SWIM Extension: Local Health Aware Probe

[ktoso]

From the Lifeguard extensions https://arxiv.org/pdf/1707.00788.pdf

• Local Health Aware Probe (LHA-Probe) replaces the probing stage of SWIM’s failure detector, which has a fixed probe period and timeout, with one where they are dynamically adjusted, based on that member’s recent fail- ure detection-related communication with other members.

[ktoso]

Where to impl hint:

    internal enum RemoteMessage {
        case ping(lastKnownStatus: Status, replyTo: ActorRef<Ack>, payload: Payload)

        /// "Ping Request" requests a SWIM probe.
        case pingReq(target: ActorRef<Message>, lastKnownStatus: Status, replyTo: ActorRef<Ack>, payload: Payload)

        /// TODO: Implement Extension: Lifeguard, Local Health Aware Probe
        /// LHAProbe adds a `nack` message to the fault detector protocol,
        /// which is sent in the case of failed indirect probes. This gives the member that
        ///  initiates the indirect probe a way to check if it is receiving timely responses
        /// from the `k` members it enlists, even if the target of their indirect pings is not responsive.
        // case nack(Payload)
    }