Redust RESP

A simple RESP parser for Rust.

This crate implements RESP2, the protocol Redis uses to communicate with clients, on top of serde. It powers the redust Redis client but has no dependency on any particular network stack.

• serde integration: deserialize RESP directly into your own types with from_bytes, or serialize them into RESP with to_bytes.
• Dynamic data: the Data enum represents any RESP value when the shape of a response isn't known ahead of time. Convert between Data and Rust types with from_data and to_data.
• Zero-copy: parsed strings borrow from the input wherever possible. Owned data from the codec shares the read buffer instead of copying out of it.
• Errors as results: RESP errors are returned as Error::Redis rather than as data.

Usage

Deserialize RESP bytes into Rust types:

use serde::Deserialize;

#[derive(Debug, Deserialize, PartialEq)]
struct Reply<'a> {
    #[serde(borrow, with = "serde_bytes")]
    name: &'a [u8],
    count: i64,
}

let bytes = b"*4\r\n+name\r\n$5\r\nredis\r\n+count\r\n:42\r\n";
let (reply, remaining) = redust_resp::from_bytes::<Reply>(bytes).unwrap();

assert_eq!(reply, Reply { name: b"redis", count: 42 });
assert!(remaining.is_empty());

Or work with dynamic Data:

use redust_resp::{from_bytes, from_data, to_bytes, Data};

let (data, _) = from_bytes::<Data>(b"*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n").unwrap();
assert_eq!(data, Data::Array(vec![Data::bulk_string("GET"), Data::bulk_string("foo")]));

let parts: Vec<&[u8]> = from_data(data.clone()).unwrap();
assert_eq!(parts, [b"GET", b"foo"]);

let mut buf = Vec::new();
to_bytes(&data, &mut buf).unwrap();
assert_eq!(buf, b"*2\r\n$3\r\nGET\r\n$3\r\nfoo\r\n");

The util module contains serde helpers for common Redis encodings, such as numbers stored in bulk strings.

Features

• codec: a tokio-util Codec which incrementally decodes RESP from a byte stream into Data.

Benchmarks

In-memory comparison with the parser built into redis-rs 1.8.0 and redis-protocol 6.0.0 (the parser used by fred). Times are criterion's median estimate; lower is better.

Parsing into dynamic data

redust borrows from the input. redust (owned) also calls Data::into_owned, as the codec does, which is the fairer comparison since the other parsers return owned values.

Encoding a SET command

Measured on an AMD Ryzen 9 3900X running Windows 10 and Rust 1.95. To reproduce, see the benches crate.