Port from mio to polling

This patch replaces the mio crate with the polling. Now that
smol-rs/polling#96 has been merged, we should be at full feature parity
with mio v0.6 now.

Fixes #7104.
Fixes #6486.

8 files changed, 606 insertions, 340 deletions

diff --git a/alacritty_terminal/Cargo.toml b/alacritty_terminal/Cargo.toml
index dc164413..7498afab 100644
--- a/alacritty_terminal/Cargo.toml
+++ b/alacritty_terminal/Cargo.toml
@@ -23,9 +23,8 @@ bitflags = { version = "2.2.1", features = ["serde"] }
 home = "0.5.5"
 libc = "0.2"
 log = "0.4"
-mio = "0.6.20"
-mio-extras = "2"
 parking_lot = "0.12.0"
+polling = "3.0.0"
 regex-automata = "0.3.6"
 serde = { version = "1", features = ["derive", "rc"] }
 serde_yaml = "0.8"
@@ -36,12 +35,11 @@ vte = { version = "0.12.0", default-features = false, features = ["ansi", "serde
 [target.'cfg(unix)'.dependencies]
 nix = { version = "0.26.2", default-features = false, features = ["term"] }
 signal-hook = "0.3.10"
-signal-hook-mio = { version = "0.2.1", features = ["support-v0_6"] }
 
 [target.'cfg(windows)'.dependencies]
-mio-anonymous-pipes = "0.2"
-miow = "0.3"
-windows-sys = { version = "0.48", features = [
+piper = "0.2.1"
+miow = "0.3.0"
+windows-sys = { version = "0.48.0", features = [
     "Win32_System_Console",
     "Win32_Foundation",
     "Win32_Security",
diff --git a/alacritty_terminal/src/event_loop.rs b/alacritty_terminal/src/event_loop.rs
index 61dc69bc..de22e49d 100644
--- a/alacritty_terminal/src/event_loop.rs
+++ b/alacritty_terminal/src/event_loop.rs
@@ -5,15 +5,14 @@ use std::collections::VecDeque;
 use std::fs::File;
 use std::io::{self, ErrorKind, Read, Write};
 use std::marker::Send;
+use std::num::NonZeroUsize;
+use std::sync::mpsc::{self, Receiver, Sender, TryRecvError};
 use std::sync::Arc;
 use std::thread::JoinHandle;
 use std::time::Instant;
 
 use log::error;
-#[cfg(not(windows))]
-use mio::unix::UnixReady;
-use mio::{self, Events, PollOpt, Ready};
-use mio_extras::channel::{self, Receiver, Sender};
+use polling::{Event as PollingEvent, Events, PollMode};
 
 use crate::event::{self, Event, EventListener, WindowSize};
 use crate::sync::FairMutex;
@@ -21,7 +20,7 @@ use crate::term::Term;
 use crate::{ansi, thread, tty};
 
 /// Max bytes to read from the PTY before forced terminal synchronization.
-const READ_BUFFER_SIZE: usize = 0x10_0000;
+pub(crate) const READ_BUFFER_SIZE: usize = 0x10_0000;
 
 /// Max bytes to read from the PTY while the terminal is locked.
 const MAX_LOCKED_READ: usize = u16::MAX as usize;
@@ -39,14 +38,14 @@ pub enum Msg {
     Resize(WindowSize),
 }
 
-/// The main event!.. loop.
+/// The main event loop.
 ///
 /// Handles all the PTY I/O and runs the PTY parser which updates terminal
 /// state.
 pub struct EventLoop<T: tty::EventedPty, U: EventListener> {
-    poll: mio::Poll,
+    poll: Arc<polling::Poller>,
     pty: T,
-    rx: Receiver<Msg>,
+    rx: PeekableReceiver<Msg>,
     tx: Sender<Msg>,
     terminal: Arc<FairMutex<Term<U>>>,
     event_proxy: U,
@@ -54,97 +53,6 @@ pub struct EventLoop<T: tty::EventedPty, U: EventListener> {
     ref_test: bool,
 }
 
-/// Helper type which tracks how much of a buffer has been written.
-struct Writing {
-    source: Cow<'static, [u8]>,
-    written: usize,
-}
-
-pub struct Notifier(pub Sender<Msg>);
-
-impl event::Notify for Notifier {
-    fn notify<B>(&self, bytes: B)
-    where
-        B: Into<Cow<'static, [u8]>>,
-    {
-        let bytes = bytes.into();
-        // terminal hangs if we send 0 bytes through.
-        if bytes.len() == 0 {
-            return;
-        }
-
-        let _ = self.0.send(Msg::Input(bytes));
-    }
-}
-
-impl event::OnResize for Notifier {
-    fn on_resize(&mut self, window_size: WindowSize) {
-        let _ = self.0.send(Msg::Resize(window_size));
-    }
-}
-
-/// All of the mutable state needed to run the event loop.
-///
-/// Contains list of items to write, current write state, etc. Anything that
-/// would otherwise be mutated on the `EventLoop` goes here.
-#[derive(Default)]
-pub struct State {
-    write_list: VecDeque<Cow<'static, [u8]>>,
-    writing: Option<Writing>,
-    parser: ansi::Processor,
-}
-
-impl State {
-    #[inline]
-    fn ensure_next(&mut self) {
-        if self.writing.is_none() {
-            self.goto_next();
-        }
-    }
-
-    #[inline]
-    fn goto_next(&mut self) {
-        self.writing = self.write_list.pop_front().map(Writing::new);
-    }
-
-    #[inline]
-    fn take_current(&mut self) -> Option<Writing> {
-        self.writing.take()
-    }
-
-    #[inline]
-    fn needs_write(&self) -> bool {
-        self.writing.is_some() || !self.write_list.is_empty()
-    }
-
-    #[inline]
-    fn set_current(&mut self, new: Option<Writing>) {
-        self.writing = new;
-    }
-}
-
-impl Writing {
-    #[inline]
-    fn new(c: Cow<'static, [u8]>) -> Writing {
-        Writing { source: c, written: 0 }
-    }
-
-    #[inline]
-    fn advance(&mut self, n: usize) {
-        self.written += n;
-    }
-
-    #[inline]
-    fn remaining_bytes(&self) -> &[u8] {
-        &self.source[self.written..]
-    }
-
-    #[inline]
-    fn finished(&self) -> bool {
-        self.written >= self.source.len()
-    }
-}
-
 impl<T, U> EventLoop<T, U>
 where
     T: tty::EventedPty + event::OnResize + Send + 'static,
@@ -158,12 +66,12 @@ where
         hold: bool,
         ref_test: bool,
     ) -> EventLoop<T, U> {
-        let (tx, rx) = channel::channel();
+        let (tx, rx) = mpsc::channel();
         EventLoop {
-            poll: mio::Poll::new().expect("create mio Poll"),
+            poll: polling::Poller::new().expect("create Poll").into(),
             pty,
             tx,
-            rx,
+            rx: PeekableReceiver::new(rx),
             terminal,
             event_proxy,
             hold,
@@ -171,15 +79,15 @@ where
         }
     }
 
