1 files changed, 78 insertions, 0 deletions
diff --git a/tokio/src/io/util/sink.rs b/tokio/src/io/util/sink.rs
new file mode 100644
index 00000000..48363658
--- /dev/null
+++ b/tokio/src/io/util/sink.rs
@@ -0,0 +1,78 @@
+use crate::io::AsyncWrite;
+
+use std::fmt;
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+/// An async writer which will move data into the void.
+///
+/// This struct is generally created by calling [`sink`][sink]. Please
+/// see the documentation of `sink()` for more details.
+///
+/// This is an asynchronous version of `std::io::Sink`.
+///
+/// [sink]: fn.sink.html
+pub struct Sink {
+    _p: (),
+}
+
+/// Creates an instance of an async writer which will successfully consume all
+/// data.
+///
+/// All calls to `poll_write` on the returned instance will return
+/// `Poll::Ready(Ok(buf.len()))` and the contents of the buffer will not be
+/// inspected.
+///
+/// This is an asynchronous version of `std::io::sink`.
+///
+/// # Examples
+///
+/// ```rust
+/// # use tokio::io::{self, AsyncWriteExt};
+/// # async fn dox() {
+/// let buffer = vec![1, 2, 3, 5, 8];
+/// let num_bytes = io::sink().write(&buffer).await.unwrap();
+/// assert_eq!(num_bytes, 5);
+/// # }
+/// ```
+pub fn sink() -> Sink {
+    Sink { _p: () }
+}
+
+impl AsyncWrite for Sink {
+    #[inline]
+    fn poll_write(
+        self: Pin<&mut Self>,
+        _: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        Poll::Ready(Ok(buf.len()))
+    }
+
+    #[inline]
+    fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    #[inline]
+    fn poll_shutdown(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl fmt::Debug for Sink {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.pad("Sink { .. }")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn assert_unpin() {
+        crate::is_unpin::<Sink>();
+    }
+}