From d512e7c45cd23a3290413e32d6fdf69f794d2ff7 Mon Sep 17 00:00:00 2001
From: Stjepan Glavina <stjepang@gmail.com>
Date: Wed, 14 Aug 2019 16:14:44 +0200
Subject: [PATCH 1/3] Add io::timeout()

---
 src/io/mod.rs     |  2 ++
 src/io/timeout.rs | 70 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)
 create mode 100644 src/io/timeout.rs

diff --git a/src/io/mod.rs b/src/io/mod.rs
index daf70b8e..aae9cb56 100644
--- a/src/io/mod.rs
+++ b/src/io/mod.rs
@@ -32,6 +32,7 @@ pub use seek::Seek;
 pub use stderr::{stderr, Stderr};
 pub use stdin::{stdin, Stdin};
 pub use stdout::{stdout, Stdout};
+pub use timeout::timeout;
 pub use write::Write;
 
 mod buf_read;
@@ -42,4 +43,5 @@ mod seek;
 mod stderr;
 mod stdin;
 mod stdout;
+mod timeout;
 mod write;
diff --git a/src/io/timeout.rs b/src/io/timeout.rs
new file mode 100644
index 00000000..5902989e
--- /dev/null
+++ b/src/io/timeout.rs
@@ -0,0 +1,70 @@
+use std::pin::Pin;
+use std::time::Duration;
+
+use futures_timer::Delay;
+use pin_utils::unsafe_pinned;
+
+use crate::future::Future;
+use crate::io;
+use crate::task::{Context, Poll};
+
+/// Awaits an I/O future or times out after a duration of time.
+///
+/// # Examples
+///
+/// ```no_run
+/// # #![feature(async_await)]
+/// # fn main() -> std::io::Result<()> { async_std::task::block_on(async {
+/// #
+/// use std::time::Duration;
+///
+/// use async_std::io;
+///
+/// let stdin = io::stdin();
+/// let mut line = String::new();
+///
+/// let dur = Duration::from_secs(5);
+/// let n = io::timeout(dur, stdin.read_line(&mut line)).await?;
+/// #
+/// # Ok(()) }) }
+/// ```
+pub async fn timeout<F, T>(dur: Duration, f: F) -> io::Result<T>
+where
+    F: Future<Output = io::Result<T>>,
+{
+    let f = TimeoutFuture {
+        future: f,
+        delay: Delay::new(dur),
+    };
+    f.await
+}
+
+struct TimeoutFuture<F> {
+    future: F,
+    delay: Delay,
+}
+
+impl<F> TimeoutFuture<F> {
+    unsafe_pinned!(future: F);
+    unsafe_pinned!(delay: Delay);
+}
+
+impl<F, T> Future for TimeoutFuture<F>
+where
+    F: Future<Output = io::Result<T>>,
+{
+    type Output = F::Output;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        match self.as_mut().future().poll(cx) {
+            Poll::Ready(v) => Poll::Ready(v),
+            Poll::Pending => match self.delay().poll(cx) {
+                Poll::Ready(_) => Poll::Ready(Err(io::Error::new(
+                    io::ErrorKind::TimedOut,
+                    "future has timed out",
+                ))),
+                Poll::Pending => Poll::Pending,
+            },
+        }
+    }
+}

From 79bfd92154cd89feb640d6336ea70c3d80a9073f Mon Sep 17 00:00:00 2001
From: Yoshua Wuyts <yoshuawuyts+github@gmail.com>
Date: Thu, 15 Aug 2019 02:55:37 +0200
Subject: [PATCH 2/3] Update src/io/timeout.rs

Co-Authored-By: Florian Gilcher <flo@andersground.net>
---
 src/io/timeout.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/io/timeout.rs b/src/io/timeout.rs
index 5902989e..a989b2df 100644
--- a/src/io/timeout.rs
+++ b/src/io/timeout.rs
@@ -61,7 +61,7 @@ where
             Poll::Pending => match self.delay().poll(cx) {
                 Poll::Ready(_) => Poll::Ready(Err(io::Error::new(
                     io::ErrorKind::TimedOut,
-                    "future has timed out",
+                    "IO operation has timed out",
                 ))),
                 Poll::Pending => Poll::Pending,
             },

From e3fc67c1cbfd56244d6bc9e0649e218c7741510b Mon Sep 17 00:00:00 2001
From: Stjepan Glavina <stjepang@gmail.com>
Date: Thu, 15 Aug 2019 17:59:48 +0200
Subject: [PATCH 3/3] Address comments

---
 examples/stdin-timeout.rs | 19 +++++--------------
 src/io/timeout.rs         | 13 +++++++------
 2 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/examples/stdin-timeout.rs b/examples/stdin-timeout.rs
index dde49e5b..04b860a2 100644
--- a/examples/stdin-timeout.rs
+++ b/examples/stdin-timeout.rs
@@ -9,22 +9,13 @@ use async_std::prelude::*;
 use async_std::task;
 
 fn main() -> io::Result<()> {
-    task::block_on(async {
+    task::block_on(io::timeout(Duration::from_secs(5), async {
         let stdin = io::stdin();
-        let mut line = String::new();
 
-        match stdin
-            .read_line(&mut line)
-            .timeout(Duration::from_secs(5))
-            .await
-        {
-            Ok(res) => {
-                res?;
-                print!("Got line: {}", line);
-            }
-            Err(_) => println!("You have only 5 seconds to enter a line. Try again :)"),
-        }
+        let mut line = String::new();
+        stdin.read_line(&mut line).await?;
 
+        print!("Got line: {}", line);
         Ok(())
-    })
+    }))
 }
diff --git a/src/io/timeout.rs b/src/io/timeout.rs
index 5902989e..b35a8030 100644
--- a/src/io/timeout.rs
+++ b/src/io/timeout.rs
@@ -20,11 +20,12 @@ use crate::task::{Context, Poll};
 ///
 /// use async_std::io;
 ///
-/// let stdin = io::stdin();
-/// let mut line = String::new();
-///
-/// let dur = Duration::from_secs(5);
-/// let n = io::timeout(dur, stdin.read_line(&mut line)).await?;
+/// io::timeout(Duration::from_secs(5), async {
+///     let stdin = io::stdin();
+///     let mut line = String::new();
+///     let n = stdin.read_line(&mut line).await?;
+/// })
+/// .await?;
 /// #
 /// # Ok(()) }) }
 /// ```
@@ -61,7 +62,7 @@ where
             Poll::Pending => match self.delay().poll(cx) {
                 Poll::Ready(_) => Poll::Ready(Err(io::Error::new(
                     io::ErrorKind::TimedOut,
-                    "future has timed out",
+                    "I/O operation has timed out",
                 ))),
                 Poll::Pending => Poll::Pending,
             },