50 lines
1.4 KiB
Rust
50 lines
1.4 KiB
Rust
use bytes::{Buf, BytesMut};
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use tokio_util::codec::{Decoder, Encoder};
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use crate::error::WireError;
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use crate::parser::{parse_message, ParsedCommand};
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/// Tokio codec for framing wire protocol messages on a TCP stream.
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///
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/// The wire protocol is naturally length-prefixed:
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/// the first 4 bytes of each message contain the total message length.
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pub struct WireCodec;
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impl Decoder for WireCodec {
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type Item = ParsedCommand;
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type Error = WireError;
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fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
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if src.len() < 4 {
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return Ok(None);
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}
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// Peek at message length
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let msg_len = i32::from_le_bytes([src[0], src[1], src[2], src[3]]) as usize;
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if src.len() < msg_len {
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// Reserve space for the rest of the message
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src.reserve(msg_len - src.len());
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return Ok(None);
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}
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match parse_message(src)? {
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Some((cmd, bytes_consumed)) => {
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src.advance(bytes_consumed);
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Ok(Some(cmd))
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}
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None => Ok(None),
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}
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}
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}
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/// Encoder for raw byte responses (already serialized by the command handlers).
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impl Encoder<Vec<u8>> for WireCodec {
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type Error = WireError;
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fn encode(&mut self, item: Vec<u8>, dst: &mut BytesMut) -> Result<(), Self::Error> {
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dst.extend_from_slice(&item);
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Ok(())
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}
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}
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