate::{Poll, Token};
+
+    let kq = unsafe { libc::kqueue() };
+    let mut kqf = SourceFd(&kq);
+    let poll = Poll::new().unwrap();
+
+    // Registering kqueue fd will fail if write is requested (On anything but
+    // some versions of macOS).
+    poll.registry()
+        .register(&mut kqf, Token(1234), Interest::READABLE)
+        .unwrap();
+}
diff --git a/third_party/rust/mio/src/sys/unix/selector/mod.rs b/third_party/rust/mio/src/sys/unix/selector/mod.rs
new file mode 100644
index 0000000000..da61e14d7e
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/selector/mod.rs
@@ -0,0 +1,35 @@
+#[cfg(any(target_os = "android", target_os = "illumos", target_os = "linux"))]
+mod epoll;
+
+#[cfg(any(target_os = "android", target_os = "illumos", target_os = "linux"))]
+pub(crate) use self::epoll::{event, Event, Events, Selector};
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd"
+))]
+mod kqueue;
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd"
+))]
+pub(crate) use self::kqueue::{event, Event, Events, Selector};
+
+/// Lowest file descriptor used in `Selector::try_clone`.
+///
+/// # Notes
+///
+/// Usually fds 0, 1 and 2 are standard in, out and error. Some application
+/// blindly assume this to be true, which means using any one of those a select
+/// could result in some interesting and unexpected errors. Avoid that by using
+/// an fd that doesn't have a pre-determined usage.
+const LOWEST_FD: libc::c_int = 3;
diff --git a/third_party/rust/mio/src/sys/unix/sourcefd.rs b/third_party/rust/mio/src/sys/unix/sourcefd.rs
new file mode 100644
index 0000000000..84e776d21d
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/sourcefd.rs
@@ -0,0 +1,116 @@
+use crate::{event, Interest, Registry, Token};
+
+use std::io;
+use std::os::unix::io::RawFd;
+
+/// Adapter for [`RawFd`] providing an [`event::Source`] implementation.
+///
+/// `SourceFd` enables registering any type with an FD with [`Poll`].
+///
+/// While only implementations for TCP and UDP are provided, Mio supports
+/// registering any FD that can be registered with the underlying OS selector.
+/// `SourceFd` provides the necessary bridge.
+///
+/// Note that `SourceFd` takes a `&RawFd`. This is because `SourceFd` **does
+/// not** take ownership of the FD. Specifically, it will not manage any
+/// lifecycle related operations, such as closing the FD on drop. It is expected
+/// that the `SourceFd` is constructed right before a call to
+/// [`Registry::register`]. See the examples for more detail.
+///
+/// [`event::Source`]: ../event/trait.Source.html
+/// [`Poll`]: ../struct.Poll.html
+/// [`Registry::register`]: ../struct.Registry.html#method.register
+///
+/// # Examples
+///
+/// Basic usage.
+///
+#[cfg_attr(
+    all(feature = "os-poll", feature = "net", feature = "os-ext"),
+    doc = "```"
+)]
+#[cfg_attr(
+    not(all(feature = "os-poll", feature = "net", feature = "os-ext")),
+    doc = "```ignore"
+)]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Interest, Poll, Token};
+/// use mio::unix::SourceFd;
+///
+/// use std::os::unix::io::AsRawFd;
+/// use std::net::TcpListener;
+///
+/// // Bind a std listener
+/// let listener = TcpListener::bind("127.0.0.1:0")?;
+///
+/// let poll = Poll::new()?;
+///
+/// // Register the listener
+/// poll.registry().register(
+///     &mut SourceFd(&listener.as_raw_fd()),
+///     Token(0),
+///     Interest::READABLE)?;
+/// #     Ok(())
+/// # }
+/// ```
+///
+/// Implementing [`event::Source`] for a custom type backed by a [`RawFd`].
+///
+#[cfg_attr(all(feature = "os-poll", feature = "os-ext"), doc = "```")]
+#[cfg_attr(not(all(feature = "os-poll", feature = "os-ext")), doc = "```ignore")]
+/// use mio::{event, Interest, Registry, Token};
+/// use mio::unix::SourceFd;
+///
+/// use std::os::unix::io::RawFd;
+/// use std::io;
+///
+/// # #[allow(dead_code)]
+/// pub struct MyIo {
+///     fd: RawFd,
+/// }
+///
+/// impl event::Source for MyIo {
+///     fn register(&mut self, registry: &Registry, token: Token, interests: Interest)
+///         -> io::Result<()>
+///     {
+///         SourceFd(&self.fd).register(registry, token, interests)
+///     }
+///
+///     fn reregister(&mut self, registry: &Registry, token: Token, interests: Interest)
+///         -> io::Result<()>
+///     {
+///         SourceFd(&self.fd).reregister(registry, token, interests)
+///     }
+///
+///     fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+///         SourceFd(&self.fd).deregister(registry)
+///     }
+/// }
+/// ```
+#[derive(Debug)]
+pub struct SourceFd<'a>(pub &'a RawFd);
+
+impl<'a> event::Source for SourceFd<'a> {
+    fn register(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        registry.selector().register(*self.0, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        registry.selector().reregister(*self.0, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        registry.selector().deregister(*self.0)
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/tcp.rs b/third_party/rust/mio/src/sys/unix/tcp.rs
new file mode 100644
index 0000000000..5b02cfcb52
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/tcp.rs
@@ -0,0 +1,113 @@
+use std::convert::TryInto;
+use std::io;
+use std::mem::{size_of, MaybeUninit};
+use std::net::{self, SocketAddr};
+use std::os::unix::io::{AsRawFd, FromRawFd};
+
+use crate::sys::unix::net::{new_socket, socket_addr, to_socket_addr};
+
+pub(crate) fn new_for_addr(address: SocketAddr) -> io::Result<libc::c_int> {
+    let domain = match address {
+        SocketAddr::V4(_) => libc::AF_INET,
+        SocketAddr::V6(_) => libc::AF_INET6,
+    };
+    new_socket(domain, libc::SOCK_STREAM)
+}
+
+pub(crate) fn bind(socket: &net::TcpListener, addr: SocketAddr) -> io::Result<()> {
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+    syscall!(bind(socket.as_raw_fd(), raw_addr.as_ptr(), raw_addr_length))?;
+    Ok(())
+}
+
+pub(crate) fn connect(socket: &net::TcpStream, addr: SocketAddr) -> io::Result<()> {
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+
+    match syscall!(connect(
+        socket.as_raw_fd(),
+        raw_addr.as_ptr(),
+        raw_addr_length
+    )) {
+        Err(err) if err.raw_os_error() != Some(libc::EINPROGRESS) => Err(err),
+        _ => Ok(()),
+    }
+}
+
+pub(crate) fn listen(socket: &net::TcpListener, backlog: u32) -> io::Result<()> {
+    let backlog = backlog.try_into().unwrap_or(i32::max_value());
+    syscall!(listen(socket.as_raw_fd(), backlog))?;
+    Ok(())
+}
+
+pub(crate) fn set_reuseaddr(socket: &net::TcpListener, reuseaddr: bool) -> io::Result<()> {
+    let val: libc::c_int = if reuseaddr { 1 } else { 0 };
+    syscall!(setsockopt(
+        socket.as_raw_fd(),
+        libc::SOL_SOCKET,
+        libc::SO_REUSEADDR,
+        &val as *const libc::c_int as *const libc::c_void,
+        size_of::<libc::c_int>() as libc::socklen_t,
+    ))?;
+    Ok(())
+}
+
+pub(crate) fn accept(listener: &net::TcpListener) -> io::Result<(net::TcpStream, SocketAddr)> {
+    let mut addr: MaybeUninit<libc::sockaddr_storage> = MaybeUninit::uninit();
+    let mut length = size_of::<libc::sockaddr_storage>() as libc::socklen_t;
+
+    // On platforms that support it we can use `accept4(2)` to set `NONBLOCK`
+    // and `CLOEXEC` in the call to accept the connection.
+    #[cfg(any(
+        // Android x86's seccomp profile forbids calls to `accept4(2)`
+        // See https://github.com/tokio-rs/mio/issues/1445 for details
+        all(
+            not(target_arch="x86"),
+            target_os = "android"
+        ),
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "illumos",
+        target_os = "linux",
+        target_os = "netbsd",
+        target_os = "openbsd"
+    ))]
+    let stream = {
+        syscall!(accept4(
+            listener.as_raw_fd(),
+            addr.as_mut_ptr() as *mut _,
+            &mut length,
+            libc::SOCK_CLOEXEC | libc::SOCK_NONBLOCK,
+        ))
+        .map(|socket| unsafe { net::TcpStream::from_raw_fd(socket) })
+    }?;
+
+    // But not all platforms have the `accept4(2)` call. Luckily BSD (derived)
+    // OSes inherit the non-blocking flag from the listener, so we just have to
+    // set `CLOEXEC`.
+    #[cfg(any(
+        all(target_arch = "x86", target_os = "android"),
+        target_os = "ios",
+        target_os = "macos",
+    ))]
+    let stream = {
+        syscall!(accept(
+            listener.as_raw_fd(),
+            addr.as_mut_ptr() as *mut _,
+            &mut length
+        ))
+        .map(|socket| unsafe { net::TcpStream::from_raw_fd(socket) })
+        .and_then(|s| {
+            syscall!(fcntl(s.as_raw_fd(), libc::F_SETFD, libc::FD_CLOEXEC))?;
+
+            // See https://github.com/tokio-rs/mio/issues/1450
+            #[cfg(all(target_arch = "x86", target_os = "android"))]
+            syscall!(fcntl(s.as_raw_fd(), libc::F_SETFL, libc::O_NONBLOCK))?;
+
+            Ok(s)
+        })
+    }?;
+
+    // This is safe because `accept` calls above ensures the address
+    // initialised.
+    unsafe { to_socket_addr(addr.as_ptr()) }.map(|addr| (stream, addr))
+}
diff --git a/third_party/rust/mio/src/sys/unix/udp.rs b/third_party/rust/mio/src/sys/unix/udp.rs
new file mode 100644
index 0000000000..5a97cbd897
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/udp.rs
@@ -0,0 +1,39 @@
+use crate::sys::unix::net::{new_ip_socket, socket_addr};
+
+use std::io;
+use std::mem;
+use std::net::{self, SocketAddr};
+use std::os::unix::io::{AsRawFd, FromRawFd};
+
+pub fn bind(addr: SocketAddr) -> io::Result<net::UdpSocket> {
+    // Gives a warning for non Apple platforms.
+    #[allow(clippy::let_and_return)]
+    let socket = new_ip_socket(addr, libc::SOCK_DGRAM);
+
+    socket.and_then(|socket| {
+        let (raw_addr, raw_addr_length) = socket_addr(&addr);
+        syscall!(bind(socket, raw_addr.as_ptr(), raw_addr_length))
+            .map_err(|err| {
+                // Close the socket if we hit an error, ignoring the error
+                // from closing since we can't pass back two errors.
+                let _ = unsafe { libc::close(socket) };
+                err
+            })
+            .map(|_| unsafe { net::UdpSocket::from_raw_fd(socket) })
+    })
+}
+
+pub(crate) fn only_v6(socket: &net::UdpSocket) -> io::Result<bool> {
+    let mut optval: libc::c_int = 0;
+    let mut optlen = mem::size_of::<libc::c_int>() as libc::socklen_t;
+
+    syscall!(getsockopt(
+        socket.as_raw_fd(),
+        libc::IPPROTO_IPV6,
+        libc::IPV6_V6ONLY,
+        &mut optval as *mut _ as *mut _,
+        &mut optlen,
+    ))?;
+
+    Ok(optval != 0)
+}
diff --git a/third_party/rust/mio/src/sys/unix/uds/datagram.rs b/third_party/rust/mio/src/sys/unix/uds/datagram.rs
new file mode 100644
index 0000000000..d3e5314fe3
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/uds/datagram.rs
@@ -0,0 +1,56 @@
+use super::{socket_addr, SocketAddr};
+use crate::sys::unix::net::new_socket;
+
+use std::io;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+
+pub(crate) fn bind(path: &Path) -> io::Result<net::UnixDatagram> {
+    let fd = new_socket(libc::AF_UNIX, libc::SOCK_DGRAM)?;
+    // Ensure the fd is closed.
+    let socket = unsafe { net::UnixDatagram::from_raw_fd(fd) };
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const _;
+    syscall!(bind(fd, sockaddr, socklen))?;
+    Ok(socket)
+}
+
+pub(crate) fn unbound() -> io::Result<net::UnixDatagram> {
+    new_socket(libc::AF_UNIX, libc::SOCK_DGRAM)
+        .map(|socket| unsafe { net::UnixDatagram::from_raw_fd(socket) })
+}
+
+pub(crate) fn pair() -> io::Result<(net::UnixDatagram, net::UnixDatagram)> {
+    super::pair(libc::SOCK_DGRAM)
+}
+
+pub(crate) fn local_addr(socket: &net::UnixDatagram) -> io::Result<SocketAddr> {
+    super::local_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn peer_addr(socket: &net::UnixDatagram) -> io::Result<SocketAddr> {
+    super::peer_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn recv_from(
+    socket: &net::UnixDatagram,
+    dst: &mut [u8],
+) -> io::Result<(usize, SocketAddr)> {
+    let mut count = 0;
+    let socketaddr = SocketAddr::new(|sockaddr, socklen| {
+        syscall!(recvfrom(
+            socket.as_raw_fd(),
+            dst.as_mut_ptr() as *mut _,
+            dst.len(),
+            0,
+            sockaddr,
+            socklen,
+        ))
+        .map(|c| {
+            count = c;
+            c as libc::c_int
+        })
+    })?;
+    Ok((count as usize, socketaddr))
+}
diff --git a/third_party/rust/mio/src/sys/unix/uds/listener.rs b/third_party/rust/mio/src/sys/unix/uds/listener.rs
new file mode 100644
index 0000000000..b6218427f2
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/uds/listener.rs
@@ -0,0 +1,94 @@
+use super::socket_addr;
+use crate::net::{SocketAddr, UnixStream};
+use crate::sys::unix::net::new_socket;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+use std::{io, mem};
+
+pub(crate) fn bind(path: &Path) -> io::Result<net::UnixListener> {
+    let socket = new_socket(libc::AF_UNIX, libc::SOCK_STREAM)?;
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const libc::sockaddr;
+
+    syscall!(bind(socket, sockaddr, socklen))
+        .and_then(|_| syscall!(listen(socket, 1024)))
+        .map_err(|err| {
+            // Close the socket if we hit an error, ignoring the error from
+            // closing since we can't pass back two errors.
+            let _ = unsafe { libc::close(socket) };
+            err
+        })
+        .map(|_| unsafe { net::UnixListener::from_raw_fd(socket) })
+}
+
+pub(crate) fn accept(listener: &net::UnixListener) -> io::Result<(UnixStream, SocketAddr)> {
+    let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+
+    // This is safe to assume because a `libc::sockaddr_un` filled with `0`
+    // bytes is properly initialized.
+    //
+    // `0` is a valid value for `sockaddr_un::sun_family`; it is
+    // `libc::AF_UNSPEC`.
+    //
+    // `[0; 108]` is a valid value for `sockaddr_un::sun_path`; it begins an
+    // abstract path.
+    let mut sockaddr = unsafe { sockaddr.assume_init() };
+
+    sockaddr.sun_family = libc::AF_UNIX as libc::sa_family_t;
+    let mut socklen = mem::size_of_val(&sockaddr) as libc::socklen_t;
+
+    #[cfg(not(any(
+        target_os = "ios",
+        target_os = "macos",
+        target_os = "netbsd",
+        // Android x86's seccomp profile forbids calls to `accept4(2)`
+        // See https://github.com/tokio-rs/mio/issues/1445 for details
+        all(
+            target_arch = "x86",
+            target_os = "android"
+        )
+    )))]
+    let socket = {
+        let flags = libc::SOCK_NONBLOCK | libc::SOCK_CLOEXEC;
+        syscall!(accept4(
+            listener.as_raw_fd(),
+            &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr,
+            &mut socklen,
+            flags
+        ))
+        .map(|socket| unsafe { net::UnixStream::from_raw_fd(socket) })
+    };
+
+    #[cfg(any(
+        target_os = "ios",
+        target_os = "macos",
+        target_os = "netbsd",
+        all(target_arch = "x86", target_os = "android")
+    ))]
+    let socket = syscall!(accept(
+        listener.as_raw_fd(),
+        &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr,
+        &mut socklen,
+    ))
+    .and_then(|socket| {
+        // Ensure the socket is closed if either of the `fcntl` calls
+        // error below.
