broker_tokio/io/util/
sink.rs

1use crate::io::AsyncWrite;
2
3use std::fmt;
4use std::io;
5use std::pin::Pin;
6use std::task::{Context, Poll};
7
8cfg_io_util! {
9    /// An async writer which will move data into the void.
10    ///
11    /// This struct is generally created by calling [`sink`][sink]. Please
12    /// see the documentation of `sink()` for more details.
13    ///
14    /// This is an asynchronous version of [`std::io::Sink`][std].
15    ///
16    /// [sink]: sink()
17    /// [std]: std::io::Sink
18    pub struct Sink {
19        _p: (),
20    }
21
22    /// Creates an instance of an async writer which will successfully consume all
23    /// data.
24    ///
25    /// All calls to [`poll_write`] on the returned instance will return
26    /// `Poll::Ready(Ok(buf.len()))` and the contents of the buffer will not be
27    /// inspected.
28    ///
29    /// This is an asynchronous version of [`std::io::sink`][std].
30    ///
31    /// [`poll_write`]: crate::io::AsyncWrite::poll_write()
32    /// [std]: std::io::sink
33    ///
34    /// # Examples
35    ///
36    /// ```
37    /// use tokio::io::{self, AsyncWriteExt};
38    ///
39    /// #[tokio::main]
40    /// async fn main() -> io::Result<()> {
41    ///     let buffer = vec![1, 2, 3, 5, 8];
42    ///     let num_bytes = io::sink().write(&buffer).await?;
43    ///     assert_eq!(num_bytes, 5);
44    ///     Ok(())
45    /// }
46    /// ```
47    pub fn sink() -> Sink {
48        Sink { _p: () }
49    }
50}
51
52impl AsyncWrite for Sink {
53    #[inline]
54    fn poll_write(
55        self: Pin<&mut Self>,
56        _: &mut Context<'_>,
57        buf: &[u8],
58    ) -> Poll<Result<usize, io::Error>> {
59        Poll::Ready(Ok(buf.len()))
60    }
61
62    #[inline]
63    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
64        Poll::Ready(Ok(()))
65    }
66
67    #[inline]
68    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
69        Poll::Ready(Ok(()))
70    }
71}
72
73impl fmt::Debug for Sink {
74    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
75        f.pad("Sink { .. }")
76    }
77}
78
79#[cfg(test)]
80mod tests {
81    use super::*;
82
83    #[test]
84    fn assert_unpin() {
85        crate::is_unpin::<Sink>();
86    }
87}
broker_tokio/io/util/sink.rs

broker_tokio/io/util/
sink.rs
