A clojure wrapper over Google Guava Cache

guava_cache.clj

(ns guava-cache
  (:refer-clojure :exclude [get])
  (:import [com.google.common.cache Cache CacheBuilder]
           (java.util Map)))

(defn create [cache-spec]
  (.build (CacheBuilder/from ^String cache-spec)))

(def ^:private nil-sentinal "ABC_NIL_SENTINAL_XYZ")

(defn get
  ([^Cache cache key]
   (let [value (.getIfPresent cache key)]
     (if-not (= value nil-sentinal)
       value
       nil)))
  ([^Cache cache key loader-fn]
   (let [value (.get cache key (fn [] (if-let [value (loader-fn)]
                                        value
                                        nil-sentinal)))]
     (if-not (= value nil-sentinal)
       value
       nil))))

(defn put
  ([^Cache cache key val]
   (.put cache key val))
  ([^Cache cache ^Map map]
    (.putAll cache map)))

(defn invalidate
  ([^Cache cache]
   (.invalidateAll cache))
  ([^Cache cache key]
   (.invalidate cache key)))