-    pub fn channel(&self) -> Sender<Msg> {
-        self.tx.clone()
+    pub fn channel(&self) -> EventLoopSender {
+        EventLoopSender { sender: self.tx.clone(), poller: self.poll.clone() }
     }
 
     /// Drain the channel.
     ///
     /// Returns `false` when a shutdown message was received.
     fn drain_recv_channel(&mut self, state: &mut State) -> bool {
-        while let Ok(msg) = self.rx.try_recv() {
+        while let Some(msg) = self.rx.recv() {
             match msg {
                 Msg::Input(input) => state.write_list.push_back(input),
                 Msg::Resize(window_size) => self.pty.on_resize(window_size),
@@ -190,20 +98,6 @@ where
         true
     }
 
-    /// Returns a `bool` indicating whether or not the event loop should continue running.
-    #[inline]
-    fn channel_event(&mut self, token: mio::Token, state: &mut State) -> bool {
-        if !self.drain_recv_channel(state) {
-            return false;
-        }
-
-        self.poll
-            .reregister(&self.rx, token, Ready::readable(), PollOpt::edge() | PollOpt::oneshot())
-            .unwrap();
-
-        true
-    }
-
     #[inline]
     fn pty_read<X>(
         &mut self,
@@ -313,17 +207,15 @@ where
             let mut state = State::default();
             let mut buf = [0u8; READ_BUFFER_SIZE];
 
-            let mut tokens = (0..).map(Into::into);
-
-            let poll_opts = PollOpt::edge() | PollOpt::oneshot();
-
-            let channel_token = tokens.next().unwrap();
-            self.poll.register(&self.rx, channel_token, Ready::readable(), poll_opts).unwrap();
+            let poll_opts = PollMode::Level;
+            let mut interest = PollingEvent::readable(0);
 
             // Register TTY through EventedRW interface.
-            self.pty.register(&self.poll, &mut tokens, Ready::readable(), poll_opts).unwrap();
+            unsafe {
+                self.pty.register(&self.poll, interest, poll_opts).unwrap();
+            }
 
-            let mut events = Events::with_capacity(1024);
+            let mut events = Events::with_capacity(NonZeroUsize::new(1024).unwrap());
 
             let mut pipe = if self.ref_test {
                 Some(File::create("./alacritty.recording").expect("create alacritty recording"))
@@ -337,7 +229,8 @@ where
                 let timeout =
                     handler.sync_timeout().map(|st| st.saturating_duration_since(Instant::now()));
 
-                if let Err(err) = self.poll.poll(&mut events, timeout) {
+                events.clear();
+                if let Err(err) = self.poll.wait(&mut events, timeout) {
                     match err.kind() {
                         ErrorKind::Interrupted => continue,
                         _ => panic!("EventLoop polling error: {err:?}"),
@@ -345,21 +238,20 @@ where
                 }
 
                 // Handle synchronized update timeout.
-                if events.is_empty() {
+                if events.is_empty() && self.rx.peek().is_none() {
                     state.parser.stop_sync(&mut *self.terminal.lock());
                     self.event_proxy.send_event(Event::Wakeup);
                     continue;
                 }
 
-                for event in events.iter() {
-                    match event.token() {
-                        token if token == channel_token => {
-                            if !self.channel_event(channel_token, &mut state) {
-                                break 'event_loop;
-                            }
-                        },
+                // Handle channel events, if there are any.
+                if !self.drain_recv_channel(&mut state) {
+                    break;
+                }
 
-                        token if token == self.pty.child_event_token() => {
+                for event in events.iter() {
+                    match event.key {
+                        tty::PTY_CHILD_EVENT_TOKEN => {
                             if let Some(tty::ChildEvent::Exited) = self.pty.next_child_event() {
                                 if self.hold {
                                     // With hold enabled, make sure the PTY is drained.
@@ -374,17 +266,13 @@ where
                             }
                         },
 
-                        token
-                            if token == self.pty.read_token()
-                                || token == self.pty.write_token() =>
-                        {
-                            #[cfg(unix)]
-                            if UnixReady::from(event.readiness()).is_hup() {
+                        tty::PTY_READ_WRITE_TOKEN => {
+                            if event.is_interrupt() {
                                 // Don't try to do I/O on a dead PTY.
                                 continue;
                             }
 
-                            if event.readiness().is_readable() {
+                            if event.readable {
                                 if let Err(err) = self.pty_read(&mut state, &mut buf, pipe.as_mut())
                                 {
                                     // On Linux, a `read` on the master side of a PTY can fail
@@ -402,7 +290,7 @@ where
                                 }
                             }
 
-                            if event.readiness().is_writable() {
+                            if event.writable {
                                 if let Err(err) = self.pty_write(&mut state) {
                                     error!("Error writing to PTY in event loop: {}", err);
                                     break 'event_loop;
@@ -414,19 +302,152 @@ where
                 }
 
                 // Register write interest if necessary.
-                let mut interest = Ready::readable();
-                if state.needs_write() {
-                    interest.insert(Ready::writable());
+                let needs_write = state.needs_write();
+                if needs_write != interest.writable {
+                    interest.writable = needs_write;
+
+                    // Re-register with new interest.
+                    self.pty.reregister(&self.poll, interest, poll_opts).unwrap();
                 }
-                // Reregister with new interest.
-                self.pty.reregister(&self.poll, interest, poll_opts).unwrap();
             }
 
