176 Scala 项目案例（项目实现）

package cn.itcast.spark
import scala.concurrent.duration._
import akka.actor.{Props, ActorSystem, Actor}
import akka.actor.Actor.Receive
import com.typesafe.config.ConfigFactory
import scala.collection.mutable
/**
  * Master为整个集群中的主节点
  * Master继承了Actor
  */
class Master extends Actor{
  //保存WorkerID和Work信息的map
  val idToWorker = new mutable.HashMap[String, WorkerInfo]
  //保存所有Worker信息的Set
  val workers = new mutable.HashSet[WorkerInfo]
  //Worker超时时间
  val WORKER_TIMEOUT = 10 * 1000
  //重新receive方法
  //导入隐式转换，用于启动定时器
  import context.dispatcher
  //构造方法执行完执行一次
  override def preStart(): Unit = {
    //启动定时器，定时执行
    context.system.scheduler.schedule(0 millis, WORKER_TIMEOUT millis, self, CheckOfTimeOutWorker)
  }
  //该方法会被反复执行，用于接收消息，通过case class模式匹配接收消息
  override def receive: Receive = {
    //Worker向Master发送的注册消息
    case RegisterWorker(id, workerHost, memory, cores) => {
      if(!idToWorker.contains(id)) {
        val worker = new WorkerInfo(id, workerHost, memory, cores)
        workers.add(worker)
        idToWorker(id) = worker
        sender ! RegisteredWorker("192.168.10.1")
      }
    }
    //Worker向Master发送的心跳消息
    case HeartBeat(workerId) => {
      val workerInfo = idToWorker(workerId)
      workerInfo.lastHeartbeat = System.currentTimeMillis()
    }
    //Master自己向自己发送的定期检查超时Worker的消息
    case CheckOfTimeOutWorker => {
      val currentTime = System.currentTimeMillis()
      val toRemove = workers.filter(w => currentTime - w.lastHeartbeat > WORKER_TIMEOUT).toArray
      for(worker <- toRemove){
        workers -= worker
        idToWorker.remove(worker.id)
      }
      println("worker size: " + workers.size)
    }
  }
}
object Master {
  //程序执行入口
  def main(args: Array[String]) {
    val host = "192.168.10.1"
    val port = 8888
    //创建ActorSystem的必要参数
    val configStr =
      s"""
         |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
         |akka.remote.netty.tcp.hostname = "$host"
         |akka.remote.netty.tcp.port = "$port"
       """.stripMargin
    val config = ConfigFactory.parseString(configStr)
    //ActorSystem是单例的，用来创建Actor
    val actorSystem = ActorSystem.create("MasterActorSystem", config)
    //启动Actor，Master会被实例化，生命周期方法会被调用
    actorSystem.actorOf(Props[Master], "Master")
  }
}

package cn.itcast.spark
import java.util.UUID
import scala.concurrent.duration._
import akka.actor.{ActorSelection, Props, ActorSystem, Actor}
import akka.actor.Actor.Receive
import com.typesafe.config.ConfigFactory
/**
  * Worker为整个集群的从节点
  * Worker继承了Actor
  */
class Worker extends Actor{
  //Worker端持有Master端的引用（代理对象）
  var master: ActorSelection = null
  //生成一个UUID，作为Worker的标识
  val id = UUID.randomUUID().toString
  //构造方法执行完执行一次
  override def preStart(): Unit = {
    //Worker向MasterActorSystem发送建立连接请求
    master = context.system.actorSelection("akka.tcp://MasterActorSystem@192.168.10.1:8888/user/Master")
    //Worker向Master发送注册消息
    master ! RegisterWorker(id, "192.168.10.1", 10240, 8)
  }
  //该方法会被反复执行，用于接收消息，通过case class模式匹配接收消息
  override def receive: Receive = {
    //Master向Worker的反馈信息
    case RegisteredWorker(masterUrl) => {
      import context.dispatcher
      //启动定时任务，向Master发送心跳
      context.system.scheduler.schedule(0 millis, 5000 millis, self, SendHeartBeat)
    }
    case SendHeartBeat => {
      println("worker send heartbeat")
      master ! HeartBeat(id)
    }
  }
}
object Worker {
  def main(args: Array[String]) {
    val clientPort = 2552
    //创建WorkerActorSystem的必要参数
    val configStr =
      s"""
         |akka.actor.provider = "akka.remote.RemoteActorRefProvider"
         |akka.remote.netty.tcp.port = $clientPort
       """.stripMargin
    val config = ConfigFactory.parseString(configStr)
    val actorSystem = ActorSystem("WorkerActorSystem", config)
    //启动Actor，Master会被实例化，生命周期方法会被调用
    actorSystem.actorOf(Props[Worker], "Worker")
  }
}