1 use futures_core::future::Future; 2 use futures_core::task::{Context, Poll}; 3 use futures_io::AsyncWrite; 4 use std::io; 5 use std::pin::Pin; 6 7 /// Future for the [`flush`](super::AsyncWriteExt::flush) method. 8 #[derive(Debug)] 9 #[must_use = "futures do nothing unless you `.await` or poll them"] 10 pub struct Flush<'a, W: ?Sized> { 11 writer: &'a mut W, 12 } 13 14 impl<W: ?Sized + Unpin> Unpin for Flush<'_, W> {} 15 16 impl<'a, W: AsyncWrite + ?Sized + Unpin> Flush<'a, W> { new(writer: &'a mut W) -> Self17 pub(super) fn new(writer: &'a mut W) -> Self { 18 Self { writer } 19 } 20 } 21 22 impl<W> Future for Flush<'_, W> 23 where W: AsyncWrite + ?Sized + Unpin, 24 { 25 type Output = io::Result<()>; 26 poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>27 fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> { 28 Pin::new(&mut *self.writer).poll_flush(cx) 29 } 30 } 31