Import mio-0.7.3

Test: None
Change-Id: I7df903972aaf06adb1ecb20a63793fcf128edb8f

32 files changed, 4676 insertions, 0 deletions

diff --git a/src/sys/mod.rs b/src/sys/mod.rs
new file mode 100644
index 0000000..8852333
--- /dev/null
+++ b/src/sys/mod.rs
@@ -0,0 +1,100 @@
+//! 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::SourceFd;
+
+    pub(crate) use self::unix::{event, Event, Events, Selector, Waker};
+
+    cfg_tcp! {
+        pub(crate) use self::unix::tcp;
+    }
+
+    cfg_udp! {
+        pub(crate) use self::unix::udp;
+    }
+
+    cfg_uds! {
+        pub use self::unix::SocketAddr;
+
+        pub(crate) use self::unix::uds;
+    }
+
+    cfg_net! {
+        pub(crate) use self::unix::IoSourceState;
+    }
+}
+
+#[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_util! {
+        mod unix;
+        pub use self::unix::SourceFd;
+    }
+
+    #[cfg(unix)]
+    cfg_uds! {
+        pub use self::unix::SocketAddr;
+    }
+}
diff --git a/src/sys/shell/mod.rs b/src/sys/shell/mod.rs
new file mode 100644
index 0000000..8303797
--- /dev/null
+++ b/src/sys/shell/mod.rs
@@ -0,0 +1,76 @@
+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_tcp! {
+    pub(crate) mod tcp;
+}
+
+cfg_udp! {
+    pub(crate) mod udp;
+}
+
+#[cfg(unix)]
+cfg_uds! {
+    pub(crate) mod uds;
+}
+
+cfg_net! {
+    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/src/sys/shell/selector.rs b/src/sys/shell/selector.rs
new file mode 100644
index 0000000..0e0c031
--- /dev/null
+++ b/src/sys/shell/selector.rs
@@ -0,0 +1,103 @@
+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(unix)]
+cfg_any_os_util! {
+    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_net! {
+    #[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/src/sys/shell/tcp.rs b/src/sys/shell/tcp.rs
new file mode 100644
index 0000000..963fccb
--- /dev/null
+++ b/src/sys/shell/tcp.rs
@@ -0,0 +1,36 @@
+use std::io;
+use std::net::{self, SocketAddr};
+
+pub(crate) type TcpSocket = i32;
+
+pub(crate) fn new_v4_socket() -> io::Result<TcpSocket> {
+    os_required!();
+}
+
+pub(crate) fn new_v6_socket() -> io::Result<TcpSocket> {
+    os_required!();
+}
+
+pub(crate) fn bind(_socket: TcpSocket, _addr: SocketAddr) -> io::Result<()> {
+    os_required!();
+}
+
+pub(crate) fn connect(_: TcpSocket, _addr: SocketAddr) -> io::Result<net::TcpStream> {
+    os_required!();
+}
+
+pub(crate) fn listen(_: TcpSocket, _: u32) -> io::Result<net::TcpListener> {
+    os_required!();
+}
+
+pub(crate) fn close(_: TcpSocket) {
+    os_required!();
+}
+
+pub(crate) fn set_reuseaddr(_: TcpSocket, _: bool) -> io::Result<()> {
+    os_required!();
+}
+
+pub fn accept(_: &net::TcpListener) -> io::Result<(net::TcpStream, SocketAddr)> {
+    os_required!();
+}
diff --git a/src/sys/shell/udp.rs b/src/sys/shell/udp.rs
new file mode 100644
index 0000000..3ff1625
--- /dev/null
+++ b/src/sys/shell/udp.rs
@@ -0,0 +1,6 @@
+use std::io;
+use std::net::{self, SocketAddr};
+
+pub fn bind(_: SocketAddr) -> io::Result<net::UdpSocket> {
+    os_required!()
+}
diff --git a/src/sys/shell/uds.rs b/src/sys/shell/uds.rs
new file mode 100644
index 0000000..c18aca0
--- /dev/null
+++ b/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/src/sys/shell/waker.rs b/src/sys/shell/waker.rs
new file mode 100644
index 0000000..bbdd7c3
--- /dev/null
+++ b/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/src/sys/unix/mod.rs b/src/sys/unix/mod.rs
new file mode 100644
index 0000000..96d7f4d
