MetricsSample.scala

package recipe

import java.util.concurrent.TimeUnit

import com.codahale.metrics._
import com.yammer.metrics.core.{HealthCheck, HealthCheckRegistry}

import scala.collection.mutable

object MetricsSample extends App {
  def startReport(): Unit = {
    val reporter = ConsoleReporter.forRegistry(metrics)
      .convertRatesTo(TimeUnit.SECONDS)
      .convertDurationsTo(TimeUnit.MILLISECONDS)
      .build()
    reporter.start(1, TimeUnit.SECONDS)

//    ConsoleReporter.forRegistry(healthChecks)
  }

  val metrics = new MetricRegistry()
  startReport()

//  Gauge
  val l = mutable.MutableList[Int]()
  metrics.register(
    MetricRegistry.name(l.getClass, "l", "size"),
    new Gauge[Int]() {
      override def getValue: Int = l.size
    }
  )

//  Meter
  val requests = metrics.meter("requests")

//  Counter
  val pendingJobs = metrics.counter(
    MetricRegistry.name("myclass", "pending-jobs"))

//  Histogram
  val responseSizes = metrics.histogram(
    MetricRegistry.name("myclass", "response-size")
  )

//  Timer
  val responseTimer = metrics.timer(
    MetricRegistry.name("myclass", "response-timer")
  )

  def foo(): Unit = {
    Thread.sleep(500 + scala.util.Random.nextInt(500))
  }

//  def using[T <: AutoCloseable, M](resource: T)(block: (M) => Unit)(args: M): Unit = {
  def using[T <: AutoCloseable, M](resource: T)(block: () => Unit): Unit = {
//    def using[T <: { def close() }, M](resource: T)(block: (M) => Unit)(args: M): Unit = {
    try {
      block()
    } finally {
      if (resource != null) resource.close()
    }
  }

  var mockDataBaseStatus = 0
  class MockDataBaseHealthCheck(name: String) extends HealthCheck(name) {
    override def check(): HealthCheck.Result = {
      if (mockDataBaseStatus != 0) HealthCheck.Result.healthy("Good")
      else HealthCheck.Result.unhealthy("NeedCheck")
    }
  }

  val healthChecks = new HealthCheckRegistry
  healthChecks.register(new MockDataBaseHealthCheck("mockDataBase"))
  new Thread() {
    for (i <- 1 to 9000) {
      requests.mark()
      l += i

      val r = scala.util.Random.nextInt(5)
      mockDataBaseStatus = r

      if (r == 0) {
        pendingJobs.dec()
      } else {
        pendingJobs.inc()
      }
      responseSizes.update(r)

      using(responseTimer.time())(foo)
    }
  }
  Thread.sleep(1200 * 1000)
}