             // The evented instances are not dropped here so deregister them explicitly.
-            let _ = self.poll.deregister(&self.rx);
             let _ = self.pty.deregister(&self.poll);
 
             (self, state)
         })
     }
 }
+
+/// Helper type which tracks how much of a buffer has been written.
+struct Writing {
+    source: Cow<'static, [u8]>,
+    written: usize,
+}
+
+pub struct Notifier(pub EventLoopSender);
+
+impl event::Notify for Notifier {
+    fn notify<B>(&self, bytes: B)
+    where
+        B: Into<Cow<'static, [u8]>>,
+    {
+        let bytes = bytes.into();
+        // Terminal hangs if we send 0 bytes through.
+        if bytes.len() == 0 {
+            return;
+        }
+
+        self.0.send(Msg::Input(bytes));
+    }
+}
+
+impl event::OnResize for Notifier {
+    fn on_resize(&mut self, window_size: WindowSize) {
+        self.0.send(Msg::Resize(window_size));
+    }
+}
+
+pub struct EventLoopSender {
+    sender: Sender<Msg>,
+    poller: Arc<polling::Poller>,
+}
+
+impl EventLoopSender {
+    pub fn send(&self, msg: Msg) {
+        let _ = self.sender.send(msg);
+        let _ = self.poller.notify();
+    }
+}
+
+/// All of the mutable state needed to run the event loop.
+///
+/// Contains list of items to write, current write state, etc. Anything that
+/// would otherwise be mutated on the `EventLoop` goes here.
+#[derive(Default)]
+pub struct State {
+    write_list: VecDeque<Cow<'static, [u8]>>,
+    writing: Option<Writing>,
+    parser: ansi::Processor,
+}
+
+impl State {
+    #[inline]
+    fn ensure_next(&mut self) {
+        if self.writing.is_none() {
+            self.goto_next();
+        }
+    }
+
+    #[inline]
+    fn goto_next(&mut self) {
+        self.writing = self.write_list.pop_front().map(Writing::new);
+    }
+
+    #[inline]
+    fn take_current(&mut self) -> Option<Writing> {
+        self.writing.take()
+    }
+
+    #[inline]
+    fn needs_write(&self) -> bool {
+        self.writing.is_some() || !self.write_list.is_empty()
+    }
+
+    #[inline]
+    fn set_current(&mut self, new: Option<Writing>) {
+        self.writing = new;
+    }
+}
+
+impl Writing {
+    #[inline]
+    fn new(c: Cow<'static, [u8]>) -> Writing {
+        Writing { source: c, written: 0 }
+    }
+
+    #[inline]
+    fn advance(&mut self, n: usize) {
+        self.written += n;
+    }
+
+    #[inline]
+    fn remaining_bytes(&self) -> &[u8] {
+        &self.source[self.written..]
+    }
+
+    #[inline]
+    fn finished(&self) -> bool {
+        self.written >= self.source.len()
+    }
+}
+
+struct PeekableReceiver<T> {
+    rx: Receiver<T>,
+    peeked: Option<T>,
+}
+
+impl<T> PeekableReceiver<T> {
+    fn new(rx: Receiver<T>) -> Self {
+        Self { rx, peeked: None }
+    }
+
+    fn peek(&mut self) -> Option<&T> {
+        if self.peeked.is_none() {
+            self.peeked = self.rx.try_recv().ok();
+        }
+
+        self.peeked.as_ref()
+    }
+
+    fn recv(&mut self) -> Option<T> {
+        if self.peeked.is_some() {
+            self.peeked.take()
+        } else {
+            match self.rx.try_recv() {
+                Err(TryRecvError::Disconnected) => panic!("event loop channel closed"),
+                res => res.ok(),
+            }
+        }
+    }
+}
diff --git a/alacritty_terminal/src/tty/mod.rs b/alacritty_terminal/src/tty/mod.rs
index 4ce277b3..315f008c 100644
--- a/alacritty_terminal/src/tty/mod.rs
+++ b/alacritty_terminal/src/tty/mod.rs
@@ -1,10 +1,13 @@
 //! TTY related functionality.
 
 use std::path::PathBuf;
+use std::sync::Arc;
 use std::{env, io};
 
 use crate::config::Config;
 
+use polling::{Event, PollMode, Poller};
+
 #[cfg(not(windows))]
 mod unix;
 #[cfg(not(windows))]
@@ -22,20 +25,15 @@ pub trait EventedReadWrite {
     type Reader: io::Read;
     type Writer: io::Write;
 
-    fn register(
-        &mut self,
-        _: &mio::Poll,
-        _: &mut dyn Iterator<Item = mio::Token>,
-        _: mio::Ready,
-        _: mio::PollOpt,
-    ) -> io::Result<()>;
-    fn reregister(&mut self, _: &mio::Poll, _: mio::Ready, _: mio::PollOpt) -> io::Result<()>;
-    fn deregister(&mut self, _: &mio::Poll) -> io::Result<()>;
+    /// # Safety
+    ///
+    /// The underlying sources must outlive their registration in the `Poller`.
+    unsafe fn register(&mut self, _: &Arc<Poller>, _: Event, _: PollMode) -> io::Result<()>;
+    fn reregister(&mut self, _: &Arc<Poller>, _: Event, _: PollMode) -> io::Result<()>;
+    fn deregister(&mut self, _: &Arc<Poller>) -> io::Result<()>;
 
     fn reader(&mut self) -> &mut Self::Reader;
-    fn read_token(&self) -> mio::Token;
     fn writer(&mut self) -> &mut Self::Writer;
-    fn write_token(&self) -> mio::Token;
 }
 
