Add impl Spawn and LocalSpawn for Arc and Rc.

Since rust-lang#1950 (0.3.0) the Spawn and LocalSpawn only require a shared reference
for spawning operations.

This adds blanket impls for `Arc<Sp: ?Sized + Spawn>` and `Rc<Sp: ?Sized + Spawn>`.
It does the same for LocalSpawn.

This allows client code to pass an Arc<Exec> when library code takes
parameters as `&dyn Spawn` or `impl Spawn`.

So far there were blanket impls for `&`, `&mut` and `Box`.

examples/functional/src/main.rs

@@ -30,9 +30,7 @@ fn main() {
         // responsible for transmission
         pool.spawn_ok(fut_tx_result);
 
-        let fut_values = rx
-            .map(|v| v * 2)
-            .collect();
+        let fut_values = rx.map(|v| v * 2).collect();
 
         // Use the executor provided to this async block to wait for the
         // future to complete.
@@ -45,4 +43,4 @@ fn main() {
     let values: Vec<i32> = executor::block_on(fut_values);
 
     println!("Values={:?}", values);
-}
+}

examples/imperative/src/main.rs

@@ -34,7 +34,7 @@ fn main() {
         // of the stream to be available.
         while let Some(v) = rx.next().await {
             pending.push(v * 2);
-        };
+        }
 
         pending
     };
@@ -45,4 +45,4 @@ fn main() {
     let values: Vec<i32> = executor::block_on(fut_values);
 
     println!("Values={:?}", values);
-}
+}

futures-channel/benches/sync_mpsc.rs

@@ -7,8 +7,8 @@ use {
     futures::{
         channel::mpsc::{self, Sender, UnboundedSender},
         ready,
-        stream::{Stream, StreamExt},
         sink::Sink,
+        stream::{Stream, StreamExt},
         task::{Context, Poll},
     },
     futures_test::task::noop_context,
@@ -25,7 +25,6 @@ fn unbounded_1_tx(b: &mut Bencher) {
         // 1000 iterations to avoid measuring overhead of initialization
         // Result should be divided by 1000
         for i in 0..1000 {
-
             // Poll, not ready, park
             assert_eq!(Poll::Pending, rx.poll_next_unpin(&mut cx));
 
@@ -73,7 +72,6 @@ fn unbounded_uncontended(b: &mut Bencher) {
     })
 }
 
-
 /// A Stream that continuously sends incrementing number of the queue
 struct TestSender {
     tx: Sender<u32>,
@@ -84,9 +82,7 @@ struct TestSender {
 impl Stream for TestSender {
     type Item = u32;
 
-    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>)
-        -> Poll<Option<Self::Item>>
-    {
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         let this = &mut *self;
         let mut tx = Pin::new(&mut this.tx);
 
@@ -123,12 +119,7 @@ fn bounded_100_tx(b: &mut Bencher) {
         // Each sender can send one item after specified capacity
         let (tx, mut rx) = mpsc::channel(0);
 
-        let mut tx: Vec<_> = (0..100).map(|_| {
-            TestSender {
-                tx: tx.clone(),
-                last: 0
-            }
-        }).collect();
+        let mut tx: Vec<_> = (0..100).map(|_| TestSender { tx: tx.clone(), last: 0 }).collect();
 
         for i in 0..10 {
             for x in &mut tx {

futures-channel/src/lib.rs

@@ -7,16 +7,12 @@
 //! library is activated, and it is activated by default.
 
 #![cfg_attr(feature = "cfg-target-has-atomic", feature(cfg_target_has_atomic))]
-
 #![cfg_attr(not(feature = "std"), no_std)]
-
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms, unreachable_pub)]
 // It cannot be included in the published code because this lints have false positives in the minimum required version.
 #![cfg_attr(test, warn(single_use_lifetimes))]
 #![warn(clippy::all)]
-
 #![doc(test(attr(deny(warnings), allow(dead_code, unused_assignments, unused_variables))))]
-
 #![doc(html_root_url = "https://docs.rs/futures-channel/0.3.0")]
 
 #[cfg(all(feature = "cfg-target-has-atomic", not(feature = "unstable")))]

futures-channel/tests/channel.rs

@@ -1,8 +1,8 @@
 use futures::channel::mpsc;
 use futures::executor::block_on;
 use futures::future::poll_fn;
-use futures::stream::StreamExt;
 use futures::sink::SinkExt;
+use futures::stream::StreamExt;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::thread;
 
