blob: 535e95b5a703c77aedf6cc6fec8f6a49876c66c6 [file] [log] [blame]
use core::marker::Unpin;
use core::pin::Pin;
use futures_core::future::Future;
use futures_core::task::{LocalWaker, Poll};
use futures_sink::Sink;
/// Future for the `Sink::send` combinator, which sends a value to a sink and
/// then waits until the sink has fully flushed.
#[derive(Debug)]
#[must_use = "futures do nothing unless polled"]
pub struct Send<'a, Si: Sink + Unpin + 'a + ?Sized> {
sink: &'a mut Si,
item: Option<Si::SinkItem>,
}
// Pinning is never projected to children
impl<Si: Sink + Unpin + ?Sized> Unpin for Send<'_, Si> {}
impl<'a, Si: Sink + Unpin + ?Sized> Send<'a, Si> {
pub(super) fn new(sink: &'a mut Si, item: Si::SinkItem) -> Self {
Send {
sink,
item: Some(item),
}
}
}
impl<Si: Sink + Unpin + ?Sized> Future for Send<'_, Si> {
type Output = Result<(), Si::SinkError>;
fn poll(
mut self: Pin<&mut Self>,
lw: &LocalWaker,
) -> Poll<Self::Output> {
let this = &mut *self;
if let Some(item) = this.item.take() {
let mut sink = Pin::new(&mut this.sink);
match sink.as_mut().poll_ready(lw) {
Poll::Ready(Ok(())) => {
if let Err(e) = sink.as_mut().start_send(item) {
return Poll::Ready(Err(e));
}
}
Poll::Ready(Err(e)) => return Poll::Ready(Err(e)),
Poll::Pending => {
this.item = Some(item);
return Poll::Pending;
}
}
}
// we're done sending the item, but want to block on flushing the
// sink
try_ready!(Pin::new(&mut this.sink).poll_flush(lw));
Poll::Ready(Ok(()))
}
}