memlay

High Performance In-Memory Nostr Relay

Features

• WebSocket-based Nostr relay protocol support on /
• Nostr message framing (EVENT, REQ, EOSE, NOTICE, OK, ERROR, CLOSED)
• Event parsing from Nostr JSON
• In-memory event storage with LRU eviction
• Event indexing by pubkey, kind, and tag references
• Subscription management with filters (kinds, authors, e-tags, p-tags, since/until)
• HTTP information endpoint at /info
• Optional disk persistence for events (JSONL format)
• Integration tests

Query Plan Optimization

The subscription manager uses a query plan that picks the most selective index first:

1. IDs - exact match, most selective
2. e-tags - referenced events
3. p-tags - referenced pubkeys
4. authors - event creators
5. kinds - event types

All filters within a single REQ are combined with AND logic.

Building

cargo build --release

Running

cargo run --release

The relay will start on 0.0.0.0:8080 by default.

Configuration

Create a config.yaml file:

bind_addr: "0.0.0.0:8080"
target_ram_percent: 80
max_bytes: 0
max_subscriptions: 300
max_limit: 5000

Or use environment variables:

MEMLAY_BIND_ADDR="0.0.0.0:8080" ./target/release/memlay

Disk Persistence

Enable event persistence to survive restarts:

# Save events to this directory
persistence_path: "/var/lib/memlay/data"

# Auto-save interval in seconds (default: 60)
persistence_interval: 60

Events are saved as JSONL (one JSON event per line) with atomic writes for crash safety.

HTTP Endpoints

• / - WebSocket upgrade for Nostr protocol
• /info - Relay information (name, description, supported NIPs)

Testing

cargo test

Example Usage

cargo run --release

Then connect with a Nostr client using WebSocket to ws://localhost:8080/