land.fast - solana tpu transaction service

sends transactions directly to solana leader validators via QUIC, minimizing network hops and latency.

WIP - do not use in production

this repo is under active development and may include permanent breaking changes.

features

• lock-free data structures - seqlock-based leader buffer for wait-free reads
• disruptor-inspired channels - zero-copy spsc/mpsc channels with pre-allocated ring buffers
• zero-copy transport - efficient quic with minimal allocations
• session resumption - tls session cache for 0-rtt connections
• rdtsc timing - nanosecond-precision measurement for connection handshake tracking
• json-rpc http api - lock-free request queue with mio-based accept thread

core components

• land-core - thin orchestration layer
• land-leader - solana leader tracker with seqlock buffer and busy-spin update loop
• land-quic - quic connection library with adaptive timing, connection pooling, session cache
• land-server - lock-free json-rpc http server using mio + spsc queue

supporting crates

• land-channel - lock-free spsc/mpsc channels inspired by lmax disruptor with pre-allocated ring buffers
• land-sync - seqlock and lock-free synchronization primitives for single-writer multi-reader scenarios
• land-timing - rdtsc-based timing infrastructure with histogram tracking for nanosecond-level measurements
• land-pubsub - low-latency websocket slot subscriber using land-channel for event-driven updates
• land-cpu - cpu topology detection, core pinning utilities, cache padding, wait strategies, memory fences
• land-traits - shared traits (LeaderLookup for zero-copy leader buffer reads)

setup

prerequisites

install openssl with quic support:

chmod +x setup.sh
./setup.sh
./set.sh

build

cd core && cargo b -r

usage

basic

./target/release/land-core \
  --rpc http://your-rpc-endpoint:8899 \
  --ws ws://your-ws-endpoint:8900 \
  --http 127.0.0.1:8080

with staked identity (priority access)

./target/release/land-core \
  --rpc http://your-rpc-endpoint:8899 \
  --ws ws://your-ws-endpoint:8900 \
  --http 127.0.0.1:8080 \
  --keypair /path/to/staked-keypair.json

environment variables

alternatively, use environment variables:

export RPC_URL=http://your-rpc-endpoint:8899
export WS_URL=ws://your-ws-endpoint:8900
export HTTP_ADDR=127.0.0.1:8080
export KEYPAIR_PATH=/path/to/staked-keypair.json

./target/release/land-core

presets

Config::mainnet()        // default mainnet configuration
Config::devnet()         // devnet configuration
Config::custom(rpc, ws)  // custom endpoints

api

send transactions via json-rpc:

curl -X POST http://127.0.0.1:8080 \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "sendTransaction",
    "params": {
      "transaction": "<base64-encoded-transaction>",
      "fanout": 3,
    }
  }'

response

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "status": "queued",
    "request_id": "000000000000001a"
  }
}

design principles

• zero-allocation - pre-allocated buffers
• lock-free - seqlock for reads, disruptor-style channels
• cache-aware - 64-byte alignment, padding to prevent false sharing, hot fields grouped
• wait strategies - configurable spin/yield/backoff for different latency/cpu trade-offs
• mixed strategies need a fix to bring more consistency

todo

• improve stability — the focus has mostly been on latency, not safety
• batching server and quic sender
• remove websocket support (agave will no longer maintain rpc/ws). switch to either grpc or gossip shreds
• add blacklist for slot bandits
• add adaptive timing based on ip perf
• add target_slot
• replace some crates

license

MIT