chore: use ready macro from `futures-core` (#1300)

48 files changed, 42 insertions, 137 deletions

diff --git a/tokio-io/Cargo.toml b/tokio-io/Cargo.toml
index 8f420495..2561ac21 100644
--- a/tokio-io/Cargo.toml
+++ b/tokio-io/Cargo.toml
@@ -24,6 +24,7 @@ publish = false
 [dependencies]
 bytes = "0.4.7"
 log = "0.4"
+futures-core-preview = "0.3.0-alpha.17"
 
 [dev-dependencies]
 pin-utils = "0.1.0-alpha.4"
diff --git a/tokio-io/src/async_read.rs b/tokio-io/src/async_read.rs
index 4eeaa7bb..1b7eaa6c 100644
--- a/tokio-io/src/async_read.rs
+++ b/tokio-io/src/async_read.rs
@@ -1,6 +1,7 @@
 //use crate::split::{ReadHalf, WriteHalf};
 //use crate::{framed, split, AsyncWrite};
 use bytes::BufMut;
+use futures_core::ready;
 use std::io;
 use std::ops::DerefMut;
 use std::pin::Pin;
diff --git a/tokio-io/src/async_write.rs b/tokio-io/src/async_write.rs
index 80ec74d1..7bcb4339 100644
--- a/tokio-io/src/async_write.rs
+++ b/tokio-io/src/async_write.rs
@@ -1,5 +1,6 @@
 //use crate::AsyncRead;
 use bytes::Buf;
+use futures_core::ready;
 use std::io;
 use std::ops::DerefMut;
 use std::pin::Pin;
diff --git a/tokio-io/src/lib.rs b/tokio-io/src/lib.rs
index 81a11f8f..165cc1ca 100644
--- a/tokio-io/src/lib.rs
+++ b/tokio-io/src/lib.rs
@@ -12,15 +12,6 @@
 //! [found online]: https://tokio.rs/docs/
 //! [low level details]: https://tokio.rs/docs/going-deeper-tokio/core-low-level/
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 mod async_read;
 mod async_write;
 
diff --git a/tokio-reactor/Cargo.toml b/tokio-reactor/Cargo.toml
index ed939a9c..f504ccae 100644
--- a/tokio-reactor/Cargo.toml
+++ b/tokio-reactor/Cargo.toml
@@ -33,6 +33,7 @@ slab = "0.4.0"
 tokio-executor = { version = "0.2.0", path = "../tokio-executor" }
 tokio-io = { version = "0.2.0", path = "../tokio-io" }
 tokio-sync = { version = "0.2.0", path = "../tokio-sync" }
+futures-core-preview = "0.3.0-alpha.17"
 
 [dev-dependencies]
 num_cpus = "1.8.0"
diff --git a/tokio-reactor/src/lib.rs b/tokio-reactor/src/lib.rs
index ff2ab686..5eae81da 100644
--- a/tokio-reactor/src/lib.rs
+++ b/tokio-reactor/src/lib.rs
@@ -32,15 +32,6 @@
 //! [`PollEvented`]: struct.PollEvented.html
 //! [reactor module]: https://docs.rs/tokio/0.1/tokio/reactor/index.html
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(v) => v,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 mod poll_evented;
 mod registration;
 mod sharded_rwlock;
diff --git a/tokio-reactor/src/poll_evented.rs b/tokio-reactor/src/poll_evented.rs
index 5b280294..50f21434 100644
--- a/tokio-reactor/src/poll_evented.rs
+++ b/tokio-reactor/src/poll_evented.rs
@@ -1,4 +1,5 @@
 use crate::{Handle, Registration};
+use futures_core::ready;
 use mio;
 use mio::event::Evented;
 use std::fmt;
diff --git a/tokio-sync/Cargo.toml b/tokio-sync/Cargo.toml
index 66022b30..e8fddf16 100644
--- a/tokio-sync/Cargo.toml
+++ b/tokio-sync/Cargo.toml
@@ -22,13 +22,13 @@ categories = ["asynchronous"]
 publish = false
 
 [features]
-async-traits = ["tokio-futures", "futures-core-preview"]
+async-traits = ["tokio-futures"]
 
