def getOrCreateLivySession()

in thriftserver/server/src/main/scala/org/apache/livy/thriftserver/LivyThriftSessionManager.scala [161:209]
49 lines of code
15 McCabe index (conditional complexity)

  def getOrCreateLivySession(
      sessionHandle: SessionHandle,
      sessionId: Option[Int],
      sessionName: Option[String],
      username: String,
      createLivySession: () => InteractiveSession): InteractiveSession = {
    sessionId match {
      case Some(id) =>
        server.livySessionManager.get(id) match {
          case None =>
            warn(s"InteractiveSession $id doesn't exist.")
            throw new IllegalArgumentException(s"Session $id doesn't exist.")
          case Some(session) if !server.isAllowedToUse(username, session) =>
            warn(s"$username has no modify permissions to InteractiveSession $id.")
            throw new IllegalAccessException(
              s"$username is not allowed to use InteractiveSession $id.")
          case Some(session) =>
            if (session.state.isActive) {
              info(s"Reusing Session $id for $sessionHandle.")
              session
            } else {
              warn(s"InteractiveSession $id is not active anymore.")
              throw new IllegalArgumentException(s"Session $id is not active anymore.")
            }
        }
      case None =>
        sessionName match {
          case Some(name) =>
            server.livySessionManager.get(name) match {
              case None =>
                createLivySession()
              case Some(session) if !server.isAllowedToUse(username, session) =>
                warn(s"$username has no modify permissions to InteractiveSession $name.")
                throw new IllegalAccessException(
                  s"$username is not allowed to use InteractiveSession $name.")
              case Some(session) =>
                if (session.state.isActive) {
                  info(s"Reusing Session $name for $sessionHandle.")
                  session
                } else {
                  warn(s"InteractiveSession $name is not active anymore.")
                  throw new IllegalArgumentException(s"Session $name is not active anymore.")
                }
            }
          case None =>
            createLivySession()
        }
    }
  }