Solana Slot Latency Tracker (Go)

This repository measures the latency between when a slot is first observed via Solana gossip and when it is confirmed via a Yellowstone gRPC stream.

What It Does

• Connects to Solana gossip and subscribes to vote messages.
• Simultaneously subscribes to slot updates from a Yellowstone gRPC endpoint.
• For each slot, records the first arrival timestamp from each source.
• When both timestamps are available, logs the latency (gossip arrival → Yellowstone slot update).
• Writes structured JSON logs to stdout and a file via zerolog.

Repository Layout

• runtime/: executable entrypoint (main.go).
• services/: TrackerService — coordinates gossip and Yellowstone subscriptions, slot tracking logic.
• .env.example: environment variable template.

Requirements

• Go 1.25.5 (as declared in go.mod).
• A Yellowstone-compatible gRPC endpoint and access token.
• UDP and TCP ports open for gossip traffic.

Configuration

Copy the example env file and fill in your values:

cp .env.example .env

Variable	Description	Example
ENV	Solana cluster (mainnet, testnet, devnet)	mainnet
GRPC_ENDPOINT	Yellowstone gRPC endpoint host	yellowstone.eu.fluxrpc.com
GRPC_TOKEN	Auth token for the gRPC endpoint	432d443f-...
UDP_PORT	UDP port for gossip traffic	8001
TCP_PORT	TCP port for gossip IP echo handshake	8001
LOG_LEVEL	Log verbosity (trace, debug, info, error)	info
LOG_FILE	Path to write the log file	gossip.log
DISPLAY_SLOTS	Whether to display slot output	true

Quick Start

go run ./runtime/main.go

On first start, if id.json is not found, a new keypair is generated and written there automatically.

How Latency Is Measured

The tracker keeps a circular ring buffer of the last 1500 slots. For each slot:

1. When a gossip vote for that slot arrives, the receive timestamp is stored.
2. When a Yellowstone slot update for the same slot arrives, the receive timestamp is stored.
3. Once both timestamps are present, the latency is computed as:

latency = yellowstone_arrival − gossip_arrival

The result is a time.Duration and is logged as the latency field on the SLOT LATENCY TRACKED log line. If Yellowstone is observed before gossip for a slot, that slot is dropped because it does not represent a valid gossip-to-Yellowstone latency.

Wire Compatibility Note

The gossip dependency (github.com/Gealber/gossip) relies on a forked binary decoder (github.com/Gealber/binary) to correctly handle Solana's bincode wire format. Because Go only applies replace directives from the main module, this repo must redeclare the replacement in its own go.mod:

replace github.com/gagliardetto/binary => github.com/Gealber/binary v0.0.0-20260419181258-89e8fe42e32c

Without this, gossip packet decoding will fail with unknown CrdsData discriminant errors caused by byte-offset drift in the upstream library.

Disclaimer

This is a narrow observability utility focused on measuring gossip-to-confirmation latency on Solana. It is not a full gossip node and does not persist or re-broadcast any state.