async-await: update to new future/task API (#919)

- Rewrite noop_waker with items from the new API and replaces
  LocalWaker with Waker.

- Bump the minimum required version for `tokio-async-await` to
  1.34.0-nightly.

- `Unpin` was added to std prelude.

- Add `cargo check` to .travis.yml

Fixes: #908

.travis.yml

@@ -49,6 +49,7 @@ matrix:
     script: |
       cd tokio-async-await
       cargo check --all
+      cargo check --features async-await-preview
 
   # This runs TSAN against nightly and allows failures to propagate up.
   - rust: nightly-2018-11-18

tokio-async-await/README.md

@@ -9,7 +9,7 @@ guarantees. You are living on the edge here.**
 ## Usage
 
 To use this crate, you need to start with a Rust 2018 edition crate, with rustc
-1.33.0-nightly or later.
+1.34.0-nightly or later.
 
 Add this to your `Cargo.toml`:
 

tokio-async-await/src/compat/backward.rs

@@ -2,8 +2,8 @@ use futures::{Future, Poll};
 
 use std::future::Future as StdFuture;
 use std::pin::Pin;
-use std::ptr::NonNull;
-use std::task::{LocalWaker, Poll as StdPoll, UnsafeWake, Waker};
+use std::ptr;
+use std::task::{Poll as StdPoll, RawWaker, RawWakerVTable, Waker};
 
 /// Convert an 0.3 `Future` to an 0.1 `Future`.
 #[derive(Debug)]
@@ -44,9 +44,9 @@ where
     fn poll(&mut self) -> Poll<Item, Error> {
         use futures::Async::*;
 
-        let local_waker = noop_local_waker();
+        let waker = noop_waker();
 
-        let res = self.0.as_mut().poll(&local_waker);
+        let res = self.0.as_mut().poll(&waker);
 
         match res {
             StdPoll::Ready(Ok(val)) => Ok(Ready(val)),
@@ -58,26 +58,26 @@ where
 
 // ===== NoopWaker =====
 
-struct NoopWaker;
-
-fn noop_local_waker() -> LocalWaker {
-    let w: NonNull<NoopWaker> = NonNull::dangling();
-    unsafe { LocalWaker::new(w) }
+fn noop_raw_waker() -> RawWaker {
+    RawWaker::new(ptr::null(), &NOOP_WAKER_VTABLE)
 }
 
 fn noop_waker() -> Waker {
-    let w: NonNull<NoopWaker> = NonNull::dangling();
-    unsafe { Waker::new(w) }
+    unsafe { Waker::new_unchecked(noop_raw_waker()) }
 }
 
-unsafe impl UnsafeWake for NoopWaker {
-    unsafe fn clone_raw(&self) -> Waker {
-        noop_waker()
-    }
+unsafe fn clone_raw(_data: *const ()) -> RawWaker {
+    noop_raw_waker()
+}
 
-    unsafe fn drop_raw(&self) {}
+unsafe fn drop_raw(_data: *const ()) {}
 
-    unsafe fn wake(&self) {
-        unimplemented!("async-await-preview currently only supports futures 0.1. Use the compatibility layer of futures 0.3 instead, if you want to use futures 0.3.");
-    }
+unsafe fn wake(_data: *const ()) {
+    unimplemented!("async-await-preview currently only supports futures 0.1. Use the compatibility layer of futures 0.3 instead, if you want to use futures 0.3.");
 }
+
+const NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable {
+    clone: clone_raw,
+    drop: drop_raw,
+    wake,
+};

tokio-async-await/src/compat/forward.rs

@@ -1,9 +1,8 @@
 use futures::{Async, Future};
 
 use std::future::Future as StdFuture;
-use std::marker::Unpin;
 use std::pin::Pin;
-use std::task::{LocalWaker, Poll as StdPoll};
+use std::task::{Poll as StdPoll, Waker};
 
 /// Converts an 0.1 `Future` into an 0.3 `Future`.
 #[derive(Debug)]
@@ -54,7 +53,7 @@ where
 {
     type Output = Result<T::Item, T::Error>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &LocalWaker) -> StdPoll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &Waker) -> StdPoll<Self::Output> {
         use futures::Async::{NotReady, Ready};
 
         // TODO: wire in cx

tokio-async-await/src/io/flush.rs

@@ -2,9 +2,8 @@ use tokio_io::AsyncWrite;
 
 use std::future::Future;
 use std::io;
-use std::marker::Unpin;
 use std::pin::Pin;
-use std::task::{LocalWaker, Poll};
+use std::task::{Poll, Waker};
 
 /// A future used to fully flush an I/O object.
 #[derive(Debug)]
@@ -24,7 +23,7 @@ impl<'a, T: AsyncWrite + ?Sized> Flush<'a, T> {
 impl<'a, T: AsyncWrite + ?Sized> Future for Flush<'a, T> {
     type Output = io::Result<()>;
 
-    fn poll(mut self: Pin<&mut Self>, _wx: &LocalWaker) -> Poll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _wx: &Waker) -> Poll<Self::Output> {
         use crate::compat::forward::convert_poll;
         convert_poll(self.writer.poll_flush())
     }

tokio-async-await/src/io/read.rs

@@ -4,7 +4,6 @@ use std::future::Future;
 use std::task::{self, Poll};
 
 use std::io;
-use std::marker::Unpin;
 use std::pin::Pin;
 
