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

This example Akka source code file (DeadlineFailureDetector.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, concurrent, config, deadlinefailuredetector, duration, event, eventstream, failuredetector, finiteduration, long, remote, time, unit

The DeadlineFailureDetector.scala Akka example source code

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

import scala.concurrent.duration.Duration
import scala.concurrent.duration.FiniteDuration
import com.typesafe.config.Config
import akka.event.EventStream
import akka.remote.FailureDetector.Clock
import akka.util.Helpers.ConfigOps

/**
 * Implementation of failure detector using an absolute timeout of missing heartbeats
 * to trigger unavailability.
 *
 * @param acceptableHeartbeatPause Duration corresponding to number of potentially lost/delayed
 *   heartbeats that will be accepted before considering it to be an anomaly.
 *
 * @param clock The clock, returning current time in milliseconds, but can be faked for testing
 *   purposes. It is only used for measuring intervals (duration).
 */
class DeadlineFailureDetector(
  val acceptableHeartbeatPause: FiniteDuration)(
    implicit clock: Clock) extends FailureDetector {

  /**
   * Constructor that reads parameters from config.
   * Expecting config properties named `acceptable-heartbeat-pause`.
   */
  def this(config: Config, ev: EventStream) =
    this(acceptableHeartbeatPause = config.getMillisDuration("acceptable-heartbeat-pause"))

  require(acceptableHeartbeatPause >= Duration.Zero, "failure-detector.acceptable-heartbeat-pause must be >= 0")

  private val acceptableHeartbeatPauseMillis = acceptableHeartbeatPause.toMillis
  @volatile private var heartbeatTimestamp = 0L //not used until active (first heartbeat)
  @volatile private var active = false

  override def isAvailable: Boolean = isAvailable(clock())

  private def isAvailable(timestamp: Long): Boolean =
    if (active) (heartbeatTimestamp + acceptableHeartbeatPauseMillis) > timestamp
    else true // treat unmanaged connections, e.g. with zero heartbeats, as healthy connections

  override def isMonitoring: Boolean = active

  final override def heartbeat(): Unit = {
    heartbeatTimestamp = clock()
    active = true
  }

}