Expose task::Context to lazy

Author: srijs

futures-executor/tests/local_pool.rs

@@ -40,7 +40,7 @@ fn run_until_single_future() {
     {
         let mut pool = LocalPool::new();
         let mut exec = pool.executor();
-        let fut = lazy(|| {
+        let fut = lazy(|_| {
             cnt += 1;
             DONE
         });
@@ -55,15 +55,15 @@ fn run_until_ignores_spawned() {
     let mut pool = LocalPool::new();
     let mut exec = pool.executor();
     exec.spawn_local(Box::new(pending())).unwrap();
-    pool.run_until(lazy(|| DONE), &mut exec).unwrap();
+    pool.run_until(lazy(|_| DONE), &mut exec).unwrap();
 }
 
 #[test]
 fn run_until_executes_spawned() {
     let (tx, rx) = oneshot::channel();
     let mut pool = LocalPool::new();
     let mut exec = pool.executor();
-    exec.spawn_local(Box::new(lazy(move || {
+    exec.spawn_local(Box::new(lazy(move |_| {
         tx.send(()).unwrap();
         DONE
     }))).unwrap();
@@ -79,8 +79,8 @@ fn run_executes_spawned() {
     let mut exec = pool.executor();
     let mut exec2 = pool.executor();
 
-    exec.spawn_local(Box::new(lazy(move || {
-        exec2.spawn_local(Box::new(lazy(move || {
+    exec.spawn_local(Box::new(lazy(move |_| {
+        exec2.spawn_local(Box::new(lazy(move |_| {
             cnt2.set(cnt2.get() + 1);
             DONE
         }))).unwrap();
@@ -103,7 +103,7 @@ fn run_spawn_many() {
 
     for _ in 0..ITER {
         let cnt = cnt.clone();
-        exec.spawn_local(Box::new(lazy(move || {
+        exec.spawn_local(Box::new(lazy(move |_| {
             cnt.set(cnt.get() + 1);
             DONE
         }))).unwrap();
@@ -120,7 +120,7 @@ fn nesting_run() {
     let mut pool = LocalPool::new();
     let mut exec = pool.executor();
 
-    exec.spawn(Box::new(lazy(|| {
+    exec.spawn(Box::new(lazy(|_| {
         let mut pool = LocalPool::new();
         let mut exec = pool.executor();
         pool.run(&mut exec);

futures-util/src/future/lazy.rs

@@ -37,16 +37,16 @@ enum _Lazy<R, F> {
 /// use futures::future::{self, FutureResult};
 ///
 /// # fn main() {
-/// let a = future::lazy(|| future::ok::<u32, u32>(1));
+/// let a = future::lazy(|_| future::ok::<u32, u32>(1));
 ///
-/// let b = future::lazy(|| -> FutureResult<u32, u32> {
+/// let b = future::lazy(|_| -> FutureResult<u32, u32> {
 ///     panic!("oh no!")
 /// });
 /// drop(b); // closure is never run
 /// # }
 /// ```
 pub fn lazy<R, F>(f: F) -> Lazy<R, F>
-    where F: FnOnce() -> R,
+    where F: FnOnce(&mut task::Context) -> R,
           R: IntoFuture
 {
     Lazy {
@@ -55,17 +55,17 @@ pub fn lazy<R, F>(f: F) -> Lazy<R, F>
 }
 
 impl<R, F> Lazy<R, F>
-    where F: FnOnce() -> R,
+    where F: FnOnce(&mut task::Context) -> R,
           R: IntoFuture,
 {
-    fn get(&mut self) -> &mut R::Future {
+    fn get(&mut self, cx: &mut task::Context) -> &mut R::Future {
         match self.inner {
             _Lazy::First(_) => {}
             _Lazy::Second(ref mut f) => return f,
             _Lazy::Moved => panic!(), // can only happen if `f()` panics
         }
         match mem::replace(&mut self.inner, _Lazy::Moved) {
-            _Lazy::First(f) => self.inner = _Lazy::Second(f().into_future()),
+            _Lazy::First(f) => self.inner = _Lazy::Second(f(cx).into_future()),
             _ => panic!(), // we already found First
         }
         match self.inner {
@@ -76,13 +76,13 @@ impl<R, F> Lazy<R, F>
 }
 