+        let s = unsafe { net::UnixStream::from_raw_fd(socket) };
+        syscall!(fcntl(socket, libc::F_SETFD, libc::FD_CLOEXEC))?;
+
+        // See https://github.com/tokio-rs/mio/issues/1450
+        #[cfg(all(target_arch = "x86", target_os = "android"))]
+        syscall!(fcntl(socket, libc::F_SETFL, libc::O_NONBLOCK))?;
+
+        Ok(s)
+    });
+
+    socket
+        .map(UnixStream::from_std)
+        .map(|stream| (stream, SocketAddr::from_parts(sockaddr, socklen)))
+}
+
+pub(crate) fn local_addr(listener: &net::UnixListener) -> io::Result<SocketAddr> {
+    super::local_addr(listener.as_raw_fd())
+}
diff --git a/third_party/rust/mio/src/sys/unix/uds/mod.rs b/third_party/rust/mio/src/sys/unix/uds/mod.rs
new file mode 100644
index 0000000000..8e28a9573a
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/uds/mod.rs
@@ -0,0 +1,149 @@
+mod socketaddr;
+pub use self::socketaddr::SocketAddr;
+
+/// Get the `sun_path` field offset of `sockaddr_un` for the target OS.
+///
+/// On Linux, this funtion equates to the same value as
+/// `size_of::<sa_family_t>()`, but some other implementations include
+/// other fields before `sun_path`, so the expression more portably
+/// describes the size of the address structure.
+pub(in crate::sys) fn path_offset(sockaddr: &libc::sockaddr_un) -> usize {
+    let base = sockaddr as *const _ as usize;
+    let path = &sockaddr.sun_path as *const _ as usize;
+    path - base
+}
+
+cfg_os_poll! {
+    use std::cmp::Ordering;
+    use std::os::unix::ffi::OsStrExt;
+    use std::os::unix::io::{RawFd, FromRawFd};
+    use std::path::Path;
+    use std::{io, mem};
+
+    pub(crate) mod datagram;
+    pub(crate) mod listener;
+    pub(crate) mod stream;
+
+    pub(in crate::sys) fn socket_addr(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
+        let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+
+        // This is safe to assume because a `libc::sockaddr_un` filled with `0`
+        // bytes is properly initialized.
+        //
+        // `0` is a valid value for `sockaddr_un::sun_family`; it is
+        // `libc::AF_UNSPEC`.
+        //
+        // `[0; 108]` is a valid value for `sockaddr_un::sun_path`; it begins an
+        // abstract path.
+        let mut sockaddr = unsafe { sockaddr.assume_init() };
+
+        sockaddr.sun_family = libc::AF_UNIX as libc::sa_family_t;
+
+        let bytes = path.as_os_str().as_bytes();
+        match (bytes.get(0), bytes.len().cmp(&sockaddr.sun_path.len())) {
+            // Abstract paths don't need a null terminator
+            (Some(&0), Ordering::Greater) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "path must be no longer than libc::sockaddr_un.sun_path",
+                ));
+            }
+            (_, Ordering::Greater) | (_, Ordering::Equal) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "path must be shorter than libc::sockaddr_un.sun_path",
+                ));
+            }
+            _ => {}
+        }
+
+        for (dst, src) in sockaddr.sun_path.iter_mut().zip(bytes.iter()) {
+            *dst = *src as libc::c_char;
+        }
+
+        let offset = path_offset(&sockaddr);
+        let mut socklen = offset + bytes.len();
+
+        match bytes.get(0) {
+            // The struct has already been zeroes so the null byte for pathname
+            // addresses is already there.
+            Some(&0) | None => {}
+            Some(_) => socklen += 1,
+        }
+
+        Ok((sockaddr, socklen as libc::socklen_t))
+    }
+
+    fn pair<T>(flags: libc::c_int) -> io::Result<(T, T)>
+        where T: FromRawFd,
+    {
+        #[cfg(not(any(target_os = "ios", target_os = "macos")))]
+        let flags = flags | libc::SOCK_NONBLOCK | libc::SOCK_CLOEXEC;
+
+        let mut fds = [-1; 2];
+        syscall!(socketpair(libc::AF_UNIX, flags, 0, fds.as_mut_ptr()))?;
+        let pair = unsafe { (T::from_raw_fd(fds[0]), T::from_raw_fd(fds[1])) };
+
+        // Darwin doesn't have SOCK_NONBLOCK or SOCK_CLOEXEC.
+        //
+        // In order to set those flags, additional `fcntl` sys calls must be
+        // performed. If a `fnctl` fails after the sockets have been created,
+        // the file descriptors will leak. Creating `pair` above ensures that if
+        // there is an error, the file descriptors are closed.
+        #[cfg(any(target_os = "ios", target_os = "macos"))]
+        {
+            syscall!(fcntl(fds[0], libc::F_SETFL, libc::O_NONBLOCK))?;
+            syscall!(fcntl(fds[0], libc::F_SETFD, libc::FD_CLOEXEC))?;
+            syscall!(fcntl(fds[1], libc::F_SETFL, libc::O_NONBLOCK))?;
+            syscall!(fcntl(fds[1], libc::F_SETFD, libc::FD_CLOEXEC))?;
+        }
+        Ok(pair)
+    }
+
+    // The following functions can't simply be replaced with a call to
+    // `net::UnixDatagram` because of our `SocketAddr` type.
+
+    fn local_addr(socket: RawFd) -> io::Result<SocketAddr> {
+        SocketAddr::new(|sockaddr, socklen| syscall!(getsockname(socket, sockaddr, socklen)))
+    }
+
+    fn peer_addr(socket: RawFd) -> io::Result<SocketAddr> {
+        SocketAddr::new(|sockaddr, socklen| syscall!(getpeername(socket, sockaddr, socklen)))
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::{path_offset, socket_addr};
+        use std::path::Path;
+        use std::str;
+
+        #[test]
+        fn pathname_address() {
+            const PATH: &str = "./foo/bar.txt";
+            const PATH_LEN: usize = 13;
+
+            // Pathname addresses do have a null terminator, so `socklen` is
+            // expected to be `PATH_LEN` + `offset` + 1.
+            let path = Path::new(PATH);
+            let (sockaddr, actual) = socket_addr(path).unwrap();
+            let offset = path_offset(&sockaddr);
+            let expected = PATH_LEN + offset + 1;
+            assert_eq!(expected as libc::socklen_t, actual)
+        }
+
+        #[test]
+        fn abstract_address() {
+            const PATH: &[u8] = &[0, 116, 111, 107, 105, 111];
+            const PATH_LEN: usize = 6;
+
+            // Abstract addresses do not have a null terminator, so `socklen` is
+            // expected to be `PATH_LEN` + `offset`.
+            let abstract_path = str::from_utf8(PATH).unwrap();
+            let path = Path::new(abstract_path);
+            let (sockaddr, actual) = socket_addr(path).unwrap();
+            let offset = path_offset(&sockaddr);
+            let expected = PATH_LEN + offset;
+            assert_eq!(expected as libc::socklen_t, actual)
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/uds/socketaddr.rs b/third_party/rust/mio/src/sys/unix/uds/socketaddr.rs
new file mode 100644
index 0000000000..4c7c411618
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/uds/socketaddr.rs
@@ -0,0 +1,130 @@
+use super::path_offset;
+use std::ffi::OsStr;
+use std::os::unix::ffi::OsStrExt;
+use std::path::Path;
+use std::{ascii, fmt};
+
+/// An address associated with a `mio` specific Unix socket.
+///
+/// This is implemented instead of imported from [`net::SocketAddr`] because
+/// there is no way to create a [`net::SocketAddr`]. One must be returned by
+/// [`accept`], so this is returned instead.
+///
+/// [`net::SocketAddr`]: std::os::unix::net::SocketAddr
+/// [`accept`]: #method.accept
+pub struct SocketAddr {
+    sockaddr: libc::sockaddr_un,
+    socklen: libc::socklen_t,
+}
+
+struct AsciiEscaped<'a>(&'a [u8]);
+
+enum AddressKind<'a> {
+    Unnamed,
+    Pathname(&'a Path),
+    Abstract(&'a [u8]),
+}
+
+impl SocketAddr {
+    fn address(&self) -> AddressKind<'_> {
+        let offset = path_offset(&self.sockaddr);
+        // Don't underflow in `len` below.
+        if (self.socklen as usize) < offset {
+            return AddressKind::Unnamed;
+        }
+        let len = self.socklen as usize - offset;
+        let path = unsafe { &*(&self.sockaddr.sun_path as *const [libc::c_char] as *const [u8]) };
+
+        // macOS seems to return a len of 16 and a zeroed sun_path for unnamed addresses
+        if len == 0
+            || (cfg!(not(any(target_os = "linux", target_os = "android")))
+                && self.sockaddr.sun_path[0] == 0)
+        {
+            AddressKind::Unnamed
+        } else if self.sockaddr.sun_path[0] == 0 {
+            AddressKind::Abstract(&path[1..len])
+        } else {
+            AddressKind::Pathname(OsStr::from_bytes(&path[..len - 1]).as_ref())
+        }
+    }
+}
+
+cfg_os_poll! {
+    use std::{io, mem};
+
+    impl SocketAddr {
+        pub(crate) fn new<F>(f: F) -> io::Result<SocketAddr>
+        where
+            F: FnOnce(*mut libc::sockaddr, &mut libc::socklen_t) -> io::Result<libc::c_int>,
+        {
+            let mut sockaddr = {
+                let sockaddr = mem::MaybeUninit::<libc::sockaddr_un>::zeroed();
+                unsafe { sockaddr.assume_init() }
+            };
+
+            let raw_sockaddr = &mut sockaddr as *mut libc::sockaddr_un as *mut libc::sockaddr;
+            let mut socklen = mem::size_of_val(&sockaddr) as libc::socklen_t;
+
+            f(raw_sockaddr, &mut socklen)?;
+            Ok(SocketAddr::from_parts(sockaddr, socklen))
+        }
+
+        pub(crate) fn from_parts(sockaddr: libc::sockaddr_un, socklen: libc::socklen_t) -> SocketAddr {
+            SocketAddr { sockaddr, socklen }
+        }
+
+        /// Returns `true` if the address is unnamed.
+        ///
+        /// Documentation reflected in [`SocketAddr`]
+        ///
+        /// [`SocketAddr`]: std::os::unix::net::SocketAddr
+        pub fn is_unnamed(&self) -> bool {
+            matches!(self.address(), AddressKind::Unnamed)
+        }
+
+        /// Returns the contents of this address if it is a `pathname` address.
+        ///
+        /// Documentation reflected in [`SocketAddr`]
+        ///
+        /// [`SocketAddr`]: std::os::unix::net::SocketAddr
+        pub fn as_pathname(&self) -> Option<&Path> {
+            if let AddressKind::Pathname(path) = self.address() {
+                Some(path)
+            } else {
+                None
+            }
+        }
+
+        /// Returns the contents of this address if it is an abstract namespace
+        /// without the leading null byte.
+        // Link to std::os::unix::net::SocketAddr pending
+        // https://github.com/rust-lang/rust/issues/85410.
+        pub fn as_abstract_namespace(&self) -> Option<&[u8]> {
+            if let AddressKind::Abstract(path) = self.address() {
+                Some(path)
+            } else {
+                None
+            }
+        }
+    }
+}
+
+impl fmt::Debug for SocketAddr {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.address() {
+            AddressKind::Unnamed => write!(fmt, "(unnamed)"),
+            AddressKind::Abstract(name) => write!(fmt, "{} (abstract)", AsciiEscaped(name)),
+            AddressKind::Pathname(path) => write!(fmt, "{:?} (pathname)", path),
+        }
+    }
+}
+
+impl<'a> fmt::Display for AsciiEscaped<'a> {
+    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(fmt, "\"")?;
+        for byte in self.0.iter().cloned().flat_map(ascii::escape_default) {
+            write!(fmt, "{}", byte as char)?;
+        }
+        write!(fmt, "\"")
+    }
+}
diff --git a/third_party/rust/mio/src/sys/unix/uds/stream.rs b/third_party/rust/mio/src/sys/unix/uds/stream.rs
new file mode 100644
index 0000000000..149dd14e1d
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/uds/stream.rs
@@ -0,0 +1,39 @@
+use super::{socket_addr, SocketAddr};
+use crate::sys::unix::net::new_socket;
+
+use std::io;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use std::os::unix::net;
+use std::path::Path;
+
+pub(crate) fn connect(path: &Path) -> io::Result<net::UnixStream> {
+    let socket = new_socket(libc::AF_UNIX, libc::SOCK_STREAM)?;
+    let (sockaddr, socklen) = socket_addr(path)?;
+    let sockaddr = &sockaddr as *const libc::sockaddr_un as *const libc::sockaddr;
+
+    match syscall!(connect(socket, sockaddr, socklen)) {
+        Ok(_) => {}
+        Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {}
+        Err(e) => {
+            // Close the socket if we hit an error, ignoring the error
+            // from closing since we can't pass back two errors.
+            let _ = unsafe { libc::close(socket) };
+
+            return Err(e);
+        }
+    }
+
+    Ok(unsafe { net::UnixStream::from_raw_fd(socket) })
+}
+
+pub(crate) fn pair() -> io::Result<(net::UnixStream, net::UnixStream)> {
+    super::pair(libc::SOCK_STREAM)
+}
+
+pub(crate) fn local_addr(socket: &net::UnixStream) -> io::Result<SocketAddr> {
+    super::local_addr(socket.as_raw_fd())
+}
+
+pub(crate) fn peer_addr(socket: &net::UnixStream) -> io::Result<SocketAddr> {
+    super::peer_addr(socket.as_raw_fd())
+}
diff --git a/third_party/rust/mio/src/sys/unix/waker.rs b/third_party/rust/mio/src/sys/unix/waker.rs
new file mode 100644
index 0000000000..684fee981e
--- /dev/null
+++ b/third_party/rust/mio/src/sys/unix/waker.rs
@@ -0,0 +1,178 @@
+#[cfg(any(target_os = "linux", target_os = "android"))]
+mod eventfd {
+    use crate::sys::Selector;
+    use crate::{Interest, Token};
+
+    use std::fs::File;
+    use std::io::{self, Read, Write};
+    use std::os::unix::io::FromRawFd;
+
+    /// Waker backed by `eventfd`.
+    ///
+    /// `eventfd` is effectively an 64 bit counter. All writes must be of 8
+    /// bytes (64 bits) and are converted (native endian) into an 64 bit
+    /// unsigned integer and added to the count. Reads must also be 8 bytes and
+    /// reset the count to 0, returning the count.
+    #[derive(Debug)]
+    pub struct Waker {
+        fd: File,
+    }
+
+    impl Waker {
+        pub fn new(selector: &Selector, token: Token) -> io::Result<Waker> {
+            syscall!(eventfd(0, libc::EFD_CLOEXEC | libc::EFD_NONBLOCK)).and_then(|fd| {
+                // Turn the file descriptor into a file first so we're ensured
+                // it's closed when dropped, e.g. when register below fails.
+                let file = unsafe { File::from_raw_fd(fd) };
+                selector
+                    .register(fd, token, Interest::READABLE)
+                    .map(|()| Waker { fd: file })
+            })
+        }
+
+        pub fn wake(&self) -> io::Result<()> {
+            let buf: [u8; 8] = 1u64.to_ne_bytes();
+            match (&self.fd).write(&buf) {
+                Ok(_) => Ok(()),
+                Err(ref err) if err.kind() == io::ErrorKind::WouldBlock => {
+                    // Writing only blocks if the counter is going to overflow.
+                    // So we'll reset the counter to 0 and wake it again.
+                    self.reset()?;
+                    self.wake()
+                }
+                Err(err) => Err(err),
+            }
+        }
+
+        /// Reset the eventfd object, only need to call this if `wake` fails.
+        fn reset(&self) -> io::Result<()> {
+            let mut buf: [u8; 8] = 0u64.to_ne_bytes();
+            match (&self.fd).read(&mut buf) {
+                Ok(_) => Ok(()),
+                // If the `Waker` hasn't been awoken yet this will return a
+                // `WouldBlock` error which we can safely ignore.
