Primary election using zookeeper

primary.scala

import com.twitter.zookeeper.ZooKeeperClient
import org.apache.zookeeper.CreateMode
import java.util.UUID

object PrimaryBootstrap {
  def main(args:Array[String]) {
    val path = args(0)

    val zk = new ZooKeeperClient("localhost:2181")
    zk.create(path, null, CreateMode.PERSISTENT)
  }
}

object Primary {
  case class Node(order:Int, guid:String, zNode:String)
  val guid = UUID.randomUUID

  def becomePrimary(path:String, zk:ZooKeeperClient) {
    val children = zk.getChildren(path)

    val nodes = children.map { 
      c => 
        val spl = c.split(":")
        Node(spl(1).toInt, spl(0), path + "/" + c)
    }.sortBy(_.order)

    println("Nodes: " + nodes)

    val index = nodes.indexWhere(_.guid.equals(guid.toString))

    if(index == 0) {
      // only one child, we are the primary
      println("I'm the primary: " + guid)
    } else if(index > 0) {
      // start watching the node before us
      zk.watchNode(nodes(index-1).zNode, { data =>
        data match {
          case Some(value) =>
            println("Node updated! " + data)
          case None =>
            println("Node " + nodes(index-1) + " deleted!")
            becomePrimary(path, zk)
        }
      })
    } else {
      println("No children found at " + path)
    }
  }

  def main(args:Array[String]) {
    val path = args(0)

    val zk = new ZooKeeperClient("localhost:2181")
    zk.create(path + "/" + guid + ":", null, CreateMode.EPHEMERAL_SEQUENTIAL)

    println("--- Starting as " + guid)

    becomePrimary(path, zk)

    Thread.sleep(60*1000)
  }
}