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use crate::io::AsyncWrite;
use bytes::Buf;
use pin_project_lite::pin_project;
use std::future::Future;
use std::io;
use std::marker::PhantomPinned;
use std::pin::Pin;
use std::task::{Context, Poll};
pin_project! {
/// A future to write some of the buffer to an `AsyncWrite`.
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct WriteAllBuf<'a, W, B> {
writer: &'a mut W,
buf: &'a mut B,
#[pin]
_pin: PhantomPinned,
}
}
/// Tries to write some bytes from the given `buf` to the writer in an
/// asynchronous manner, returning a future.
pub(crate) fn write_all_buf<'a, W, B>(writer: &'a mut W, buf: &'a mut B) -> WriteAllBuf<'a, W, B>
where
W: AsyncWrite + Unpin,
B: Buf,
{
WriteAllBuf {
writer,
buf,
_pin: PhantomPinned,
}
}
impl<W, B> Future for WriteAllBuf<'_, W, B>
where
W: AsyncWrite + Unpin,
B: Buf,
{
type Output = io::Result<()>;
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<io::Result<()>> {
let me = self.project();
while me.buf.has_remaining() {
let n = ready!(Pin::new(&mut *me.writer).poll_write(cx, me.buf.chunk())?);
me.buf.advance(n);
if n == 0 {
return Poll::Ready(Err(io::ErrorKind::WriteZero.into()));
}
}
Poll::Ready(Ok(()))
}
}