@@ -11,9 +11,7 @@ fn sequence() {
     let (tx, rx) = mpsc::channel(1);
 
     let amt = 20;
-    let t = thread::spawn(move || {
-        block_on(send_sequence(amt, tx))
-    });
+    let t = thread::spawn(move || block_on(send_sequence(amt, tx)));
     let list: Vec<_> = block_on(rx.collect());
     let mut list = list.into_iter();
     for i in (1..=amt).rev() {
@@ -34,9 +32,7 @@ async fn send_sequence(n: u32, mut sender: mpsc::Sender<u32>) {
 fn drop_sender() {
     let (tx, mut rx) = mpsc::channel::<u32>(1);
     drop(tx);
-    let f = poll_fn(|cx| {
-        rx.poll_next_unpin(cx)
-    });
+    let f = poll_fn(|cx| rx.poll_next_unpin(cx));
     assert_eq!(block_on(f), None)
 }
 

futures-channel/tests/mpsc-close.rs

@@ -8,9 +8,7 @@ use std::thread;
 fn smoke() {
     let (mut sender, receiver) = mpsc::channel(1);
 
-    let t = thread::spawn(move || {
-        while let Ok(()) = block_on(sender.send(42)) {}
-    });
+    let t = thread::spawn(move || while let Ok(()) = block_on(sender.send(42)) {});
 
     // `receiver` needs to be dropped for `sender` to stop sending and therefore before the join.
     block_on(receiver.take(3).for_each(|_| futures::future::ready(())));

futures-channel/tests/mpsc.rs

@@ -1,13 +1,13 @@
 use futures::channel::{mpsc, oneshot};
 use futures::executor::{block_on, block_on_stream};
-use futures::future::{FutureExt, poll_fn};
-use futures::stream::{Stream, StreamExt};
+use futures::future::{poll_fn, FutureExt};
+use futures::pin_mut;
 use futures::sink::{Sink, SinkExt};
+use futures::stream::{Stream, StreamExt};
 use futures::task::{Context, Poll};
-use futures::pin_mut;
 use futures_test::task::{new_count_waker, noop_context};
-use std::sync::{Arc, Mutex};
 use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::{Arc, Mutex};
 use std::thread;
 
 trait AssertSend: Send {}
@@ -77,7 +77,7 @@ fn send_shared_recv() {
 fn send_recv_threads() {
     let (mut tx, rx) = mpsc::channel::<i32>(16);
 
-    let t = thread::spawn(move|| {
+    let t = thread::spawn(move || {
         block_on(tx.send(1)).unwrap();
     });
 
@@ -204,7 +204,7 @@ fn stress_shared_unbounded() {
     const NTHREADS: u32 = 8;
     let (tx, rx) = mpsc::unbounded::<i32>();
 
-    let t = thread::spawn(move|| {
+    let t = thread::spawn(move || {
         let result: Vec<_> = block_on(rx.collect());
         assert_eq!(result.len(), (AMT * NTHREADS) as usize);
         for item in result {
@@ -215,7 +215,7 @@ fn stress_shared_unbounded() {
     for _ in 0..NTHREADS {
         let tx = tx.clone();
 
-        thread::spawn(move|| {
+        thread::spawn(move || {
             for _ in 0..AMT {
                 tx.unbounded_send(1).unwrap();
             }
@@ -233,7 +233,7 @@ fn stress_shared_bounded_hard() {
     const NTHREADS: u32 = 8;
     let (tx, rx) = mpsc::channel::<i32>(0);
 
-    let t = thread::spawn(move|| {
+    let t = thread::spawn(move || {
         let result: Vec<_> = block_on(rx.collect());
         assert_eq!(result.len(), (AMT * NTHREADS) as usize);
         for item in result {
@@ -296,9 +296,9 @@ fn stress_receiver_multi_task_bounded_hard() {
                             }
                             Poll::Ready(None) => {
                                 *rx_opt = None;
-                                break
-                            },
-                            Poll::Pending => {},
+                                break;
+                            }
+                            Poll::Pending => {}
                         }
                     }
                 } else {
@@ -310,7 +310,6 @@ fn stress_receiver_multi_task_bounded_hard() {
         th.push(t);
     }
 