+                Err(ref err) if err.kind() == io::ErrorKind::WouldBlock => Ok(()),
+                Err(err) => Err(err),
+            }
+        }
+    }
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+pub use self::eventfd::Waker;
+
+#[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+mod kqueue {
+    use crate::sys::Selector;
+    use crate::Token;
+
+    use std::io;
+
+    /// Waker backed by kqueue user space notifications (`EVFILT_USER`).
+    ///
+    /// The implementation is fairly simple, first the kqueue must be setup to
+    /// receive waker events this done by calling `Selector.setup_waker`. Next
+    /// we need access to kqueue, thus we need to duplicate the file descriptor.
+    /// Now waking is as simple as adding an event to the kqueue.
+    #[derive(Debug)]
+    pub struct Waker {
+        selector: Selector,
+        token: Token,
+    }
+
+    impl Waker {
+        pub fn new(selector: &Selector, token: Token) -> io::Result<Waker> {
+            selector.try_clone().and_then(|selector| {
+                selector
+                    .setup_waker(token)
+                    .map(|()| Waker { selector, token })
+            })
+        }
+
+        pub fn wake(&self) -> io::Result<()> {
+            self.selector.wake(self.token)
+        }
+    }
+}
+
+#[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))]
+pub use self::kqueue::Waker;
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "illumos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+))]
+mod pipe {
+    use crate::sys::unix::Selector;
+    use crate::{Interest, Token};
+
+    use std::fs::File;
+    use std::io::{self, Read, Write};
+    use std::os::unix::io::FromRawFd;
+
+    /// Waker backed by a unix pipe.
+    ///
+    /// Waker controls both the sending and receiving ends and empties the pipe
+    /// if writing to it (waking) fails.
+    #[derive(Debug)]
+    pub struct Waker {
+        sender: File,
+        receiver: File,
+    }
+
+    impl Waker {
+        pub fn new(selector: &Selector, token: Token) -> io::Result<Waker> {
+            let mut fds = [-1; 2];
+            syscall!(pipe2(fds.as_mut_ptr(), libc::O_NONBLOCK | libc::O_CLOEXEC))?;
+            // Turn the file descriptors into files first so we're ensured
+            // they're closed when dropped, e.g. when register below fails.
+            let sender = unsafe { File::from_raw_fd(fds[1]) };
+            let receiver = unsafe { File::from_raw_fd(fds[0]) };
+            selector
+                .register(fds[0], token, Interest::READABLE)
+                .map(|()| Waker { sender, receiver })
+        }
+
+        pub fn wake(&self) -> io::Result<()> {
+            // The epoll emulation on some illumos systems currently requires
+            // the pipe buffer to be completely empty for an edge-triggered
+            // wakeup on the pipe read side.
+            #[cfg(target_os = "illumos")]
+            self.empty();
+
+            match (&self.sender).write(&[1]) {
+                Ok(_) => Ok(()),
+                Err(ref err) if err.kind() == io::ErrorKind::WouldBlock => {
+                    // The reading end is full so we'll empty the buffer and try
+                    // again.
+                    self.empty();
+                    self.wake()
+                }
+                Err(ref err) if err.kind() == io::ErrorKind::Interrupted => self.wake(),
+                Err(err) => Err(err),
+            }
+        }
+
+        /// Empty the pipe's buffer, only need to call this if `wake` fails.
+        /// This ignores any errors.
+        fn empty(&self) {
+            let mut buf = [0; 4096];
+            loop {
+                match (&self.receiver).read(&mut buf) {
+                    Ok(n) if n > 0 => continue,
+                    _ => return,
+                }
+            }
+        }
+    }
+}
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "illumos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+))]
+pub use self::pipe::Waker;
diff --git a/third_party/rust/mio/src/sys/windows/afd.rs b/third_party/rust/mio/src/sys/windows/afd.rs
new file mode 100644
index 0000000000..6eae3bc035
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/afd.rs
@@ -0,0 +1,237 @@
+use ntapi::ntioapi::{IO_STATUS_BLOCK_u, IO_STATUS_BLOCK};
+use ntapi::ntioapi::{NtCancelIoFileEx, NtDeviceIoControlFile};
+use ntapi::ntrtl::RtlNtStatusToDosError;
+use std::fmt;
+use std::fs::File;
+use std::io;
+use std::mem::size_of;
+use std::os::windows::io::AsRawHandle;
+use std::ptr::null_mut;
+use winapi::shared::ntdef::{HANDLE, LARGE_INTEGER, NTSTATUS, PVOID, ULONG};
+use winapi::shared::ntstatus::{STATUS_NOT_FOUND, STATUS_PENDING, STATUS_SUCCESS};
+
+const IOCTL_AFD_POLL: ULONG = 0x00012024;
+
+/// Winsock2 AFD driver instance.
+///
+/// All operations are unsafe due to IO_STATUS_BLOCK parameter are being used by Afd driver during STATUS_PENDING before I/O Completion Port returns its result.
+#[derive(Debug)]
+pub struct Afd {
+    fd: File,
+}
+
+#[repr(C)]
+#[derive(Debug)]
+pub struct AfdPollHandleInfo {
+    pub handle: HANDLE,
+    pub events: ULONG,
+    pub status: NTSTATUS,
+}
+
+unsafe impl Send for AfdPollHandleInfo {}
+
+#[repr(C)]
+pub struct AfdPollInfo {
+    pub timeout: LARGE_INTEGER,
+    // Can have only value 1.
+    pub number_of_handles: ULONG,
+    pub exclusive: ULONG,
+    pub handles: [AfdPollHandleInfo; 1],
+}
+
+impl fmt::Debug for AfdPollInfo {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("AfdPollInfo").finish()
+    }
+}
+
+impl Afd {
+    /// Poll `Afd` instance with `AfdPollInfo`.
+    ///
+    /// # Unsafety
+    ///
+    /// This function is unsafe due to memory of `IO_STATUS_BLOCK` still being used by `Afd` instance while `Ok(false)` (`STATUS_PENDING`).
+    /// `iosb` needs to be untouched after the call while operation is in effective at ALL TIME except for `cancel` method.
+    /// So be careful not to `poll` twice while polling.
+    /// User should deallocate there overlapped value when error to prevent memory leak.
+    pub unsafe fn poll(
+        &self,
+        info: &mut AfdPollInfo,
+        iosb: *mut IO_STATUS_BLOCK,
+        overlapped: PVOID,
+    ) -> io::Result<bool> {
+        let info_ptr: PVOID = info as *mut _ as PVOID;
+        (*iosb).u.Status = STATUS_PENDING;
+        let status = NtDeviceIoControlFile(
+            self.fd.as_raw_handle(),
+            null_mut(),
+            None,
+            overlapped,
+            iosb,
+            IOCTL_AFD_POLL,
+            info_ptr,
+            size_of::<AfdPollInfo>() as u32,
+            info_ptr,
+            size_of::<AfdPollInfo>() as u32,
+        );
+        match status {
+            STATUS_SUCCESS => Ok(true),
+            STATUS_PENDING => Ok(false),
+            _ => Err(io::Error::from_raw_os_error(
+                RtlNtStatusToDosError(status) as i32
+            )),
+        }
+    }
+
+    /// Cancel previous polled request of `Afd`.
+    ///
+    /// iosb needs to be used by `poll` first for valid `cancel`.
+    ///
+    /// # Unsafety
+    ///
+    /// This function is unsafe due to memory of `IO_STATUS_BLOCK` still being used by `Afd` instance while `Ok(false)` (`STATUS_PENDING`).
+    /// Use it only with request is still being polled so that you have valid `IO_STATUS_BLOCK` to use.
+    /// User should NOT deallocate there overlapped value after the `cancel` to prevent double free.
+    pub unsafe fn cancel(&self, iosb: *mut IO_STATUS_BLOCK) -> io::Result<()> {
+        if (*iosb).u.Status != STATUS_PENDING {
+            return Ok(());
+        }
+
+        let mut cancel_iosb = IO_STATUS_BLOCK {
+            u: IO_STATUS_BLOCK_u { Status: 0 },
+            Information: 0,
+        };
+        let status = NtCancelIoFileEx(self.fd.as_raw_handle(), iosb, &mut cancel_iosb);
+        if status == STATUS_SUCCESS || status == STATUS_NOT_FOUND {
+            return Ok(());
+        }
+        Err(io::Error::from_raw_os_error(
+            RtlNtStatusToDosError(status) as i32
+        ))
+    }
+}
+
+cfg_io_source! {
+    use std::mem::zeroed;
+    use std::os::windows::io::{FromRawHandle, RawHandle};
+    use std::sync::atomic::{AtomicUsize, Ordering};
+
+    use miow::iocp::CompletionPort;
+    use ntapi::ntioapi::{NtCreateFile, FILE_OPEN};
+    use winapi::shared::ntdef::{OBJECT_ATTRIBUTES, UNICODE_STRING, USHORT, WCHAR};
+    use winapi::um::handleapi::INVALID_HANDLE_VALUE;
+    use winapi::um::winbase::{SetFileCompletionNotificationModes, FILE_SKIP_SET_EVENT_ON_HANDLE};
+    use winapi::um::winnt::{SYNCHRONIZE, FILE_SHARE_READ, FILE_SHARE_WRITE};
+
+    const AFD_HELPER_ATTRIBUTES: OBJECT_ATTRIBUTES = OBJECT_ATTRIBUTES {
+        Length: size_of::<OBJECT_ATTRIBUTES>() as ULONG,
+        RootDirectory: null_mut(),
+        ObjectName: &AFD_OBJ_NAME as *const _ as *mut _,
+        Attributes: 0,
+        SecurityDescriptor: null_mut(),
+        SecurityQualityOfService: null_mut(),
+    };
+
+    const AFD_OBJ_NAME: UNICODE_STRING = UNICODE_STRING {
+        Length: (AFD_HELPER_NAME.len() * size_of::<WCHAR>()) as USHORT,
+        MaximumLength: (AFD_HELPER_NAME.len() * size_of::<WCHAR>()) as USHORT,
+        Buffer: AFD_HELPER_NAME.as_ptr() as *mut _,
+    };
+
+    const AFD_HELPER_NAME: &[WCHAR] = &[
+        '\\' as _,
+        'D' as _,
+        'e' as _,
+        'v' as _,
+        'i' as _,
+        'c' as _,
+        'e' as _,
+        '\\' as _,
+        'A' as _,
+        'f' as _,
+        'd' as _,
+        '\\' as _,
+        'M' as _,
+        'i' as _,
+        'o' as _
+    ];
+
+    static NEXT_TOKEN: AtomicUsize = AtomicUsize::new(0);
+
+    impl AfdPollInfo {
+        pub fn zeroed() -> AfdPollInfo {
+            unsafe { zeroed() }
+        }
+    }
+
+    impl Afd {
+        /// Create new Afd instance.
+        pub fn new(cp: &CompletionPort) -> io::Result<Afd> {
+            let mut afd_helper_handle: HANDLE = INVALID_HANDLE_VALUE;
+            let mut iosb = IO_STATUS_BLOCK {
+                u: IO_STATUS_BLOCK_u { Status: 0 },
+                Information: 0,
+            };
+
+            unsafe {
+                let status = NtCreateFile(
+                    &mut afd_helper_handle as *mut _,
+                    SYNCHRONIZE,
+                    &AFD_HELPER_ATTRIBUTES as *const _ as *mut _,
+                    &mut iosb,
+                    null_mut(),
+                    0,
+                    FILE_SHARE_READ | FILE_SHARE_WRITE,
+                    FILE_OPEN,
+                    0,
+                    null_mut(),
+                    0,
+                );
+                if status != STATUS_SUCCESS {
+                    let raw_err = io::Error::from_raw_os_error(
+                        RtlNtStatusToDosError(status) as i32
+                    );
+                    let msg = format!("Failed to open \\Device\\Afd\\Mio: {}", raw_err);
+                    return Err(io::Error::new(raw_err.kind(), msg));
+                }
+                let fd = File::from_raw_handle(afd_helper_handle as RawHandle);
+                // Increment by 2 to reserve space for other types of handles.
+                // Non-AFD types (currently only NamedPipe), use odd numbered
+                // tokens. This allows the selector to differentate between them
+                // and dispatch events accordingly.
+                let token = NEXT_TOKEN.fetch_add(2, Ordering::Relaxed) + 2;
+                let afd = Afd { fd };
+                cp.add_handle(token, &afd.fd)?;
+                match SetFileCompletionNotificationModes(
+                    afd_helper_handle,
+                    FILE_SKIP_SET_EVENT_ON_HANDLE,
+                ) {
+                    0 => Err(io::Error::last_os_error()),
+                    _ => Ok(afd),
+                }
+            }
+        }
+    }
+}
+
+pub const POLL_RECEIVE: u32 = 0b0_0000_0001;
+pub const POLL_RECEIVE_EXPEDITED: u32 = 0b0_0000_0010;
+pub const POLL_SEND: u32 = 0b0_0000_0100;
+pub const POLL_DISCONNECT: u32 = 0b0_0000_1000;
+pub const POLL_ABORT: u32 = 0b0_0001_0000;
+pub const POLL_LOCAL_CLOSE: u32 = 0b0_0010_0000;
+// Not used as it indicated in each event where a connection is connected, not
+// just the first time a connection is established.
+// Also see https://github.com/piscisaureus/wepoll/commit/8b7b340610f88af3d83f40fb728e7b850b090ece.
+pub const POLL_CONNECT: u32 = 0b0_0100_0000;
+pub const POLL_ACCEPT: u32 = 0b0_1000_0000;
+pub const POLL_CONNECT_FAIL: u32 = 0b1_0000_0000;
+
+pub const KNOWN_EVENTS: u32 = POLL_RECEIVE
+    | POLL_RECEIVE_EXPEDITED
+    | POLL_SEND
+    | POLL_DISCONNECT
+    | POLL_ABORT
+    | POLL_LOCAL_CLOSE
+    | POLL_ACCEPT
+    | POLL_CONNECT_FAIL;
diff --git a/third_party/rust/mio/src/sys/windows/event.rs b/third_party/rust/mio/src/sys/windows/event.rs
new file mode 100644
index 0000000000..a49252a296
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/event.rs
@@ -0,0 +1,162 @@
+use std::fmt;
+
+use miow::iocp::CompletionStatus;
+
+use super::afd;
+use crate::Token;
+
+#[derive(Clone)]
+pub struct Event {
+    pub flags: u32,
+    pub data: u64,
+}
+
+pub fn token(event: &Event) -> Token {
+    Token(event.data as usize)
+}
+
+impl Event {
+    pub(super) fn new(token: Token) -> Event {
+        Event {
+            flags: 0,
+            data: usize::from(token) as u64,
+        }
+    }
+
+    pub(super) fn set_readable(&mut self) {
+        self.flags |= afd::POLL_RECEIVE
+    }
+
+    #[cfg(feature = "os-ext")]
+    pub(super) fn set_writable(&mut self) {
+        self.flags |= afd::POLL_SEND;
+    }
+
+    pub(super) fn from_completion_status(status: &CompletionStatus) -> Event {
+        Event {
+            flags: status.bytes_transferred(),
+            data: status.token() as u64,
+        }
+    }
+
+    pub(super) fn to_completion_status(&self) -> CompletionStatus {
+        CompletionStatus::new(self.flags, self.data as usize, std::ptr::null_mut())
+    }
+}
+
+pub(crate) const READABLE_FLAGS: u32 = afd::POLL_RECEIVE
+    | afd::POLL_DISCONNECT
+    | afd::POLL_ACCEPT
+    | afd::POLL_ABORT
+    | afd::POLL_CONNECT_FAIL;
+pub(crate) const WRITABLE_FLAGS: u32 = afd::POLL_SEND | afd::POLL_ABORT | afd::POLL_CONNECT_FAIL;
+pub(crate) const ERROR_FLAGS: u32 = afd::POLL_CONNECT_FAIL;
+pub(crate) const READ_CLOSED_FLAGS: u32 =
+    afd::POLL_DISCONNECT | afd::POLL_ABORT | afd::POLL_CONNECT_FAIL;
+pub(crate) const WRITE_CLOSED_FLAGS: u32 = afd::POLL_ABORT | afd::POLL_CONNECT_FAIL;
+
+pub fn is_readable(event: &Event) -> bool {
+    event.flags & READABLE_FLAGS != 0
+}
+
+pub fn is_writable(event: &Event) -> bool {
+    event.flags & WRITABLE_FLAGS != 0
+}
+
+pub fn is_error(event: &Event) -> bool {
+    event.flags & ERROR_FLAGS != 0
+}
+
+pub fn is_read_closed(event: &Event) -> bool {
+    event.flags & READ_CLOSED_FLAGS != 0
+}
+
+pub fn is_write_closed(event: &Event) -> bool {
+    event.flags & WRITE_CLOSED_FLAGS != 0
+}
+
+pub fn is_priority(event: &Event) -> bool {
+    event.flags & afd::POLL_RECEIVE_EXPEDITED != 0
+}
+
+pub fn is_aio(_: &Event) -> bool {
+    // Not supported.
