Ugly mitigation of CLJ-1152 (PermGen) bugs in the protocols case

clj1152.clj

;; Ugly mitigation of http://dev.clojure.org/jira/browse/CLJ-1152 in
;; the protocols case.  Motivation: Need to eval lots domain-specific
;; language code rendered in core.logic.  Approach: Start a thread to
;; purge protocol caches every second.  You should probable write a
;; fancier version.

(defn protocol? [x]
  (and (instance? clojure.lang.PersistentArrayMap x)
       (boolean (:on-interface x))))

(defn protocols
  "Get a seq of protocols in the given namespace."
  ([namespace]
     (binding [*ns* (if (symbol? namespace)
                      (find-ns namespace)
                      namespace)]
       (doall (filter protocol?
                      (map var-get
                           (filter var?
                                   (map second
                                        (ns-map *ns*))))))))
  ([]
     (protocols *ns*)))

(defonce simple-protocol-cache-cleaner
  ;; Starts a simple daemon thread that purges the caches for all protocols in the current namespace.
  (let [interval 1000 ;; ms
        ps (protocols *ns*)]
    (doto (new Thread (fn []
                        (loop [i 0]
                          (doseq [p ps] (-reset-methods p))
                          (Thread/sleep interval)
                          (recur (inc i)))))
      (.setDaemon true)
      (.start))))