 [dependencies]
 async-util = { git = "https://github.com/tokio-rs/async" }
 tokio-futures = { path = "../tokio-futures", optional = true }
 fnv = "1.0.6"
-futures-core-preview = { version = "0.3.0-alpha.17", optional = true }
+futures-core-preview = { version = "0.3.0-alpha.17" }
 
 [dev-dependencies]
 env_logger = { version = "0.5", default-features = false }
diff --git a/tokio-sync/src/lib.rs b/tokio-sync/src/lib.rs
index 384740ac..00f9b700 100644
--- a/tokio-sync/src/lib.rs
+++ b/tokio-sync/src/lib.rs
@@ -21,19 +21,6 @@ macro_rules! debug {
     }
 }
 
-/// Unwrap a ready value or propagate `Poll::Pending`.
-#[macro_export]
-macro_rules! ready {
-    ($e:expr) => {{
-        use std::task::Poll::{Pending, Ready};
-
-        match $e {
-            Ready(v) => v,
-            Pending => return Pending,
-        }
-    }};
-}
-
 macro_rules! if_fuzz {
     ($($t:tt)*) => {{
         if false { $($t)* }
diff --git a/tokio-sync/src/lock.rs b/tokio-sync/src/lock.rs
index 10f6a112..8b2bc0bc 100644
--- a/tokio-sync/src/lock.rs
+++ b/tokio-sync/src/lock.rs
@@ -42,6 +42,7 @@
 
 use crate::semaphore;
 
+use futures_core::ready;
 use std::cell::UnsafeCell;
 use std::fmt;
 use std::future::Future;
diff --git a/tokio-sync/src/oneshot.rs b/tokio-sync/src/oneshot.rs
index 910d24dd..86f1cd82 100644
--- a/tokio-sync/src/oneshot.rs
+++ b/tokio-sync/src/oneshot.rs
@@ -2,6 +2,7 @@
 
 use crate::loom::{sync::atomic::AtomicUsize, sync::CausalCell};
 
+use futures_core::ready;
 use std::fmt;
 use std::future::Future;
 use std::mem::{self, ManuallyDrop};
diff --git a/tokio-sync/src/watch.rs b/tokio-sync/src/watch.rs
index ed35b0aa..91d5d2b5 100644
--- a/tokio-sync/src/watch.rs
+++ b/tokio-sync/src/watch.rs
@@ -58,6 +58,7 @@ use crate::task::AtomicWaker;
 use core::task::Poll::{Pending, Ready};
 use core::task::{Context, Poll};
 use fnv::FnvHashMap;
+use futures_core::ready;
 use std::ops;
 use std::sync::atomic::AtomicUsize;
 use std::sync::atomic::Ordering::SeqCst;
diff --git a/tokio-sync/tests/fuzz_oneshot.rs b/tokio-sync/tests/fuzz_oneshot.rs
index f8987af6..eb4dfcde 100644
--- a/tokio-sync/tests/fuzz_oneshot.rs
+++ b/tokio-sync/tests/fuzz_oneshot.rs
@@ -1,19 +1,6 @@
 #![deny(warnings, rust_2018_idioms)]
 #![feature(async_await)]
 
-/// Unwrap a ready value or propagate `Async::Pending`.
-#[macro_export]
-macro_rules! ready {
-    ($e:expr) => {{
-        use std::task::Poll::{Pending, Ready};
-
-        match $e {
-            Ready(v) => v,
-            Pending => return Pending,
-        }
-    }};
-}
-
 #[path = "../src/oneshot.rs"]
 #[allow(warnings)]
 mod oneshot;
diff --git a/tokio-sync/tests/fuzz_semaphore.rs b/tokio-sync/tests/fuzz_semaphore.rs
index ca2fda8b..55d6bf0d 100644
--- a/tokio-sync/tests/fuzz_semaphore.rs
+++ b/tokio-sync/tests/fuzz_semaphore.rs
@@ -10,6 +10,7 @@ mod semaphore;
 use crate::semaphore::*;
 
 use async_util::future::poll_fn;
+use futures_core::ready;
 use loom::futures::block_on;
 use loom::thread;
 use std::future::Future;
@@ -20,19 +21,6 @@ use std::sync::Arc;
 use std::task::Poll::Ready;
 use std::task::{Context, Poll};
 