--- /dev/null
+++ b/src/sys/unix/mod.rs
@@ -0,0 +1,74 @@
+/// 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 net;
+
+    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_tcp! {
+        pub(crate) mod tcp;
+    }
+
+    cfg_udp! {
+        pub(crate) mod udp;
+    }
+
+    cfg_uds! {
+        pub(crate) mod uds;
+        pub use self::uds::SocketAddr;
+    }
+
+    cfg_net! {
+        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_not_os_poll! {
+    cfg_uds! {
+        mod uds;
+        pub use self::uds::SocketAddr;
+    }
+
+    cfg_any_os_util! {
+        mod sourcefd;
+        pub use self::sourcefd::SourceFd;
+    }
+}
diff --git a/src/sys/unix/net.rs b/src/sys/unix/net.rs
new file mode 100644
index 0000000..2671b42
--- /dev/null
+++ b/src/sys/unix/net.rs
@@ -0,0 +1,103 @@
+#[cfg(all(feature = "os-poll", any(feature = "tcp", feature = "udp")))]
+use std::net::SocketAddr;
+
+#[cfg(all(feature = "os-poll", any(feature = "udp")))]
+pub(crate) fn new_ip_socket(
+    addr: SocketAddr,
+    socket_type: libc::c_int,
+) -> std::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.
+#[cfg(all(
+    feature = "os-poll",
+    any(feature = "tcp", feature = "udp", feature = "uds")
+))]
+pub(crate) fn new_socket(
+    domain: libc::c_int,
+    socket_type: libc::c_int,
+) -> std::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,
+            std::mem::size_of::<libc::c_int>() as libc::socklen_t
+        ))
+        .map(|_| socket)
+    });
+
+    // Darwin doesn't have SOCK_NONBLOCK or SOCK_CLOEXEC. Not sure about
+    // Solaris, couldn't find anything online.
+    #[cfg(any(target_os = "ios", target_os = "macos", target_os = "solaris"))]
+    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
+}
+
+#[cfg(all(feature = "os-poll", any(feature = "tcp", feature = "udp")))]
+pub(crate) fn socket_addr(addr: &SocketAddr) -> (*const libc::sockaddr, libc::socklen_t) {
+    use std::mem::size_of_val;
+
+    match addr {
+        SocketAddr::V4(ref addr) => (
+            addr as *const _ as *const libc::sockaddr,
+            size_of_val(addr) as libc::socklen_t,
+        ),
+        SocketAddr::V6(ref addr) => (
+            addr as *const _ as *const libc::sockaddr,
+            size_of_val(addr) as libc::socklen_t,
+        ),
+    }
+}
+
+/// `storage` must be initialised to `sockaddr_in` or `sockaddr_in6`.
+#[cfg(all(feature = "os-poll", feature = "tcp"))]
+pub(crate) unsafe fn to_socket_addr(
+    storage: *const libc::sockaddr_storage,
+) -> std::io::Result<SocketAddr> {
+    match (*storage).ss_family as libc::c_int {
+        libc::AF_INET => Ok(SocketAddr::V4(
+            *(storage as *const libc::sockaddr_in as *const _),
+        )),
+        libc::AF_INET6 => Ok(SocketAddr::V6(
+            *(storage as *const libc::sockaddr_in6 as *const _),
+        )),
+        _ => Err(std::io::ErrorKind::InvalidInput.into()),
+    }
+}
diff --git a/src/sys/unix/selector/epoll.rs b/src/sys/unix/selector/epoll.rs
new file mode 100644
index 0000000..13f1617
--- /dev/null
+++ b/src/sys/unix/selector/epoll.rs
@@ -0,0 +1,235 @@
+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::{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,
+}
+
+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,
+        })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        syscall!(dup(self.ep)).map(|ep| Selector {
+            // It's the same selector, so we use the same id.
