FilesBenchmark.scala

@State(Scope.Thread)
class FilesBenchmark {

  private[this] var target: Path = _

  @Setup
  def setup() = {
    val file = File.createTempFile("fs2-benchmarks-", "-walk")
    file.delete()
    file.mkdir()
    target = Path(file.toString)    // ewwwww

    val MaxDepth = 4
    val Names = 'A'.to('E').toList.map(_.toString)

    def loop(cwd: File, depth: Int): Unit = {
      if (depth < MaxDepth) {
        Names foreach { name =>
          val sub = new File(cwd, name)
          sub.mkdir()
          loop(sub, depth + 1)
        }
      } else if (depth == MaxDepth) {
        Names foreach { name =>
          val sub = new File(cwd, name)
          sub.createNewFile()
          loop(sub, depth + 1)
        }
      }
    }

    loop(file, 0)
  }

  @Benchmark
  def countFiles(): Int = {
    Files[IO]
      .walk(target)
      .chunks
      .map(_.size)
      .fold(0)(_ + _)
      .compile
      .lastOrError
      .unsafeRunSync()
  }

}