-/// Unwrap a ready value or propagate `Poll::Pending`.
-#[macro_export]
-macro_rules! ready {
-    ($e:expr) => {{
-        use std::task::Poll::{Pending, Ready};
-
-        match $e {
-            Ready(v) => v,
-            Pending => return Pending,
-        }
-    }};
-}
-
 #[test]
 fn basic_usage() {
     const NUM: usize = 2;
diff --git a/tokio-tcp/Cargo.toml b/tokio-tcp/Cargo.toml
index 2bb387d9..776f14b9 100644
--- a/tokio-tcp/Cargo.toml
+++ b/tokio-tcp/Cargo.toml
@@ -22,7 +22,7 @@ categories = ["asynchronous"]
 publish = false
 
 [features]
-incoming = ["futures-core-preview"]
+incoming = []
 
 [dependencies]
 async-util = { git = "https://github.com/tokio-rs/async" }
@@ -33,7 +33,7 @@ mio = "0.6.14"
 iovec = "0.1"
 
 # optionals
-futures-core-preview = { version = "0.3.0-alpha.17", optional = true }
+futures-core-preview = { version = "0.3.0-alpha.17" }
 
 [dev-dependencies]
 #env_logger = { version = "0.5", default-features = false }
diff --git a/tokio-tcp/src/incoming.rs b/tokio-tcp/src/incoming.rs
index 566734de..00c2e01d 100644
--- a/tokio-tcp/src/incoming.rs
+++ b/tokio-tcp/src/incoming.rs
@@ -1,5 +1,6 @@
 use super::TcpListener;
 use super::TcpStream;
+use futures_core::ready;
 use futures_core::stream::Stream;
 use std::io;
 use std::pin::Pin;
diff --git a/tokio-tcp/src/lib.rs b/tokio-tcp/src/lib.rs
index d50e4b6e..3a8e04b3 100644
--- a/tokio-tcp/src/lib.rs
+++ b/tokio-tcp/src/lib.rs
@@ -23,15 +23,6 @@
 //! [incoming_method]: struct.TcpListener.html#method.incoming
 //! [`Incoming`]: struct.Incoming.html
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 #[cfg(feature = "incoming")]
 mod incoming;
 mod listener;
diff --git a/tokio-tcp/src/listener.rs b/tokio-tcp/src/listener.rs
index 50621d00..8fa1b4bc 100644
--- a/tokio-tcp/src/listener.rs
+++ b/tokio-tcp/src/listener.rs
@@ -1,6 +1,7 @@
 #[cfg(feature = "incoming")]
 use super::incoming::Incoming;
 use super::TcpStream;
+use futures_core::ready;
 use mio;
 use std::convert::TryFrom;
 use std::fmt;
diff --git a/tokio-tcp/src/stream.rs b/tokio-tcp/src/stream.rs
index f2253a5e..e621f870 100644
--- a/tokio-tcp/src/stream.rs
+++ b/tokio-tcp/src/stream.rs
@@ -1,5 +1,6 @@
 use crate::split::{split, TcpStreamReadHalf, TcpStreamWriteHalf};
 use bytes::{Buf, BufMut};
+use futures_core::ready;
 use iovec::IoVec;
 use mio;
 use std::convert::TryFrom;
diff --git a/tokio-test/Cargo.toml b/tokio-test/Cargo.toml
index 95e94896..92573a83 100644
--- a/tokio-test/Cargo.toml
+++ b/tokio-test/Cargo.toml
@@ -28,6 +28,7 @@ tokio-executor = { version = "0.2.0", path = "../tokio-executor" }
 tokio-io = { version = "0.2.0", path = "../tokio-io" }
 tokio-sync = { version = "0.2.0", path = "../tokio-sync" }
 tokio-timer = { version = "0.3.0", path = "../tokio-timer" }
+futures-core-preview = "0.3.0-alpha.17"
 
 [dev-dependencies]
 tokio = { path = "../tokio" }
diff --git a/tokio-test/src/io.rs b/tokio-test/src/io.rs
index 568a81fc..881ffe1a 100644
--- a/tokio-test/src/io.rs
+++ b/tokio-test/src/io.rs
@@ -20,6 +20,7 @@ use std::task::{self, Poll, Waker};
 use std::time::{Duration, Instant};
 use std::{cmp, io};
 
