1use core::marker::PhantomData;
2use core::pin::Pin;
3use futures_core::future::Future;
4use futures_core::task::{Context, Poll};
5use futures_sink::Sink;
6
7/// Future for the [`flush`](super::SinkExt::flush) method.
8#[derive(Debug)]
9#[must_use = "futures do nothing unless you `.await` or poll them"]
10pub struct Flush<'a, Si: ?Sized, Item> {
11 sink: &'a mut Si,
12 _phantom: PhantomData<fn(Item)>,
13}
14
15// Pin is never projected to a field.
16impl<Si: Unpin + ?Sized, Item> Unpin for Flush<'_, Si, Item> {}
17
18/// A future that completes when the sink has finished processing all
19/// pending requests.
20///
21/// The sink itself is returned after flushing is complete; this adapter is
22/// intended to be used when you want to stop sending to the sink until
23/// all current requests are processed.
24impl<'a, Si: Sink<Item> + Unpin + ?Sized, Item> Flush<'a, Si, Item> {
25 pub(super) fn new(sink: &'a mut Si) -> Self {
26 Self { sink, _phantom: PhantomData }
27 }
28}
29
30impl<Si: Sink<Item> + Unpin + ?Sized, Item> Future for Flush<'_, Si, Item> {
31 type Output = Result<(), Si::Error>;
32
33 fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
34 Pin::new(&mut self.sink).poll_flush(cx)
35 }
36}
37