🎉 Add resource usage limits.

backend/src/app/rlimits.clj

@@ -0,0 +1,48 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; This Source Code Form is "Incompatible With Secondary Licenses", as
+;; defined by the Mozilla Public License, v. 2.0.
+;;
+;; Copyright (c) 2020-2021 UXBOX Labs SL
+
+(ns app.rlimits
+  "Resource usage limits (in other words: semaphores)."
+  (:require
+   [app.common.exceptions :as ex]
+   [app.common.spec :as us]
+   [clojure.spec.alpha :as s]
+   [integrant.core :as ig])
+  (:import
+   java.util.concurrent.Semaphore))
+
+(s/def ::rlimit  #(instance? Semaphore %))
+(s/def ::rlimits (s/map-of ::us/keyword ::rlimit))
+
+(derive ::password ::instance)
+(derive ::image ::instance)
+
+(defmethod ig/pre-init-spec ::instance [_]
+  (s/spec int?))
+
+(defmethod ig/init-key ::instance
+  [_ permits]
+  (Semaphore. (int permits)))
+
+(defn acquire!
+  [sem]
+  (.acquire ^Semaphore sem))
+
+(defn release!
+  [sem]
+  (.release ^Semaphore sem))
+
+(defmacro execute
+  [rlinst & body]
+  `(try
+     (acquire! ~rlinst)
+     ~@body
+     (finally
+       (release! ~rlinst))))
+