tokio_stream/wrappers/
mpsc_unbounded.rs

1use crate::Stream;
2use std::pin::Pin;
3use std::task::{Context, Poll};
4use tokio::sync::mpsc::UnboundedReceiver;
5
6/// A wrapper around [`tokio::sync::mpsc::UnboundedReceiver`] that implements [`Stream`].
7///
8/// # Example
9///
10/// ```
11/// use tokio::sync::mpsc;
12/// use tokio_stream::wrappers::UnboundedReceiverStream;
13/// use tokio_stream::StreamExt;
14///
15/// # #[tokio::main(flavor = "current_thread")]
16/// # async fn main() -> Result<(), tokio::sync::mpsc::error::SendError<u8>> {
17/// let (tx, rx) = mpsc::unbounded_channel();
18/// tx.send(10)?;
19/// tx.send(20)?;
20/// # // prevent the doc test from hanging
21/// drop(tx);
22///
23/// let mut stream = UnboundedReceiverStream::new(rx);
24/// assert_eq!(stream.next().await, Some(10));
25/// assert_eq!(stream.next().await, Some(20));
26/// assert_eq!(stream.next().await, None);
27/// # Ok(())
28/// # }
29/// ```
30///
31/// [`tokio::sync::mpsc::UnboundedReceiver`]: struct@tokio::sync::mpsc::UnboundedReceiver
32/// [`Stream`]: trait@crate::Stream
33#[derive(Debug)]
34pub struct UnboundedReceiverStream<T> {
35    inner: UnboundedReceiver<T>,
36}
37
38impl<T> UnboundedReceiverStream<T> {
39    /// Create a new `UnboundedReceiverStream`.
40    pub fn new(recv: UnboundedReceiver<T>) -> Self {
41        Self { inner: recv }
42    }
43
44    /// Get back the inner `UnboundedReceiver`.
45    pub fn into_inner(self) -> UnboundedReceiver<T> {
46        self.inner
47    }
48
49    /// Closes the receiving half of a channel without dropping it.
50    ///
51    /// This prevents any further messages from being sent on the channel while
52    /// still enabling the receiver to drain messages that are buffered.
53    pub fn close(&mut self) {
54        self.inner.close();
55    }
56}
57
58impl<T> Stream for UnboundedReceiverStream<T> {
59    type Item = T;
60
61    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
62        self.inner.poll_recv(cx)
63    }
64
65    /// Returns the bounds of the stream based on the underlying receiver.
66    ///
67    /// For open channels, it returns `(receiver.len(), None)`.
68    ///
69    /// For closed channels, it returns `(receiver.len(), receiver.len())`.
70    fn size_hint(&self) -> (usize, Option<usize>) {
71        if self.inner.is_closed() {
72            let len = self.inner.len();
73            (len, Some(len))
74        } else {
75            (self.inner.len(), None)
76        }
77    }
78}
79
80impl<T> AsRef<UnboundedReceiver<T>> for UnboundedReceiverStream<T> {
81    fn as_ref(&self) -> &UnboundedReceiver<T> {
82        &self.inner
83    }
84}
85
86impl<T> AsMut<UnboundedReceiver<T>> for UnboundedReceiverStream<T> {
87    fn as_mut(&mut self) -> &mut UnboundedReceiver<T> {
88        &mut self.inner
89    }
90}
91
92impl<T> From<UnboundedReceiver<T>> for UnboundedReceiverStream<T> {
93    fn from(recv: UnboundedReceiver<T>) -> Self {
94        Self::new(recv)
95    }
96}
tokio_stream/wrappers/mpsc_unbounded.rs

tokio_stream/wrappers/
mpsc_unbounded.rs