+            #[cfg(debug_assertions)]
+            id: self.id,
+            ep,
+        })
+    }
+
+    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_net! {
+    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(any(target_os = "linux", target_os = "solaris"))]
+            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/src/sys/unix/selector/kqueue.rs b/src/sys/unix/selector/kqueue.rs
new file mode 100644
index 0000000..2ebac9a
--- /dev/null
+++ b/src/sys/unix/selector/kqueue.rs
@@ -0,0 +1,676 @@
+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::{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 = "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 = "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,
+}
+
+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,
+            })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        syscall!(dup(self.kq)).map(|kq| Selector {
+            // It's the same selector, so we use the same id.
+            #[cfg(debug_assertions)]
+            id: self.id,
+            kq,
+        })
+    }
+
+    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])
+    }
+
+    // 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_net! {
+    #[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 = "dragonfly"))]
+            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]
+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/src/sys/unix/selector/mod.rs b/src/sys/unix/selector/mod.rs
new file mode 100644
index 0000000..7525898
--- /dev/null
+++ b/src/sys/unix/selector/mod.rs
@@ -0,0 +1,35 @@
+#[cfg(any(
+    target_os = "android",
+    target_os = "illumos",
+    target_os = "linux",
+    target_os = "solaris"
+))]
+mod epoll;
+
+#[cfg(any(
+    target_os = "android",
+    target_os = "illumos",
+    target_os = "linux",
+    target_os = "solaris"
+))]
+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};
diff --git a/src/sys/unix/sourcefd.rs b/src/sys/unix/sourcefd.rs
new file mode 100644
index 0000000..68511d7
--- /dev/null
+++ b/src/sys/unix/sourcefd.rs
@@ -0,0 +1,108 @@
+use crate::{event, poll, 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.
+///
+/// ```
+/// # 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`].
+///
+/// ```
+/// 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<()> {
+        poll::selector(registry).register(*self.0, token, interests)
+    }
+
+    fn reregister(
+        &mut self,
+        registry: &Registry,
+        token: Token,
+        interests: Interest,
+    ) -> io::Result<()> {
+        poll::selector(registry).reregister(*self.0, token, interests)
+    }
+
+    fn deregister(&mut self, registry: &Registry) -> io::Result<()> {
+        poll::selector(registry).deregister(*self.0)
+    }
+}
diff --git a/src/sys/unix/tcp.rs b/src/sys/unix/tcp.rs
new file mode 100644
index 0000000..9d59632
--- /dev/null
+++ b/src/sys/unix/tcp.rs
@@ -0,0 +1,103 @@
+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 type TcpSocket = libc::c_int;
+
+pub(crate) fn new_v4_socket() -> io::Result<TcpSocket> {
+    new_socket(libc::AF_INET, libc::SOCK_STREAM)
+}
+
+pub(crate) fn new_v6_socket() -> io::Result<TcpSocket> {
+    new_socket(libc::AF_INET6, libc::SOCK_STREAM)
+}
+
+pub(crate) fn bind(socket: TcpSocket, addr: SocketAddr) -> io::Result<()> {
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+    syscall!(bind(socket, raw_addr, raw_addr_length))?;
+    Ok(())
+}
+
+pub(crate) fn connect(socket: TcpSocket, addr: SocketAddr) -> io::Result<net::TcpStream> {
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+
+    match syscall!(connect(socket, raw_addr, raw_addr_length)) {
+        Err(err) if err.raw_os_error() != Some(libc::EINPROGRESS) => {
+            Err(err)
+        }
+        _ => {
+            Ok(unsafe { net::TcpStream::from_raw_fd(socket) })
+        }
+    }
+}
+
+pub(crate) fn listen(socket: TcpSocket, backlog: u32) -> io::Result<net::TcpListener> {
+    use std::convert::TryInto;
+