+use futures_core::ready;
 use tokio_io::{AsyncRead, AsyncWrite};
 use tokio_sync::mpsc;
 use tokio_timer::{clock, timer, Delay};
diff --git a/tokio-test/src/lib.rs b/tokio-test/src/lib.rs
index 00d38897..7cfd428c 100644
--- a/tokio-test/src/lib.rs
+++ b/tokio-test/src/lib.rs
@@ -20,15 +20,6 @@
 //! assert_ready!(fut.poll());
 //! ```
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 pub mod clock;
 pub mod io;
 mod macros;
diff --git a/tokio-threadpool/Cargo.toml b/tokio-threadpool/Cargo.toml
index cb3b454a..e4f90c7a 100644
--- a/tokio-threadpool/Cargo.toml
+++ b/tokio-threadpool/Cargo.toml
@@ -25,6 +25,7 @@ publish = false
 [dependencies]
 tokio-executor = { version = "0.2.0", path = "../tokio-executor" }
 tokio-sync = { version = "0.2.0", path = "../tokio-sync" }
+futures-core-preview = "0.3.0-alpha.17"
 
 arc-waker = { git = "https://github.com/tokio-rs/async" }
 crossbeam-deque = "0.7.0"
diff --git a/tokio-threadpool/src/blocking.rs b/tokio-threadpool/src/blocking.rs
index c50a28ac..72028836 100644
--- a/tokio-threadpool/src/blocking.rs
+++ b/tokio-threadpool/src/blocking.rs
@@ -1,5 +1,6 @@
 use crate::worker::Worker;
 
+use futures_core::ready;
 use std::error::Error;
 use std::fmt;
 use std::task::Poll;
diff --git a/tokio-threadpool/src/lib.rs b/tokio-threadpool/src/lib.rs
index dcf95933..888dbe8c 100644
--- a/tokio-threadpool/src/lib.rs
+++ b/tokio-threadpool/src/lib.rs
@@ -131,15 +131,6 @@
 
 pub mod park;
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 mod blocking;
 mod builder;
 mod callback;
diff --git a/tokio-threadpool/tests/blocking.rs b/tokio-threadpool/tests/blocking.rs
index e5ef81a6..01259481 100644
--- a/tokio-threadpool/tests/blocking.rs
+++ b/tokio-threadpool/tests/blocking.rs
@@ -5,6 +5,7 @@ use tokio_test::*;
 use tokio_threadpool::*;
 
 use async_util::future::poll_fn;
+use futures_core::ready;
 use rand::*;
 use std::sync::atomic::Ordering::*;
 use std::sync::atomic::*;
@@ -13,15 +14,6 @@ use std::task::{Poll, Waker};
 use std::thread;
 use std::time::Duration;
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 #[test]
 fn basic() {
     let _ = ::env_logger::try_init();
diff --git a/tokio-timer/Cargo.toml b/tokio-timer/Cargo.toml
index e6e5853a..5cdbaa49 100644
--- a/tokio-timer/Cargo.toml
+++ b/tokio-timer/Cargo.toml
@@ -22,18 +22,18 @@ Timer facilities for Tokio
 publish = false
 
 [features]
-async-traits = ["futures-core-preview"]
+async-traits = []
 
 [dependencies]
 tokio-executor = { version = "0.2.0", path = "../tokio-executor" }
 tokio-sync = { version = "0.2.0", path = "../tokio-sync" }
+futures-core-preview = "0.3.0-alpha.17"
 
 async-util = { git = "https://github.com/tokio-rs/async" }
 crossbeam-utils = "0.6.0"
 # Backs `DelayQueue`
 slab = "0.4.1"
 # optionals
-futures-core-preview = { version = "0.3.0-alpha.17", optional = true }
 
