1 files changed, 102 insertions, 0 deletions
diff --git a/src/async_tokio.rs b/src/async_tokio.rs
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+++ b/src/async_tokio.rs
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+// Copyright (c) 2018 The rust-gpio-cdev Project Developers.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Wrapper for asynchronous programming using Tokio.
+
+use futures::ready;
+use futures::stream::Stream;
+use futures::task::{Context, Poll};
+use tokio::io::unix::{AsyncFd, TryIoError};
+
+use std::os::unix::io::AsRawFd;
+use std::pin::Pin;
+
+use super::event_err;
+use super::{LineEvent, LineEventHandle, Result};
+
+/// Wrapper around a `LineEventHandle` which implements a `futures::stream::Stream` for interrupts.
+///
+/// # Example
+///
+/// The following example waits for state changes on an input line.
+///
+/// ```no_run
+/// use futures::stream::StreamExt;
+/// use gpio_cdev::{AsyncLineEventHandle, Chip, EventRequestFlags, LineRequestFlags};
+///
+/// async fn print_events(line: u32) -> Result<(), gpio_cdev::Error> {
+///     let mut chip = Chip::new("/dev/gpiochip0")?;
+///     let line = chip.get_line(line)?;
+///     let mut events = AsyncLineEventHandle::new(line.events(
+///         LineRequestFlags::INPUT,
+///         EventRequestFlags::BOTH_EDGES,
+///         "gpioevents",
+///     )?)?;
+///
+///     loop {
+///         match events.next().await {
+///             Some(event) => println!("{:?}", event?),
+///             None => break,
+///         };
+///     }
+///
+///     Ok(())
+/// }
+///
+/// # #[tokio::main]
+/// # async fn main() {
+/// #     print_events(42).await.unwrap();
+/// # }
+/// ```
+pub struct AsyncLineEventHandle {
+    asyncfd: AsyncFd<LineEventHandle>,
+}
+
+impl AsyncLineEventHandle {
+    /// Wraps the specified `LineEventHandle`.
+    ///
+    /// # Arguments
+    ///
+    /// * `handle` - handle to be wrapped.
+    pub fn new(handle: LineEventHandle) -> Result<AsyncLineEventHandle> {
+        // The file descriptor needs to be configured for non-blocking I/O for PollEvented to work.
+        let fd = handle.file.as_raw_fd();
+        unsafe {
+            let flags = libc::fcntl(fd, libc::F_GETFL, 0);
+            libc::fcntl(fd, libc::F_SETFL, flags | libc::O_NONBLOCK);
+        }
+
+        Ok(AsyncLineEventHandle {
+            asyncfd: AsyncFd::new(handle)?,
+        })
+    }
+}
+
+impl Stream for AsyncLineEventHandle {
+    type Item = Result<LineEvent>;
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
+        loop {
+            let mut guard = ready!(self.asyncfd.poll_read_ready_mut(cx))?;
+            match guard.try_io(|inner| inner.get_mut().read_event()) {
+                Err(TryIoError { .. }) => {
+                    // Continue
+                }
+                Ok(Ok(Some(event))) => return Poll::Ready(Some(Ok(event))),
+                Ok(Ok(None)) => return Poll::Ready(Some(Err(event_err(nix::errno::Errno::EIO)))),
+                Ok(Err(err)) => return Poll::Ready(Some(Err(err.into()))),
+            }
+        }
+    }
+}
+
+impl AsRef<LineEventHandle> for AsyncLineEventHandle {
+    fn as_ref(&self) -> &LineEventHandle {
+        self.asyncfd.get_ref()
+    }
+}