Bench2.scala

Bench2.scala

package benchmark

object Bench2 extends App {
  
  val num = args.headOption.map(_.toInt).getOrElse(1000)

def time(f: => Unit) = {
  val start = System.nanoTime()
  f
  System.nanoTime() - start
}

def whileBenchmark1(times: Int) = {
  time {
    var i,j,k = 0
    var x: Any = null
//println( "num = " + num )
    while(i < times) {
      while(j < num) {
        while(k < num) {
          x = new Object()
          k += 1
        }
        k = 0
        j += 1
      }
      j = 0
      i += 1
    }
  }
}

def whileBenchmark2(times: Int) = {
  time {
    var i,j,k = 0
    var x = 0L
    while(i < times) {
      while(j < num) {
        while(k < num) {
          x += 1
          k += 1
        }
        k = 0
        j += 1
      }
      j = 0
      i += 1
    }
  }
}

def forBenchmark1(times: Int) = {
  time{
    var obj: Any = null
    for(i <- 0 until times; j <- 0 until num; k <- 0 until num)
      obj = new Object
  }
} 

def forBenchmark2(times: Int) = {
  time{
    var x: Long = 0
    for(i <- 0 until times; j <- 0 until num; k <- 0 until num)
      x += 1
  }
}

def test(name: String, bench: Int => Long) {
  println(name + " took " + bench(10000)/10000000.0 + " µs per run" )
}

println( "Running benchmarks for n = " + num )

test("while1", whileBenchmark1 _)
test("while2", whileBenchmark2 _)

test("for1", forBenchmark1 _)
test("for2", forBenchmark2 _)

}