Trait AsyncRead

pub trait AsyncRead {
    type Error;

    // Required method
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut [u8],
    ) -> Poll<Result<usize, Self::Error>>;

    // Provided method
    fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self> 
       where Self: Unpin { ... }
}

Available on crate feature io only.

Read bytes asynchronously.

Required Associated Types

type Error

Required Methods

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize, Self::Error>>

Attempt to read from the AsyncRead into buf. On success, returns Poll::Ready(Ok(num_bytes_read)). If no data is available for reading, this method returns Poll::Pending and arranges for the current task to be woken.

Provided Methods

fn read<'a>(&'a mut self, buf: &'a mut [u8]) -> Read<'a, Self>

where Self: Unpin,

Tries to read some bytes directly into the given buf in asynchronous manner, returning a future type.

The returned future will resolve to both the I/O stream and the buffer as well as the number of bytes read once the read operation is completed.

use async_hal::io::AsyncRead;

let mut bytes = [1, 2, 3].as_ref();
let mut buf = [0; 3];

bytes.read(&mut buf).await?;   

assert_eq!([1, 2, 3], buf);

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl AsyncRead for &[u8]

type Error = Void

fn poll_read( self: Pin<&mut Self>, _cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize, Void>>

impl<T: ?Sized + AsyncRead + Unpin> AsyncRead for &mut T

type Error = <T as AsyncRead>::Error

fn poll_read( self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &mut [u8], ) -> Poll<Result<usize, Self::Error>>

Implementors

impl<R: AsyncRead> AsyncRead for BufReader<'_, R>

type Error = <R as AsyncRead>::Error

impl<T, E> AsyncRead for Reader<T>

where T: Stream<Item = Result<u8, E>> + Unpin,

type Error = E