+    let backlog = backlog.try_into().unwrap_or(i32::max_value());
+    syscall!(listen(socket, backlog))?;
+    Ok(unsafe { net::TcpListener::from_raw_fd(socket) })
+}
+
+pub(crate) fn close(socket: TcpSocket) {
+    let _ = unsafe { net::TcpStream::from_raw_fd(socket) };
+}
+
+pub(crate) fn set_reuseaddr(socket: TcpSocket, reuseaddr: bool) -> io::Result<()> {
+    let val: libc::c_int = if reuseaddr { 1 } else { 0 };
+    syscall!(setsockopt(
+        socket,
+        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 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(
+        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(target_os = "ios", target_os = "macos", target_os = "solaris"))]
+    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)).map(|_| 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/src/sys/unix/udp.rs b/src/sys/unix/udp.rs
new file mode 100644
index 0000000..947a60a
--- /dev/null
+++ b/src/sys/unix/udp.rs
@@ -0,0 +1,23 @@
+use crate::sys::unix::net::{new_ip_socket, socket_addr};
+
+use std::io;
+use std::net::{self, SocketAddr};
+use std::os::unix::io::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, 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) })
+    })
+}
diff --git a/src/sys/unix/uds/datagram.rs b/src/sys/unix/uds/datagram.rs
new file mode 100644
index 0000000..d3e5314
--- /dev/null
+++ b/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/src/sys/unix/uds/listener.rs b/src/sys/unix/uds/listener.rs
new file mode 100644
index 0000000..b8fb5a9
--- /dev/null
+++ b/src/sys/unix/uds/listener.rs
@@ -0,0 +1,83 @@
+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",
+        target_os = "solaris"
+    )))]
+    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",
+        target_os = "solaris"
+    ))]
+    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)).map(|_| 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/src/sys/unix/uds/mod.rs b/src/sys/unix/uds/mod.rs
new file mode 100644
index 0000000..3ec829f
--- /dev/null
+++ b/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", target_os = "solaris")))]
+        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 and Solaris do not 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", target_os = "solaris"))]
+        {
+            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/src/sys/unix/uds/socketaddr.rs b/src/sys/unix/uds/socketaddr.rs
new file mode 100644
index 0000000..69f311a
--- /dev/null
+++ b/src/sys/unix/uds/socketaddr.rs
@@ -0,0 +1,120 @@
+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);
+        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 {
+            if let AddressKind::Unnamed = self.address() {
+                true
+            } else {
+                false
+            }
+        }
+
+        /// 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
+            }
+        }
+    }
+}
+
+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 AsciiEscaped =====
+
+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/src/sys/unix/uds/stream.rs b/src/sys/unix/uds/stream.rs
new file mode 100644
index 0000000..149dd14
--- /dev/null
+++ b/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/src/sys/unix/waker.rs b/src/sys/unix/waker.rs
new file mode 100644
index 0000000..1305bd6
--- /dev/null
+++ b/src/sys/unix/waker.rs
@@ -0,0 +1,174 @@
+#[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",
+    target_os = "solaris"
+))]
+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<()> {
+            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",
+    target_os = "solaris"
+))]
+pub use self::pipe::Waker;
diff --git a/src/sys/windows/afd.rs b/src/sys/windows/afd.rs
new file mode 100644
index 0000000..82c8e9e
--- /dev/null
+++ b/src/sys/windows/afd.rs
@@ -0,0 +1,236 @@
+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_net! {
+    use miow::iocp::CompletionPort;
+    use ntapi::ntioapi::FILE_OPEN;
+    use ntapi::ntioapi::NtCreateFile;
+    use std::mem::zeroed;
