Concurrent.scala

object Concurrent extends IOApp {

  override def run(args: List[String]): IO[ExitCode] = {

    (0 to 10).toList
      .parTraverse(run)
      .as(ExitCode.Success)

  }

  private def run(id: Int): IO[String] = {
    val idx = id % types.length
    val tpe = types(idx)
    IO.shift *>
      op(id.toString, tpe).withLogContext(_.id(id.toString)) <* IO.shift
  }

  private def op(id: String, tpe: String): IO[String] = {
    for {
      _      <- log.info(s"op start [static id = $id]")
      _      <- IO.shift
      result <- opInner(id, tpe).withLogContext(_.tpe(tpe))
      _      <- IO.shift
      _      <- log.info(s"op end [static id = $id]")
    } yield result
  }

  private def opInner(id: String, tpe: String): IO[String] =
    for {
      _      <- log.info(s"op_inner start [static id = $id, static type = $tpe]")
      _      <- IO.shift
      result <- IO("user")
      _      <- IO.shift
      _      <- log.info(s"op_inner end [static id = $id, static type = $tpe]")
    } yield result

  private val log: Logger[IO] = Slf4jLogger.getLogger[IO].mdc
  private val types = Vector("type1", "type2", "type3")
}