gistfile1.txt

(defmethod perform :start
  [_ config components roles]
  (println "Starting persistent service" components)
  (let [system (volatile! (system/create-system config components roles))
        runtime (Runtime/getRuntime)
        shutdown? (promise)]
    (.addShutdownHook runtime
                      (Thread. (fn []
                                 (println "Shutting down persistent service")
                                 (system/stop @system)
                                 (println "Shut down cleanly")
                                 (deliver shutdown? true))))
    (vswap! system system/start)
    @shutdown?))