+    use std::os::windows::io::{FromRawHandle, RawHandle};
+    use std::sync::atomic::{AtomicUsize, Ordering};
+    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;
+    use winapi::um::winnt::{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 as ULONG,
+                    FILE_SHARE_READ | FILE_SHARE_WRITE,
+                    FILE_OPEN,
+                    0 as ULONG,
+                    null_mut(),
+                    0 as ULONG,
+                );
+                if status != STATUS_SUCCESS {
+                    return Err(io::Error::from_raw_os_error(
+                        RtlNtStatusToDosError(status) as i32
+                    ));
+                }
+                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 = 0b000_000_001;
+pub const POLL_RECEIVE_EXPEDITED: u32 = 0b000_000_010;
+pub const POLL_SEND: u32 = 0b000_000_100;
+pub const POLL_DISCONNECT: u32 = 0b000_001_000;
+pub const POLL_ABORT: u32 = 0b000_010_000;
+pub const POLL_LOCAL_CLOSE: u32 = 0b000_100_000;
+// 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 = 0b001_000_000;
+pub const POLL_ACCEPT: u32 = 0b010_000_000;
+pub const POLL_CONNECT_FAIL: u32 = 0b100_000_000;
+
+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/src/sys/windows/event.rs b/src/sys/windows/event.rs
new file mode 100644
index 0000000..235074a
--- /dev/null
+++ b/src/sys/windows/event.rs
@@ -0,0 +1,161 @@
+use std::fmt;
+
+use miow::iocp::CompletionStatus;
+
+use super::afd;
+use crate::Token;
+
+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-util")]
+    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/src/sys/windows/io_status_block.rs b/src/sys/windows/io_status_block.rs
new file mode 100644
index 0000000..db6729c
--- /dev/null
+++ b/src/sys/windows/io_status_block.rs
@@ -0,0 +1,39 @@
+use ntapi::ntioapi::IO_STATUS_BLOCK;
+use std::fmt;
+use std::ops::{Deref, DerefMut};
+
+pub struct IoStatusBlock(IO_STATUS_BLOCK);
+
+cfg_net! {
+    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/src/sys/windows/mod.rs b/src/sys/windows/mod.rs
new file mode 100644
index 0000000..7bba6dd
--- /dev/null
+++ b/src/sys/windows/mod.rs
@@ -0,0 +1,149 @@
+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)
+            }
+        }};
+    }
+}
+
+cfg_tcp! {
+    pub(crate) mod tcp;
+}
+
+cfg_udp! {
+    pub(crate) mod udp;
+}
+
+#[cfg(feature = "os-util")]
+pub(crate) mod named_pipe;
+
+mod waker;
+pub(crate) use waker::Waker;
+
+cfg_net! {
+    use std::io;
+    use std::os::windows::io::RawSocket;
+    use std::pin::Pin;
+    use std::sync::{Arc, Mutex};
+
+    use crate::{poll, Interest, Registry, Token};
+
+    mod net;
+
+    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 {
+                poll::selector(registry)
+                    .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) => {
+                    poll::selector(registry)
+                        .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/src/sys/windows/named_pipe.rs b/src/sys/windows/named_pipe.rs
new file mode 100644
index 0000000..a5688ce
--- /dev/null
+++ b/src/sys/windows/named_pipe.rs
@@ -0,0 +1,709 @@
+use crate::{poll, Registry};
+use crate::event::Source;
+use crate::sys::windows::{Event, Overlapped};
+use winapi::um::minwinbase::OVERLAPPED_ENTRY;
+
+use std::ffi::OsStr;
+use std::fmt;
+use std::io::{self, Read, Write};
+use std::mem;
+use std::os::windows::io::{AsRawHandle, FromRawHandle, IntoRawHandle, RawHandle};
+use std::slice;
+use std::sync::atomic::{AtomicUsize, AtomicBool};
+use std::sync::atomic::Ordering::{Relaxed, SeqCst};
+use std::sync::{Arc, Mutex};
+
+use crate::{Interest, Token};
+use miow::iocp::{CompletionPort, CompletionStatus};
+use miow::pipe;
+use winapi::shared::winerror::{ERROR_BROKEN_PIPE, ERROR_PIPE_LISTENING};
+use winapi::um::ioapiset::CancelIoEx;
+
+/// # Safety
+///
+/// Only valid if the strict is annotated with `#[repr(C)]`. This is only used
+/// with `Overlapped` and `Inner`, which are correctly annotated.
