Cluster

The Cluster module provides cluster-wide operations for distributed systems. It operates across all nodes in a Kit cluster, providing a higher-level abstraction over individual node operations.

Cluster vs Node

While Node manages individual connections, Cluster provides operations that span all connected nodes automatically.

Cluster Information

Cluster.nodes

() -> List String

Returns a list of all nodes in the cluster (self + connected nodes).

nodes = Cluster.nodes
println "Cluster nodes: ${nodes}"

Cluster.size

() -> Int

Returns the number of nodes in the cluster (always at least 1).

if Cluster.size < 3 then
  println "Warning: Cluster below minimum size"

Broadcasting

Cluster.broadcast

String -> a -> Result Int ClusterError

Sends a message to all actors with the given name across all nodes. Returns Ok count of successful sends.

# Broadcast reset to all "worker" actors in the cluster
match Cluster.broadcast "worker" :reset
  | Ok count -> println "Reset ${count} workers"
  | Err e -> println "Broadcast failed: ${e}"

Error Types

type ClusterError =
  | BroadcastFailed { message: String }
  | ClusterError { message: String }

Complete Example

# Start this node
Node.start "master@192.168.1.1:9000"

# Connect to worker nodes
Node.connect "worker-1@192.168.1.2:9000"
Node.connect "worker-2@192.168.1.3:9000"

# Check cluster status
println "Cluster has ${Cluster.size} nodes"
println "Nodes: ${Cluster.nodes}"

# Broadcast a command to all workers
Cluster.broadcast "worker" {task: "process-data"}

# Monitor cluster health
if Cluster.size < 3 then
  println "Warning: Some workers may be down"