 /// Events concerning TTY child processes.
@@ -51,8 +49,6 @@ pub enum ChildEvent {
 /// notified if the PTY child process does something we care about (other than writing to the TTY).
 /// In particular, this allows for race-free child exit notification on UNIX (cf. `SIGCHLD`).
 pub trait EventedPty: EventedReadWrite {
-    fn child_event_token(&self) -> mio::Token;
-
     /// Tries to retrieve an event.
     ///
     /// Returns `Some(event)` on success, or `None` if there are no events to retrieve.
diff --git a/alacritty_terminal/src/tty/unix.rs b/alacritty_terminal/src/tty/unix.rs
index fd99edee..4523666e 100644
--- a/alacritty_terminal/src/tty/unix.rs
+++ b/alacritty_terminal/src/tty/unix.rs
@@ -2,26 +2,34 @@
 
 use std::ffi::CStr;
 use std::fs::File;
-use std::io::{Error, ErrorKind, Result};
+use std::io::{Error, ErrorKind, Read, Result};
 use std::mem::MaybeUninit;
 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
+use std::os::unix::net::UnixStream;
 use std::os::unix::process::CommandExt;
 use std::process::{Child, Command, Stdio};
+use std::sync::Arc;
 use std::{env, ptr};
 
 use libc::{self, c_int, winsize, TIOCSCTTY};
 use log::error;
-use mio::unix::EventedFd;
 use nix::pty::openpty;
 #[cfg(any(target_os = "linux", target_os = "macos"))]
 use nix::sys::termios::{self, InputFlags, SetArg};
+use polling::{Event, PollMode, Poller};
 use signal_hook::consts as sigconsts;
-use signal_hook_mio::v0_6::Signals;
+use signal_hook::low_level::pipe as signal_pipe;
 
 use crate::config::PtyConfig;
 use crate::event::{OnResize, WindowSize};
 use crate::tty::{ChildEvent, EventedPty, EventedReadWrite};
 
+// Interest in PTY read/writes.
+pub(crate) const PTY_READ_WRITE_TOKEN: usize = 0;
+
+// Interest in new child events.
+pub(crate) const PTY_CHILD_EVENT_TOKEN: usize = 1;
+
 macro_rules! die {
     ($($arg:tt)*) => {{
         error!($($arg)*);
@@ -103,9 +111,7 @@ fn get_pw_entry(buf: &mut [i8; 1024]) -> Result<Passwd<'_>> {
 pub struct Pty {
     child: Child,
     file: File,
-    token: mio::Token,
-    signals: Signals,
-    signals_token: mio::Token,
+    signals: UnixStream,
 }
 
 impl Pty {
@@ -254,7 +260,14 @@ pub fn new(config: &PtyConfig, window_size: WindowSize, window_id: u64) -> Resul
     }
 
     // Prepare signal handling before spawning child.
-    let signals = Signals::new([sigconsts::SIGCHLD]).expect("error preparing signal handling");
+    let signals = {
+        let (sender, recv) = UnixStream::pair()?;
+
+        // Register the recv end of the pipe for SIGCHLD.
+        signal_pipe::register(sigconsts::SIGCHLD, sender)?;
+        recv.set_nonblocking(true)?;
+        recv
+    };
 
     match builder.spawn() {
         Ok(child) => {
@@ -264,13 +277,7 @@ pub fn new(config: &PtyConfig, window_size: WindowSize, window_id: u64) -> Resul
                 set_nonblocking(master);
             }
 
-            let mut pty = Pty {
-                child,
-                file: unsafe { File::from_raw_fd(master) },
-                token: mio::Token::from(0),
-                signals,
-                signals_token: mio::Token::from(0),
-            };
+            let mut pty = Pty { child, file: unsafe { File::from_raw_fd(master) }, signals };
             pty.on_resize(window_size);
             Ok(pty)
         },
@@ -300,46 +307,47 @@ impl EventedReadWrite for Pty {
     type Writer = File;
 
     #[inline]
-    fn register(
+    unsafe fn register(
         &mut self,
-        poll: &mio::Poll,
-        token: &mut dyn Iterator<Item = mio::Token>,
-        interest: mio::Ready,
-        poll_opts: mio::PollOpt,
+        poll: &Arc<Poller>,
+        mut interest: Event,
+        poll_opts: PollMode,
     ) -> Result<()> {
-        self.token = token.next().unwrap();
-        poll.register(&EventedFd(&self.file.as_raw_fd()), self.token, interest, poll_opts)?;
+        interest.key = PTY_READ_WRITE_TOKEN;
+        unsafe {
+            poll.add_with_mode(&self.file, interest, poll_opts)?;
+        }
 
-        self.signals_token = token.next().unwrap();
-        poll.register(
-            &self.signals,
-            self.signals_token,
-            mio::Ready::readable(),
-            mio::PollOpt::level(),
-        )
+        unsafe {
+            poll.add_with_mode(
+                &self.signals,
+                Event::readable(PTY_CHILD_EVENT_TOKEN),
+                PollMode::Level,
+            )
+        }
     }
 
     #[inline]
     fn reregister(
         &mut self,
-        poll: &mio::Poll,
-        interest: mio::Ready,
-        poll_opts: mio::PollOpt,
+        poll: &Arc<Poller>,
+        mut interest: Event,
+        poll_opts: PollMode,
     ) -> Result<()> {
-        poll.reregister(&EventedFd(&self.file.as_raw_fd()), self.token, interest, poll_opts)?;
+        interest.key = PTY_READ_WRITE_TOKEN;
+        poll.modify_with_mode(&self.file, interest, poll_opts)?;
 
-        poll.reregister(
+        poll.modify_with_mode(
             &self.signals,
-            self.signals_token,
-            mio::Ready::readable(),
-            mio::PollOpt::level(),
+            Event::readable(PTY_CHILD_EVENT_TOKEN),
+            PollMode::Level,
         )
     }
 
     #[inline]
-    fn deregister(&mut self, poll: &mio::Poll) -> Result<()> {
-        poll.deregister(&EventedFd(&self.file.as_raw_fd()))?;
-        poll.deregister(&self.signals)
+    fn deregister(&mut self, poll: &Arc<Poller>) -> Result<()> {
+        poll.delete(&self.file)?;
+        poll.delete(&self.signals)
     }
 
