server.clj

;; server
(defonce server-list (atom []))

(defonce appender (atom nil))
(defonce appending-fiber (atom nil))
(defonce subscriber (atom identity))

(defn subscribe [f]
  (reset! subscriber f))

(defn publish-to-client [m]
  (@subscriber m))

(defn get-snapshot []
  (publish-to-client {:type :snapshot :val @server-list}))

(defn append-to-list []
  (when (< 9 (count @server-list))
    (swap! server-list butlast))
  (let [incremental (rand-nth (range 100))]
    (swap! server-list conj incremental)
    (publish-to-client {:type :incremental :val incremental})))

(defn server-start []
  (reset! appending-fiber (doto (org.jetlang.fibers.ThreadFiber.) .start))
  (reset! appender (.scheduleAtFixedRate @appending-fiber
                                         append-to-list 500 500
                                         java.util.concurrent.TimeUnit/MILLISECONDS)))

(defn server-stop []
  (.dispose @appender)
  (.dispose @appending-fiber))