helius-stream

Resilient Helius WebSocket client for Solana. Gap detection, reconnect backoff, circuit-breaker state. Extracted from a battle-tested MEV engine that ran 15h on Solana mainnet.

Why

solana-client pulls 200+ transitive dependencies. For workloads that only need account subscriptions, that's a heavy tax. helius-stream does one thing: subscribe to accounts via Helius WebSocket and surface updates as a typed stream, with built-in health tracking so you can wire a circuit breaker in 3 lines.

Dependency count: 8 direct, ~25 transitive.

Quick start

use helius_stream::{HeliusStream, StreamConfig};

let config = StreamConfig::mainnet(std::env::var("HELIUS_API_KEY")?);
let mut stream = HeliusStream::connect(config)?;

// USDC mint
stream.subscribe_account_b58("EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v")?;

while let Some(update) = stream.next_update() {
    if stream.is_safe_for_simulation() {
        println!("slot={} lamports={}", update.slot, update.lamports);
    }
}

Run the included example:

HELIUS_API_KEY=your_key cargo run --example basic_stream

What you get

HeliusStream — synchronous WebSocket client. Subscribe to accounts, receive AccountUpdate events.
StreamHealth — slot-gap detection, staleness tracking, gap rate.
ReconnectPolicy — exponential backoff with cap (default: 100ms → 10s).
StreamState — typed state machine (Connected, Degraded, Stale, Failed) for circuit-breaker logic.
No panics in normal operation — all errors via StreamError.

What you don't get

Async API. v0.1 is sync; wrap in spawn_blocking if you need tokio. Async feature flag planned for v0.2.
Multi-stream orchestration. Open multiple HeliusStream instances yourself.
Program subscriptions, log subscriptions, signature subscriptions. v0.1 covers only accountSubscribe. PRs welcome.
A Solana SDK. This is an RPC client, not a transaction builder.

Provenance

Extracted from prometheus9, a Rust MEV engine that ran 15 hours on Solana mainnet monitoring cross-DEX SOL/USDC arbitrage. The engine captured zero opportunities — the market was efficient to within 29 bps. The infrastructure code, however, proved itself: gap detection, auto-reconnect, and zero crashes across 15 hours. That infrastructure is this crate.

Performance

Single connection, single thread, on a €4.50/mo Hetzner CX22:

~1,500 updates/hour sustained
~50ms p50 from server send to next_update() return
~1,200 slot gaps observed over 15 hours (network variance, not crate bug)

License

Apache-2.0. Includes patent grant — contributors automatically grant patent rights for their contributions, and the grant terminates if a user initiates patent litigation. See LICENSE.

Contributing

Issues and PRs at github.com/ginugokz/helius-stream-rs. For paid work (custom protocols, async port, audit support), see the author's contact.

helius-stream 0.1.0