Function register_default_subsystems

nodedb-cluster/src/bootstrap/start.rs:67–112

Register the default set of cluster subsystems into `registry`. Called by [`start_cluster`] after the initial cluster state is resolved and the `BootstrapCtx` is assembled. The four subsystems are: 1. `SwimSubsystem` (root, `deps = []`) — failure detector with `RoutingLivenessHook` attached before the UDP socket opens. `RoutingLivenessHook` is NOT its own subsystem; it is wired inside `SwimSubsy

(
    registry: &mut SubsystemRegistry,
    config: &ClusterConfig,
    ctx: &BootstrapCtx,
    executor: Arc<MigrationExecutor>,
)

/// registered as a top-level subsystem because it is sync/cheap and runs
/// directly on the SWIM detector event loop, not as a separate task.
pub fn register_default_subsystems(
    registry: &mut SubsystemRegistry,
    config: &ClusterConfig,
    ctx: &BootstrapCtx,
    executor: Arc<MigrationExecutor>,
) -> crate::error::Result<()> {
    let swim_cfg = SwimSubsystemConfig {
        swim: crate::swim::config::SwimConfig::default(),
        local_id: NodeId::try_new(config.node_id.to_string()).map_err(|e| {
            crate::error::ClusterError::Config {
                detail: format!("node_id is not a valid ID: {e}"),
            }
        })?,
        // Use the explicit SWIM UDP addr if set; otherwise let the OS
        // pick an ephemeral port by binding to port 0 on the listen addr.
        swim_addr: config.swim_udp_addr.unwrap_or_else(|| {
            let mut a = config.listen_addr;
            a.set_port(0);
            a
        }),
        seeds: config.seed_nodes.clone(),
    };

    registry.register(Arc::new(SwimSubsystem::new(
        swim_cfg,
        Arc::clone(&ctx.routing),
        Arc::clone(&ctx.topology),
        vec![],
    )));

    registry.register(Arc::new(ReachabilitySubsystem::new(
        ReachabilityDriverConfig::default(),
    )));

    registry.register(Arc::new(DecommissionSubsystem::new(
        ctx.transport.node_id(),
        Duration::from_secs(5),
    )));

    registry.register(Arc::new(RebalancerSubsystem::new(
        RebalancerLoopConfig::default(),
        executor,
    )));

    Ok(())
}

/// Start the cluster state machine — bootstrap, join, or restart.
///