1 use core::marker::PhantomData; 2 use core::pin::Pin; 3 use futures_core::future::Future; 4 use futures_core::task::{Context, Poll}; 5 use 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"] 10 pub 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. 16 impl<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. 24 impl<'a, Si: Sink<Item> + Unpin + ?Sized, Item> Flush<'a, Si, Item> { new(sink: &'a mut Si) -> Self25 pub(super) fn new(sink: &'a mut Si) -> Self { 26 Self { 27 sink, 28 _phantom: PhantomData, 29 } 30 } 31 } 32 33 impl<Si: Sink<Item> + Unpin + ?Sized, Item> Future for Flush<'_, Si, Item> { 34 type Output = Result<(), Si::Error>; 35 poll( mut self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Self::Output>36 fn poll( 37 mut self: Pin<&mut Self>, 38 cx: &mut Context<'_>, 39 ) -> Poll<Self::Output> { 40 Pin::new(&mut self.sink).poll_flush(cx) 41 } 42 } 43