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//! Asynchronous signal handling for Tokio.
//!
//! Note that signal handling is in general a very tricky topic and should be
//! used with great care. This crate attempts to implement 'best practice' for
//! signal handling, but it should be evaluated for your own applications' needs
//! to see if it's suitable.
//!
//! There are some fundamental limitations of this crate documented on the OS
//! specific structures, as well.
//!
//! # Examples
//!
//! Print on "ctrl-c" notification.
//!
//! ```rust,no_run
//! use tokio::signal;
//!
//! #[tokio::main]
//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! signal::ctrl_c().await?;
//! println!("ctrl-c received!");
//! Ok(())
//! }
//! ```
//!
//! Wait for SIGHUP on Unix
//!
//! ```rust,no_run
//! # #[cfg(unix)] {
//! use tokio::signal::unix::{signal, SignalKind};
//!
//! #[tokio::main]
//! async fn main() -> Result<(), Box<dyn std::error::Error>> {
//! // An infinite stream of hangup signals.
//! let mut stream = signal(SignalKind::hangup())?;
//!
//! // Print whenever a HUP signal is received
//! loop {
//! stream.recv().await;
//! println!("got signal HUP");
//! }
//! }
//! # }
//! ```
use crate::sync::watch::Receiver;
use std::task::{Context, Poll};
mod ctrl_c;
pub use ctrl_c::ctrl_c;
pub(crate) mod registry;
mod os {
#[cfg(unix)]
pub(crate) use super::unix::{OsExtraData, OsStorage};
#[cfg(windows)]
pub(crate) use super::windows::{OsExtraData, OsStorage};
}
pub mod unix;
pub mod windows;
mod reusable_box;
use self::reusable_box::ReusableBoxFuture;
#[derive(Debug)]
struct RxFuture {
inner: ReusableBoxFuture<Receiver<()>>,
}
async fn make_future(mut rx: Receiver<()>) -> Receiver<()> {
match rx.changed().await {
Ok(()) => rx,
Err(_) => panic!("signal sender went away"),
}
}
impl RxFuture {
fn new(rx: Receiver<()>) -> Self {
Self {
inner: ReusableBoxFuture::new(make_future(rx)),
}
}
async fn recv(&mut self) -> Option<()> {
use crate::future::poll_fn;
poll_fn(|cx| self.poll_recv(cx)).await
}
fn poll_recv(&mut self, cx: &mut Context<'_>) -> Poll<Option<()>> {
match self.inner.poll(cx) {
Poll::Pending => Poll::Pending,
Poll::Ready(rx) => {
self.inner.set(make_future(rx));
Poll::Ready(Some(()))
}
}
}
}