 [dev-dependencies]
 rand = "0.7"
diff --git a/tokio-timer/src/delay.rs b/tokio-timer/src/delay.rs
index 7411e071..41210690 100644
--- a/tokio-timer/src/delay.rs
+++ b/tokio-timer/src/delay.rs
@@ -1,4 +1,5 @@
 use crate::timer::{HandlePriv, Registration};
+use futures_core::ready;
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{self, Poll};
diff --git a/tokio-timer/src/delay_queue.rs b/tokio-timer/src/delay_queue.rs
index 79b1d29f..d9d0f36c 100644
--- a/tokio-timer/src/delay_queue.rs
+++ b/tokio-timer/src/delay_queue.rs
@@ -9,6 +9,7 @@ use crate::timer::Handle;
 use crate::wheel::{self, Wheel};
 use crate::{Delay, Error};
 
+use futures_core::ready;
 use slab::Slab;
 use std::cmp;
 use std::future::Future;
diff --git a/tokio-timer/src/interval.rs b/tokio-timer/src/interval.rs
index e112d07a..f0448640 100644
--- a/tokio-timer/src/interval.rs
+++ b/tokio-timer/src/interval.rs
@@ -1,6 +1,7 @@
 use crate::clock;
 use crate::Delay;
 
+use futures_core::ready;
 use std::future::Future;
 use std::pin::Pin;
 use std::task::{self, Poll};
diff --git a/tokio-timer/src/lib.rs b/tokio-timer/src/lib.rs
index 48b9ba00..36449472 100644
--- a/tokio-timer/src/lib.rs
+++ b/tokio-timer/src/lib.rs
@@ -32,15 +32,6 @@
 //! [`Interval`]: struct.Interval.html
 //! [`Timer`]: timer/struct.Timer.html
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(v) => v,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 pub mod clock;
 pub mod delay_queue;
 #[cfg(feature = "async-traits")]
diff --git a/tokio-timer/src/throttle.rs b/tokio-timer/src/throttle.rs
index 494c42cc..dae09320 100644
--- a/tokio-timer/src/throttle.rs
+++ b/tokio-timer/src/throttle.rs
@@ -1,6 +1,7 @@
 //! Slow down a stream by enforcing a delay between items.
 
 use crate::{clock, Delay};
+use futures_core::ready;
 use futures_core::Stream;
 use std::{
     future::Future,
diff --git a/tokio-timer/src/timeout.rs b/tokio-timer/src/timeout.rs
index a8ce0d52..18068778 100644
--- a/tokio-timer/src/timeout.rs
+++ b/tokio-timer/src/timeout.rs
@@ -6,6 +6,8 @@
 
 use crate::clock::now;
 use crate::Delay;
+#[cfg(feature = "async-traits")]
+use futures_core::ready;
 use std::fmt;
 use std::future::Future;
 use std::pin::Pin;
diff --git a/tokio-udp/Cargo.toml b/tokio-udp/Cargo.toml
index d3dc66d8..2af96b5d 100644
--- a/tokio-udp/Cargo.toml
+++ b/tokio-udp/Cargo.toml
@@ -28,6 +28,7 @@ tokio-reactor = { version = "0.2.0", path = "../tokio-reactor" }
 # bytes = "0.4"
 mio = "0.6.14"
 log = "0.4"
+futures-core-preview = "0.3.0-alpha.17"
 
 [dev-dependencies]
 env_logger = { version = "0.5", default-features = false }
diff --git a/tokio-udp/src/lib.rs b/tokio-udp/src/lib.rs
index 2fe90a8f..13ffeeec 100644
--- a/tokio-udp/src/lib.rs
+++ b/tokio-udp/src/lib.rs
@@ -12,15 +12,6 @@
 //! Reading and writing to it can be done using futures, which return the
 //! [`Recv`], [`Send`], [`RecvFrom`] and [`SendTo`] structs respectively.
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 // mod frame;
 mod recv;
 mod recv_from;
diff --git a/tokio-udp/src/socket.rs b/tokio-udp/src/socket.rs
index 55648a42..6cbec5f8 100644
--- a/tokio-udp/src/socket.rs
+++ b/tokio-udp/src/socket.rs
@@ -1,5 +1,6 @@
 use super::split::{split, UdpSocketRecvHalf, UdpSocketSendHalf};
 use super::{Recv, RecvFrom, Send, SendTo};
+use futures_core::ready;
 use mio;
 use std::convert::TryFrom;
 use std::fmt;
diff --git a/tokio-uds/Cargo.toml b/tokio-uds/Cargo.toml
index 2d941ec4..8a4437dc 100644
--- a/tokio-uds/Cargo.toml
+++ b/tokio-uds/Cargo.toml
@@ -22,11 +22,11 @@ categories = ["asynchronous"]
 publish = false
 