+    false
+}
+
+pub fn is_lio(_: &Event) -> bool {
+    // Not supported.
+    false
+}
+
+pub fn debug_details(f: &mut fmt::Formatter<'_>, event: &Event) -> fmt::Result {
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    fn check_flags(got: &u32, want: &u32) -> bool {
+        (got & want) != 0
+    }
+    debug_detail!(
+        FlagsDetails(u32),
+        check_flags,
+        afd::POLL_RECEIVE,
+        afd::POLL_RECEIVE_EXPEDITED,
+        afd::POLL_SEND,
+        afd::POLL_DISCONNECT,
+        afd::POLL_ABORT,
+        afd::POLL_LOCAL_CLOSE,
+        afd::POLL_CONNECT,
+        afd::POLL_ACCEPT,
+        afd::POLL_CONNECT_FAIL,
+    );
+
+    f.debug_struct("event")
+        .field("flags", &FlagsDetails(event.flags))
+        .field("data", &event.data)
+        .finish()
+}
+
+pub struct Events {
+    /// Raw I/O event completions are filled in here by the call to `get_many`
+    /// on the completion port above. These are then processed to run callbacks
+    /// which figure out what to do after the event is done.
+    pub statuses: Box<[CompletionStatus]>,
+
+    /// Literal events returned by `get` to the upwards `EventLoop`. This file
+    /// doesn't really modify this (except for the waker), instead almost all
+    /// events are filled in by the `ReadinessQueue` from the `poll` module.
+    pub events: Vec<Event>,
+}
+
+impl Events {
+    pub fn with_capacity(cap: usize) -> Events {
+        // Note that it's possible for the output `events` to grow beyond the
+        // capacity as it can also include deferred events, but that's certainly
+        // not the end of the world!
+        Events {
+            statuses: vec![CompletionStatus::zero(); cap].into_boxed_slice(),
+            events: Vec::with_capacity(cap),
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.events.is_empty()
+    }
+
+    pub fn capacity(&self) -> usize {
+        self.events.capacity()
+    }
+
+    pub fn len(&self) -> usize {
+        self.events.len()
+    }
+
+    pub fn get(&self, idx: usize) -> Option<&Event> {
+        self.events.get(idx)
+    }
+
+    pub fn clear(&mut self) {
+        self.events.clear();
+        for status in self.statuses.iter_mut() {
+            *status = CompletionStatus::zero();
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/io_status_block.rs b/third_party/rust/mio/src/sys/windows/io_status_block.rs
new file mode 100644
index 0000000000..3e60334961
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/io_status_block.rs
@@ -0,0 +1,40 @@
+use std::fmt;
+use std::ops::{Deref, DerefMut};
+
+use ntapi::ntioapi::IO_STATUS_BLOCK;
+
+pub struct IoStatusBlock(IO_STATUS_BLOCK);
+
+cfg_io_source! {
+    use ntapi::ntioapi::IO_STATUS_BLOCK_u;
+
+    impl IoStatusBlock {
+        pub fn zeroed() -> Self {
+            Self(IO_STATUS_BLOCK {
+                u: IO_STATUS_BLOCK_u { Status: 0 },
+                Information: 0,
+            })
+        }
+    }
+}
+
+unsafe impl Send for IoStatusBlock {}
+
+impl Deref for IoStatusBlock {
+    type Target = IO_STATUS_BLOCK;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl DerefMut for IoStatusBlock {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl fmt::Debug for IoStatusBlock {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("IoStatusBlock").finish()
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/mod.rs b/third_party/rust/mio/src/sys/windows/mod.rs
new file mode 100644
index 0000000000..7048351355
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/mod.rs
@@ -0,0 +1,147 @@
+mod afd;
+mod io_status_block;
+
+pub mod event;
+pub use event::{Event, Events};
+
+mod selector;
+pub use selector::{Selector, SelectorInner, SockState};
+
+mod overlapped;
+use overlapped::Overlapped;
+
+// Macros must be defined before the modules that use them
+cfg_net! {
+    /// Helper macro to execute a system call that returns an `io::Result`.
+    //
+    // Macro must be defined before any modules that uses them.
+    macro_rules! syscall {
+        ($fn: ident ( $($arg: expr),* $(,)* ), $err_test: path, $err_value: expr) => {{
+            let res = unsafe { $fn($($arg, )*) };
+            if $err_test(&res, &$err_value) {
+                Err(io::Error::last_os_error())
+            } else {
+                Ok(res)
+            }
+        }};
+    }
+
+    mod net;
+
+    pub(crate) mod tcp;
+    pub(crate) mod udp;
+}
+
+cfg_os_ext! {
+    pub(crate) mod named_pipe;
+}
+
+mod waker;
+pub(crate) use waker::Waker;
+
+cfg_io_source! {
+    use std::io;
+    use std::os::windows::io::RawSocket;
+    use std::pin::Pin;
+    use std::sync::{Arc, Mutex};
+
+    use crate::{Interest, Registry, Token};
+
+    struct InternalState {
+        selector: Arc<SelectorInner>,
+        token: Token,
+        interests: Interest,
+        sock_state: Pin<Arc<Mutex<SockState>>>,
+    }
+
+    impl Drop for InternalState {
+        fn drop(&mut self) {
+            let mut sock_state = self.sock_state.lock().unwrap();
+            sock_state.mark_delete();
+        }
+    }
+
+    pub struct IoSourceState {
+        // This is `None` if the socket has not yet been registered.
+        //
+        // We box the internal state to not increase the size on the stack as the
+        // type might move around a lot.
+        inner: Option<Box<InternalState>>,
+    }
+
+    impl IoSourceState {
+        pub fn new() -> IoSourceState {
+            IoSourceState { inner: None }
+        }
+
+        pub fn do_io<T, F, R>(&self, f: F, io: &T) -> io::Result<R>
+        where
+            F: FnOnce(&T) -> io::Result<R>,
+        {
+            let result = f(io);
+            if let Err(ref e) = result {
+                if e.kind() == io::ErrorKind::WouldBlock {
+                    self.inner.as_ref().map_or(Ok(()), |state| {
+                        state
+                            .selector
+                            .reregister(state.sock_state.clone(), state.token, state.interests)
+                    })?;
+                }
+            }
+            result
+        }
+
+        pub fn register(
+            &mut self,
+            registry: &Registry,
+            token: Token,
+            interests: Interest,
+            socket: RawSocket,
+        ) -> io::Result<()> {
+            if self.inner.is_some() {
+                Err(io::ErrorKind::AlreadyExists.into())
+            } else {
+                registry
+                    .selector()
+                    .register(socket, token, interests)
+                    .map(|state| {
+                        self.inner = Some(Box::new(state));
+                    })
+            }
+        }
+
+        pub fn reregister(
+            &mut self,
+            registry: &Registry,
+            token: Token,
+            interests: Interest,
+        ) -> io::Result<()> {
+            match self.inner.as_mut() {
+                Some(state) => {
+                    registry
+                        .selector()
+                        .reregister(state.sock_state.clone(), token, interests)
+                        .map(|()| {
+                            state.token = token;
+                            state.interests = interests;
+                        })
+                }
+                None => Err(io::ErrorKind::NotFound.into()),
+            }
+        }
+
+        pub fn deregister(&mut self) -> io::Result<()> {
+            match self.inner.as_mut() {
+                Some(state) => {
+                    {
+                        let mut sock_state = state.sock_state.lock().unwrap();
+                        sock_state.mark_delete();
+                    }
+                    self.inner = None;
+                    Ok(())
+                }
+                None => Err(io::ErrorKind::NotFound.into()),
+            }
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/named_pipe.rs b/third_party/rust/mio/src/sys/windows/named_pipe.rs
new file mode 100644
index 0000000000..adda51f23c
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/named_pipe.rs
@@ -0,0 +1,782 @@
+use std::ffi::OsStr;
+use std::io::{self, Read, Write};
+use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
+use std::sync::atomic::Ordering::{Relaxed, SeqCst};
+use std::sync::atomic::{AtomicBool, AtomicUsize};
+use std::sync::{Arc, Mutex};
+use std::{fmt, mem, slice};
+
+use miow::iocp::{CompletionPort, CompletionStatus};
+use miow::pipe;
+use winapi::shared::winerror::{ERROR_BROKEN_PIPE, ERROR_PIPE_LISTENING};
+use winapi::um::ioapiset::CancelIoEx;
+use winapi::um::minwinbase::{OVERLAPPED, OVERLAPPED_ENTRY};
+
+use crate::event::Source;
+use crate::sys::windows::{Event, Overlapped};
+use crate::Registry;
+use crate::{Interest, Token};
+
+/// Non-blocking windows named pipe.
+///
+/// This structure internally contains a `HANDLE` which represents the named
+/// pipe, and also maintains state associated with the mio event loop and active
+/// I/O operations that have been scheduled to translate IOCP to a readiness
+/// model.
+///
+/// Note, IOCP is a *completion* based model whereas mio is a *readiness* based
+/// model. To bridge this, `NamedPipe` performs internal buffering. Writes are
+/// written to an internal buffer and the buffer is submitted to IOCP. IOCP
+/// reads are submitted using internal buffers and `NamedPipe::read` reads from
+/// this internal buffer.
+///
+/// # Trait implementations
+///
+/// The `Read` and `Write` traits are implemented for `NamedPipe` and for
+/// `&NamedPipe`. This represents that a named pipe can be concurrently read and
+/// written to and also can be read and written to at all. Typically a named
+/// pipe needs to be connected to a client before it can be read or written,
+/// however.
+///
+/// Note that for I/O operations on a named pipe to succeed then the named pipe
+/// needs to be associated with an event loop. Until this happens all I/O
+/// operations will return a "would block" error.
+///
+/// # Managing connections
+///
+/// The `NamedPipe` type supports a `connect` method to connect to a client and
+/// a `disconnect` method to disconnect from that client. These two methods only
+/// work once a named pipe is associated with an event loop.
+///
+/// The `connect` method will succeed asynchronously and a completion can be
+/// detected once the object receives a writable notification.
+///
+/// # Named pipe clients
+///
+/// Currently to create a client of a named pipe server then you can use the
+/// `OpenOptions` type in the standard library to create a `File` that connects
+/// to a named pipe. Afterwards you can use the `into_raw_handle` method coupled
+/// with the `NamedPipe::from_raw_handle` method to convert that to a named pipe
+/// that can operate asynchronously. Don't forget to pass the
+/// `FILE_FLAG_OVERLAPPED` flag when opening the `File`.
+pub struct NamedPipe {
+    inner: Arc<Inner>,
+}
+
+/// # Notes
+///
+/// The memory layout of this structure must be fixed as the
+/// `ptr_from_*_overlapped` methods depend on it, see the `ptr_from` test.
+#[repr(C)]
+struct Inner {
+    // NOTE: careful modifying the order of these three fields, the `ptr_from_*`
+    // methods depend on the layout!
+    connect: Overlapped,
+    read: Overlapped,
+    write: Overlapped,
+    // END NOTE.
+    handle: pipe::NamedPipe,
+    connecting: AtomicBool,
+    io: Mutex<Io>,
+    pool: Mutex<BufferPool>,
+}
+
+impl Inner {
+    /// Converts a pointer to `Inner.connect` to a pointer to `Inner`.
+    ///
+    /// # Unsafety
+    ///
+    /// Caller must ensure `ptr` is pointing to `Inner.connect`.
+    unsafe fn ptr_from_conn_overlapped(ptr: *mut OVERLAPPED) -> *const Inner {
+        // `connect` is the first field, so the pointer are the same.
+        ptr.cast()
+    }
+
+    /// Same as [`ptr_from_conn_overlapped`] but for `Inner.read`.
+    unsafe fn ptr_from_read_overlapped(ptr: *mut OVERLAPPED) -> *const Inner {
+        // `read` is after `connect: Overlapped`.
+        (ptr as *mut Overlapped).wrapping_sub(1) as *const Inner
+    }
+
+    /// Same as [`ptr_from_conn_overlapped`] but for `Inner.write`.
+    unsafe fn ptr_from_write_overlapped(ptr: *mut OVERLAPPED) -> *const Inner {
+        // `read` is after `connect: Overlapped` and `read: Overlapped`.
+        (ptr as *mut Overlapped).wrapping_sub(2) as *const Inner
+    }
+}
+
+#[test]
+fn ptr_from() {
+    use std::mem::ManuallyDrop;
+    use std::ptr;
+
+    let pipe = unsafe { ManuallyDrop::new(NamedPipe::from_raw_handle(ptr::null_mut())) };
+    let inner: &Inner = &pipe.inner;
+    assert_eq!(
+        inner as *const Inner,
+        unsafe { Inner::ptr_from_conn_overlapped(&inner.connect as *const _ as *mut OVERLAPPED) },
+        "`ptr_from_conn_overlapped` incorrect"
+    );
+    assert_eq!(
+        inner as *const Inner,
+        unsafe { Inner::ptr_from_read_overlapped(&inner.read as *const _ as *mut OVERLAPPED) },
+        "`ptr_from_read_overlapped` incorrect"
+    );
+    assert_eq!(
+        inner as *const Inner,
+        unsafe { Inner::ptr_from_write_overlapped(&inner.write as *const _ as *mut OVERLAPPED) },
+        "`ptr_from_write_overlapped` incorrect"
+    );
+}
+
+struct Io {
+    // Uniquely identifies the selector associated with this named pipe
+    cp: Option<Arc<CompletionPort>>,
+    // Token used to identify events
+    token: Option<Token>,
+    read: State,
+    write: State,
+    connect_error: Option<io::Error>,
+}
+
+#[derive(Debug)]
+enum State {
+    None,
+    Pending(Vec<u8>, usize),
+    Ok(Vec<u8>, usize),
+    Err(io::Error),
+}
+
+// Odd tokens are for named pipes
+static NEXT_TOKEN: AtomicUsize = AtomicUsize::new(1);
+
+fn would_block() -> io::Error {
+    io::ErrorKind::WouldBlock.into()
+}
+
+impl NamedPipe {
+    /// Creates a new named pipe at the specified `addr` given a "reasonable
+    /// set" of initial configuration options.
+    pub fn new<A: AsRef<OsStr>>(addr: A) -> io::Result<NamedPipe> {
+        let pipe = pipe::NamedPipe::new(addr)?;
+        // Safety: nothing actually unsafe about this. The trait fn includes
+        // `unsafe`.
+        Ok(unsafe { NamedPipe::from_raw_handle(pipe.into_raw_handle()) })
+    }
+
+    /// Attempts to call `ConnectNamedPipe`, if possible.
+    ///
+    /// This function will attempt to connect this pipe to a client in an
+    /// asynchronous fashion. If the function immediately establishes a
+    /// connection to a client then `Ok(())` is returned. Otherwise if a
+    /// connection attempt was issued and is now in progress then a "would
+    /// block" error is returned.
+    ///
+    /// When the connection is finished then this object will be flagged as
+    /// being ready for a write, or otherwise in the writable state.
+    ///
+    /// # Errors
+    ///
+    /// This function will return a "would block" error if the pipe has not yet
+    /// been registered with an event loop, if the connection operation has
+    /// previously been issued but has not yet completed, or if the connect
+    /// itself was issued and didn't finish immediately.
+    ///
+    /// Normal I/O errors from the call to `ConnectNamedPipe` are returned
+    /// immediately.
+    pub fn connect(&self) -> io::Result<()> {
+        // "Acquire the connecting lock" or otherwise just make sure we're the
+        // only operation that's using the `connect` overlapped instance.
+        if self.inner.connecting.swap(true, SeqCst) {
+            return Err(would_block());
+        }
+
+        // Now that we've flagged ourselves in the connecting state, issue the
+        // connection attempt. Afterwards interpret the return value and set
+        // internal state accordingly.
