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use crate::io::{AsyncBufRead, AsyncWrite};
use std::future::Future;
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
cfg_io_util! {
#[derive(Debug)]
#[must_use = "futures do nothing unless you `.await` or poll them"]
struct CopyBuf<'a, R: ?Sized, W: ?Sized> {
reader: &'a mut R,
writer: &'a mut W,
amt: u64,
}
pub async fn copy_buf<'a, R, W>(reader: &'a mut R, writer: &'a mut W) -> io::Result<u64>
where
R: AsyncBufRead + Unpin + ?Sized,
W: AsyncWrite + Unpin + ?Sized,
{
CopyBuf {
reader,
writer,
amt: 0,
}.await
}
}
impl<R, W> Future for CopyBuf<'_, R, W>
where
R: AsyncBufRead + Unpin + ?Sized,
W: AsyncWrite + Unpin + ?Sized,
{
type Output = io::Result<u64>;
fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
loop {
let me = &mut *self;
let buffer = ready!(Pin::new(&mut *me.reader).poll_fill_buf(cx))?;
if buffer.is_empty() {
ready!(Pin::new(&mut self.writer).poll_flush(cx))?;
return Poll::Ready(Ok(self.amt));
}
let i = ready!(Pin::new(&mut *me.writer).poll_write(cx, buffer))?;
if i == 0 {
return Poll::Ready(Err(std::io::ErrorKind::WriteZero.into()));
}
self.amt += i as u64;
Pin::new(&mut *self.reader).consume(i);
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn assert_unpin() {
use std::marker::PhantomPinned;
crate::is_unpin::<CopyBuf<'_, PhantomPinned, PhantomPinned>>();
}
}