-
     for i in 0..AMT {
         block_on(tx.send(i)).unwrap();
     }
@@ -327,7 +326,7 @@ fn stress_receiver_multi_task_bounded_hard() {
 /// after sender dropped.
 #[test]
 fn stress_drop_sender() {
-    fn list() -> impl Stream<Item=i32> {
+    fn list() -> impl Stream<Item = i32> {
         let (tx, rx) = mpsc::channel(1);
         thread::spawn(move || {
             block_on(send_one_two_three(tx));
@@ -405,9 +404,7 @@ fn stress_poll_ready() {
         let mut threads = Vec::new();
         for _ in 0..NTHREADS {
             let sender = tx.clone();
-            threads.push(thread::spawn(move || {
-                block_on(stress_poll_ready_sender(sender, AMT))
-            }));
+            threads.push(thread::spawn(move || block_on(stress_poll_ready_sender(sender, AMT))));
         }
         drop(tx);
 
@@ -434,7 +431,7 @@ fn try_send_1() {
         for i in 0..N {
             loop {
                 if tx.try_send(i).is_ok() {
-                    break
+                    break;
                 }
             }
         }
@@ -529,8 +526,8 @@ fn same_receiver() {
 
 #[test]
 fn hash_receiver() {
-    use std::hash::Hasher;
     use std::collections::hash_map::DefaultHasher;
+    use std::hash::Hasher;
 
     let mut hasher_a1 = DefaultHasher::new();
     let mut hasher_a2 = DefaultHasher::new();

futures-channel/tests/oneshot.rs

@@ -1,6 +1,6 @@
 use futures::channel::oneshot::{self, Sender};
 use futures::executor::block_on;
-use futures::future::{Future, FutureExt, poll_fn};
+use futures::future::{poll_fn, Future, FutureExt};
 use futures::task::{Context, Poll};
 use futures_test::task::panic_waker_ref;
 use std::pin::Pin;
@@ -83,7 +83,7 @@ fn close() {
     rx.close();
     block_on(poll_fn(|cx| {
         match rx.poll_unpin(cx) {
-            Poll::Ready(Err(_)) => {},
+            Poll::Ready(Err(_)) => {}
             _ => panic!(),
         };
         assert!(tx.poll_canceled(cx).is_ready());

futures-core/src/future.rs

@@ -66,14 +66,12 @@ pub trait TryFuture: Future + private_try_future::Sealed {
     /// This method is a stopgap for a compiler limitation that prevents us from
     /// directly inheriting from the `Future` trait; in the future it won't be
     /// needed.
-    fn try_poll(
-        self: Pin<&mut Self>,
-        cx: &mut Context<'_>,
-    ) -> Poll<Result<Self::Ok, Self::Error>>;
+    fn try_poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<Self::Ok, Self::Error>>;
 }
 
 impl<F, T, E> TryFuture for F
-    where F: ?Sized + Future<Output = Result<T, E>>
+where
+    F: ?Sized + Future<Output = Result<T, E>>,
 {
     type Ok = T;
     type Error = E;
@@ -86,8 +84,8 @@ impl<F, T, E> TryFuture for F
 
 #[cfg(feature = "alloc")]
 mod if_alloc {
-    use alloc::boxed::Box;
     use super::*;
+    use alloc::boxed::Box;
 
     impl<F: FusedFuture + ?Sized + Unpin> FusedFuture for Box<F> {
         fn is_terminated(&self) -> bool {

futures-core/src/lib.rs

@@ -1,16 +1,12 @@
 //! Core traits and types for asynchronous operations in Rust.
 
 #![cfg_attr(feature = "cfg-target-has-atomic", feature(cfg_target_has_atomic))]
-
 #![cfg_attr(not(feature = "std"), no_std)]
-
 #![warn(missing_docs, missing_debug_implementations, rust_2018_idioms, unreachable_pub)]
 // It cannot be included in the published code because this lints have false positives in the minimum required version.
 #![cfg_attr(test, warn(single_use_lifetimes))]
 #![warn(clippy::all)]
-
 #![doc(test(attr(deny(warnings), allow(dead_code, unused_assignments, unused_variables))))]
-
 #![doc(html_root_url = "https://docs.rs/futures-core/0.3.0")]
 
 #[cfg(all(feature = "cfg-target-has-atomic", not(feature = "unstable")))]
@@ -20,10 +16,12 @@ compile_error!("The `cfg-target-has-atomic` feature requires the `unstable` feat
 extern crate alloc;
 
 pub mod future;
-#[doc(hidden)] pub use self::future::{Future, FusedFuture, TryFuture};
+#[doc(hidden)]
+pub use self::future::{FusedFuture, Future, TryFuture};
 
 pub mod stream;
-#[doc(hidden)] pub use self::stream::{Stream, FusedStream, TryStream};
+#[doc(hidden)]
+pub use self::stream::{FusedStream, Stream, TryStream};
 
 #[macro_use]
 pub mod task;