+macro_rules! offset_of {
+    ($t:ty, $($field:ident).+) => (
+        &(*(0 as *const $t)).$($field).+ as *const _ as usize
+    )
+}
+
+macro_rules! overlapped2arc {
+    ($e:expr, $t:ty, $($field:ident).+) => ({
+        let offset = offset_of!($t, $($field).+);
+        debug_assert!(offset < mem::size_of::<$t>());
+        Arc::from_raw(($e as usize - offset) as *mut $t)
+    })
+}
+
+/// 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>,
+}
+
+#[repr(C)]
+struct Inner {
+    handle: pipe::NamedPipe,
+
+    connect: Overlapped,
+    connecting: AtomicBool,
+
+    read: Overlapped,
+    write: Overlapped,
+
+    io: Mutex<Io>,
+
+    pool: Mutex<BufferPool>,
+}
+
+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,
+    read_interest: bool,
+    write: State,
+    write_interest: bool,
+    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,
+                    read_interest: false,
+                    write: State::None,
+                    write_interest: false,
+                    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 => {}
+            _ => {
+                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);
+        Inner::schedule_write(&self.inner, owned_buf, 0, &mut io, None);
+        Ok(buf.len())
+    }
+
+    fn flush(&mut self) -> io::Result<()> {      
+        Ok(())  
+    }
+}
+
+impl Source for NamedPipe {
+    fn register(&mut self, registry: &Registry, token: Token, interest: 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() {
+            io.cp = Some(poll::selector(registry).clone_port());
+
+            let inner_token = NEXT_TOKEN.fetch_add(2, Relaxed) + 2;
+            poll::selector(registry).inner.cp.add_handle(inner_token, &self.inner.handle)?;
+        }
+
+        io.token = Some(token);
+        io.read_interest = interest.is_readable();
+        io.write_interest = interest.is_writable();
+        drop(io);
+
+        Inner::post_register(&self.inner, None);
+
+        Ok(())
+    }
+
+    fn reregister(&mut self, registry: &Registry, token: Token, interest: Interest) -> io::Result<()> { 
+        let mut io = self.inner.io.lock().unwrap();
+
+        io.check_association(registry, true)?;
+
+        io.token = Some(token);
+        io.read_interest = interest.is_readable();
+        io.write_interest = interest.is_writable();
+        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();
+
+            match io.read {
+                State::Pending(..) => {
+                    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
+            }
+        }
+    }
+
+    fn schedule_write(me: &Arc<Inner>, buf: Vec<u8>, pos: usize, io: &mut Io, events: Option<&mut Vec<Event>>) {
+        // 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)
+        };
+
+        match e {
+            // See `connect` above for the rationale behind `forget`
+            Ok(_) => {
+                io.write = State::Pending(buf, pos);
+                mem::forget(me.clone())
+            }
+            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();
+        if Inner::schedule_read(&me, &mut io, events.as_mut().map(|ptr| &mut **ptr)) {
+            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 { overlapped2arc!(status.overlapped(), Inner, connect) };
+
+    // 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 { overlapped2arc!(status.overlapped(), Inner, read) };
+
+    // 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 { overlapped2arc!(status.overlapped(), Inner, write) };
+
+    // 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) {
+        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 !poll::selector(registry).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/src/sys/windows/net.rs b/src/sys/windows/net.rs
new file mode 100644
index 0000000..f825ee3
--- /dev/null
+++ b/src/sys/windows/net.rs
@@ -0,0 +1,58 @@
+use std::io;
+use std::mem::size_of_val;
+use std::net::SocketAddr;
+use std::sync::Once;
+
+use winapi::ctypes::c_int;
+use winapi::shared::ws2def::SOCKADDR;
+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.
