futures_util/stream/stream/
catch_unwind.rs

1use futures_core::stream::{FusedStream, Stream};
2use futures_core::task::{Context, Poll};
3use pin_project_lite::pin_project;
4use std::any::Any;
5use std::boxed::Box;
6use std::panic::{catch_unwind, AssertUnwindSafe, UnwindSafe};
7use std::pin::Pin;
8
9pin_project! {
10    /// Stream for the [`catch_unwind`](super::StreamExt::catch_unwind) method.
11    #[derive(Debug)]
12    #[must_use = "streams do nothing unless polled"]
13    pub struct CatchUnwind<St> {
14        #[pin]
15        stream: St,
16        caught_unwind: bool,
17    }
18}
19
20impl<St: Stream + UnwindSafe> CatchUnwind<St> {
21    pub(super) fn new(stream: St) -> Self {
22        Self { stream, caught_unwind: false }
23    }
24
25    delegate_access_inner!(stream, St, ());
26}
27
28impl<St: Stream + UnwindSafe> Stream for CatchUnwind<St> {
29    type Item = Result<St::Item, Box<dyn Any + Send>>;
30
31    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
32        let mut this = self.project();
33
34        if *this.caught_unwind {
35            Poll::Ready(None)
36        } else {
37            let res = catch_unwind(AssertUnwindSafe(|| this.stream.as_mut().poll_next(cx)));
38
39            match res {
40                Ok(poll) => poll.map(|opt| opt.map(Ok)),
41                Err(e) => {
42                    *this.caught_unwind = true;
43                    Poll::Ready(Some(Err(e)))
44                }
45            }
46        }
47    }
48
49    fn size_hint(&self) -> (usize, Option<usize>) {
50        if self.caught_unwind {
51            (0, Some(0))
52        } else {
53            self.stream.size_hint()
54        }
55    }
56}
57
58impl<St: FusedStream + UnwindSafe> FusedStream for CatchUnwind<St> {
59    fn is_terminated(&self) -> bool {
60        self.caught_unwind || self.stream.is_terminated()
61    }
62}
futures_util/stream/stream/catch_unwind.rs

futures_util/stream/stream/
catch_unwind.rs