+        let res = unsafe {
+            let overlapped = self.inner.connect.as_ptr() as *mut _;
+            self.inner.handle.connect_overlapped(overlapped)
+        };
+
+        match res {
+            // The connection operation finished immediately, so let's schedule
+            // reads/writes and such.
+            Ok(true) => {
+                self.inner.connecting.store(false, SeqCst);
+                Inner::post_register(&self.inner, None);
+                Ok(())
+            }
+
+            // If the overlapped operation was successful and didn't finish
+            // immediately then we forget a copy of the arc we hold
+            // internally. This ensures that when the completion status comes
+            // in for the I/O operation finishing it'll have a reference
+            // associated with it and our data will still be valid. The
+            // `connect_done` function will "reify" this forgotten pointer to
+            // drop the refcount on the other side.
+            Ok(false) => {
+                mem::forget(self.inner.clone());
+                Err(would_block())
+            }
+
+            Err(e) => {
+                self.inner.connecting.store(false, SeqCst);
+                Err(e)
+            }
+        }
+    }
+
+    /// Takes any internal error that has happened after the last I/O operation
+    /// which hasn't been retrieved yet.
+    ///
+    /// This is particularly useful when detecting failed attempts to `connect`.
+    /// After a completed `connect` flags this pipe as writable then callers
+    /// must invoke this method to determine whether the connection actually
+    /// succeeded. If this function returns `None` then a client is connected,
+    /// otherwise it returns an error of what happened and a client shouldn't be
+    /// connected.
+    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
+        Ok(self.inner.io.lock().unwrap().connect_error.take())
+    }
+
+    /// Disconnects this named pipe from a connected client.
+    ///
+    /// This function will disconnect the pipe from a connected client, if any,
+    /// transitively calling the `DisconnectNamedPipe` function.
+    ///
+    /// After a `disconnect` is issued, then a `connect` may be called again to
+    /// connect to another client.
+    pub fn disconnect(&self) -> io::Result<()> {
+        self.inner.handle.disconnect()
+    }
+}
+
+impl FromRawHandle for NamedPipe {
+    unsafe fn from_raw_handle(handle: RawHandle) -> NamedPipe {
+        NamedPipe {
+            inner: Arc::new(Inner {
+                // Safety: not really unsafe
+                handle: pipe::NamedPipe::from_raw_handle(handle),
+                // transmutes to straddle winapi versions (mio 0.6 is on an
+                // older winapi)
+                connect: Overlapped::new(connect_done),
+                connecting: AtomicBool::new(false),
+                read: Overlapped::new(read_done),
+                write: Overlapped::new(write_done),
+                io: Mutex::new(Io {
+                    cp: None,
+                    token: None,
+                    read: State::None,
+                    write: State::None,
+                    connect_error: None,
+                }),
+                pool: Mutex::new(BufferPool::with_capacity(2)),
+            }),
+        }
+    }
+}
+
+impl Read for NamedPipe {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        <&NamedPipe as Read>::read(&mut &*self, buf)
+    }
+}
+
+impl Write for NamedPipe {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        <&NamedPipe as Write>::write(&mut &*self, buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        <&NamedPipe as Write>::flush(&mut &*self)
+    }
+}
+
+impl<'a> Read for &'a NamedPipe {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let mut state = self.inner.io.lock().unwrap();
+
+        if state.token.is_none() {
+            return Err(would_block());
+        }
+
+        match mem::replace(&mut state.read, State::None) {
+            // In theory not possible with `token` checked above,
+            // but return would block for now.
+            State::None => Err(would_block()),
+
+            // A read is in flight, still waiting for it to finish
+            State::Pending(buf, amt) => {
+                state.read = State::Pending(buf, amt);
+                Err(would_block())
+            }
+
+            // We previously read something into `data`, try to copy out some
+            // data. If we copy out all the data schedule a new read and
+            // otherwise store the buffer to get read later.
+            State::Ok(data, cur) => {
+                let n = {
+                    let mut remaining = &data[cur..];
+                    remaining.read(buf)?
+                };
+                let next = cur + n;
+                if next != data.len() {
+                    state.read = State::Ok(data, next);
+                } else {
+                    self.inner.put_buffer(data);
+                    Inner::schedule_read(&self.inner, &mut state, None);
+                }
+                Ok(n)
+            }
+
+            // Looks like an in-flight read hit an error, return that here while
+            // we schedule a new one.
+            State::Err(e) => {
+                Inner::schedule_read(&self.inner, &mut state, None);
+                if e.raw_os_error() == Some(ERROR_BROKEN_PIPE as i32) {
+                    Ok(0)
+                } else {
+                    Err(e)
+                }
+            }
+        }
+    }
+}
+
+impl<'a> Write for &'a NamedPipe {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        // Make sure there's no writes pending
+        let mut io = self.inner.io.lock().unwrap();
+
+        if io.token.is_none() {
+            return Err(would_block());
+        }
+
+        match io.write {
+            State::None => {}
+            State::Err(_) => match mem::replace(&mut io.write, State::None) {
+                State::Err(e) => return Err(e),
+                // `io` is locked, so this branch is unreachable
+                _ => unreachable!(),
+            },
+            // any other state should be handled in `write_done`
+            _ => {
+                return Err(would_block());
+            }
+        }
+
+        // Move `buf` onto the heap and fire off the write
+        let mut owned_buf = self.inner.get_buffer();
+        owned_buf.extend(buf);
+        match Inner::maybe_schedule_write(&self.inner, owned_buf, 0, &mut io)? {
+            // Some bytes are written immediately
+            Some(n) => Ok(n),
+            // Write operation is anqueued for whole buffer
+            None => Ok(buf.len()),
+        }
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        Ok(())
+    }
+}
+
+impl Source for NamedPipe {
+    fn register(&mut self, registry: &Registry, token: Token, _: Interest) -> io::Result<()> {
+        let mut io = self.inner.io.lock().unwrap();
+
+        io.check_association(registry, false)?;
+
+        if io.token.is_some() {
+            return Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                "I/O source already registered with a `Registry`",
+            ));
+        }
+
+        if io.cp.is_none() {
+            let selector = registry.selector();
+
+            io.cp = Some(selector.clone_port());
+
+            let inner_token = NEXT_TOKEN.fetch_add(2, Relaxed) + 2;
+            selector
+                .inner
+                .cp
+                .add_handle(inner_token, &self.inner.handle)?;
+        }
+
+        io.token = Some(token);
+        drop(io);
+
+        Inner::post_register(&self.inner, None);
+
+        Ok(())
+    }
+
+    fn reregister(&mut self, registry: &Registry, token: Token, _: Interest) -> io::Result<()> {
+        let mut io = self.inner.io.lock().unwrap();
+
+        io.check_association(registry, true)?;
+
+        io.token = Some(token);
+        drop(io);
+
+        Inner::post_register(&self.inner, None);
+
+        Ok(())
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        let mut io = self.inner.io.lock().unwrap();
+
+        io.check_association(registry, true)?;
+
+        if io.token.is_none() {
+            return Err(io::Error::new(
+                io::ErrorKind::NotFound,
+                "I/O source not registered with `Registry`",
+            ));
+        }
+
+        io.token = None;
+        Ok(())
+    }
+}
+
+impl AsRawHandle for NamedPipe {
+    fn as_raw_handle(&self) -> RawHandle {
+        self.inner.handle.as_raw_handle()
+    }
+}
+
+impl fmt::Debug for NamedPipe {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.handle.fmt(f)
+    }
+}
+
+impl Drop for NamedPipe {
+    fn drop(&mut self) {
+        // Cancel pending reads/connects, but don't cancel writes to ensure that
+        // everything is flushed out.
+        unsafe {
+            if self.inner.connecting.load(SeqCst) {
+                drop(cancel(&self.inner.handle, &self.inner.connect));
+            }
+
+            let io = self.inner.io.lock().unwrap();
+            if let State::Pending(..) = io.read {
+                drop(cancel(&self.inner.handle, &self.inner.read));
+            }
+        }
+    }
+}
+
+impl Inner {
+    /// Schedules a read to happen in the background, executing an overlapped
+    /// operation.
+    ///
+    /// This function returns `true` if a normal error happens or if the read
+    /// is scheduled in the background. If the pipe is no longer connected
+    /// (ERROR_PIPE_LISTENING) then `false` is returned and no read is
+    /// scheduled.
+    fn schedule_read(me: &Arc<Inner>, io: &mut Io, events: Option<&mut Vec<Event>>) -> bool {
+        // Check to see if a read is already scheduled/completed
+        match io.read {
+            State::None => {}
+            _ => return true,
+        }
+
+        // Allocate a buffer and schedule the read.
+        let mut buf = me.get_buffer();
+        let e = unsafe {
+            let overlapped = me.read.as_ptr() as *mut _;
+            let slice = slice::from_raw_parts_mut(buf.as_mut_ptr(), buf.capacity());
+            me.handle.read_overlapped(slice, overlapped)
+        };
+
+        match e {
+            // See `NamedPipe::connect` above for the rationale behind `forget`
+            Ok(_) => {
+                io.read = State::Pending(buf, 0); // 0 is ignored on read side
+                mem::forget(me.clone());
+                true
+            }
+
+            // If ERROR_PIPE_LISTENING happens then it's not a real read error,
+            // we just need to wait for a connect.
+            Err(ref e) if e.raw_os_error() == Some(ERROR_PIPE_LISTENING as i32) => false,
+
+            // If some other error happened, though, we're now readable to give
+            // out the error.
+            Err(e) => {
+                io.read = State::Err(e);
+                io.notify_readable(events);
+                true
+            }
+        }
+    }
+
+    /// Maybe schedules overlapped write operation.
+    ///
+    /// * `None` means that overlapped operation was enqueued
+    /// * `Some(n)` means that `n` bytes was immediately written.
+    ///   Note, that `write_done` will fire anyway to clean up the state.
+    fn maybe_schedule_write(
+        me: &Arc<Inner>,
+        buf: Vec<u8>,
+        pos: usize,
+        io: &mut Io,
+    ) -> io::Result<Option<usize>> {
+        // Very similar to `schedule_read` above, just done for the write half.
+        let e = unsafe {
+            let overlapped = me.write.as_ptr() as *mut _;
+            me.handle.write_overlapped(&buf[pos..], overlapped)
+        };
+
+        // See `connect` above for the rationale behind `forget`
+        match e {
+            // `n` bytes are written immediately
+            Ok(Some(n)) => {
+                io.write = State::Ok(buf, pos);
+                mem::forget(me.clone());
+                Ok(Some(n))
+            }
+            // write operation is enqueued
+            Ok(None) => {
+                io.write = State::Pending(buf, pos);
+                mem::forget(me.clone());
+                Ok(None)
+            }
+            Err(e) => Err(e),
+        }
+    }
+
+    fn schedule_write(
+        me: &Arc<Inner>,
+        buf: Vec<u8>,
+        pos: usize,
+        io: &mut Io,
+        events: Option<&mut Vec<Event>>,
+    ) {
+        match Inner::maybe_schedule_write(me, buf, pos, io) {
+            Ok(Some(_)) => {
+                // immediate result will be handled in `write_done`,
+                // so we'll reinterpret the `Ok` state
+                let state = mem::replace(&mut io.write, State::None);
+                io.write = match state {
+                    State::Ok(buf, pos) => State::Pending(buf, pos),
+                    // io is locked, so this branch is unreachable
+                    _ => unreachable!(),
+                };
+                mem::forget(me.clone());
+            }
+            Ok(None) => (),
+            Err(e) => {
+                io.write = State::Err(e);
+                io.notify_writable(events);
+            }
+        }
+    }
+
+    fn post_register(me: &Arc<Inner>, mut events: Option<&mut Vec<Event>>) {
+        let mut io = me.io.lock().unwrap();
+        #[allow(clippy::needless_option_as_deref)]
+        if Inner::schedule_read(me, &mut io, events.as_deref_mut()) {
+            if let State::None = io.write {
+                io.notify_writable(events);
+            }
+        }
+    }
+
+    fn get_buffer(&self) -> Vec<u8> {
+        self.pool.lock().unwrap().get(4 * 1024)
+    }
+
+    fn put_buffer(&self, buf: Vec<u8>) {
+        self.pool.lock().unwrap().put(buf)
+    }
+}
+
+unsafe fn cancel<T: AsRawHandle>(handle: &T, overlapped: &Overlapped) -> io::Result<()> {
+    let ret = CancelIoEx(handle.as_raw_handle(), overlapped.as_ptr() as *mut _);
+    // `CancelIoEx` returns 0 on error:
+    // https://docs.microsoft.com/en-us/windows/win32/fileio/cancelioex-func
+    if ret == 0 {
+        Err(io::Error::last_os_error())
+    } else {
+        Ok(())
+    }
+}
+
+fn connect_done(status: &OVERLAPPED_ENTRY, events: Option<&mut Vec<Event>>) {
+    let status = CompletionStatus::from_entry(status);
+
+    // Acquire the `Arc<Inner>`. Note that we should be guaranteed that
+    // the refcount is available to us due to the `mem::forget` in
+    // `connect` above.
+    let me = unsafe { Arc::from_raw(Inner::ptr_from_conn_overlapped(status.overlapped())) };
+
+    // Flag ourselves as no longer using the `connect` overlapped instances.
+    let prev = me.connecting.swap(false, SeqCst);
+    assert!(prev, "NamedPipe was not previously connecting");
+
+    // Stash away our connect error if one happened
+    debug_assert_eq!(status.bytes_transferred(), 0);
+    unsafe {
+        match me.handle.result(status.overlapped()) {
+            Ok(n) => debug_assert_eq!(n, 0),
+            Err(e) => me.io.lock().unwrap().connect_error = Some(e),
+        }
+    }
+
+    // We essentially just finished a registration, so kick off a
+    // read and register write readiness.
+    Inner::post_register(&me, events);
+}
+
+fn read_done(status: &OVERLAPPED_ENTRY, events: Option<&mut Vec<Event>>) {
+    let status = CompletionStatus::from_entry(status);
+
+    // Acquire the `FromRawArc<Inner>`. Note that we should be guaranteed that
+    // the refcount is available to us due to the `mem::forget` in
+    // `schedule_read` above.
+    let me = unsafe { Arc::from_raw(Inner::ptr_from_read_overlapped(status.overlapped())) };
+
+    // Move from the `Pending` to `Ok` state.
+    let mut io = me.io.lock().unwrap();
+    let mut buf = match mem::replace(&mut io.read, State::None) {
+        State::Pending(buf, _) => buf,
+        _ => unreachable!(),
+    };
+    unsafe {
+        match me.handle.result(status.overlapped()) {
+            Ok(n) => {
+                debug_assert_eq!(status.bytes_transferred() as usize, n);
+                buf.set_len(status.bytes_transferred() as usize);
+                io.read = State::Ok(buf, 0);
+            }
+            Err(e) => {
+                debug_assert_eq!(status.bytes_transferred(), 0);
+                io.read = State::Err(e);
+            }
+        }
+    }
+
+    // Flag our readiness that we've got data.
+    io.notify_readable(events);
+}
+
+fn write_done(status: &OVERLAPPED_ENTRY, events: Option<&mut Vec<Event>>) {
+    let status = CompletionStatus::from_entry(status);
+
+    // Acquire the `Arc<Inner>`. Note that we should be guaranteed that
+    // the refcount is available to us due to the `mem::forget` in
+    // `schedule_write` above.
+    let me = unsafe { Arc::from_raw(Inner::ptr_from_write_overlapped(status.overlapped())) };
+
+    // Make the state change out of `Pending`. If we wrote the entire buffer
+    // then we're writable again and otherwise we schedule another write.
