stabilize benchmark

  def run : Unit = {

    print_title("Metric#sample")

    for (n <- List(1000, 10000, 1000000))

    for (n <- List(200000, 1000000, 5000000))

      for (t <- List(1, 2, 4, 8, 16, 32, 64))

      bm_metric(n, t)

  }

  private def bm_metric(samples: Int, threads: Int) : Unit = {

    val preheat = 10

    val tests = 100

    val tdiff = (0.toLong /: (1 to tests + preheat)) ((s, n) => {

      val metric = new Metric(

        MetricKey("fnord", "sum", 1.toLong))

      for (n <- (1 to samples))

        metric.sample(23)

    val t1 = FnordMetric.now

    print_res(samples + " values, " + threads + " thread(s)", t0, t1)

      if (n < preheat)

        0

      else

        s + (FnordMetric.now - t0)

    })

    print_res(samples + " values, " + threads + " thread(s)",

      tdiff / tests)

  }

  // HACK !!! ;)

  private def print_res(title: String, t0: Long, t1: Long) =

  private def print_res(title: String, tdiff: Long) =

    println("  * " + title +

      (("" /: (1 to (30 - title.length)))((m,c) => m + " ")) + " => " +

      (t1-t0) + "ms")

      tdiff + "ms")

  // HACK !!! ;)

  private def print_title(title: String) =