1//! Asynchronous signal handling for Tokio.
2//!
3//! Note that signal handling is in general a very tricky topic and should be
4//! used with great care. This crate attempts to implement 'best practice' for
5//! signal handling, but it should be evaluated for your own applications' needs
6//! to see if it's suitable.
7//!
8//! There are some fundamental limitations of this crate documented on the OS
9//! specific structures, as well.
10//!
11//! # Examples
12//!
13//! Print on "ctrl-c" notification.
14//!
15//! ```rust,no_run
16//! use tokio::signal;
17//!
18//! #[tokio::main]
19//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
20//! signal::ctrl_c().await?;
21//! println!("ctrl-c received!");
22//! Ok(())
23//! }
24//! ```
25//!
26//! Wait for SIGHUP on Unix
27//!
28//! ```rust,no_run
29//! # #[cfg(unix)] {
30//! use tokio::signal::unix::{signal, SignalKind};
31//!
32//! #[tokio::main]
33//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
34//! // An infinite stream of hangup signals.
35//! let mut stream = signal(SignalKind::hangup())?;
36//!
37//! // Print whenever a HUP signal is received
38//! loop {
39//! stream.recv().await;
40//! println!("got signal HUP");
41//! }
42//! }
43//! # }
44//! ```
45use crate::sync::watch::Receiver;
46use std::task::{Context, Poll};
47
48mod ctrl_c;
49pub use ctrl_c::ctrl_c;
50
51pub(crate) mod registry;
52
53mod os {
54 #[cfg(unix)]
55 pub(crate) use super::unix::{OsExtraData, OsStorage};
56
57 #[cfg(windows)]
58 pub(crate) use super::windows::{OsExtraData, OsStorage};
59}
60
61pub mod unix;
62pub mod windows;
63
64mod reusable_box;
65use self::reusable_box::ReusableBoxFuture;
66
67#[derive(Debug)]
68struct RxFuture {
69 inner: ReusableBoxFuture<Receiver<()>>,
70}
71
72async fn make_future(mut rx: Receiver<()>) -> Receiver<()> {
73 rx.changed().await.expect("signal sender went away");
74 rx
75}
76
77impl RxFuture {
78 fn new(rx: Receiver<()>) -> Self {
79 Self {
80 inner: ReusableBoxFuture::new(make_future(rx)),
81 }
82 }
83
84 async fn recv(&mut self) -> Option<()> {
85 use crate::future::poll_fn;
86 poll_fn(|cx| self.poll_recv(cx)).await
87 }
88
89 fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
90 match self.inner.poll(cx) {
91 Poll::Pending => Poll::Pending,
92 Poll::Ready(rx) => {
93 self.inner.set(make_future(rx));
94 Poll::Ready(Some(()))
95 }
96 }
97 }
98}
99