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#![warn(rust_2018_idioms)]
use tokio::{prelude::*, stream::StreamExt};
use tokio_test::assert_ok;
use tokio_util::codec::{Decoder, Encoder, Framed, FramedParts};
use bytes::{Buf, BufMut, BytesMut};
use std::io::{self, Read};
use std::pin::Pin;
use std::task::{Context, Poll};
const INITIAL_CAPACITY: usize = 8 * 1024;
/// Encode and decode u32 values.
struct U32Codec;
impl Decoder for U32Codec {
type Item = u32;
type Error = io::Error;
fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<u32>> {
if buf.len() < 4 {
return Ok(None);
}
let n = buf.split_to(4).get_u32();
Ok(Some(n))
}
}
impl Encoder<u32> for U32Codec {
type Error = io::Error;
fn encode(&mut self, item: u32, dst: &mut BytesMut) -> io::Result<()> {
// Reserve space
dst.reserve(4);
dst.put_u32(item);
Ok(())
}
}
/// This value should never be used
struct DontReadIntoThis;
impl Read for DontReadIntoThis {
fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
Err(io::Error::new(
io::ErrorKind::Other,
"Read into something you weren't supposed to.",
))
}
}
impl AsyncRead for DontReadIntoThis {
fn poll_read(
self: Pin<&mut Self>,
_cx: &mut Context<'_>,
_buf: &mut tokio::io::ReadBuf<'_>,
) -> Poll<io::Result<()>> {
unreachable!()
}
}
#[tokio::test]
async fn can_read_from_existing_buf() {
let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
let mut framed = Framed::from_parts(parts);
let num = assert_ok!(framed.next().await.unwrap());
assert_eq!(num, 42);
}
#[test]
fn external_buf_grows_to_init() {
let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
let framed = Framed::from_parts(parts);
let FramedParts { read_buf, .. } = framed.into_parts();
assert_eq!(read_buf.capacity(), INITIAL_CAPACITY);
}
#[test]
fn external_buf_does_not_shrink() {
let mut parts = FramedParts::new(DontReadIntoThis, U32Codec);
parts.read_buf = BytesMut::from(&vec![0; INITIAL_CAPACITY * 2][..]);
let framed = Framed::from_parts(parts);
let FramedParts { read_buf, .. } = framed.into_parts();
assert_eq!(read_buf.capacity(), INITIAL_CAPACITY * 2);
}
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