signal: move into tokio-net (#1463)

tokio-net/src/signal/ctrl_c.rs

@@ -0,0 +1,57 @@
+#[cfg(unix)]
+use super::unix::Signal as Inner;
+#[cfg(windows)]
+use super::windows::Event as Inner;
+use crate::driver::Handle;
+
+use futures_core::stream::Stream;
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+/// Represents a stream which receives "ctrl-c" notifications sent to the process.
+///
+/// In general signals are handled very differently across Unix and Windows, but
+/// this is somewhat cross platform in terms of how it can be handled. A ctrl-c
+/// event to a console process can be represented as a stream for both Windows
+/// and Unix.
+///
+/// Note that there are a number of caveats listening for signals, and you may
+/// wish to read up on the documentation in the `unix` or `windows` module to
+/// take a peek.
+///
+/// Notably, a notification to this process notifies *all* streams listening to
+/// this event. Moreover, the notifications **are coalesced** if they aren't processed
+/// quickly enough. This means that if two notifications are received back-to-back,
+/// then the stream may only receive one item about the two notifications.
+#[must_use = "streams do nothing unless polled"]
+#[derive(Debug)]
+pub struct CtrlC {
+    inner: Inner,
+}
+
+impl CtrlC {
+    /// Creates a new stream which receives "ctrl-c" notifications sent to the
+    /// process.
+    ///
+    /// This function binds to the default reactor.
+    pub fn new() -> io::Result<Self> {
+        Self::with_handle(&Handle::default())
+    }
+
+    /// Creates a new stream which receives "ctrl-c" notifications sent to the
+    /// process.
+    ///
+    /// This function binds to reactor specified by `handle`.
+    pub fn with_handle(handle: &Handle) -> io::Result<Self> {
+        Inner::ctrl_c(handle).map(|inner| Self { inner })
+    }
+}
+
+impl Stream for CtrlC {
+    type Item = ();
+
+    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        Pin::new(&mut self.inner).poll_next(cx)
+    }
+}