 impl<R, F> Future for Lazy<R, F>
-    where F: FnOnce() -> R,
+    where F: FnOnce(&mut task::Context) -> R,
           R: IntoFuture,
 {
     type Item = R::Item;
     type Error = R::Error;
 
     fn poll(&mut self, cx: &mut task::Context) -> Poll<R::Item, R::Error> {
-        self.get().poll(cx)
+        self.get(cx).poll(cx)
     }
 }

futures-util/src/future/mod.rs

@@ -741,7 +741,7 @@ pub trait FutureExt: Future {
     /// let mut future = future::ok::<i32, u32>(2);
     /// assert!(block_on(future.catch_unwind()).is_ok());
     ///
-    /// let mut future = future::lazy(|| -> FutureResult<i32, u32> {
+    /// let mut future = future::lazy(|_| -> FutureResult<i32, u32> {
     ///     panic!();
     ///     future::ok::<i32, u32>(2)
     /// });

futures/src/lib.rs

@@ -119,7 +119,7 @@ pub mod executor {
     //! ```
     //! use futures::executor::ThreadPool;
     //! # use futures::future::{Future, lazy};
-    //! # let my_app: Box<Future<Item = (), Error = ()>> = Box::new(lazy(|| Ok(())));
+    //! # let my_app: Box<Future<Item = (), Error = ()>> = Box::new(lazy(|_| Ok(())));
     //!
     //! // assumping `my_app: Future`
     //! ThreadPool::new().run(my_app);

tests/bilock.rs

@@ -14,7 +14,7 @@ use support::*;
 
 #[test]
 fn smoke() {
-    let future = future::lazy(|| {
+    let future = future::lazy(|_| {
         let (a, b) = BiLock::new(1);
 
         {

tests/ready_queue.rs

@@ -13,7 +13,7 @@ impl AssertSendSync for FuturesUnordered<()> {}
 
 #[test]
 fn basic_usage() {
-    future::lazy(move || {
+    future::lazy(move |_| {
         let mut queue = FuturesUnordered::new();
         let (tx1, rx1) = oneshot::channel();
         let (tx2, rx2) = oneshot::channel();
@@ -43,7 +43,7 @@ fn basic_usage() {
 
 #[test]
 fn resolving_errors() {
-    future::lazy(move || {
+    future::lazy(move |_| {
         let mut queue = FuturesUnordered::new();
         let (tx1, rx1) = oneshot::channel();
         let (tx2, rx2) = oneshot::channel();
@@ -73,7 +73,7 @@ fn resolving_errors() {
 
 #[test]
 fn dropping_ready_queue() {
-    future::lazy(move || {
+    future::lazy(move |_| {
         let mut queue = FuturesUnordered::new();
         let (mut tx1, rx1) = oneshot::channel::<()>();
         let (mut tx2, rx2) = oneshot::channel::<()>();
@@ -148,7 +148,7 @@ fn stress() {
 
 #[test]
 fn panicking_future_dropped() {
-    future::lazy(move || {
+    future::lazy(move |_| {
         let mut queue = FuturesUnordered::new();
         queue.push(future::poll_fn(|| -> Poll<i32, i32> {
             panic!()

tests/shared.rs

@@ -185,7 +185,7 @@ fn recursive_poll_with_unpark() {
     let f1 = run_stream.shared();
     let f2 = f1.clone();
     let f3 = f1.clone();
-    tx0.unbounded_send(Box::new(future::lazy(move || {
+    tx0.unbounded_send(Box::new(future::lazy(move |_| {
         task::current().notify();
         f1.map(|_|()).map_err(|_|())
             .select(rx1.map_err(|_|()))

tests/sink.rs

@@ -109,7 +109,7 @@ impl<S: Sink> Future for StartSendFut<S> {
 fn mpsc_blocking_start_send() {
     let (mut tx, mut rx) = mpsc::channel::<i32>(0);
 
-    futures::future::lazy(|| {
+    futures::future::lazy(|_| {
         assert_eq!(tx.start_send(0).unwrap(), AsyncSink::Ready);
 
         let flag = Flag::new();