+    let mut io = me.io.lock().unwrap();
+    let (buf, pos) = match mem::replace(&mut io.write, State::None) {
+        // `Ok` here means, that the operation was completed immediately
+        // `bytes_transferred` is already reported to a client
+        State::Ok(..) => {
+            io.notify_writable(events);
+            return;
+        }
+        State::Pending(buf, pos) => (buf, pos),
+        _ => unreachable!(),
+    };
+
+    unsafe {
+        match me.handle.result(status.overlapped()) {
+            Ok(n) => {
+                debug_assert_eq!(status.bytes_transferred() as usize, n);
+                let new_pos = pos + (status.bytes_transferred() as usize);
+                if new_pos == buf.len() {
+                    me.put_buffer(buf);
+                    io.notify_writable(events);
+                } else {
+                    Inner::schedule_write(&me, buf, new_pos, &mut io, events);
+                }
+            }
+            Err(e) => {
+                debug_assert_eq!(status.bytes_transferred(), 0);
+                io.write = State::Err(e);
+                io.notify_writable(events);
+            }
+        }
+    }
+}
+
+impl Io {
+    fn check_association(&self, registry: &Registry, required: bool) -> io::Result<()> {
+        match self.cp {
+            Some(ref cp) if !registry.selector().same_port(cp) => Err(io::Error::new(
+                io::ErrorKind::AlreadyExists,
+                "I/O source already registered with a different `Registry`",
+            )),
+            None if required => Err(io::Error::new(
+                io::ErrorKind::NotFound,
+                "I/O source not registered with `Registry`",
+            )),
+            _ => Ok(()),
+        }
+    }
+
+    fn notify_readable(&self, events: Option<&mut Vec<Event>>) {
+        if let Some(token) = self.token {
+            let mut ev = Event::new(token);
+            ev.set_readable();
+
+            if let Some(events) = events {
+                events.push(ev);
+            } else {
+                let _ = self.cp.as_ref().unwrap().post(ev.to_completion_status());
+            }
+        }
+    }
+
+    fn notify_writable(&self, events: Option<&mut Vec<Event>>) {
+        if let Some(token) = self.token {
+            let mut ev = Event::new(token);
+            ev.set_writable();
+
+            if let Some(events) = events {
+                events.push(ev);
+            } else {
+                let _ = self.cp.as_ref().unwrap().post(ev.to_completion_status());
+            }
+        }
+    }
+}
+
+struct BufferPool {
+    pool: Vec<Vec<u8>>,
+}
+
+impl BufferPool {
+    fn with_capacity(cap: usize) -> BufferPool {
+        BufferPool {
+            pool: Vec::with_capacity(cap),
+        }
+    }
+
+    fn get(&mut self, default_cap: usize) -> Vec<u8> {
+        self.pool
+            .pop()
+            .unwrap_or_else(|| Vec::with_capacity(default_cap))
+    }
+
+    fn put(&mut self, mut buf: Vec<u8>) {
+        if self.pool.len() < self.pool.capacity() {
+            unsafe {
+                buf.set_len(0);
+            }
+            self.pool.push(buf);
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/net.rs b/third_party/rust/mio/src/sys/windows/net.rs
new file mode 100644
index 0000000000..db1896f198
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/net.rs
@@ -0,0 +1,108 @@
+use std::io;
+use std::mem;
+use std::net::SocketAddr;
+use std::sync::Once;
+
+use winapi::ctypes::c_int;
+use winapi::shared::in6addr::{in6_addr_u, IN6_ADDR};
+use winapi::shared::inaddr::{in_addr_S_un, IN_ADDR};
+use winapi::shared::ws2def::{ADDRESS_FAMILY, AF_INET, AF_INET6, SOCKADDR, SOCKADDR_IN};
+use winapi::shared::ws2ipdef::{SOCKADDR_IN6_LH_u, SOCKADDR_IN6_LH};
+use winapi::um::winsock2::{ioctlsocket, socket, FIONBIO, INVALID_SOCKET, SOCKET};
+
+/// Initialise the network stack for Windows.
+pub(crate) fn init() {
+    static INIT: Once = Once::new();
+    INIT.call_once(|| {
+        // Let standard library call `WSAStartup` for us, we can't do it
+        // ourselves because otherwise using any type in `std::net` would panic
+        // when it tries to call `WSAStartup` a second time.
+        drop(std::net::UdpSocket::bind("127.0.0.1:0"));
+    });
+}
+
+/// Create a new non-blocking socket.
+pub(crate) fn new_ip_socket(addr: SocketAddr, socket_type: c_int) -> io::Result<SOCKET> {
+    use winapi::um::winsock2::{PF_INET, PF_INET6};
+
+    let domain = match addr {
+        SocketAddr::V4(..) => PF_INET,
+        SocketAddr::V6(..) => PF_INET6,
+    };
+
+    new_socket(domain, socket_type)
+}
+
+pub(crate) fn new_socket(domain: c_int, socket_type: c_int) -> io::Result<SOCKET> {
+    syscall!(
+        socket(domain, socket_type, 0),
+        PartialEq::eq,
+        INVALID_SOCKET
+    )
+    .and_then(|socket| {
+        syscall!(ioctlsocket(socket, FIONBIO, &mut 1), PartialEq::ne, 0).map(|_| socket as SOCKET)
+    })
+}
+
+/// A type with the same memory layout as `SOCKADDR`. Used in converting Rust level
+/// SocketAddr* types into their system representation. The benefit of this specific
+/// type over using `SOCKADDR_STORAGE` is that this type is exactly as large as it
+/// needs to be and not a lot larger. And it can be initialized cleaner from Rust.
+#[repr(C)]
+pub(crate) union SocketAddrCRepr {
+    v4: SOCKADDR_IN,
+    v6: SOCKADDR_IN6_LH,
+}
+
+impl SocketAddrCRepr {
+    pub(crate) fn as_ptr(&self) -> *const SOCKADDR {
+        self as *const _ as *const SOCKADDR
+    }
+}
+
+pub(crate) fn socket_addr(addr: &SocketAddr) -> (SocketAddrCRepr, c_int) {
+    match addr {
+        SocketAddr::V4(ref addr) => {
+            // `s_addr` is stored as BE on all machine and the array is in BE order.
+            // So the native endian conversion method is used so that it's never swapped.
+            let sin_addr = unsafe {
+                let mut s_un = mem::zeroed::<in_addr_S_un>();
+                *s_un.S_addr_mut() = u32::from_ne_bytes(addr.ip().octets());
+                IN_ADDR { S_un: s_un }
+            };
+
+            let sockaddr_in = SOCKADDR_IN {
+                sin_family: AF_INET as ADDRESS_FAMILY,
+                sin_port: addr.port().to_be(),
+                sin_addr,
+                sin_zero: [0; 8],
+            };
+
+            let sockaddr = SocketAddrCRepr { v4: sockaddr_in };
+            (sockaddr, mem::size_of::<SOCKADDR_IN>() as c_int)
+        }
+        SocketAddr::V6(ref addr) => {
+            let sin6_addr = unsafe {
+                let mut u = mem::zeroed::<in6_addr_u>();
+                *u.Byte_mut() = addr.ip().octets();
+                IN6_ADDR { u }
+            };
+            let u = unsafe {
+                let mut u = mem::zeroed::<SOCKADDR_IN6_LH_u>();
+                *u.sin6_scope_id_mut() = addr.scope_id();
+                u
+            };
+
+            let sockaddr_in6 = SOCKADDR_IN6_LH {
+                sin6_family: AF_INET6 as ADDRESS_FAMILY,
+                sin6_port: addr.port().to_be(),
+                sin6_addr,
+                sin6_flowinfo: addr.flowinfo(),
+                u,
+            };
+
+            let sockaddr = SocketAddrCRepr { v6: sockaddr_in6 };
+            (sockaddr, mem::size_of::<SOCKADDR_IN6_LH>() as c_int)
+        }
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/overlapped.rs b/third_party/rust/mio/src/sys/windows/overlapped.rs
new file mode 100644
index 0000000000..837b78b60a
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/overlapped.rs
@@ -0,0 +1,37 @@
+use crate::sys::windows::Event;
+
+use std::cell::UnsafeCell;
+use std::fmt;
+
+#[cfg(feature = "os-ext")]
+use winapi::um::minwinbase::OVERLAPPED;
+use winapi::um::minwinbase::OVERLAPPED_ENTRY;
+
+#[repr(C)]
+pub(crate) struct Overlapped {
+    inner: UnsafeCell<miow::Overlapped>,
+    pub(crate) callback: fn(&OVERLAPPED_ENTRY, Option<&mut Vec<Event>>),
+}
+
+#[cfg(feature = "os-ext")]
+impl Overlapped {
+    pub(crate) fn new(cb: fn(&OVERLAPPED_ENTRY, Option<&mut Vec<Event>>)) -> Overlapped {
+        Overlapped {
+            inner: UnsafeCell::new(miow::Overlapped::zero()),
+            callback: cb,
+        }
+    }
+
+    pub(crate) fn as_ptr(&self) -> *const OVERLAPPED {
+        unsafe { (*self.inner.get()).raw() }
+    }
+}
+
+impl fmt::Debug for Overlapped {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Overlapped").finish()
+    }
+}
+
+unsafe impl Send for Overlapped {}
+unsafe impl Sync for Overlapped {}
diff --git a/third_party/rust/mio/src/sys/windows/selector.rs b/third_party/rust/mio/src/sys/windows/selector.rs
new file mode 100644
index 0000000000..133fefe895
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/selector.rs
@@ -0,0 +1,748 @@
+use super::afd::{self, Afd, AfdPollInfo};
+use super::io_status_block::IoStatusBlock;
+use super::Event;
+use crate::sys::Events;
+
+cfg_net! {
+    use crate::sys::event::{
+        ERROR_FLAGS, READABLE_FLAGS, READ_CLOSED_FLAGS, WRITABLE_FLAGS, WRITE_CLOSED_FLAGS,
+    };
+    use crate::Interest;
+}
+
+use miow::iocp::{CompletionPort, CompletionStatus};
+use std::collections::VecDeque;
+use std::io;
+use std::marker::PhantomPinned;
+use std::os::windows::io::RawSocket;
+use std::pin::Pin;
+#[cfg(debug_assertions)]
+use std::sync::atomic::AtomicUsize;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+use winapi::shared::ntdef::NT_SUCCESS;
+use winapi::shared::ntdef::{HANDLE, PVOID};
+use winapi::shared::ntstatus::STATUS_CANCELLED;
+use winapi::shared::winerror::{ERROR_INVALID_HANDLE, ERROR_IO_PENDING, WAIT_TIMEOUT};
+use winapi::um::minwinbase::OVERLAPPED;
+
+#[derive(Debug)]
+struct AfdGroup {
+    #[cfg_attr(not(feature = "net"), allow(dead_code))]
+    cp: Arc<CompletionPort>,
+    afd_group: Mutex<Vec<Arc<Afd>>>,
+}
+
+impl AfdGroup {
+    pub fn new(cp: Arc<CompletionPort>) -> AfdGroup {
+        AfdGroup {
+            afd_group: Mutex::new(Vec::new()),
+            cp,
+        }
+    }
+
+    pub fn release_unused_afd(&self) {
+        let mut afd_group = self.afd_group.lock().unwrap();
+        afd_group.retain(|g| Arc::strong_count(g) > 1);
+    }
+}
+
+cfg_io_source! {
+    const POLL_GROUP__MAX_GROUP_SIZE: usize = 32;
+
+    impl AfdGroup {
+        pub fn acquire(&self) -> io::Result<Arc<Afd>> {
+            let mut afd_group = self.afd_group.lock().unwrap();
+            if afd_group.len() == 0 {
+                self._alloc_afd_group(&mut afd_group)?;
+            } else {
+                // + 1 reference in Vec
+                if Arc::strong_count(afd_group.last().unwrap()) > POLL_GROUP__MAX_GROUP_SIZE  {
+                    self._alloc_afd_group(&mut afd_group)?;
+                }
+            }
+
+            match afd_group.last() {
+                Some(arc) => Ok(arc.clone()),
+                None => unreachable!(
+                    "Cannot acquire afd, {:#?}, afd_group: {:#?}",
+                    self, afd_group
+                ),
+            }
+        }
+
+        fn _alloc_afd_group(&self, afd_group: &mut Vec<Arc<Afd>>) -> io::Result<()> {
+            let afd = Afd::new(&self.cp)?;
+            let arc = Arc::new(afd);
+            afd_group.push(arc);
+            Ok(())
+        }
+    }
+}
+
+#[derive(Debug)]
+enum SockPollStatus {
+    Idle,
+    Pending,
+    Cancelled,
+}
+
+#[derive(Debug)]
+pub struct SockState {
+    iosb: IoStatusBlock,
+    poll_info: AfdPollInfo,
+    afd: Arc<Afd>,
+
+    base_socket: RawSocket,
+
+    user_evts: u32,
+    pending_evts: u32,
+
+    user_data: u64,
+
+    poll_status: SockPollStatus,
+    delete_pending: bool,
+
+    // last raw os error
+    error: Option<i32>,
+
+    _pinned: PhantomPinned,
+}
+
+impl SockState {
+    fn update(&mut self, self_arc: &Pin<Arc<Mutex<SockState>>>) -> io::Result<()> {
+        assert!(!self.delete_pending);
+
+        // make sure to reset previous error before a new update
+        self.error = None;
+
+        if let SockPollStatus::Pending = self.poll_status {
+            if (self.user_evts & afd::KNOWN_EVENTS & !self.pending_evts) == 0 {
+                /* All the events the user is interested in are already being monitored by
+                 * the pending poll operation. It might spuriously complete because of an
+                 * event that we're no longer interested in; when that happens we'll submit
+                 * a new poll operation with the updated event mask. */
+            } else {
+                /* A poll operation is already pending, but it's not monitoring for all the
+                 * events that the user is interested in. Therefore, cancel the pending
+                 * poll operation; when we receive it's completion package, a new poll
+                 * operation will be submitted with the correct event mask. */
+                if let Err(e) = self.cancel() {
+                    self.error = e.raw_os_error();
+                    return Err(e);
+                }
+                return Ok(());
+            }
+        } else if let SockPollStatus::Cancelled = self.poll_status {
+            /* The poll operation has already been cancelled, we're still waiting for
+             * it to return. For now, there's nothing that needs to be done. */
+        } else if let SockPollStatus::Idle = self.poll_status {
+            /* No poll operation is pending; start one. */
+            self.poll_info.exclusive = 0;
+            self.poll_info.number_of_handles = 1;
+            *unsafe { self.poll_info.timeout.QuadPart_mut() } = std::i64::MAX;
+            self.poll_info.handles[0].handle = self.base_socket as HANDLE;
+            self.poll_info.handles[0].status = 0;
+            self.poll_info.handles[0].events = self.user_evts | afd::POLL_LOCAL_CLOSE;
+
+            // Increase the ref count as the memory will be used by the kernel.
+            let overlapped_ptr = into_overlapped(self_arc.clone());
+
+            let result = unsafe {
+                self.afd
+                    .poll(&mut self.poll_info, &mut *self.iosb, overlapped_ptr)
+            };
+            if let Err(e) = result {
+                let code = e.raw_os_error().unwrap();
+                if code == ERROR_IO_PENDING as i32 {
+                    /* Overlapped poll operation in progress; this is expected. */
+                } else {
+                    // Since the operation failed it means the kernel won't be
+                    // using the memory any more.
+                    drop(from_overlapped(overlapped_ptr as *mut _));
+                    if code == ERROR_INVALID_HANDLE as i32 {
+                        /* Socket closed; it'll be dropped. */
+                        self.mark_delete();
+                        return Ok(());
+                    } else {
+                        self.error = e.raw_os_error();
+                        return Err(e);
+                    }
+                }
+            }
+
+            self.poll_status = SockPollStatus::Pending;
+            self.pending_evts = self.user_evts;
+        } else {
+            unreachable!("Invalid poll status during update, {:#?}", self)
+        }
+
+        Ok(())
+    }
+
+    fn cancel(&mut self) -> io::Result<()> {
+        match self.poll_status {
+            SockPollStatus::Pending => {}
+            _ => unreachable!("Invalid poll status during cancel, {:#?}", self),
+        };
+        unsafe {
+            self.afd.cancel(&mut *self.iosb)?;
+        }
+        self.poll_status = SockPollStatus::Cancelled;
+        self.pending_evts = 0;
+        Ok(())
+    }
+
+    // This is the function called from the overlapped using as Arc<Mutex<SockState>>. Watch out for reference counting.
+    fn feed_event(&mut self) -> Option<Event> {
+        self.poll_status = SockPollStatus::Idle;
+        self.pending_evts = 0;
+
+        let mut afd_events = 0;
+        // We use the status info in IO_STATUS_BLOCK to determine the socket poll status. It is unsafe to use a pointer of IO_STATUS_BLOCK.