     #[inline]
@@ -348,43 +356,32 @@ impl EventedReadWrite for Pty {
     }
 
     #[inline]
-    fn read_token(&self) -> mio::Token {
-        self.token
-    }
-
-    #[inline]
     fn writer(&mut self) -> &mut File {
         &mut self.file
     }
-
-    #[inline]
-    fn write_token(&self) -> mio::Token {
-        self.token
-    }
 }
 
 impl EventedPty for Pty {
     #[inline]
     fn next_child_event(&mut self) -> Option<ChildEvent> {
-        self.signals.pending().next().and_then(|signal| {
-            if signal != sigconsts::SIGCHLD {
-                return None;
-            }
-
-            match self.child.try_wait() {
-                Err(e) => {
-                    error!("Error checking child process termination: {}", e);
-                    None
-                },
-                Ok(None) => None,
-                Ok(_) => Some(ChildEvent::Exited),
+        // See if there has been a SIGCHLD.
+        let mut buf = [0u8; 1];
+        if let Err(err) = self.signals.read(&mut buf) {
+            if err.kind() != ErrorKind::WouldBlock {
+                error!("Error reading from signal pipe: {}", err);
             }
-        })
-    }
+            return None;
+        }
 
-    #[inline]
-    fn child_event_token(&self) -> mio::Token {
-        self.signals_token
+        // Match on the child process.
+        match self.child.try_wait() {
+            Err(err) => {
+                error!("Error checking child process termination: {}", err);
+                None
+            },
+            Ok(None) => None,
+            Ok(_) => Some(ChildEvent::Exited),
+        }
     }
 }
 
diff --git a/alacritty_terminal/src/tty/windows/blocking.rs b/alacritty_terminal/src/tty/windows/blocking.rs
new file mode 100644
index 00000000..3c74be4a
--- /dev/null
+++ b/alacritty_terminal/src/tty/windows/blocking.rs
@@ -0,0 +1,276 @@
+//! Code for running a reader/writer on another thread while driving it through `polling`.
+
+use std::io::prelude::*;
+use std::marker::PhantomData;
+use std::sync::{Arc, Mutex};
+use std::task::{Context, Poll, Wake, Waker};
+use std::{io, thread};
+
+use piper::{pipe, Reader, Writer};
+use polling::os::iocp::{CompletionPacket, PollerIocpExt};
+use polling::{Event, PollMode, Poller};
+
+use crate::thread::spawn_named;
+
+struct Registration {
+    interest: Mutex<Option<Interest>>,
+    end: PipeEnd,
+}
+
+#[derive(Copy, Clone)]
+enum PipeEnd {
+    Reader,
+    Writer,
+}
+
+struct Interest {
+    /// The event to send about completion.
+    event: Event,
+
+    /// The poller to send the event to.
+    poller: Arc<Poller>,
+
+    /// The mode that we are in.
+    mode: PollMode,
+}
+
+/// Poll a reader in another thread.
+pub struct UnblockedReader<R> {
+    /// The event to send about completion.
+    interest: Arc<Registration>,
+
+    /// The pipe that we are reading from.
+    pipe: Reader,
+
+    /// Is this the first time registering?
+    first_register: bool,
+
+    /// We logically own the reader, but we don't actually use it.
+    _reader: PhantomData<R>,
+}
+
+impl<R: Read + Send + 'static> UnblockedReader<R> {
+    /// Spawn a new unblocked reader.
+    pub fn new(mut source: R, pipe_capacity: usize) -> Self {
+        // Create a new pipe.
+        let (reader, mut writer) = pipe(pipe_capacity);
+        let interest = Arc::new(Registration {
+            interest: Mutex::<Option<Interest>>::new(None),
+            end: PipeEnd::Reader,
+        });
+
+        // Spawn the reader thread.
+        spawn_named("alacritty-tty-reader-thread", move || {
+            let waker = Waker::from(Arc::new(ThreadWaker(thread::current())));
+            let mut context = Context::from_waker(&waker);
+
+            loop {
+                // Read from the reader into the pipe.
+                match writer.poll_fill(&mut context, &mut source) {
+                    Poll::Ready(Ok(0)) => {
+                        // Either the pipe is closed or the reader is at its EOF.
+                        // In any case, we are done.
+                        return;
+                    },
+
+                    Poll::Ready(Ok(_)) => {
+                        // Keep reading.
+                        continue;
+                    },
+
+                    Poll::Ready(Err(e)) if e.kind() == io::ErrorKind::Interrupted => {
+                        // We were interrupted; continue.
+                        continue;
+                    },
+
+                    Poll::Ready(Err(e)) => {
+                        log::error!("error writing to pipe: {}", e);
+                        return;
+                    },
+
+                    Poll::Pending => {
+                        // We are now waiting on the other end to advance. Park the
+                        // thread until they do.
+                        thread::park();
+                    },
+                }
+            }
+        });
+
+        Self { interest, pipe: reader, first_register: true, _reader: PhantomData }
+    }
+
+    /// Register interest in the reader.
+    pub fn register(&mut self, poller: &Arc<Poller>, event: Event, mode: PollMode) {
+        let mut interest = self.interest.interest.lock().unwrap();
+        *interest = Some(Interest { event, poller: poller.clone(), mode });
+
+        // Send the event to start off with if we have any data.
+        if (!self.pipe.is_empty() && event.readable) || self.first_register {
+            self.first_register = false;
+            poller.post(CompletionPacket::new(event)).ok();
+        }
+    }
+
