Struct tokio::net::tcp::ReadHalf

pub struct ReadHalf<'a>(_);

Borrowed read half of a TcpStream, created by split.

Reading from a ReadHalf is usually done using the convenience methods found on the AsyncReadExt trait.

Implementations

impl ReadHalf<'_>

pub fn poll_peek(
    &mut self,
    cx: &mut Context<'_>,
    buf: &mut ReadBuf<'_>
) -> Poll<Result<usize>>

Attempt to receive data on the socket, without removing that data from the queue, registering the current task for wakeup if data is not yet available.

Note that on multiple calls to poll_peek or poll_read, only the Waker from the Context passed to the most recent call is scheduled to receive a wakeup.

See the TcpStream::poll_peek level documenation for more details.

Examples

use tokio::io::{self, ReadBuf};
use tokio::net::TcpStream;

use futures::future::poll_fn;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut stream = TcpStream::connect("127.0.0.1:8000").await?;
    let (mut read_half, _) = stream.split();
    let mut buf = [0; 10];
    let mut buf = ReadBuf::new(&mut buf);

    poll_fn(|cx| {
        read_half.poll_peek(cx, &mut buf)
    }).await?;

    Ok(())
}

pub async fn peek(&mut self, buf: &mut [u8]) -> Result<usize>

Receives data on the socket from the remote address to which it is connected, without removing that data from the queue. On success, returns the number of bytes peeked.

See the TcpStream::peek level documenation for more details.

Examples

use tokio::net::TcpStream;
use tokio::io::AsyncReadExt;
use std::error::Error;

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    // Connect to a peer
    let mut stream = TcpStream::connect("127.0.0.1:8080").await?;
    let (mut read_half, _) = stream.split();

    let mut b1 = [0; 10];
    let mut b2 = [0; 10];

    // Peek at the data
    let n = read_half.peek(&mut b1).await?;

    // Read the data
    assert_eq!(n, read_half.read(&mut b2[..n]).await?);
    assert_eq!(&b1[..n], &b2[..n]);

    Ok(())
}

The read method is defined on the AsyncReadExt trait.

Trait Implementations

impl AsRef<TcpStream> for ReadHalf<'_>

fn as_ref(&self) -> &TcpStream

Performs the conversion.

impl AsyncRead for ReadHalf<'_>

fn poll_read(
    self: Pin<&mut Self>,
    cx: &mut Context<'_>,
    buf: &mut ReadBuf<'_>
) -> Poll<Result<()>>

Attempts to read from the AsyncRead into buf.

impl<'a> Debug for ReadHalf<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.