+#[cfg(feature = "udp")]
+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)
+    })
+}
+
+pub(crate) fn socket_addr(addr: &SocketAddr) -> (*const SOCKADDR, c_int) {
+    match addr {
+        SocketAddr::V4(ref addr) => (
+            addr as *const _ as *const SOCKADDR,
+            size_of_val(addr) as c_int,
+        ),
+        SocketAddr::V6(ref addr) => (
+            addr as *const _ as *const SOCKADDR,
+            size_of_val(addr) as c_int,
+        ),
+    }
+}
diff --git a/src/sys/windows/overlapped.rs b/src/sys/windows/overlapped.rs
new file mode 100644
index 0000000..3708f9e
--- /dev/null
+++ b/src/sys/windows/overlapped.rs
@@ -0,0 +1,37 @@
+use crate::sys::windows::Event;
+
+use std::cell::UnsafeCell;
+use std::fmt;
+
+use winapi::um::minwinbase::OVERLAPPED_ENTRY;
+#[cfg(feature = "os-util")]
+use winapi::um::minwinbase::OVERLAPPED;
+
+#[repr(C)]
+pub(crate) struct Overlapped {
+    inner: UnsafeCell<miow::Overlapped>,
+    pub(crate) callback: fn(&OVERLAPPED_ENTRY, Option<&mut Vec<Event>>),
+}
+
+#[cfg(feature = "os-util")]
+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/src/sys/windows/selector.rs b/src/sys/windows/selector.rs
new file mode 100644
index 0000000..792a5c5
--- /dev/null
+++ b/src/sys/windows/selector.rs
@@ -0,0 +1,745 @@
+use super::afd::{self, Afd, AfdPollInfo};
+use super::io_status_block::IoStatusBlock;
+use super::Event;
+use crate::sys::event::{
+    ERROR_FLAGS, READABLE_FLAGS, READ_CLOSED_FLAGS, WRITABLE_FLAGS, WRITE_CLOSED_FLAGS,
+};
+use crate::sys::Events;
+use crate::Interest;
+
+use miow::iocp::{CompletionPort, CompletionStatus};
+use std::collections::VecDeque;
+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 std::io;
+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 {
+    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_net! {
+    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 + 1 {
+                    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>,
+
+    raw_socket: RawSocket,
+    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.
+
+        // Reset readable event
+        if (afd_events & interests_to_afd_flags(Interest::READABLE)) != 0 {
+            self.user_evts &= !(interests_to_afd_flags(Interest::READABLE));
+        }
+        // Reset writable event
+        if (afd_events & interests_to_afd_flags(Interest::WRITABLE)) != 0 {
+            self.user_evts &= !interests_to_afd_flags(Interest::WRITABLE);
+        }
+
+        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_net! {
+    impl SockState {
+        fn new(raw_socket: RawSocket, afd: Arc<Afd>) -> io::Result<SockState> {
+            Ok(SockState {
+                iosb: IoStatusBlock::zeroed(),
+                poll_info: AfdPollInfo::zeroed(),
+                afd,
+                raw_socket,
+                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>,
+}
+
+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),
+            }
+        })
+    }
+
+    pub fn try_clone(&self) -> io::Result<Selector> {
+        Ok(Selector {
+            #[cfg(debug_assertions)]
+            id: self.id,
+            inner: Arc::clone(&self.inner),
+        })
+    }
+
+    /// # 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)
+    }
+
+    pub(super) fn clone_port(&self) -> Arc<CompletionPort> {
+        self.inner.cp.clone()
+    }
+
+    #[cfg(feature = "os-util")]
+    pub(super) fn same_port(&self, other: &Arc<CompletionPort>) -> bool {
+        Arc::ptr_eq(&self.inner.cp, other)
+    }
+}
+
+cfg_net! {
+    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;
+                }
+                return Ok(());
+            }
+        } else {
+            self.select2(&mut events.statuses, &mut events.events, timeout)?;
+            return Ok(());
+        }
+    }
+
+    pub fn select2(
+        &self,
+        statuses: &mut [CompletionStatus],
+        events: &mut Vec<Event>,
+        timeout: Option<Duration>,
+    ) -> io::Result<usize> {
+        assert_eq!(self.is_polling.swap(true, Ordering::AcqRel), false);
+
+        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();
+            match sock_guard.feed_event() {
+                Some(e) => {
+                    events.push(e);
+                    n += 1;
+                }
+                None => {}
+            }
+
+            if !sock_guard.is_pending_deletion() {
+                update_queue.push_back(sock_state.clone());
+            }
+        }
+        self.afd_group.release_unused_afd();
+        n
+    }
+}
+
+cfg_net! {
+    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();
+    }
+}
+
+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/src/sys/windows/tcp.rs b/src/sys/windows/tcp.rs
new file mode 100644
index 0000000..c5b0410
--- /dev/null
+++ b/src/sys/windows/tcp.rs
@@ -0,0 +1,96 @@
+use std::io;
+use std::net::{self, SocketAddr};
+use std::os::windows::io::FromRawSocket;
+use std::os::windows::raw::SOCKET as StdSocket; // winapi uses usize, stdlib uses u32/u64.
