penpot/frontend/src/app/util/cache.cljs
2022-12-07 15:05:38 +01:00

48 lines
1.2 KiB
Clojure

;; 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/.
;;
;; Copyright (c) KALEIDOS INC
(ns app.util.cache
(:require
[app.util.time :as dt]
[beicon.core :as rx]))
(defonce cache (atom {}))
(defonce pending (atom {}))
(defn with-cache
[{:keys [key max-age]} observable]
(let [entry (get @cache key)
pending-entry (get @pending key)
age (when entry
(dt/diff (dt/now)
(:created-at entry)))]
(cond
(and (some? entry) (< age max-age))
(rx/of (:data entry))
(some? pending-entry)
pending-entry
:else
(let [subject (rx/subject)]
(do
(swap! pending assoc key subject)
(rx/subscribe
observable
(fn [data]
(let [entry {:created-at (dt/now) :data data}]
(swap! cache assoc key entry))
(swap! pending dissoc key)
(rx/push! subject data)
(rx/end! subject))
#(do
(swap! pending dissoc key)
(rx/error! subject %))))
subject))))