1use crate::io::AsyncWrite;
2
3use pin_project_lite::pin_project;
4use std::future::Future;
5use std::io;
6use std::marker::PhantomPinned;
7use std::mem;
8use std::pin::Pin;
9use std::task::{ready, Context, Poll};
10
11pin_project! {
12 #[derive(Debug)]
13 #[must_use = "futures do nothing unless you `.await` or poll them"]
14 pub struct WriteAll<'a, W: ?Sized> {
15 writer: &'a mut W,
16 buf: &'a [u8],
17 // Make this future `!Unpin` for compatibility with async trait methods.
18 #[pin]
19 _pin: PhantomPinned,
20 }
21}
22
23pub(crate) fn write_all<'a, W>(writer: &'a mut W, buf: &'a [u8]) -> WriteAll<'a, W>
24where
25 W: AsyncWrite + Unpin + ?Sized,
26{
27 WriteAll {
28 writer,
29 buf,
30 _pin: PhantomPinned,
31 }
32}
33
34impl<W> Future for WriteAll<'_, W>
35where
36 W: AsyncWrite + Unpin + ?Sized,
37{
38 type Output = io::Result<()>;
39
40 fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
41 let me: Projection<'_, '_, W> = self.project();
42 while !me.buf.is_empty() {
43 let n: usize = ready!(Pin::new(&mut *me.writer).poll_write(cx, me.buf))?;
44 {
45 let (_, rest: &[u8]) = mem::take(&mut *me.buf).split_at(mid:n);
46 *me.buf = rest;
47 }
48 if n == 0 {
49 return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
50 }
51 }
52
53 Poll::Ready(Ok(()))
54 }
55}
56