1 files changed, 87 insertions, 0 deletions
diff --git a/third_party/rust/tokio/src/io/util/sink.rs b/third_party/rust/tokio/src/io/util/sink.rs
new file mode 100644
index 0000000000..05ee773fa3
--- /dev/null
+++ b/third_party/rust/tokio/src/io/util/sink.rs
@@ -0,0 +1,87 @@
+use crate::io::AsyncWrite;
+
+use std::fmt;
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+cfg_io_util! {
+    /// 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`][std].
+    ///
+    /// [sink]: sink()
+    /// [std]: std::io::Sink
+    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`][std].
+    ///
+    /// [`poll_write`]: crate::io::AsyncWrite::poll_write()
+    /// [std]: std::io::sink
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use tokio::io::{self, AsyncWriteExt};
+    ///
+    /// #[tokio::main]
+    /// async fn main() -> io::Result<()> {
+    ///     let buffer = vec![1, 2, 3, 5, 8];
+    ///     let num_bytes = io::sink().write(&buffer).await?;
+    ///     assert_eq!(num_bytes, 5);
+    ///     Ok(())
+    /// }
+    /// ```
+    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>();
+    }
+}