+    /// Deregister interest in the reader.
+    pub fn deregister(&self) {
+        let mut interest = self.interest.interest.lock().unwrap();
+        *interest = None;
+    }
+
+    /// Try to read from the reader.
+    pub fn try_read(&mut self, buf: &mut [u8]) -> usize {
+        let waker = Waker::from(self.interest.clone());
+
+        match self.pipe.poll_drain_bytes(&mut Context::from_waker(&waker), buf) {
+            Poll::Pending => 0,
+            Poll::Ready(n) => n,
+        }
+    }
+}
+
+impl<R: Read + Send + 'static> Read for UnblockedReader<R> {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        Ok(self.try_read(buf))
+    }
+}
+
+/// Poll a writer in another thread.
+pub struct UnblockedWriter<W> {
+    /// The interest to send about completion.
+    interest: Arc<Registration>,
+
+    /// The pipe that we are writing to.
+    pipe: Writer,
+
+    /// We logically own the writer, but we don't actually use it.
+    _reader: PhantomData<W>,
+}
+
+impl<W: Write + Send + 'static> UnblockedWriter<W> {
+    /// Spawn a new unblocked writer.
+    pub fn new(mut sink: W, pipe_capacity: usize) -> Self {
+        // Create a new pipe.
+        let (mut reader, writer) = pipe(pipe_capacity);
+        let interest = Arc::new(Registration {
+            interest: Mutex::<Option<Interest>>::new(None),
+            end: PipeEnd::Writer,
+        });
+
+        // Spawn the writer thread.
+        spawn_named("alacritty-tty-writer-thread", move || {
+            let waker = Waker::from(Arc::new(ThreadWaker(thread::current())));
+            let mut context = Context::from_waker(&waker);
+
+            loop {
+                // Write from the pipe into the writer.
+                match reader.poll_drain(&mut context, &mut sink) {
+                    Poll::Ready(Ok(0)) => {
+                        // Either the pipe is closed or the writer is full.
+                        // In any case, we are done.
+                        return;
+                    },
+
+                    Poll::Ready(Ok(_)) => {
+                        // Keep writing.
+                        continue;
+                    },
+
+                    Poll::Ready(Err(e)) if e.kind() == io::ErrorKind::Interrupted => {
+                        // We were interrupted; continue.
+                        continue;
+                    },
+
+                    Poll::Ready(Err(e)) => {
+                        log::error!("error writing to pipe: {}", e);
+                        return;
+                    },
+
+                    Poll::Pending => {
+                        // We are now waiting on the other end to advance. Park the
+                        // thread until they do.
+                        thread::park();
+                    },
+                }
+            }
+        });
+
+        Self { interest, pipe: writer, _reader: PhantomData }
+    }
+
+    /// Register interest in the writer.
+    pub fn register(&self, poller: &Arc<Poller>, event: Event, mode: PollMode) {
+        let mut interest = self.interest.interest.lock().unwrap();
+        *interest = Some(Interest { event, poller: poller.clone(), mode });
+
+        // Send the event to start off with if we have room for data.
+        if !self.pipe.is_full() && event.writable {
+            poller.post(CompletionPacket::new(event)).ok();
+        }
+    }
+
+    /// Deregister interest in the writer.
+    pub fn deregister(&self) {
+        let mut interest = self.interest.interest.lock().unwrap();
+        *interest = None;
+    }
+
+    /// Try to write to the writer.
+    pub fn try_write(&mut self, buf: &[u8]) -> usize {
+        let waker = Waker::from(self.interest.clone());
+
+        match self.pipe.poll_fill_bytes(&mut Context::from_waker(&waker), buf) {
+            Poll::Pending => 0,
+            Poll::Ready(n) => n,
+        }
+    }
+}
+
+impl<W: Write + Send + 'static> Write for UnblockedWriter<W> {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        Ok(self.try_write(buf))
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        // Nothing to flush.
+        Ok(())
+    }
+}
+
+struct ThreadWaker(thread::Thread);
+
+impl Wake for ThreadWaker {
+    fn wake(self: Arc<Self>) {
+        self.0.unpark();
+    }
+
+    fn wake_by_ref(self: &Arc<Self>) {
+        self.0.unpark();
+    }
+}
+
+impl Wake for Registration {
+    fn wake(self: Arc<Self>) {
+        self.wake_by_ref();
+    }
+
+    fn wake_by_ref(self: &Arc<Self>) {
+        let mut interest_lock = self.interest.lock().unwrap();
+        if let Some(interest) = interest_lock.as_ref() {
+            // Send the event to the poller.
+            let send_event = match self.end {
+                PipeEnd::Reader => interest.event.readable,
+                PipeEnd::Writer => interest.event.writable,
+            };
+
+            if send_event {
+                interest.poller.post(CompletionPacket::new(interest.event)).ok();
+
+                // Clear the event if we're in oneshot mode.
+                if matches!(interest.mode, PollMode::Oneshot | PollMode::EdgeOneshot) {
+                    *interest_lock = None;
+                }
+            }
+        }
+    }
+}
diff --git a/alacritty_terminal/src/tty/windows/child.rs b/alacritty_terminal/src/tty/windows/child.rs
index 19c8a195..6bc9ed20 100644
--- a/alacritty_terminal/src/tty/windows/child.rs
+++ b/alacritty_terminal/src/tty/windows/child.rs
@@ -1,8 +1,10 @@
 use std::ffi::c_void;
 use std::io::Error;
 use std::sync::atomic::{AtomicPtr, Ordering};
+use std::sync::{mpsc, Arc, Mutex};
 
