ChainRPC

Production-grade, multi-provider RPC transport layer for EVM blockchains.

Built-in retry, circuit breaker, rate limiting, tiered caching, request deduplication, auto-batching, multi-chain routing, MEV protection, and Prometheus metrics — all composable via a single Arc<dyn RpcTransport> trait.

DedupTransport(CacheTransport(BackpressureTransport(ProviderPool(HttpRpcClient))))

Every layer wraps Arc<dyn RpcTransport> and itself implements RpcTransport. Stack what you need, skip what you don't.

Quick Start

Rust

# Cargo.toml
[dependencies]
chainrpc-core = "0.1"
chainrpc-http = "0.1"

use chainrpc_http::HttpRpcClient;
use chainrpc_core::transport::RpcTransport;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let client = HttpRpcClient::default_for("https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY");

    // Typed call — auto-deserializes the response
    let block: String = client.call(1, "eth_blockNumber", vec![]).await?;
    println!("Latest block: {block}");

    Ok(())
}

Multi-Provider Failover

use chainrpc_http::pool_from_urls;

let pool = pool_from_urls(&[
    "https://eth-mainnet.g.alchemy.com/v2/KEY1",
    "https://mainnet.infura.io/v3/KEY2",
    "https://rpc.ankr.com/eth",
])?;

// Round-robin with automatic failover when a provider's circuit breaker opens
let block = pool.send(JsonRpcRequest::auto("eth_blockNumber", vec![])).await?;
println!("Healthy: {}/{}", pool.healthy_count(), pool.len());

Tiered Caching + Dedup

use chainrpc_core::cache::{CacheTransport, CacheConfig, CacheTierResolver};
use chainrpc_core::dedup::DedupTransport;

// Cache with smart tier resolution:
//   eth_getTransactionReceipt → Immutable (1h TTL)
//   eth_blockNumber → Volatile (2s TTL)
//   eth_sendRawTransaction → NeverCache
let cached = CacheTransport::new(Arc::new(client), CacheConfig {
    tier_resolver: Some(CacheTierResolver::new()),
    max_entries: 4096,
    ..Default::default()
});

// Deduplicate concurrent identical requests
let dedup = DedupTransport::new(Arc::new(cached));

Features

Policy Engine

• Rate Limiter — Token-bucket with CU-aware mode (knows eth_getLogs = 75 CU, eth_blockNumber = 10 CU)
• Circuit Breaker — Three-state (Closed/Open/HalfOpen), configurable failure threshold and reset timeout
• Retry Policy — Exponential backoff with jitter, respects method safety (never retries eth_sendTransaction)
• Method Safety — Classifies 40+ EVM methods as Safe / Idempotent / Unsafe

Provider Pool

• 5 selection strategies: RoundRobin, Priority, WeightedRoundRobin, LatencyBased, Sticky
• Per-provider circuit breaker + automatic failover
• Atomic metrics (success/failure counts, latency, rate-limit hits)
• Background health checking

Caching & Dedup

• 4-tier cache: Immutable (1h), SemiStable (5m), Volatile (2s), NeverCache
• Smart tier resolution based on method + parameters
• Reorg-aware invalidation (invalidate_for_reorg(block))
• Request deduplication (N concurrent callers = 1 HTTP call)

Advanced

• Auto-Batching — Collects individual calls into JSON-RPC batch requests within a time window
• Multi-Chain Router — Route by chain ID, parallel cross-chain queries
• Request Hedging — Race primary + backup, return first response
• Backpressure — Concurrency limiting, fail-fast when overloaded
• Archive Routing — Route historical queries to archive nodes
• MEV Protection — Detect 12 MEV-susceptible selectors, route to private relays
• Gas Estimation — EIP-1559 recommendations (Slow/Standard/Fast/Urgent)
• Tx Lifecycle — Send, track, poll receipt, detect stuck, nonce management, gas bumping
• CU Budget Tracking — Monitor compute unit consumption against monthly budgets
• Solana Support — Commitment levels (Processed/Confirmed/Finalized), 50+ method safety classification, CU costs
• Geo-Aware Routing — Route to geographically closest provider with automatic proximity-based fallback
• Gas Bumping — Speed up or cancel stuck transactions with EIP-1559 compliant replacement (Percentage/Double/SpeedTier/Cancel)
• Reorg Detection — Sliding block hash window, configurable safe depth, reorg callbacks for cache invalidation

Lifecycle & Observability

• Graceful shutdown with signal handling and drain timeout
• Cooperative cancellation tokens (parent/child hierarchy)
• Per-provider Prometheus metrics export
• Structured tracing integration

Crate Structure

chainrpc/
  crates/
    chainrpc-core/       # 31 modules — trait, types, all middleware
    chainrpc-http/       # HTTP transport (reqwest) with retry loop
    chainrpc-ws/         # WebSocket transport (tokio-tungstenite)
    chainrpc-providers/  # Pre-configured Alchemy, Infura, Ankr profiles
  bindings/
    node/                # TypeScript (napi-rs)
    python/              # Python (PyO3 + maturin)
    go/                  # Go (cgo)
    java/                # Java (JNI)
  cli/                   # CLI tool (call, pool, bench)
  examples/              # 26 runnable examples
  docs/                  # Architecture, modules, API reference

Examples

26 examples covering every module. See examples/README.md for the full index.

Documentation

Language Bindings

Test Coverage

262 tests, 0 failures

chainrpc-core:      250 tests (all 31 modules)
chainrpc-providers:   6 tests (URL construction)
chainrpc-ws:          3 tests (subscription management)
Doc-tests:            3 tests

cd chainrpc && cargo test --workspace

License

MIT