+
+use winapi::um::winsock2::{
+    self,
+    closesocket, PF_INET, PF_INET6, SOCKET, SOCKET_ERROR, SOCK_STREAM,
+};
+
+use crate::sys::windows::net::{init, new_socket, socket_addr};
+
+pub(crate) type TcpSocket = SOCKET;
+
+pub(crate) fn new_v4_socket() -> io::Result<TcpSocket> {
+    init();
+    new_socket(PF_INET, SOCK_STREAM)
+}
+
+pub(crate) fn new_v6_socket() -> io::Result<TcpSocket> {
+    init();
+    new_socket(PF_INET6, SOCK_STREAM)
+}
+
+pub(crate) fn bind(socket: TcpSocket, addr: SocketAddr) -> io::Result<()> {
+    use winsock2::bind;
+
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+    syscall!(
+        bind(socket, raw_addr, raw_addr_length),
+        PartialEq::eq,
+        SOCKET_ERROR
+    )?;
+    Ok(())
+}
+
+pub(crate) fn connect(socket: TcpSocket, addr: SocketAddr) -> io::Result<net::TcpStream> {
+    use winsock2::connect;
+
+    let (raw_addr, raw_addr_length) = socket_addr(&addr);
+
+    let res = syscall!(
+        connect(socket, raw_addr, raw_addr_length),
+        PartialEq::eq,
+        SOCKET_ERROR
+    );
+
+    match res {
+        Err(err) if err.kind() != io::ErrorKind::WouldBlock => {
+            Err(err)
+        }
+        _ => {
+            Ok(unsafe { net::TcpStream::from_raw_socket(socket as StdSocket) })
+        }
+    }
+}
+
+pub(crate) fn listen(socket: TcpSocket, backlog: u32) -> io::Result<net::TcpListener> {
+    use winsock2::listen;
+    use std::convert::TryInto;
+
+    let backlog = backlog.try_into().unwrap_or(i32::max_value());
+    syscall!(listen(socket, backlog), PartialEq::eq, SOCKET_ERROR)?;
+    Ok(unsafe { net::TcpListener::from_raw_socket(socket as StdSocket) })
+}
+
+pub(crate) fn close(socket: TcpSocket) {
+    let _ = unsafe { closesocket(socket) };
+}
+
+pub(crate) fn set_reuseaddr(socket: TcpSocket, reuseaddr: bool) -> io::Result<()> {
+    use winapi::ctypes::{c_char, c_int};
+    use winapi::shared::minwindef::{BOOL, TRUE, FALSE};
+    use winapi::um::winsock2::{setsockopt, SOCKET_ERROR, SO_REUSEADDR, SOL_SOCKET};
+    use std::mem::size_of;
+
+    let val: BOOL = if reuseaddr { TRUE } else { FALSE };
+
+    match unsafe { setsockopt(
+        socket,
+        SOL_SOCKET,
+        SO_REUSEADDR,
+        &val as *const _ as *const c_char,
+        size_of::<BOOL>() as c_int,
+    ) } {
+        0 => Ok(()),
+        SOCKET_ERROR => Err(io::Error::last_os_error()),
+        _ => panic!("unexpected return value"),
+    }
+}
+
+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/src/sys/windows/udp.rs b/src/sys/windows/udp.rs
new file mode 100644
index 0000000..667c775
--- /dev/null
+++ b/src/sys/windows/udp.rs
@@ -0,0 +1,27 @@
+use std::io;
+use std::net::{self, SocketAddr};
+use std::os::windows::io::FromRawSocket;
+use std::os::windows::raw::SOCKET as StdSocket; // winapi uses usize, stdlib uses u32/u64.
+
+use winapi::um::winsock2::{bind as win_bind, closesocket, 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, 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) })
+    })
+}
diff --git a/src/sys/windows/waker.rs b/src/sys/windows/waker.rs
new file mode 100644
index 0000000..ab12c3c
--- /dev/null
+++ b/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())
+    }
+}