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net: Add try_read_buf and try_recv_buf #3351

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merged 7 commits into from Jan 2, 2021
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cssivision
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@cssivision cssivision commented Dec 26, 2020

Refs: #3313

two questions:

  • what i have done was in the right direction?
  • what a vectored read function should look like?
    function signature like below?
pub fn try_read_vectored<B: BufMut>(&self, buf: &mut [B]) -> io::Result<usize>;

@Darksonn
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Yeah, this is the right direction. As for vectored reads, I realized that this is mainly relevant for writes rather than reads, so you don't need to do that. (The way you do it for writes is call chunks_vectored inside the write buf method.)

buf: &'a mut B,
) -> io::Result<usize>
where
&'a E: io::Read + 'a,
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I don't think this lifetime is necessary.

Suggested change
&'a E: io::Read + 'a,
&'a E: io::Read,

Comment on lines 183 to 188
let dst = buf.chunk_mut();
let dst = &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>]);
let mut buf = ReadBuf::uninit(dst);

let b = &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]);
let n = self.io.as_ref().unwrap().read(b)?;
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You don't have to go through ReadBuf here.

Suggested change
let dst = buf.chunk_mut();
let dst = &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>]);
let mut buf = ReadBuf::uninit(dst);
let b = &mut *(buf.unfilled_mut() as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]);
let n = self.io.as_ref().unwrap().read(b)?;
let dst = buf.chunk_mut();
let dst = &mut *(dst as *mut _ as *mut [std::mem::MaybeUninit<u8>] as *mut [u8]);
let n = self.io.as_ref().unwrap().read(dst)?;

Comment on lines 690 to 693
pub fn try_recv_buf<B: BufMut>(&self, buf: &mut B) -> io::Result<usize> {
self.io
.registration()
.try_io(Interest::READABLE, || unsafe { self.io.read_buf(buf) })
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You will need to do something different for the recv_buf variants. I'm not sure there is an equivalent trait to Read for datagram types.

Comment on lines 564 to 565
/// Try to read data from the stream into the provided buffer, advancing the
/// buffer's internal cursor, returning how many bytes were read.
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@Darksonn Darksonn Dec 26, 2020

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The documentation could use an example. You can take inspiration from the existing try_read methods, but reading into a vector created using Vec::with_capacity(1024) to show how you can read into the unused capacity of a vector.

@cssivision cssivision changed the title [WIP] net: Add try_read_buf and try_recv_buf net: Add try_read_buf and try_recv_buf Dec 27, 2020
@cssivision
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not sure whether or not it's a good idea to put this in io-util feature.

tokio/src/net/tcp/stream.rs Outdated Show resolved Hide resolved
tokio/src/net/unix/datagram/socket.rs Outdated Show resolved Hide resolved
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The changes seem reasonable to me.

tokio/tests/uds_stream.rs Show resolved Hide resolved
@taiki-e taiki-e added A-tokio Area: The main tokio crate M-net Module: tokio/net labels Jan 2, 2021
@Darksonn Darksonn merged commit 3b6bee8 into tokio-rs:master Jan 2, 2021
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Darksonn commented Jan 2, 2021

Thank you for the PR!

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3 participants