-use mio_extras::channel::{channel, Receiver, Sender};
+use polling::os::iocp::{CompletionPacket, PollerIocpExt};
+use polling::{Event, Poller};
 
 use windows_sys::Win32::Foundation::{BOOLEAN, HANDLE};
 use windows_sys::Win32::System::Threading::{
@@ -12,27 +14,43 @@ use windows_sys::Win32::System::Threading::{
 
 use crate::tty::ChildEvent;
 
+struct Interest {
+    poller: Arc<Poller>,
+    event: Event,
+}
+
+struct ChildExitSender {
+    sender: mpsc::Sender<ChildEvent>,
+    interest: Arc<Mutex<Option<Interest>>>,
+}
+
 /// WinAPI callback to run when child process exits.
 extern "system" fn child_exit_callback(ctx: *mut c_void, timed_out: BOOLEAN) {
     if timed_out != 0 {
         return;
     }
 
-    let event_tx: Box<_> = unsafe { Box::from_raw(ctx as *mut Sender<ChildEvent>) };
-    let _ = event_tx.send(ChildEvent::Exited);
+    let event_tx: Box<_> = unsafe { Box::from_raw(ctx as *mut ChildExitSender) };
+    let _ = event_tx.sender.send(ChildEvent::Exited);
+    let interest = event_tx.interest.lock().unwrap();
+    if let Some(interest) = interest.as_ref() {
+        interest.poller.post(CompletionPacket::new(interest.event)).ok();
+    }
 }
 
 pub struct ChildExitWatcher {
     wait_handle: AtomicPtr<c_void>,
-    event_rx: Receiver<ChildEvent>,
+    event_rx: mpsc::Receiver<ChildEvent>,
+    interest: Arc<Mutex<Option<Interest>>>,
 }
 
 impl ChildExitWatcher {
     pub fn new(child_handle: HANDLE) -> Result<ChildExitWatcher, Error> {
-        let (event_tx, event_rx) = channel::<ChildEvent>();
+        let (event_tx, event_rx) = mpsc::channel();
 
         let mut wait_handle: HANDLE = 0;
-        let sender_ref = Box::new(event_tx);
+        let interest = Arc::new(Mutex::new(None));
+        let sender_ref = Box::new(ChildExitSender { sender: event_tx, interest: interest.clone() });
 
         let success = unsafe {
             RegisterWaitForSingleObject(
@@ -51,13 +69,22 @@ impl ChildExitWatcher {
             Ok(ChildExitWatcher {
                 wait_handle: AtomicPtr::from(wait_handle as *mut c_void),
                 event_rx,
+                interest,
             })
         }
     }
 
-    pub fn event_rx(&self) -> &Receiver<ChildEvent> {
+    pub fn event_rx(&self) -> &mpsc::Receiver<ChildEvent> {
         &self.event_rx
     }
+
+    pub fn register(&self, poller: &Arc<Poller>, event: Event) {
+        *self.interest.lock().unwrap() = Some(Interest { poller: poller.clone(), event });
+    }
+
+    pub fn deregister(&self) {
+        *self.interest.lock().unwrap() = None;
+    }
 }
 
 impl Drop for ChildExitWatcher {
@@ -72,36 +99,28 @@ impl Drop for ChildExitWatcher {
 mod tests {
     use std::os::windows::io::AsRawHandle;
     use std::process::Command;
+    use std::sync::Arc;
     use std::time::Duration;
 
-    use mio::{Events, Poll, PollOpt, Ready, Token};
-
+    use super::super::PTY_CHILD_EVENT_TOKEN;
     use super::*;
 
     #[test]
     pub fn event_is_emitted_when_child_exits() {
         const WAIT_TIMEOUT: Duration = Duration::from_millis(200);
 
+        let poller = Arc::new(Poller::new().unwrap());
+
         let mut child = Command::new("cmd.exe").spawn().unwrap();
         let child_exit_watcher = ChildExitWatcher::new(child.as_raw_handle() as HANDLE).unwrap();
-
-        let mut events = Events::with_capacity(1);
-        let poll = Poll::new().unwrap();
-        let child_events_token = Token::from(0usize);
-
-        poll.register(
-            child_exit_watcher.event_rx(),
-            child_events_token,
-            Ready::readable(),
-            PollOpt::oneshot(),
-        )
-        .unwrap();
+        child_exit_watcher.register(&poller, Event::readable(PTY_CHILD_EVENT_TOKEN));
 
         child.kill().unwrap();
 
         // Poll for the event or fail with timeout if nothing has been sent.
-        poll.poll(&mut events, Some(WAIT_TIMEOUT)).unwrap();
-        assert_eq!(events.iter().next().unwrap().token(), child_events_token);
+        let mut events = polling::Events::new();
+        poller.wait(&mut events, Some(WAIT_TIMEOUT)).unwrap();
+        assert_eq!(events.iter().next().unwrap().key, PTY_CHILD_EVENT_TOKEN);
         // Verify that at least one `ChildEvent::Exited` was received.
         assert_eq!(child_exit_watcher.event_rx().try_recv(), Ok(ChildEvent::Exited));
     }
diff --git a/alacritty_terminal/src/tty/windows/conpty.rs b/alacritty_terminal/src/tty/windows/conpty.rs
index c9ed631e..12189371 100644
--- a/alacritty_terminal/src/tty/windows/conpty.rs
+++ b/alacritty_terminal/src/tty/windows/conpty.rs
@@ -3,8 +3,6 @@ use std::io::Error;
 use std::os::windows::io::IntoRawHandle;
 use std::{mem, ptr};
 
-use mio_anonymous_pipes::{EventedAnonRead, EventedAnonWrite};
-
 use windows_sys::core::{HRESULT, PWSTR};
 use windows_sys::Win32::Foundation::{HANDLE, S_OK};
 use windows_sys::Win32::System::Console::{
@@ -21,9 +19,12 @@ use windows_sys::Win32::System::Threading::{
 
 use crate::config::PtyConfig;
 use crate::event::{OnResize, WindowSize};
+use crate::tty::windows::blocking::{UnblockedReader, UnblockedWriter};
 use crate::tty::windows::child::ChildExitWatcher;
 use crate::tty::windows::{cmdline, win32_string, Pty};
 
+const PIPE_CAPACITY: usize = crate::event_loop::READ_BUFFER_SIZE;
+
 /// Load the pseudoconsole API from conpty.dll if possible, otherwise use the
 /// standard Windows API.
 ///
@@ -220,8 +221,8 @@ pub fn new(config: &PtyConfig, window_size: WindowSize) -> Option<Pty> {
         }
     }
 
-    let conin = EventedAnonWrite::new(conin);
-    let conout = EventedAnonRead::new(conout);
+    let conin = UnblockedWriter::new(conin, PIPE_CAPACITY);
+    let conout = UnblockedReader::new(conout, PIPE_CAPACITY);
 
     let child_watcher = ChildExitWatcher::new(proc_info.hProcess).unwrap();
     let conpty = Conpty { handle: pty_handle as HPCON, api };
diff --git a/alacritty_terminal/src/tty/windows/mod.rs b/alacritty_terminal/src/tty/windows/mod.rs
index 57925f4c..080f6e83 100644
--- a/alacritty_terminal/src/tty/windows/mod.rs
+++ b/alacritty_terminal/src/tty/windows/mod.rs
@@ -3,17 +3,27 @@ use std::io::{self, Error, ErrorKind, Result};
 use std::iter::once;
 use std::os::windows::ffi::OsStrExt;
 use std::sync::mpsc::TryRecvError;
+use std::sync::Arc;
 
 use crate::config::{Program, PtyConfig};
 use crate::event::{OnResize, WindowSize};
 use crate::tty::windows::child::ChildExitWatcher;
 use crate::tty::{ChildEvent, EventedPty, EventedReadWrite};
 
