This is a library for establishing a dynamic cluster of servers. It is built for ZIO and it uses a variant of the SWIM (Scalable Weakly-consistent Infection-style Process Group Membership) gossip protocol.

It provides the Swim service, which can be used for dynamically retrieving the addresses of all servers in the cluster, as well as their current status (Alive, Suspicious, Failed).

trait Swim:
  /**
    * Emits the current memberlist and then subsequent updates.
    */
  def members: UStream[Map[Address, MemberStatus]]

This project is in WIP status.

WIP

This implementation uses the notion of ticks instead of a local clock. The tick interval is configurable, and all other intervals are defined as multiples of this interval.

The ZPure data type of zio-prelude is used heavily to purely model the logic of the internal SWIM state machine

• An anti-entropy mechanism is probably necessary to ensure quick convergence. Inspiration can be taken from Serf's implementation
• Currently, if a node is declared failed without crashing and restarting, it will be declared failed and will be ignored. In these cases the node needs to be forced to go through a new join process.
• A thorough automated test suite should be put in place.
• A final implementation for the Channel service should be provided.