ntex-rt 4.1.0

ntex runtime
Documentation 
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use std::{fmt, pin::Pin, task::Context, task::Poll, task::ready};

use async_task::Task;

#[derive(Debug)]
/// A spawned task.
pub struct JoinHandle<T> {
    task: Option<Task<T>>,
}

impl<T> JoinHandle<T> {
    pub(crate) fn new(task: Task<T>) -> Self {
        JoinHandle { task: Some(task) }
    }

    /// Cancels the task.
    pub fn cancel(mut self) {
        if let Some(t) = self.task.take() {
            drop(t.cancel());
        }
    }

    /// Detaches the task so it continues running independently.
    pub fn detach(mut self) {
        if let Some(t) = self.task.take() {
            t.detach();
        }
    }

    /// Returns `true` if the task has finished.
    pub fn is_finished(&self) -> bool {
        match &self.task {
            Some(fut) => fut.is_finished(),
            None => true,
        }
    }
}

impl<T> Drop for JoinHandle<T> {
    fn drop(&mut self) {
        if let Some(fut) = self.task.take() {
            fut.detach();
        }
    }
}

impl<T> Future for JoinHandle<T> {
    type Output = Result<T, JoinError>;

    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
        Poll::Ready(match self.task.as_mut() {
            Some(fut) => Ok(ready!(Pin::new(fut).poll(cx))),
            None => Err(JoinError),
        })
    }
}

/// Error returned when a task handle no longer contains a task.
#[derive(Debug, Copy, Clone)]
pub struct JoinError;

impl fmt::Display for JoinError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "JoinError")
    }
}

impl std::error::Error for JoinError {}

#[cfg(all(test, not(feature = "tokio"), not(feature = "compio")))]
mod tests {
    use std::future::{pending, poll_fn};

    use crate::{Handle, System, testing::TestRunner};

    #[test]
    fn join_handle() {
        System::new("test", TestRunner).block_on(async {
            let hnd = crate::spawn(pending::<()>());
            assert!(!hnd.is_finished());
            hnd.cancel();

            assert_eq!(crate::spawn(async { 1 }).await.unwrap(), 1);

            let hnd = crate::spawn(async {});
            poll_fn(|cx| {
                if hnd.is_finished() {
                    std::task::Poll::Ready(())
                } else {
                    cx.waker().wake_by_ref();
                    std::task::Poll::Pending
                }
            })
            .await;

            let hnd = Handle::current().clone();
            hnd.notify().unwrap();
        });
        assert_eq!(super::JoinError.to_string(), "JoinError");
        assert_eq!(crate::rt_default::JoinError.to_string(), "JoinError");
    }
}