Replace JSON With a Binary Quote Protocol: PR Review

JSON encoding and decoding is 9% of CPU on the quote service. This adds a small wire crate that encodes quote requests as length-prefixed fields in a fixed order, and switches the gateway to it. In a microbenchmark, encode and decode are 6x faster than serde_json, and staging p99 dropped by 4 ms. Both services deploy from the monorepo, so they ship together.

Acrates/wire/src/lib.rs1 of 3

Files Changed

crates/wire/src/

services/gateway/src/

crates/wire/tests/

crates/wire/src/lib.rs

Rust · Click a line number to comment · Tap a line to comment

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//! Compact binary encoding for quote requests between the gateway and the quote service.

use std::io::{self, Read, Write};

pub struct QuoteRequest {

pub sku: String,

pub quantity: u32,

pub region: String,

}

pub fn write_request<W: Write>(w: &mut W, req: &QuoteRequest) -> io::Result<()> {

write_str(w, &req.sku)?;

w.write_all(&req.quantity.to_ne_bytes())?;

write_str(w, &req.region)

}

pub fn read_request<R: Read>(r: &mut R) -> io::Result<QuoteRequest> {

let sku = read_str(r)?;

let mut quantity = [0u8; 4];

r.read_exact(&mut quantity)?;

let region = read_str(r)?;

Ok(QuoteRequest { sku, quantity: u32::from_ne_bytes(quantity), region })

}

fn write_str<W: Write>(w: &mut W, s: &str) -> io::Result<()> {

w.write_all(&(s.len() as u32).to_ne_bytes())?;

w.write_all(s.as_bytes())

}

fn read_str<R: Read>(r: &mut R) -> io::Result<String> {

let mut len = [0u8; 4];

r.read_exact(&mut len)?;

let mut buf = vec![0u8; u32::from_ne_bytes(len) as usize];

r.read_exact(&mut buf)?;

Ok(String::from_utf8(buf).unwrap())

}

crates/wire/src/lib.rs

services/gateway/src/quote_client.rs

crates/wire/tests/roundtrip.rs