Struct tokio_util::io::StreamReader

pub struct StreamReader<S, B> { /* fields omitted */ }

This is supported on crate feature io only.

Convert a Stream of byte chunks into an AsyncRead.

This type performs the inverse operation of ReaderStream.

Example

use bytes::Bytes;
use tokio::io::{AsyncReadExt, Result};
use tokio_util::io::StreamReader;

// Create a stream from an iterator.
let stream = tokio_stream::iter(vec![
    Result::Ok(Bytes::from_static(&[0, 1, 2, 3])),
    Result::Ok(Bytes::from_static(&[4, 5, 6, 7])),
    Result::Ok(Bytes::from_static(&[8, 9, 10, 11])),
]);

// Convert it to an AsyncRead.
let mut read = StreamReader::new(stream);

// Read five bytes from the stream.
let mut buf = [0; 5];
read.read_exact(&mut buf).await?;
assert_eq!(buf, [0, 1, 2, 3, 4]);

// Read the rest of the current chunk.
assert_eq!(read.read(&mut buf).await?, 3);
assert_eq!(&buf[..3], [5, 6, 7]);

// Read the next chunk.
assert_eq!(read.read(&mut buf).await?, 4);
assert_eq!(&buf[..4], [8, 9, 10, 11]);

// We have now reached the end.
assert_eq!(read.read(&mut buf).await?, 0);

Implementations

impl<S, B, E> StreamReader<S, B> where
    S: Stream<Item = Result<B, E>>,
    B: Buf,
    E: Into<Error>, 

pub fn new(stream: S) -> Self

Convert a stream of byte chunks into an AsyncRead.

The item should be a Result with the ok variant being something that implements the Buf trait (e.g. Vec<u8> or Bytes). The error should be convertible into an io error.

impl<S, B> StreamReader<S, B>

pub fn get_ref(&self) -> &S

Gets a reference to the underlying stream.

It is inadvisable to directly read from the underlying stream.

pub fn get_mut(&mut self) -> &mut S

Gets a mutable reference to the underlying stream.

It is inadvisable to directly read from the underlying stream.

pub fn get_pin_mut(self: Pin<&mut Self>) -> Pin<&mut S>

Gets a pinned mutable reference to the underlying stream.

It is inadvisable to directly read from the underlying stream.

pub fn into_inner(self) -> S

Consumes this BufWriter, returning the underlying stream.

Note that any leftover data in the internal buffer is lost.

Trait Implementations

impl<S, B, E> AsyncBufRead for StreamReader<S, B> where
    S: Stream<Item = Result<B, E>>,
    B: Buf,
    E: Into<Error>, 

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

Attempts to return the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(self: Pin<&mut Self>, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to poll_read.

impl<S, B, E> AsyncRead for StreamReader<S, B> where
    S: Stream<Item = Result<B, E>>,
    B: Buf,
    E: Into<Error>, 

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

Attempts to read from the AsyncRead into buf.

impl<S: Debug, B: Debug> Debug for StreamReader<S, B>

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

Formats the value using the given formatter.

impl<'__pin, S, B> Unpin for StreamReader<S, B> where
    __Origin<'__pin, S, B>: Unpin,