 [features]
-async-traits = ["futures-core-preview"]
+async-traits = []
 
 [dependencies]
 bytes = "0.4.8"
-futures-core-preview = { version = "0.3.0-alpha.17", optional = true }
+futures-core-preview = { version = "0.3.0-alpha.17" }
 iovec = "0.1.2"
 libc = "0.2.42"
 log = "0.4.2"
diff --git a/tokio-uds/src/datagram.rs b/tokio-uds/src/datagram.rs
index 87d1d49b..6213a625 100644
--- a/tokio-uds/src/datagram.rs
+++ b/tokio-uds/src/datagram.rs
@@ -1,4 +1,5 @@
 use crate::{Recv, RecvFrom, Send, SendTo};
+use futures_core::ready;
 use mio::Ready;
 use mio_uds;
 use std::fmt;
diff --git a/tokio-uds/src/incoming.rs b/tokio-uds/src/incoming.rs
index 1a16302a..0bdbcad5 100644
--- a/tokio-uds/src/incoming.rs
+++ b/tokio-uds/src/incoming.rs
@@ -1,6 +1,7 @@
 #![cfg(feature = "async-traits")]
 
 use crate::{UnixListener, UnixStream};
+use futures_core::ready;
 use futures_core::stream::Stream;
 use std::io;
 use std::pin::Pin;
diff --git a/tokio-uds/src/lib.rs b/tokio-uds/src/lib.rs
index fef2a5c5..9ea1135b 100644
--- a/tokio-uds/src/lib.rs
+++ b/tokio-uds/src/lib.rs
@@ -8,15 +8,6 @@
 //!
 //! This crate provides APIs for using Unix Domain Sockets with Tokio.
 
-macro_rules! ready {
-    ($e:expr) => {
-        match $e {
-            ::std::task::Poll::Ready(t) => t,
-            ::std::task::Poll::Pending => return ::std::task::Poll::Pending,
-        }
-    };
-}
-
 mod datagram;
 // mod frame;
 mod incoming;
diff --git a/tokio-uds/src/listener.rs b/tokio-uds/src/listener.rs
index e875344a..17c50305 100644
--- a/tokio-uds/src/listener.rs
+++ b/tokio-uds/src/listener.rs
@@ -1,4 +1,5 @@
 use crate::UnixStream;
+use futures_core::ready;
 use mio::Ready;
 use mio_uds;
 use std::convert::TryFrom;
diff --git a/tokio-uds/src/stream.rs b/tokio-uds/src/stream.rs
index dfaa4fd9..7d13245f 100644
--- a/tokio-uds/src/stream.rs
+++ b/tokio-uds/src/stream.rs
@@ -1,5 +1,6 @@
 use crate::ucred::{self, UCred};
 use bytes::{Buf, BufMut};
+use futures_core::ready;
 use iovec::IoVec;
 use mio::Ready;
 use mio_uds;
diff --git a/tokio/Cargo.toml b/tokio/Cargo.toml
index 52bee83c..3eaeff97 100644
--- a/tokio/Cargo.toml
+++ b/tokio/Cargo.toml
@@ -62,6 +62,7 @@ uds = ["tokio-uds"]
 [dependencies]
 # Only non-optional dependency...
 #futures = "0.1.20"
+futures-core-preview = "0.3.0-alpha.17"
 
 # Everything else is optional...
 bytes = { version = "0.4", optional = true }
diff --git a/tokio/src/io/copy.rs b/tokio/src/io/copy.rs
index cc8e71dd..a324cbf8 100644
--- a/tokio/src/io/copy.rs
+++ b/tokio/src/io/copy.rs
@@ -1,3 +1,4 @@
+use futures_core::ready;
 use std::future::Future;
 use std::io;
 use std::pin::Pin;
diff --git a/tokio/src/io/read_exact.rs b/tokio/src/io/read_exact.rs
index 32320814..82b95362 100644
--- a/tokio/src/io/read_exact.rs
+++ b/tokio/sr