quick_protobuf_codec/
lib.rs

1#![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
2
3use asynchronous_codec::{Decoder, Encoder};
4use bytes::{Bytes, BytesMut};
5use quick_protobuf::{BytesReader, MessageRead, MessageWrite, Writer};
6use std::marker::PhantomData;
7use unsigned_varint::codec::UviBytes;
8
9/// [`Codec`] implements [`Encoder`] and [`Decoder`], uses [`unsigned_varint`]
10/// to prefix messages with their length and uses [`quick_protobuf`] and a provided
11/// `struct` implementing [`MessageRead`] and [`MessageWrite`] to do the encoding.
12pub struct Codec<In, Out = In> {
13    uvi: UviBytes,
14    phantom: PhantomData<(In, Out)>,
15}
16
17impl<In, Out> Codec<In, Out> {
18    /// Create new [`Codec`].
19    ///
20    /// Parameter `max_message_len_bytes` determines the maximum length of the
21    /// Protobuf message. The limit does not include the bytes needed for the
22    /// [`unsigned_varint`].
23    pub fn new(max_message_len_bytes: usize) -> Self {
24        let mut uvi = UviBytes::default();
25        uvi.set_max_len(max_message_len_bytes);
26        Self {
27            uvi,
28            phantom: PhantomData,
29        }
30    }
31}
32
33impl<In: MessageWrite, Out> Encoder for Codec<In, Out> {
34    type Item = In;
35    type Error = Error;
36
37    fn encode(&mut self, item: Self::Item, dst: &mut BytesMut) -> Result<(), Self::Error> {
38        let mut encoded_msg = Vec::new();
39        let mut writer = Writer::new(&mut encoded_msg);
40        item.write_message(&mut writer)
41            .expect("Encoding to succeed");
42        self.uvi.encode(Bytes::from(encoded_msg), dst)?;
43
44        Ok(())
45    }
46}
47
48impl<In, Out> Decoder for Codec<In, Out>
49where
50    Out: for<'a> MessageRead<'a>,
51{
52    type Item = Out;
53    type Error = Error;
54
55    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
56        let msg = match self.uvi.decode(src)? {
57            None => return Ok(None),
58            Some(msg) => msg,
59        };
60
61        let mut reader = BytesReader::from_bytes(&msg);
62        let message = Self::Item::from_reader(&mut reader, &msg)
63            .map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))?;
64        Ok(Some(message))
65    }
66}
67
68#[derive(thiserror::Error, Debug)]
69#[error("Failed to encode/decode message")]
70pub struct Error(#[from] std::io::Error);
71
72impl From<Error> for std::io::Error {
73    fn from(e: Error) -> Self {
74        e.0
75    }
76}
quick_protobuf_codec/lib.rs

quick_protobuf_codec/
lib.rs
