Kamon Metrics Collector

MetricsCollector.scala

import java.nio.LongBuffer

import akka.actor.{ActorLogging, Actor}
import kamon.metric._
import kamon.metric.instrument.{Histogram, CollectionContext}

class MetricsCollector extends Actor with ActorLogging {
  import MetricsCollector._

  def ms(nanos: Long) = nanos / 1000 / 1000

  var histograms: Map[Entity, Histogram.Snapshot] = Map.empty

  def extractMetrics(): Iterable[EntityMetrics] = histograms.map { case (entity, histogram) =>
    EntityMetrics(entity.name, ms(histogram.min), ms(histogram.max), ms(histogram.sum / histogram.numberOfMeasurements))
  }

  def receive = {
    case tickSnapshot: SubscriptionsDispatcher.TickMetricSnapshot =>
      tickSnapshot.metrics.map { case (entity, snapshot) =>
        snapshot.histogram("elapsed-time").map { newHistogram =>
          val histogram = histograms.get(entity).getOrElse(Histogram.Snapshot.empty)
          val mergedHistograms = histogram.merge(newHistogram, collectionContext)
          histograms += (entity -> mergedHistograms)
        }
      }
    case GetMetrics => sender ! extractMetrics()
  }

  val collectionContext = new CollectionContext {
    val buffer: LongBuffer = LongBuffer.allocate(10000)
  }
}

object MetricsCollector {
  case class EntityMetrics(name: String, min: Long, max: Long, avg: Long)
  case object GetMetrics
}