Benchmark for scala.util.control.TailCalls

TailCallBenchmark.scala

import org.junit._

class TailCallBenchmark {
  import scala.util.continuations._

  @Test
  def test() {
    import scala.util.control.TailCalls._

    def unwind(): Unit @cps[TailRec[Unit]] = {
      shift { (continue: Unit => TailRec[Unit]) =>
        continue()
        tailcall(continue())
      }
    }

    def complexCpsFunction1(i: Int): Unit @cps[TailRec[Unit]] = {
      if (i > 0) {
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(0)
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(0)
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(0)
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(0)
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(0)
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        unwind()
        complexCpsFunction1(i - 1)

      }
    }

    def complexCpsFunction2(i: Int): Unit @cps[TailRec[Unit]] = {
      if (i > 0) {
        complexCpsFunction1(10)
        complexCpsFunction2(i - 1)
      }
    }

    def complexCpsFunction3(i: Int): Unit @cps[TailRec[Unit]] = {
      if (i > 0) {
        complexCpsFunction2(10)
        complexCpsFunction3(i - 1)
      }
    }
    for (j <- 0 until 10) {
      System.gc()
      val start = System.nanoTime()
      for (i <- 0 until 1000) {
        reset {
          complexCpsFunction3(10)
          shift { (continue: Unit => Unit) =>
            done()
          }
        }.result
      }
      println("time:" + (System.nanoTime() - start))
    }
    System.gc()
  }

}