Function tokio::io::copy

source ·
pub async fn copy<'a, R, W>(reader: &'a mut R, writer: &'a mut W) -> Result<u64>where
    R: AsyncRead + Unpin + ?Sized,
    W: AsyncWrite + Unpin + ?Sized,
Expand description

Asynchronously copies the entire contents of a reader into a writer.

This function returns a future that will continuously read data from reader and then write it into writer in a streaming fashion until reader returns EOF.

On success, the total number of bytes that were copied from reader to writer is returned.

This is an asynchronous version of std::io::copy.


The returned future will return an error immediately if any call to poll_read or poll_write returns an error.


use tokio::io;

let mut reader: &[u8] = b"hello";
let mut writer: Vec<u8> = vec![];

io::copy(&mut reader, &mut writer).await?;

assert_eq!(&b"hello"[..], &writer[..]);