Akka/Scala example source code file (FailureDetector.scala)

This example Akka source code file (FailureDetector.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Akka and Scala source code examples by using tags.

All credit for the original source code belongs to akka.io; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Akka tags/keywords

akka, boolean, clock, failuredetector, long, remote, unit

The FailureDetector.scala Akka example source code

/**
 * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
 */
package akka.remote

import java.util.concurrent.TimeUnit.NANOSECONDS

/**
 * A failure detector must be a thread-safe mutable construct that registers heartbeat events of a resource and is able to
 * decide the availability of that monitored resource.
 */
trait FailureDetector {

  /**
   * Returns true if the resource is considered to be up and healthy and returns false otherwise.
   */
  def isAvailable: Boolean

  /**
   * Returns true if the failure detector has received any heartbeats and started monitoring
   * of the resource.
   */
  def isMonitoring: Boolean

  /**
   * Notifies the FailureDetector that a heartbeat arrived from the monitored resource. This causes the FailureDetector
   * to update its state.
   */
  def heartbeat(): Unit

}

object FailureDetector {

  /**
   * Abstraction of a clock that returns time in milliseconds. Clock can only be used to measure elapsed
   * time and is not related to any other notion of system or wall-clock time.
   */
  // Abstract class to be able to extend it from Java
  abstract class Clock extends (() ⇒ Long)

  implicit val defaultClock = new Clock {
    def apply() = NANOSECONDS.toMillis(System.nanoTime)
  }
}