io: add a copy_bidirectional utility #3230
Conversation
Darksonn
added
A-tokio
| ) -> Poll<io::Result<u64>> | ||
| where A: AsyncRead + AsyncWrite + Unpin + ?Sized, B: AsyncRead + AsyncWrite + Unpin + ?Sized | ||
| { |
There was a problem hiding this comment.
I'm surprised rustfmt is accepting this. Maybe the cfg_* macro is stopping it?
Please rustfmt the contents of this file.
| loop { | ||
| match state { | ||
| TransferState::Running(buf) => { | ||
| *state = TransferState::ShuttingDown(ready!(dbg!(buf.poll_copy(cx, r.as_mut(), w.as_mut())))?); |
There was a problem hiding this comment.
There seems to be a stray dbg! here. I'd also prefer to have the ready! on a separate line to make it more clear that this doesn't unconditionally update the state.
|
|
||
| *state = TransferState::Done(*count); | ||
| } | ||
| TransferState::Done(count) => break Poll::Ready(Ok(*count)), |
There was a problem hiding this comment.
When using a loop in this way, I think this is clearer.
| TransferState::Done(count) => break Poll::Ready(Ok(*count)), | |
| TransferState::Done(count) => return Poll::Ready(Ok(*count)), |
| } | ||
| } | ||
|
|
||
| impl<'a, A, B> std::future::Future for CopyBidirectional<'a, A, B> |
There was a problem hiding this comment.
nit: I'd prefer to import Future.
| use tokio::{ | ||
| io::{self}, | ||
| task::JoinHandle, | ||
| }; | ||
|
|
||
| use std::time::Duration; | ||
| use tokio::io::{AsyncReadExt, AsyncWriteExt}; | ||
| use tokio::net::TcpStream; |
There was a problem hiding this comment.
| use tokio::{ | |
| io::{self}, | |
| task::JoinHandle, | |
| }; | |
| use std::time::Duration; | |
| use tokio::io::{AsyncReadExt, AsyncWriteExt}; | |
| use tokio::net::TcpStream; | |
| use std::time::Duration; | |
| use tokio::io::{self, AsyncReadExt, AsyncWriteExt}; | |
| use tokio::net::TcpStream; | |
| use tokio::task::JoinHandle; |
| let handle = tokio::spawn(async move { | ||
| let (r1, r2) = tokio::io::copy_bidirectional(&mut b1, &mut a1).await?; | ||
| Ok((r2, r1)) | ||
| }); |
There was a problem hiding this comment.
In the other you just return directly, here you use the question mark. I don't mind either way, but it's nice to be consistent.
|
|
||
| #[tokio::test] | ||
| async fn test_basic_transfer() { | ||
| symmetric(|_handle, mut a, mut b| async move { |
There was a problem hiding this comment.
I usually prefer to join the handles, as we otherwise don't catch panics in the task.
Darksonn
added
the
S-waiting-on-author
|
Closing in favor of #3572. |
Motivation
While there is a unidirectional copy utility currently, bidirectional copying between two streams (eg, proxying connections) is a bit tricky to do seamlessly and correctly due to the need to propagate EOFs and handle various error conditions.
Solution
This change adds a helper that can be used to, for example, glue together two
TcpStreams and forward data across them.