+        unsafe {
+            if self.delete_pending {
+                return None;
+            } else if self.iosb.u.Status == STATUS_CANCELLED {
+                /* The poll request was cancelled by CancelIoEx. */
+            } else if !NT_SUCCESS(self.iosb.u.Status) {
+                /* The overlapped request itself failed in an unexpected way. */
+                afd_events = afd::POLL_CONNECT_FAIL;
+            } else if self.poll_info.number_of_handles < 1 {
+                /* This poll operation succeeded but didn't report any socket events. */
+            } else if self.poll_info.handles[0].events & afd::POLL_LOCAL_CLOSE != 0 {
+                /* The poll operation reported that the socket was closed. */
+                self.mark_delete();
+                return None;
+            } else {
+                afd_events = self.poll_info.handles[0].events;
+            }
+        }
+
+        afd_events &= self.user_evts;
+
+        if afd_events == 0 {
+            return None;
+        }
+
+        // In mio, we have to simulate Edge-triggered behavior to match API usage.
+        // The strategy here is to intercept all read/write from user that could cause WouldBlock usage,
+        // then reregister the socket to reset the interests.
+        self.user_evts &= !afd_events;
+
+        Some(Event {
+            data: self.user_data,
+            flags: afd_events,
+        })
+    }
+
+    pub fn is_pending_deletion(&self) -> bool {
+        self.delete_pending
+    }
+
+    pub fn mark_delete(&mut self) {
+        if !self.delete_pending {
+            if let SockPollStatus::Pending = self.poll_status {
+                drop(self.cancel());
+            }
+
+            self.delete_pending = true;
+        }
+    }
+
+    fn has_error(&self) -> bool {
+        self.error.is_some()
+    }
+}
+
+cfg_io_source! {
+    impl SockState {
+        fn new(raw_socket: RawSocket, afd: Arc<Afd>) -> io::Result<SockState> {
+            Ok(SockState {
+                iosb: IoStatusBlock::zeroed(),
+                poll_info: AfdPollInfo::zeroed(),
+                afd,
+                base_socket: get_base_socket(raw_socket)?,
+                user_evts: 0,
+                pending_evts: 0,
+                user_data: 0,
+                poll_status: SockPollStatus::Idle,
+                delete_pending: false,
+                error: None,
+                _pinned: PhantomPinned,
+            })
+        }
+
+        /// True if need to be added on update queue, false otherwise.
+        fn set_event(&mut self, ev: Event) -> bool {
+            /* afd::POLL_CONNECT_FAIL and afd::POLL_ABORT are always reported, even when not requested by the caller. */
+            let events = ev.flags | afd::POLL_CONNECT_FAIL | afd::POLL_ABORT;
+
+            self.user_evts = events;
+            self.user_data = ev.data;
+
+            (events & !self.pending_evts) != 0
+        }
+    }
+}
+
+impl Drop for SockState {
+    fn drop(&mut self) {
+        self.mark_delete();
+    }
+}
+
+/// Converts the pointer to a `SockState` into a raw pointer.
+/// To revert see `from_overlapped`.
+fn into_overlapped(sock_state: Pin<Arc<Mutex<SockState>>>) -> PVOID {
+    let overlapped_ptr: *const Mutex<SockState> =
+        unsafe { Arc::into_raw(Pin::into_inner_unchecked(sock_state)) };
+    overlapped_ptr as *mut _
+}
+
+/// Convert a raw overlapped pointer into a reference to `SockState`.
+/// Reverts `into_overlapped`.
+fn from_overlapped(ptr: *mut OVERLAPPED) -> Pin<Arc<Mutex<SockState>>> {
+    let sock_ptr: *const Mutex<SockState> = ptr as *const _;
+    unsafe { Pin::new_unchecked(Arc::from_raw(sock_ptr)) }
+}
+
+/// Each Selector has a globally unique(ish) ID associated with it. This ID
+/// gets tracked by `TcpStream`, `TcpListener`, etc... when they are first
+/// registered with the `Selector`. If a type that is previously associated with
+/// a `Selector` attempts to register itself with a different `Selector`, the
+/// operation will return with an error. This matches windows behavior.
+#[cfg(debug_assertions)]
+static NEXT_ID: AtomicUsize = AtomicUsize::new(0);
+
+/// Windows implementaion of `sys::Selector`
+///
+/// Edge-triggered event notification is simulated by resetting internal event flag of each socket state `SockState`
+/// and setting all events back by intercepting all requests that could cause `io::ErrorKind::WouldBlock` happening.
+///
+/// This selector is currently only support socket due to `Afd` driver is winsock2 specific.
+#[derive(Debug)]
+pub struct Selector {
+    #[cfg(debug_assertions)]
+    id: usize,
+    pub(super) inner: Arc<SelectorInner>,
+    #[cfg(debug_assertions)]
+    has_waker: AtomicBool,
+}
+
+impl Selector {
+    pub fn new() -> io::Result<Selector> {
+        SelectorInner::new().map(|inner| {
+            #[cfg(debug_assertions)]
+            let id = NEXT_ID.fetch_add(1, Ordering::Relaxed) + 1;
+            Selector {
+                #[cfg(debug_assertions)]
+                id,
+                inner: Arc::new(inner),
+                #[cfg(debug_assertions)]
+                has_waker: AtomicBool::new(false),
+            }
+        })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        Ok(Selector {
+            #[cfg(debug_assertions)]
+            id: self.id,
+            inner: Arc::clone(&self.inner),
+            #[cfg(debug_assertions)]
+            has_waker: AtomicBool::new(self.has_waker.load(Ordering::Acquire)),
+        })
+    }
+
+    /// # Safety
+    ///
+    /// This requires a mutable reference to self because only a single thread
+    /// can poll IOCP at a time.
+    pub fn select(&mut self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        self.inner.select(events, timeout)
+    }
+
+    #[cfg(debug_assertions)]
+    pub fn register_waker(&self) -> bool {
+        self.has_waker.swap(true, Ordering::AcqRel)
+    }
+
+    pub(super) fn clone_port(&self) -> Arc<CompletionPort> {
+        self.inner.cp.clone()
+    }
+
+    #[cfg(feature = "os-ext")]
+    pub(super) fn same_port(&self, other: &Arc<CompletionPort>) -> bool {
+        Arc::ptr_eq(&self.inner.cp, other)
+    }
+}
+
+cfg_io_source! {
+    use super::InternalState;
+    use crate::Token;
+
+    impl Selector {
+        pub(super) fn register(
+            &self,
+            socket: RawSocket,
+            token: Token,
+            interests: Interest,
+        ) -> io::Result<InternalState> {
+            SelectorInner::register(&self.inner, socket, token, interests)
+        }
+
+        pub(super) fn reregister(
+            &self,
+            state: Pin<Arc<Mutex<SockState>>>,
+            token: Token,
+            interests: Interest,
+        ) -> io::Result<()> {
+            self.inner.reregister(state, token, interests)
+        }
+
+        #[cfg(debug_assertions)]
+        pub fn id(&self) -> usize {
+            self.id
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct SelectorInner {
+    pub(super) cp: Arc<CompletionPort>,
+    update_queue: Mutex<VecDeque<Pin<Arc<Mutex<SockState>>>>>,
+    afd_group: AfdGroup,
+    is_polling: AtomicBool,
+}
+
+// We have ensured thread safety by introducing lock manually.
+unsafe impl Sync for SelectorInner {}
+
+impl SelectorInner {
+    pub fn new() -> io::Result<SelectorInner> {
+        CompletionPort::new(0).map(|cp| {
+            let cp = Arc::new(cp);
+            let cp_afd = Arc::clone(&cp);
+
+            SelectorInner {
+                cp,
+                update_queue: Mutex::new(VecDeque::new()),
+                afd_group: AfdGroup::new(cp_afd),
+                is_polling: AtomicBool::new(false),
+            }
+        })
+    }
+
+    /// # Safety
+    ///
+    /// May only be calling via `Selector::select`.
+    pub fn select(&self, events: &mut Events, timeout: Option<Duration>) -> io::Result<()> {
+        events.clear();
+
+        if timeout.is_none() {
+            loop {
+                let len = self.select2(&mut events.statuses, &mut events.events, None)?;
+                if len == 0 {
+                    continue;
+                }
+                break Ok(());
+            }
+        } else {
+            self.select2(&mut events.statuses, &mut events.events, timeout)?;
+            Ok(())
+        }
+    }
+
+    pub fn select2(
+        &self,
+        statuses: &mut [CompletionStatus],
+        events: &mut Vec<Event>,
+        timeout: Option<Duration>,
+    ) -> io::Result<usize> {
+        assert!(!self.is_polling.swap(true, Ordering::AcqRel));
+
+        unsafe { self.update_sockets_events() }?;
+
+        let result = self.cp.get_many(statuses, timeout);
+
+        self.is_polling.store(false, Ordering::Relaxed);
+
+        match result {
+            Ok(iocp_events) => Ok(unsafe { self.feed_events(events, iocp_events) }),
+            Err(ref e) if e.raw_os_error() == Some(WAIT_TIMEOUT as i32) => Ok(0),
+            Err(e) => Err(e),
+        }
+    }
+
+    unsafe fn update_sockets_events(&self) -> io::Result<()> {
+        let mut update_queue = self.update_queue.lock().unwrap();
+        for sock in update_queue.iter_mut() {
+            let mut sock_internal = sock.lock().unwrap();
+            if !sock_internal.is_pending_deletion() {
+                sock_internal.update(sock)?;
+            }
+        }
+
+        // remove all sock which do not have error, they have afd op pending
+        update_queue.retain(|sock| sock.lock().unwrap().has_error());
+
+        self.afd_group.release_unused_afd();
+        Ok(())
+    }
+
+    // It returns processed count of iocp_events rather than the events itself.
+    unsafe fn feed_events(
+        &self,
+        events: &mut Vec<Event>,
+        iocp_events: &[CompletionStatus],
+    ) -> usize {
+        let mut n = 0;
+        let mut update_queue = self.update_queue.lock().unwrap();
+        for iocp_event in iocp_events.iter() {
+            if iocp_event.overlapped().is_null() {
+                events.push(Event::from_completion_status(iocp_event));
+                n += 1;
+                continue;
+            } else if iocp_event.token() % 2 == 1 {
+                // Handle is a named pipe. This could be extended to be any non-AFD event.
+                let callback = (*(iocp_event.overlapped() as *mut super::Overlapped)).callback;
+
+                let len = events.len();
+                callback(iocp_event.entry(), Some(events));
+                n += events.len() - len;
+                continue;
+            }
+
+            let sock_state = from_overlapped(iocp_event.overlapped());
+            let mut sock_guard = sock_state.lock().unwrap();
+            if let Some(e) = sock_guard.feed_event() {
+                events.push(e);
+                n += 1;
+            }
+
+            if !sock_guard.is_pending_deletion() {
+                update_queue.push_back(sock_state.clone());
+            }
+        }
+        self.afd_group.release_unused_afd();
+        n
+    }
+}
+
+cfg_io_source! {
+    use std::mem::size_of;
+    use std::ptr::null_mut;
+    use winapi::um::mswsock;
+    use winapi::um::winsock2::WSAGetLastError;
+    use winapi::um::winsock2::{WSAIoctl, SOCKET_ERROR};
+
+    impl SelectorInner {
+        fn register(
+            this: &Arc<Self>,
+            socket: RawSocket,
+            token: Token,
+            interests: Interest,
+        ) -> io::Result<InternalState> {
+            let flags = interests_to_afd_flags(interests);
+
+            let sock = {
+                let sock = this._alloc_sock_for_rawsocket(socket)?;
+                let event = Event {
+                    flags,
+                    data: token.0 as u64,
+                };
+                sock.lock().unwrap().set_event(event);
+                sock
+            };
+
+            let state = InternalState {
+                selector: this.clone(),
+                token,
+                interests,
+                sock_state: sock.clone(),
+            };
+
+            this.queue_state(sock);
+            unsafe { this.update_sockets_events_if_polling()? };
+
+            Ok(state)
+        }
+
+        // Directly accessed in `IoSourceState::do_io`.
+        pub(super) fn reregister(
+            &self,
+            state: Pin<Arc<Mutex<SockState>>>,
+            token: Token,
+            interests: Interest,
+        ) -> io::Result<()> {
+            {
+                let event = Event {
+                    flags: interests_to_afd_flags(interests),
+                    data: token.0 as u64,
+                };
+
+                state.lock().unwrap().set_event(event);
+            }
+
+            // FIXME: a sock which has_error true should not be re-added to
+            // the update queue because it's already there.
+            self.queue_state(state);
+            unsafe { self.update_sockets_events_if_polling() }
+        }
+
+        /// This function is called by register() and reregister() to start an
+        /// IOCTL_AFD_POLL operation corresponding to the registered events, but
+        /// only if necessary.
+        ///
+        /// Since it is not possible to modify or synchronously cancel an AFD_POLL
+        /// operation, and there can be only one active AFD_POLL operation per
+        /// (socket, completion port) pair at any time, it is expensive to change
+        /// a socket's event registration after it has been submitted to the kernel.
+        ///
+        /// Therefore, if no other threads are polling when interest in a socket
+        /// event is (re)registered, the socket is added to the 'update queue', but
+        /// the actual syscall to start the IOCTL_AFD_POLL operation is deferred
+        /// until just before the GetQueuedCompletionStatusEx() syscall is made.
+        ///
+        /// However, when another thread is already blocked on
+        /// GetQueuedCompletionStatusEx() we tell the kernel about the registered
+        /// socket event(s) immediately.
+        unsafe fn update_sockets_events_if_polling(&self) -> io::Result<()> {
+            if self.is_polling.load(Ordering::Acquire) {
+                self.update_sockets_events()
+            } else {
+                Ok(())
+            }
+        }
+
+        fn queue_state(&self, sock_state: Pin<Arc<Mutex<SockState>>>) {
+            let mut update_queue = self.update_queue.lock().unwrap();
+            update_queue.push_back(sock_state);
+        }
+
+        fn _alloc_sock_for_rawsocket(
+            &self,
+            raw_socket: RawSocket,
+        ) -> io::Result<Pin<Arc<Mutex<SockState>>>> {
+            let afd = self.afd_group.acquire()?;
+            Ok(Arc::pin(Mutex::new(SockState::new(raw_socket, afd)?)))
+        }
+    }
+
+    fn try_get_base_socket(raw_socket: RawSocket, ioctl: u32) -> Result<RawSocket, i32> {
+        let mut base_socket: RawSocket = 0;
+        let mut bytes: u32 = 0;
+        unsafe {
+            if WSAIoctl(
+                raw_socket as usize,
+                ioctl,
+                null_mut(),
+                0,
+                &mut base_socket as *mut _ as PVOID,
+                size_of::<RawSocket>() as u32,
+                &mut bytes,
+                null_mut(),
+                None,
+            ) != SOCKET_ERROR
+            {
+                Ok(base_socket)
+            } else {
+                Err(WSAGetLastError())
+            }
+        }
+    }
+
+    fn get_base_socket(raw_socket: RawSocket) -> io::Result<RawSocket> {
+        let res = try_get_base_socket(raw_socket, mswsock::SIO_BASE_HANDLE);
+        if let Ok(base_socket) = res {
+            return Ok(base_socket);
+        }
+
+        // The `SIO_BASE_HANDLE` should not be intercepted by LSPs, therefore
+        // it should not fail as long as `raw_socket` is a valid socket. See
+        // https://docs.microsoft.com/en-us/windows/win32/winsock/winsock-ioctls.
+        // However, at least one known LSP deliberately breaks it, so we try
+        // some alternative IOCTLs, starting with the most appropriate one.
+        for &ioctl in &[
+            mswsock::SIO_BSP_HANDLE_SELECT,
+            mswsock::SIO_BSP_HANDLE_POLL,
+            mswsock::SIO_BSP_HANDLE,
+        ] {
+            if let Ok(base_socket) = try_get_base_socket(raw_socket, ioctl) {
+                // Since we know now that we're dealing with an LSP (otherwise
+                // SIO_BASE_HANDLE would't have failed), only return any result
+                // when it is different from the original `raw_socket`.
+                if base_socket != raw_socket {
+                    return Ok(base_socket);
+                }
+            }
+        }
+
+        // If the alternative IOCTLs also failed, return the original error.
