ntex_rt/
handle.rs

1use std::{fmt, pin::Pin, task::Context, task::Poll, task::ready};
2
3use async_task::Task;
4
5#[derive(Debug)]
6/// A spawned task.
7pub struct JoinHandle<T> {
8    task: Option<Task<T>>,
9}
10
11impl<T> JoinHandle<T> {
12    pub(crate) fn new(task: Task<T>) -> Self {
13        JoinHandle { task: Some(task) }
14    }
15
16    /// Cancels the task.
17    pub fn cancel(mut self) {
18        if let Some(t) = self.task.take() {
19            drop(t.cancel());
20        }
21    }
22
23    /// Detaches the task so it continues running independently.
24    pub fn detach(mut self) {
25        if let Some(t) = self.task.take() {
26            t.detach();
27        }
28    }
29
30    /// Returns `true` if the task has finished.
31    pub fn is_finished(&self) -> bool {
32        match &self.task {
33            Some(fut) => fut.is_finished(),
34            None => true,
35        }
36    }
37}
38
39impl<T> Drop for JoinHandle<T> {
40    fn drop(&mut self) {
41        if let Some(fut) = self.task.take() {
42            fut.detach();
43        }
44    }
45}
46
47impl<T> Future for JoinHandle<T> {
48    type Output = Result<T, JoinError>;
49
50    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
51        Poll::Ready(match self.task.as_mut() {
52            Some(fut) => Ok(ready!(Pin::new(fut).poll(cx))),
53            None => Err(JoinError),
54        })
55    }
56}
57
58/// Error returned when a task handle no longer contains a task.
59#[derive(Debug, Copy, Clone)]
60pub struct JoinError;
61
62impl fmt::Display for JoinError {
63    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
64        write!(f, "JoinError")
65    }
66}
67
68impl std::error::Error for JoinError {}
69
70#[cfg(all(test, not(feature = "tokio"), not(feature = "compio")))]
71mod tests {
72    use std::future::{pending, poll_fn};
73
74    use crate::{Handle, System, testing::TestRunner};
75
76    #[test]
77    fn join_handle() {
78        System::new("test", TestRunner).block_on(async {
79            let hnd = crate::spawn(pending::<()>());
80            assert!(!hnd.is_finished());
81            hnd.cancel();
82
83            assert_eq!(crate::spawn(async { 1 }).await.unwrap(), 1);
84
85            let hnd = crate::spawn(async {});
86            poll_fn(|cx| {
87                if hnd.is_finished() {
88                    std::task::Poll::Ready(())
89                } else {
90                    cx.waker().wake_by_ref();
91                    std::task::Poll::Pending
92                }
93            })
94            .await;
95
96            let hnd = Handle::current().clone();
97            hnd.notify().unwrap();
98        });
99        assert_eq!(super::JoinError.to_string(), "JoinError");
100        assert_eq!(crate::rt_default::JoinError.to_string(), "JoinError");
101    }
102}
ntex_rt/handle.rs

ntex_rt/
handle.rs
