Yammer metrics CPU guage

cpu_gauge.scala

  import com.yammer.metrics.Metrics
  import com.yammer.metrics.core.{Gauge, MetricName}
  import management.{RuntimeMXBean, ManagementFactory}
  import com.sun.management.UnixOperatingSystemMXBean


  class PercentCpuGauge extends Gauge[Double] {

    val runBean: RuntimeMXBean = ManagementFactory.getRuntimeMXBean
    val osBean: UnixOperatingSystemMXBean = ManagementFactory.getOperatingSystemMXBean.asInstanceOf[UnixOperatingSystemMXBean]

    var lastUptime: Long = runBean.getUptime
    var lastCpuTime: Long = osBean.getProcessCpuTime

    def value() = {
      var retVal: Double = 0.00
      var upTime = runBean.getUptime
      var elapsedTime = upTime - lastUptime

      if ( elapsedTime > 0 ) {
        var cpuTime = osBean.getProcessCpuTime
        // Uptime in milliseconds but cpu time in nanoseconds
        // correction should be 10^6 but multiply but multiply by 100 for percentage
        retVal = (cpuTime - lastCpuTime)/(elapsedTime.toDouble * 10000)
        lastUptime = upTime
        lastCpuTime = cpuTime
      }

      retVal
    }
  }

  val cpuGauge = new PercentCpuGauge()
  val newCpuGuage = Metrics.newGauge(new MetricName(cpuGauge.getClass, "cpu_percentage"), cpuGauge)