Oven Queue

oven.clj

(ns oven
  (:require [clojure.core.async :refer [>!! alts!! chan close! dropping-buffer
                                        thread]]))

(defonce tray (atom '()))
(defonce oven (atom nil))
(defonce orders (chan (dropping-buffer 3)))

(defn recipe [inp]
  (Thread/sleep 1000)
  (keyword (str "cake-" (str inp))))

(defn stop-the-oven []
  (some-> @oven close!))

(defn start-the-oven []
  (stop-the-oven)
  (let [oven-exit-ch (chan)]
    (thread
      (loop [oven-turn-off oven-exit-ch]
        (let [[order _] (alts!! [oven-turn-off orders])]
          (if (some? order)
            (let [{:keys [who recipe]} order]
              (println "handling recipe from" who)
              (swap! tray conj {:cake (recipe)
                                :by who})
              (Thread/sleep 1000)
              (recur oven-turn-off))
            (println "oven is turning-off!")))))
    (reset! oven oven-exit-ch)))

(def i (atom 0))
(defn put-recipe-in-the-oven [who]
  (swap! i inc)
  (let [who (str who "-" @i)
        order {:who who
               :recipe #(recipe @i)}]
    (println "putting order from" who)
    (>!! orders order)))

(defn whats-going-on? []
  #_what-to-do-here?)

(comment
  (start-the-oven)
  (stop-the-oven)

  (put-recipe-in-the-oven "chera")

  @tray
  (reset! tray '())
  (Thread/activeCount)
  (.. (Thread/getAllStackTraces) keySet)

  (= (whats-going-on?)
     {:remaining-orders [{:recipe "some" :who "chera-3"}]
      :in-oven [{:recipe "some" :who "chera-2"}]}))