gwyh: Gossip Wit Your Homies 💖 ✨

Gwyh (pronounced gwyh) is a library for building gossip-based services in Rust. Gwyh has some unique features that make it lightning quick and especially cool:

• UDP-based
• Built-in congestion control
• Super quick dissemination (broadcasts always take quickest path)
• 100% async, based on Tokio
• Built-in transport layer encryption using super-fast XSalsa20 via dryoc
• Effortlessly scales to thousands of nodes without compromising speed
• Zonal awareness, with several distribution strategies to choose from

Gwyh can provide the gossip protocol layer for your service, but gwyh is not appropriate for all uses. Messages broadcasted with gwyh aren't acknowledged, and there's no guarantee that broadcasts will be delivered. Gwyh's speed comes with the trade-off of ignoring a lot of best practices regarding packet delivery over unreliable or semi-reliable networks (mainly from the lack of delivery acknowledgement).

Do not be deterred, however, because gwyh is a great fit for eventually consistent systems provided your own protocol is idempotent and can tolerate the occasional dropped message.

Gwyh was designed to work well with globally distributed networks where latency is variable and the fastest path is difficult to estimate. Gwyh's wire protocol uses strong encryption that allows you to even use it over the Internet without requiring additional layers (like a VPN) if you choose, although practically speaking this may not work because each gwyh instance must be reachable (i.e., it won't work behind a NAT or load balancer).

Gwyh is optimized for sending small messages quickly. In the context of gwyh, a small message is one which fits inside a single UDP pocket (a bit less than 64KiB). Gwyh can handle messages that are multiple packets in length, but doing so incurs some additional overhead. Building a stream protocol, for example, on top of gwyh is not the best use of it.

Protocol

See docs/PROTOCOL.md for details on gwyh's underlying protocol.

Examples

TODO: add examples here