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// SPDX-License-Identifier: MIT OR Apache-2.0
// Copyright (c) 2026 Noyalib. All rights reserved.
//! `tokio_async` — parse a YAML stream from a tokio `AsyncRead`
//! source without `spawn_blocking`, and from a
//! `tokio_util::codec::Framed` pipeline.
//!
//! Run: `cargo run --example tokio_async_reader --features tokio`
#[cfg(feature = "tokio")]
#[tokio::main(flavor = "current_thread")]
async fn main() {
use bytes::BytesMut;
use noyalib::tokio_async::{YamlDecoder, from_async_reader_multi};
use serde::Deserialize;
use tokio::io::BufReader;
use tokio_util::codec::Decoder;
#[derive(Debug, Deserialize)]
struct Pkg {
name: String,
version: String,
}
let stream = b"\
---
name: noyalib
version: 0.0.6
---
name: noya-cli
version: 0.0.6
---
name: noyalib-lsp
version: 0.0.6
";
// ── Pattern 1: drain-and-parse via from_async_reader_multi ──
let mut buf_reader = BufReader::new(&stream[..]);
let docs: Vec<Pkg> = from_async_reader_multi(&mut buf_reader)
.await
.expect("parse multi");
println!("from_async_reader_multi:");
for (i, pkg) in docs.iter().enumerate() {
println!(" [{i}] {} {}", pkg.name, pkg.version);
}
// ── Pattern 2: streaming codec via YamlDecoder directly ──
//
// For brevity the example feeds the whole buffer in one shot
// and drives `decode` / `decode_eof` by hand. In a real
// server you'd wrap the codec in `tokio_util::codec::FramedRead`
// and pull items via `futures::StreamExt::next` — that pulls
// in `futures-util`, which is intentionally not a noyalib dep.
let mut decoder = YamlDecoder::<Pkg>::new();
let mut buf = BytesMut::from(&stream[..]);
println!("\nYamlDecoder (manual drive):");
let mut i = 0;
while let Some(pkg) = decoder.decode(&mut buf).expect("decode") {
println!(" [{i}] {} {}", pkg.name, pkg.version);
i += 1;
}
if let Some(pkg) = decoder.decode_eof(&mut buf).expect("decode_eof") {
println!(" [{i}] {} {}", pkg.name, pkg.version);
}
// ── Pattern 3: untrusted-network frame-size cap (v0.0.6) ──
//
// Production services driving `YamlDecoder` over a network
// stream MUST cap inter-frame buffer growth or an adversarial
// producer that streams without `---` can pin arbitrary memory.
// Set the cap with `max_frame_size(usize)` — when the buffer
// exceeds it, the next `decode` call returns `Error::Io`.
let mut guarded = YamlDecoder::<Pkg>::new().max_frame_size(64);
// Stream a single doc whose first line is longer than 64 bytes
// and no `---` boundary lands inside the cap.
let oversize =
b"name: a-very-long-package-name-that-definitely-exceeds-sixty-four-bytes\nversion: '1'\n";
let mut buf = BytesMut::from(&oversize[..]);
match guarded.decode(&mut buf) {
Err(e) => println!("\nmax_frame_size(64) rejected the oversize frame: {e}"),
Ok(_) => println!("\nunexpected: oversize frame should have been rejected"),
}
}
#[cfg(not(feature = "tokio"))]
fn main() {
eprintln!("This example requires the `tokio` feature.");
eprintln!("Run with: cargo run --example tokio_async_reader --features tokio");
}