pub fn poll_read_buf<T: AsyncRead + ?Sized, B: BufMut>(
io: Pin<&mut T>,
cx: &mut Context<'_>,
buf: &mut B,
) -> Poll<Result<usize>>
Expand description
Try to read data from an AsyncRead
into an implementer of the BufMut
trait.
ยงExample
use bytes::{Bytes, BytesMut};
use tokio_stream as stream;
use tokio::io::Result;
use tokio_util::io::{StreamReader, poll_read_buf};
use std::future::poll_fn;
use std::pin::Pin;
// Create a reader from an iterator. This particular reader will always be
// ready.
let mut read = StreamReader::new(stream::iter(vec![Result::Ok(Bytes::from_static(&[0, 1, 2, 3]))]));
let mut buf = BytesMut::new();
let mut reads = 0;
loop {
reads += 1;
let n = poll_fn(|cx| poll_read_buf(Pin::new(&mut read), cx, &mut buf)).await?;
if n == 0 {
break;
}
}
// one or more reads might be necessary.
assert!(reads >= 1);
assert_eq!(&buf[..], &[0, 1, 2, 3]);