+mod blocking;
 mod child;
 mod conpty;
 
+use blocking::{UnblockedReader, UnblockedWriter};
 use conpty::Conpty as Backend;
-use mio_anonymous_pipes::{EventedAnonRead as ReadPipe, EventedAnonWrite as WritePipe};
+use miow::pipe::{AnonRead, AnonWrite};
+use polling::{Event, Poller};
+
+pub const PTY_CHILD_EVENT_TOKEN: usize = 1;
+pub const PTY_READ_WRITE_TOKEN: usize = 2;
+
+type ReadPipe = UnblockedReader<AnonRead>;
+type WritePipe = UnblockedWriter<AnonWrite>;
 
 pub struct Pty {
     // XXX: Backend is required to be the first field, to ensure correct drop order. Dropping
@@ -21,9 +31,6 @@ pub struct Pty {
     backend: Backend,
     conout: ReadPipe,
     conin: WritePipe,
-    read_token: mio::Token,
-    write_token: mio::Token,
-    child_event_token: mio::Token,
     child_watcher: ChildExitWatcher,
 }
 
@@ -39,51 +46,29 @@ impl Pty {
         conin: impl Into<WritePipe>,
         child_watcher: ChildExitWatcher,
     ) -> Self {
-        Self {
-            backend: backend.into(),
-            conout: conout.into(),
-            conin: conin.into(),
-            read_token: 0.into(),
-            write_token: 0.into(),
-            child_event_token: 0.into(),
-            child_watcher,
-        }
+        Self { backend: backend.into(), conout: conout.into(), conin: conin.into(), child_watcher }
     }
 }
 
+fn with_key(mut event: Event, key: usize) -> Event {
+    event.key = key;
+    event
+}
+
 impl EventedReadWrite for Pty {
     type Reader = ReadPipe;
     type Writer = WritePipe;
 
     #[inline]
-    fn register(
+    unsafe fn register(
         &mut self,
-        poll: &mio::Poll,
-        token: &mut dyn Iterator<Item = mio::Token>,
-        interest: mio::Ready,
-        poll_opts: mio::PollOpt,
+        poll: &Arc<Poller>,
+        interest: polling::Event,
+        poll_opts: polling::PollMode,
     ) -> io::Result<()> {
-        self.read_token = token.next().unwrap();
-        self.write_token = token.next().unwrap();
-
-        if interest.is_readable() {
-            poll.register(&self.conout, self.read_token, mio::Ready::readable(), poll_opts)?
-        } else {
-            poll.register(&self.conout, self.read_token, mio::Ready::empty(), poll_opts)?
-        }
-        if interest.is_writable() {
-            poll.register(&self.conin, self.write_token, mio::Ready::writable(), poll_opts)?
-        } else {
-            poll.register(&self.conin, self.write_token, mio::Ready::empty(), poll_opts)?
-        }
-
-        self.child_event_token = token.next().unwrap();
-        poll.register(
-            self.child_watcher.event_rx(),
-            self.child_event_token,
-            mio::Ready::readable(),
-            poll_opts,
-        )?;
+        self.conin.register(poll, with_key(interest, PTY_READ_WRITE_TOKEN), poll_opts);
+        self.conout.register(poll, with_key(interest, PTY_READ_WRITE_TOKEN), poll_opts);
+        self.child_watcher.register(poll, with_key(interest, PTY_CHILD_EVENT_TOKEN));
 
         Ok(())
     }
@@ -91,36 +76,23 @@ impl EventedReadWrite for Pty {
     #[inline]
     fn reregister(
         &mut self,
-        poll: &mio::Poll,
-        interest: mio::Ready,
-        poll_opts: mio::PollOpt,
+        poll: &Arc<Poller>,
+        interest: polling::Event,
+        poll_opts: polling::PollMode,
     ) -> io::Result<()> {
-        if interest.is_readable() {
-            poll.reregister(&self.conout, self.read_token, mio::Ready::readable(), poll_opts)?;
-        } else {
-            poll.reregister(&self.conout, self.read_token, mio::Ready::empty(), poll_opts)?;
-        }
-        if interest.is_writable() {
-            poll.reregister(&self.conin, self.write_token, mio::Ready::writable(), poll_opts)?;
-        } else {
-            poll.reregister(&self.conin, self.write_token, mio::Ready::empty(), poll_opts)?;
-        }
-
-        poll.reregister(
-            self.child_watcher.event_rx(),
-            self.child_event_token,
-            mio::Ready::readable(),
-            poll_opts,
-        )?;
+        self.conin.register(poll, with_key(interest, PTY_READ_WRITE_TOKEN), poll_opts);
+        self.conout.register(poll, with_key(interest, PTY_READ_WRITE_TOKEN), poll_opts);
+        self.child_watcher.register(poll, with_key(interest, PTY_CHILD_EVENT_TOKEN));
 
         Ok(())
     }
 
     #[inline]
-    fn deregister(&mut self, poll: &mio::Poll) -> io::Result<()> {
-        poll.deregister(&self.conout)?;
-        poll.deregister(&self.conin)?;
-        poll.deregister(self.child_watcher.event_rx())?;
+    fn deregister(&mut self, _poll: &Arc<Poller>) -> io::Result<()> {
+        self.conin.deregister();
+        self.conout.deregister();
+        self.child_watcher.deregister();
+
         Ok(())
     }
 
@@ -130,26 +102,12 @@ impl EventedReadWrite for Pty {
     }
 
     #[inline]
-    fn read_token(&self) -> mio::Token {
-        self.read_token
-    }
-
-    #[inline]
     fn writer(&mut self) -> &mut Self::Writer {
         &mut self.conin
     }
-
-    #[inline]
-    fn write_token(&self) -> mio::Token {
-        self.write_token
-    }
 }
 
 impl EventedPty for Pty {
-    fn child_event_token(&self) -> mio::Token {
-        self.child_event_token
-    }
-
     fn next_child_event(&mut self) -> Option<ChildEvent> {
         match self.child_watcher.event_rx().try_recv() {
             Ok(ev) => Some(ev),