+        let os_error = res.unwrap_err();
+        let err = io::Error::from_raw_os_error(os_error);
+        Err(err)
+    }
+}
+
+impl Drop for SelectorInner {
+    fn drop(&mut self) {
+        loop {
+            let events_num: usize;
+            let mut statuses: [CompletionStatus; 1024] = [CompletionStatus::zero(); 1024];
+
+            let result = self
+                .cp
+                .get_many(&mut statuses, Some(std::time::Duration::from_millis(0)));
+            match result {
+                Ok(iocp_events) => {
+                    events_num = iocp_events.iter().len();
+                    for iocp_event in iocp_events.iter() {
+                        if iocp_event.overlapped().is_null() {
+                            // Custom event
+                        } else if iocp_event.token() % 2 == 1 {
+                            // Named pipe, dispatch the event so it can release resources
+                            let callback = unsafe {
+                                (*(iocp_event.overlapped() as *mut super::Overlapped)).callback
+                            };
+
+                            callback(iocp_event.entry(), None);
+                        } else {
+                            // drain sock state to release memory of Arc reference
+                            let _sock_state = from_overlapped(iocp_event.overlapped());
+                        }
+                    }
+                }
+
+                Err(_) => {
+                    break;
+                }
+            }
+
+            if events_num == 0 {
+                // continue looping until all completion statuses have been drained
+                break;
+            }
+        }
+
+        self.afd_group.release_unused_afd();
+    }
+}
+
+cfg_net! {
+    fn interests_to_afd_flags(interests: Interest) -> u32 {
+        let mut flags = 0;
+
+        if interests.is_readable() {
+            flags |= READABLE_FLAGS | READ_CLOSED_FLAGS | ERROR_FLAGS;
+        }
+
+        if interests.is_writable() {
+            flags |= WRITABLE_FLAGS | WRITE_CLOSED_FLAGS | ERROR_FLAGS;
+        }
+
+        flags
+    }
+}
diff --git a/third_party/rust/mio/src/sys/windows/tcp.rs b/third_party/rust/mio/src/sys/windows/tcp.rs
new file mode 100644
index 0000000000..b3f05aec65
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/tcp.rs
@@ -0,0 +1,71 @@
+use std::io;
+use std::net::{self, SocketAddr};
+use std::os::windows::io::AsRawSocket;
+
+use winapi::um::winsock2::{self, PF_INET, PF_INET6, SOCKET, SOCKET_ERROR, SOCK_STREAM};
+
+use crate::sys::windows::net::{init, new_socket, socket_addr};
+
+pub(crate) fn new_for_addr(address: SocketAddr) -> io::Result<SOCKET> {
+    init();
+    let domain = match address {
+        SocketAddr::V4(_) => PF_INET,
+        SocketAddr::V6(_) => PF_INET6,
+    };
+    new_socket(domain, SOCK_STREAM)
+}
+
+pub(crate) fn bind(socket: &net::TcpListener, addr: SocketAddr) -> io::Result<()> {
+    use winsock2::bind;
+
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+    syscall!(
+        bind(
+            socket.as_raw_socket() as _,
+            raw_addr.as_ptr(),
+            raw_addr_length
+        ),
+        PartialEq::eq,
+        SOCKET_ERROR
+    )?;
+    Ok(())
+}
+
+pub(crate) fn connect(socket: &net::TcpStream, addr: SocketAddr) -> io::Result<()> {
+    use winsock2::connect;
+
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+    let res = syscall!(
+        connect(
+            socket.as_raw_socket() as _,
+            raw_addr.as_ptr(),
+            raw_addr_length
+        ),
+        PartialEq::eq,
+        SOCKET_ERROR
+    );
+
+    match res {
+        Err(err) if err.kind() != io::ErrorKind::WouldBlock => Err(err),
+        _ => Ok(()),
+    }
+}
+
+pub(crate) fn listen(socket: &net::TcpListener, backlog: u32) -> io::Result<()> {
+    use std::convert::TryInto;
+    use winsock2::listen;
+
+    let backlog = backlog.try_into().unwrap_or(i32::max_value());
+    syscall!(
+        listen(socket.as_raw_socket() as _, backlog),
+        PartialEq::eq,
+        SOCKET_ERROR
+    )?;
+    Ok(())
+}
+
+pub(crate) fn accept(listener: &net::TcpListener) -> io::Result<(net::TcpStream, SocketAddr)> {
+    // The non-blocking state of `listener` is inherited. See
+    // https://docs.microsoft.com/en-us/windows/win32/api/winsock2/nf-winsock2-accept#remarks.
+    listener.accept()
+}
diff --git a/third_party/rust/mio/src/sys/windows/udp.rs b/third_party/rust/mio/src/sys/windows/udp.rs
new file mode 100644
index 0000000000..825ecccff4
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/udp.rs
@@ -0,0 +1,53 @@
+use std::io;
+use std::mem::{self, MaybeUninit};
+use std::net::{self, SocketAddr};
+use std::os::windows::io::{AsRawSocket, FromRawSocket};
+use std::os::windows::raw::SOCKET as StdSocket; // winapi uses usize, stdlib uses u32/u64.
+
+use winapi::ctypes::c_int;
+use winapi::shared::ws2def::IPPROTO_IPV6;
+use winapi::shared::ws2ipdef::IPV6_V6ONLY;
+use winapi::um::winsock2::{bind as win_bind, closesocket, getsockopt, SOCKET_ERROR, SOCK_DGRAM};
+
+use crate::sys::windows::net::{init, new_ip_socket, socket_addr};
+
+pub fn bind(addr: SocketAddr) -> io::Result<net::UdpSocket> {
+    init();
+    new_ip_socket(addr, SOCK_DGRAM).and_then(|socket| {
+        let (raw_addr, raw_addr_length) = socket_addr(&addr);
+        syscall!(
+            win_bind(socket, raw_addr.as_ptr(), raw_addr_length,),
+            PartialEq::eq,
+            SOCKET_ERROR
+        )
+        .map_err(|err| {
+            // Close the socket if we hit an error, ignoring the error
+            // from closing since we can't pass back two errors.
+            let _ = unsafe { closesocket(socket) };
+            err
+        })
+        .map(|_| unsafe { net::UdpSocket::from_raw_socket(socket as StdSocket) })
+    })
+}
+
+pub(crate) fn only_v6(socket: &net::UdpSocket) -> io::Result<bool> {
+    let mut optval: MaybeUninit<c_int> = MaybeUninit::uninit();
+    let mut optlen = mem::size_of::<c_int>() as c_int;
+
+    syscall!(
+        getsockopt(
+            socket.as_raw_socket() as usize,
+            IPPROTO_IPV6 as c_int,
+            IPV6_V6ONLY as c_int,
+            optval.as_mut_ptr().cast(),
+            &mut optlen,
+        ),
+        PartialEq::eq,
+        SOCKET_ERROR
+    )?;
+
+    debug_assert_eq!(optlen as usize, mem::size_of::<c_int>());
+    // Safety: `getsockopt` initialised `optval` for us.
+    let optval = unsafe { optval.assume_init() };
+    Ok(optval != 0)
+}
diff --git a/third_party/rust/mio/src/sys/windows/waker.rs b/third_party/rust/mio/src/sys/windows/waker.rs
new file mode 100644
index 0000000000..ab12c3c689
--- /dev/null
+++ b/third_party/rust/mio/src/sys/windows/waker.rs
@@ -0,0 +1,29 @@
+use crate::sys::windows::Event;
+use crate::sys::windows::Selector;
+use crate::Token;
+
+use miow::iocp::CompletionPort;
+use std::io;
+use std::sync::Arc;
+
+#[derive(Debug)]
+pub struct Waker {
+    token: Token,
+    port: Arc<CompletionPort>,
+}
+
+impl Waker {
+    pub fn new(selector: &Selector, token: Token) -> io::Result<Waker> {
+        Ok(Waker {
+            token,
+            port: selector.clone_port(),
+        })
+    }
+
+    pub fn wake(&self) -> io::Result<()> {
+        let mut ev = Event::new(self.token);
+        ev.set_readable();
+
+        self.port.post(ev.to_completion_status())
+    }
+}
diff --git a/third_party/rust/mio/src/token.rs b/third_party/rust/mio/src/token.rs
new file mode 100644
index 0000000000..91601cde0c
--- /dev/null
+++ b/third_party/rust/mio/src/token.rs
@@ -0,0 +1,138 @@
+/// Associates readiness events with [`event::Source`]s.
+///
+/// `Token` is a wrapper around `usize` and is used as an argument to
+/// [`Registry::register`] and [`Registry::reregister`].
+///
+/// See [`Poll`] for more documentation on polling.
+///
+/// [`event::Source`]: ./event/trait.Source.html
+/// [`Poll`]: struct.Poll.html
+/// [`Registry::register`]: struct.Registry.html#method.register
+/// [`Registry::reregister`]: struct.Registry.html#method.reregister
+///
+/// # Example
+///
+/// Using `Token` to track which socket generated the event. In this example,
+/// `HashMap` is used, but usually something like [`slab`] is better.
+///
+/// [`slab`]: https://crates.io/crates/slab
+///
+#[cfg_attr(all(feature = "os-poll", feature = "net"), doc = "```")]
+#[cfg_attr(not(all(feature = "os-poll", feature = "net")), doc = "```ignore")]
+/// # use std::error::Error;
+/// # fn main() -> Result<(), Box<dyn Error>> {
+/// use mio::{Events, Interest, Poll, Token};
+/// use mio::net::TcpListener;
+///
+/// use std::thread;
+/// use std::io::{self, Read};
+/// use std::collections::HashMap;
+///
+/// // After this number of sockets is accepted, the server will shutdown.
+/// const MAX_SOCKETS: usize = 32;
+///
+/// // Pick a token that will not be used by any other socket and use that one
+/// // for the listener.
+/// const LISTENER: Token = Token(1024);
+///
+/// // Used to store the sockets.
+/// let mut sockets = HashMap::new();
+///
+/// // This is used to generate a unique token for a socket
+/// let mut next_socket_index = 0;
+///
+/// // The `Poll` instance
+/// let mut poll = Poll::new()?;
+///
+/// // Tcp listener
+/// let mut listener = TcpListener::bind("127.0.0.1:0".parse()?)?;
+///
+/// // Register the listener
+/// poll.registry().register(&mut listener, LISTENER, Interest::READABLE)?;
+///
+/// // Spawn a thread that will connect a bunch of sockets then close them
+/// let addr = listener.local_addr()?;
+/// thread::spawn(move || {
+///     use std::net::TcpStream;
+///
+///     // +1 here is to connect an extra socket to signal the socket to close
+///     for _ in 0..(MAX_SOCKETS+1) {
+///         // Connect then drop the socket
+///         let _ = TcpStream::connect(addr).unwrap();
+///     }
+/// });
+///
+/// // Event storage
+/// let mut events = Events::with_capacity(1024);
+///
+/// // Read buffer, this will never actually get filled
+/// let mut buf = [0; 256];
+///
+/// // The main event loop
+/// loop {
+///     // Wait for events
+///     poll.poll(&mut events, None)?;
+///
+///     for event in &events {
+///         match event.token() {
+///             LISTENER => {
+///                 // Perform operations in a loop until `WouldBlock` is
+///                 // encountered.
+///                 loop {
+///                     match listener.accept() {
+///                         Ok((mut socket, _)) => {
+///                             // Shutdown the server
+///                             if next_socket_index == MAX_SOCKETS {
+///                                 return Ok(());
+///                             }
+///
+///                             // Get the token for the socket
+///                             let token = Token(next_socket_index);
+///                             next_socket_index += 1;
+///
+///                             // Register the new socket w/ poll
+///                             poll.registry().register(&mut socket, token, Interest::READABLE)?;
+///
+///                             // Store the socket
+///                             sockets.insert(token, socket);
+///                         }
+///                         Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+///                             // Socket is not ready anymore, stop accepting
+///                             break;
+///                         }
+///                         e => panic!("err={:?}", e), // Unexpected error
+///                     }
+///                 }
+///             }
+///             token => {
+///                 // Always operate in a loop
+///                 loop {
+///                     match sockets.get_mut(&token).unwrap().read(&mut buf) {
+///                         Ok(0) => {
+///                             // Socket is closed, remove it from the map
+///                             sockets.remove(&token);
+///                             break;
+///                         }
+///                         // Data is not actually sent in this example
+///                         Ok(_) => unreachable!(),
+///                         Err(ref e) if e.kind() == io::ErrorKind::WouldBlock => {
+///                             // Socket is not ready anymore, stop reading
+///                             break;
+///                         }
+///                         e => panic!("err={:?}", e), // Unexpected error
+///                     }
+///                 }
+///             }
+///         }
+///     }
+/// }
+/// # }
+/// ```
+#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Token(pub usize);
+
+impl From<Token> for usize {
+    fn from(val: Token) -> usize {
+        val.0
+    }
+}
diff --git a/third_party/rust/mio/src/waker.rs b/third_party/rust/mio/src/waker.rs
new file mode 100644
index 0000000000..b0cfe36b65
--- /dev/null
+++ b/third_party/rust/mio/src/waker.rs
@@ -0,0 +1,96 @@
+use crate::{sys, Registry, Token};
+
+use std::io;
+
+/// Waker allows cross-thread waking of [`Poll`].
+///
+/// When created it will cause events with [`readable`] readiness and the
+/// provided `token` if [`wake`] is called, possibly from another thread.
+///
+/// [`Poll`]: struct.Poll.html
+/// [`readable`]: ./event/struct.Event.html#method.is_readable
+/// [`wake`]: struct.Waker.html#method.wake
+///
+/// # Notes
+///
+/// `Waker` events are only guaranteed to be delivered while the `Waker` value
+/// is alive.
+///
+/// Only a single `Waker` can be active per [`Poll`], if multiple threads need
+/// access to the `Waker` it can be shared via for example an `Arc`. What
+/// happens if multiple `Waker`s are registered with the same `Poll` is
+/// unspecified.
+///
+/// # Implementation notes
+///
+/// On platforms that support kqueue this will use the `EVFILT_USER` event
+/// filter, see [implementation notes of `Poll`] to see what platforms support
+/// kqueue. On Linux it uses [eventfd].
+///
+/// [implementation notes of `Poll`]: struct.Poll.html#implementation-notes
+/// [eventfd]: http://man7.org/linux/man-pages/man2/eventfd.2.html
+///
+/// # Examples
+///
+/// Wake a [`Poll`] instance from another thread.
+///
+#[cfg_attr(feature = "os-poll", doc = "```")]
+#[cfg_attr(not(feature = "os-poll"), doc = "```ignore")]
+/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
+/// use std::thread;
+/// use std::time::Duration;
+/// use std::sync::Arc;
+///
+/// use mio::{Events, Token, Poll, Waker};
+///
+/// const WAKE_TOKEN: Token = Token(10);
+///
+/// let mut poll = Poll::new()?;
+/// let mut events = Events::with_capacity(2);
+///
+/// let waker = Arc::new(Waker::new(poll.registry(), WAKE_TOKEN)?);
+///
+/// // We need to keep the Waker alive, so we'll create a clone for the
+/// // thread we create below.
+/// let waker1 = waker.clone();
+/// let handle = thread::spawn(move || {
+///     // Working hard, or hardly working?
+///     thread::sleep(Duration::from_millis(500));
+///
+///     // Now we'll wake the queue on the other thread.
+///     waker1.wake().expect("unable to wake");
+/// });
+///
+/// // On our current thread we'll poll for events, without a timeout.
+/// poll.poll(&mut events, None)?;
+///
+/// // After about 500 milliseconds we should be awoken by the other thread and
+/// // get a single event.
+/// assert!(!events.is_empty());
+/// let waker_event = events.iter().next().unwrap();
+/// assert!(waker_event.is_readable());
+/// assert_eq!(waker_event.token(), WAKE_TOKEN);
+/// # handle.join().unwrap();
+/// #     Ok(())
+/// # }
+/// ```
+#[derive(Debug)]
+pub struct Waker {
+    inner: sys::Waker,
+}
+
+impl Waker {
+    /// Create a new `Waker`.
+    pub fn new(registry: &Registry, token: Token) -> io::Result<Waker> {
+        #[cfg(debug_assertions)]
+        registry.register_waker();
+        sys::Waker::new(registry.selector(), token).map(|inner| Waker { inner })
+    }
+
+    /// Wake up the [`Poll`] associated with this `Waker`.
+    ///
+    /// [`Poll`]: struct.Poll.html
+    pub fn wake(&self) -> io::Result<()> {
+        self.inner.wake()
+    }
+}