1 files changed, 100 insertions, 0 deletions
diff --git a/third_party/rust/futures-util/src/sink/send_all.rs b/third_party/rust/futures-util/src/sink/send_all.rs
new file mode 100644
index 0000000000..1302dd2148
--- /dev/null
+++ b/third_party/rust/futures-util/src/sink/send_all.rs
@@ -0,0 +1,100 @@
+use crate::stream::{Fuse, StreamExt, TryStreamExt};
+use core::fmt;
+use core::pin::Pin;
+use futures_core::future::Future;
+use futures_core::ready;
+use futures_core::stream::{Stream, TryStream};
+use futures_core::task::{Context, Poll};
+use futures_sink::Sink;
+
+/// Future for the [`send_all`](super::SinkExt::send_all) method.
+#[allow(explicit_outlives_requirements)] // https://github.com/rust-lang/rust/issues/60993
+#[must_use = "futures do nothing unless you `.await` or poll them"]
+pub struct SendAll<'a, Si, St>
+where
+    Si: ?Sized,
+    St: ?Sized + TryStream,
+{
+    sink: &'a mut Si,
+    stream: Fuse<&'a mut St>,
+    buffered: Option<St::Ok>,
+}
+
+impl<Si, St> fmt::Debug for SendAll<'_, Si, St>
+where
+    Si: fmt::Debug + ?Sized,
+    St: fmt::Debug + ?Sized + TryStream,
+    St::Ok: fmt::Debug,
+{
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("SendAll")
+            .field("sink", &self.sink)
+            .field("stream", &self.stream)
+            .field("buffered", &self.buffered)
+            .finish()
+    }
+}
+
+// Pinning is never projected to any fields
+impl<Si, St> Unpin for SendAll<'_, Si, St>
+where
+    Si: Unpin + ?Sized,
+    St: TryStream + Unpin + ?Sized,
+{
+}
+
+impl<'a, Si, St, Ok, Error> SendAll<'a, Si, St>
+where
+    Si: Sink<Ok, Error = Error> + Unpin + ?Sized,
+    St: TryStream<Ok = Ok, Error = Error> + Stream + Unpin + ?Sized,
+{
+    pub(super) fn new(sink: &'a mut Si, stream: &'a mut St) -> Self {
+        Self { sink, stream: stream.fuse(), buffered: None }
+    }
+
+    fn try_start_send(
+        &mut self,
+        cx: &mut Context<'_>,
+        item: St::Ok,
+    ) -> Poll<Result<(), Si::Error>> {
+        debug_assert!(self.buffered.is_none());
+        match Pin::new(&mut self.sink).poll_ready(cx)? {
+            Poll::Ready(()) => Poll::Ready(Pin::new(&mut self.sink).start_send(item)),
+            Poll::Pending => {
+                self.buffered = Some(item);
+                Poll::Pending
+            }
+        }
+    }
+}
+
+impl<Si, St, Ok, Error> Future for SendAll<'_, Si, St>
+where
+    Si: Sink<Ok, Error = Error> + Unpin + ?Sized,
+    St: Stream<Item = Result<Ok, Error>> + Unpin + ?Sized,
+{
+    type Output = Result<(), Error>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
+        let this = &mut *self;
+        // If we've got an item buffered already, we need to write it to the
+        // sink before we can do anything else
+        if let Some(item) = this.buffered.take() {
+            ready!(this.try_start_send(cx, item))?
+        }
+
+        loop {
+            match this.stream.try_poll_next_unpin(cx)? {
+                Poll::Ready(Some(item)) => ready!(this.try_start_send(cx, item))?,
+                Poll::Ready(None) => {
+                    ready!(Pin::new(&mut this.sink).poll_flush(cx))?;
+                    return Poll::Ready(Ok(()));
+                }
+                Poll::Pending => {
+                    ready!(Pin::new(&mut this.sink).poll_flush(cx))?;
+                    return Poll::Pending;
+                }
+            }
+        }
+    }
+}