 /// A future which can be used to read bytes.
@@ -26,7 +25,7 @@ impl<'a, T: AsyncRead + ?Sized> Read<'a, T> {
 impl<'a, T: AsyncRead + ?Sized> Future for Read<'a, T> {
     type Output = io::Result<usize>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &task::Waker) -> Poll<Self::Output> {
         use crate::compat::forward::convert_poll;
 
         let this = &mut *self;

tokio-async-await/src/io/read_exact.rs

@@ -4,7 +4,6 @@ use std::future::Future;
 use std::task::{self, Poll};
 
 use std::io;
-use std::marker::Unpin;
 use std::mem;
 use std::pin::Pin;
 
@@ -31,7 +30,7 @@ fn eof() -> io::Error {
 impl<'a, T: AsyncRead + ?Sized> Future for ReadExact<'a, T> {
     type Output = io::Result<()>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &task::Waker) -> Poll<Self::Output> {
         use crate::compat::forward::convert_poll;
 
         let this = &mut *self;

tokio-async-await/src/io/write.rs

@@ -4,7 +4,6 @@ use std::future::Future;
 use std::task::{self, Poll};
 
 use std::io;
-use std::marker::Unpin;
 use std::pin::Pin;
 
 /// A future used to write data.
@@ -26,7 +25,7 @@ impl<'a, T: AsyncWrite + ?Sized> Write<'a, T> {
 impl<'a, T: AsyncWrite + ?Sized> Future for Write<'a, T> {
     type Output = io::Result<usize>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<io::Result<usize>> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &task::Waker) -> Poll<io::Result<usize>> {
         use crate::compat::forward::convert_poll;
 
         let this = &mut *self;

tokio-async-await/src/io/write_all.rs

@@ -4,7 +4,6 @@ use std::future::Future;
 use std::task::{self, Poll};
 
 use std::io;
-use std::marker::Unpin;
 use std::mem;
 use std::pin::Pin;
 
@@ -31,7 +30,7 @@ fn zero_write() -> io::Error {
 impl<'a, T: AsyncWrite + ?Sized> Future for WriteAll<'a, T> {
     type Output = io::Result<()>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<io::Result<()>> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &task::Waker) -> Poll<io::Result<()>> {
         use crate::compat::forward::convert_poll;
 
         let this = &mut *self;

tokio-async-await/src/lib.rs

@@ -1,11 +1,5 @@
 #![cfg(feature = "async-await-preview")]
-#![feature(
-    rust_2018_preview,
-    arbitrary_self_types,
-    async_await,
-    await_macro,
-    futures_api
-)]
+#![feature(rust_2018_preview, async_await, await_macro, futures_api)]
 #![doc(html_root_url = "https://docs.rs/tokio-async-await/0.1.5")]
 #![deny(missing_docs, missing_debug_implementations)]
 #![cfg_attr(test, deny(warnings))]

tokio-async-await/src/sink/mod.rs

@@ -6,8 +6,6 @@ pub use self::send::Send;
 
 use futures::Sink;
 
-use std::marker::Unpin;
-
 /// An extension trait which adds utility methods to `Sink` types.
 pub trait SinkExt: Sink {
     /// Send an item into the sink.

tokio-async-await/src/sink/send.rs

@@ -3,7 +3,6 @@ use futures::Sink;
 use std::future::Future;
 use std::task::{self, Poll};
 
-use std::marker::Unpin;
 use std::pin::Pin;
 
 /// Future for the `SinkExt::send_async` combinator, which sends a value to a
@@ -28,7 +27,7 @@ impl<'a, T: Sink + Unpin + ?Sized> Send<'a, T> {
 impl<T: Sink + Unpin + ?Sized> Future for Send<'_, T> {
     type Output = Result<(), T::SinkError>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &task::LocalWaker) -> Poll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &task::Waker) -> Poll<Self::Output> {
         use crate::compat::forward::convert_poll;
         use futures::AsyncSink::{NotReady, Ready};
 

tokio-async-await/src/stream/mod.rs

@@ -6,8 +6,6 @@ pub use self::next::Next;
 
 use futures::Stream;
 
-use std::marker::Unpin;
-
 /// An extension trait which adds utility methods to `Stream` types.
 pub trait StreamExt: Stream {
     /// Creates a future that resolves to the next item in the stream.

tokio-async-await/src/stream/next.rs

@@ -1,9 +1,8 @@
 use futures::Stream;
 
 use std::future::Future;
-use std::marker::Unpin;
 use std::pin::Pin;
-use std::task::{LocalWaker, Poll};
+use std::task::{Poll, Waker};
 
 /// A future of the next element of a stream.
 #[derive(Debug)]
@@ -22,7 +21,7 @@ impl<'a, T: Stream + Unpin> Next<'a, T> {
 impl<'a, T: Stream + Unpin> Future for Next<'a, T> {
     type Output = Option<Result<T::Item, T::Error>>;
 
-    fn poll(mut self: Pin<&mut Self>, _lw: &LocalWaker) -> Poll<Self::Output> {
+    fn poll(mut self: Pin<&mut Self>, _waker: &Waker) -> Poll<Self::Output> {
         use crate::compat::forward::convert_poll_stream;
 
         convert_poll_stream(self.stream.poll())