1#![warn(rust_2018_idioms)]
2
3use tokio_stream::StreamExt;
4use tokio_test::assert_ok;
5use tokio_util::codec::{Decoder, Encoder, Framed, FramedParts};
6
7use bytes::{Buf, BufMut, BytesMut};
8use std::io::{self, Read};
9use std::pin::Pin;
10use std::task::{Context, Poll};
11
12const INITIAL_CAPACITY: usize = 8 * 1024;
13
14/// Encode and decode u32 values.
15#[derive(Default)]
16struct U32Codec {
17 read_bytes: usize,
18}
19
20impl Decoder for U32Codec {
21 type Item = u32;
22 type Error = io::Error;
23
24 fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<u32>> {
25 if buf.len() < 4 {
26 return Ok(None);
27 }
28
29 let n = buf.split_to(4).get_u32();
30 self.read_bytes += 4;
31 Ok(Some(n))
32 }
33}
34
35impl Encoder<u32> for U32Codec {
36 type Error = io::Error;
37
38 fn encode(&mut self, item: u32, dst: &mut BytesMut) -> io::Result<()> {
39 // Reserve space
40 dst.reserve(4);
41 dst.put_u32(item);
42 Ok(())
43 }
44}
45
46/// Encode and decode u64 values.
47#[derive(Default)]
48struct U64Codec {
49 read_bytes: usize,
50}
51
52impl Decoder for U64Codec {
53 type Item = u64;
54 type Error = io::Error;
55
56 fn decode(&mut self, buf: &mut BytesMut) -> io::Result<Option<u64>> {
57 if buf.len() < 8 {
58 return Ok(None);
59 }
60
61 let n = buf.split_to(8).get_u64();
62 self.read_bytes += 8;
63 Ok(Some(n))
64 }
65}
66
67impl Encoder<u64> for U64Codec {
68 type Error = io::Error;
69
70 fn encode(&mut self, item: u64, dst: &mut BytesMut) -> io::Result<()> {
71 // Reserve space
72 dst.reserve(8);
73 dst.put_u64(item);
74 Ok(())
75 }
76}
77
78/// This value should never be used
79struct DontReadIntoThis;
80
81impl Read for DontReadIntoThis {
82 fn read(&mut self, _: &mut [u8]) -> io::Result<usize> {
83 Err(io::Error::new(
84 io::ErrorKind::Other,
85 "Read into something you weren't supposed to.",
86 ))
87 }
88}
89
90impl tokio::io::AsyncRead for DontReadIntoThis {
91 fn poll_read(
92 self: Pin<&mut Self>,
93 _cx: &mut Context<'_>,
94 _buf: &mut tokio::io::ReadBuf<'_>,
95 ) -> Poll<io::Result<()>> {
96 unreachable!()
97 }
98}
99
100#[tokio::test]
101async fn can_read_from_existing_buf() {
102 let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
103 parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
104
105 let mut framed = Framed::from_parts(parts);
106 let num = assert_ok!(framed.next().await.unwrap());
107
108 assert_eq!(num, 42);
109 assert_eq!(framed.codec().read_bytes, 4);
110}
111
112#[tokio::test]
113async fn can_read_from_existing_buf_after_codec_changed() {
114 let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
115 parts.read_buf = BytesMut::from(&[0, 0, 0, 42, 0, 0, 0, 0, 0, 0, 0, 84][..]);
116
117 let mut framed = Framed::from_parts(parts);
118 let num = assert_ok!(framed.next().await.unwrap());
119
120 assert_eq!(num, 42);
121 assert_eq!(framed.codec().read_bytes, 4);
122
123 let mut framed = framed.map_codec(|codec| U64Codec {
124 read_bytes: codec.read_bytes,
125 });
126 let num = assert_ok!(framed.next().await.unwrap());
127
128 assert_eq!(num, 84);
129 assert_eq!(framed.codec().read_bytes, 12);
130}
131
132#[test]
133fn external_buf_grows_to_init() {
134 let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
135 parts.read_buf = BytesMut::from(&[0, 0, 0, 42][..]);
136
137 let framed = Framed::from_parts(parts);
138 let FramedParts { read_buf, .. } = framed.into_parts();
139
140 assert_eq!(read_buf.capacity(), INITIAL_CAPACITY);
141}
142
143#[test]
144fn external_buf_does_not_shrink() {
145 let mut parts = FramedParts::new(DontReadIntoThis, U32Codec::default());
146 parts.read_buf = BytesMut::from(&vec![0; INITIAL_CAPACITY * 2][..]);
147
148 let framed = Framed::from_parts(parts);
149 let FramedParts { read_buf, .. } = framed.into_parts();
150
151 assert_eq!(read_buf.capacity(), INITIAL_CAPACITY * 2);
152}
153