Add hotreload functionality

src/xiana/hotreload.clj

@@ -0,0 +1,43 @@
+(ns xiana.hotreload
+  (:require
+   [clojure.core.async :refer [go-loop]]
+   [ns-tracker.core :refer [ns-tracker]]))
+
+;;; reloader function from ring.middleware.reload
+
+(defn- reloader [dirs retry?]
+  (let [modified-namespaces (ns-tracker dirs)
+        load-queue (java.util.concurrent.LinkedBlockingDeque.)]
+    (fn []
+      (locking load-queue
+        (doseq [ns-sym (reverse (modified-namespaces))]
+          (.push load-queue ns-sym))
+        (loop []
+          (when-let [ns-sym (.peek load-queue)]
+            (if retry?
+              (do (require ns-sym :reload) (.remove load-queue))
+              (do (.remove load-queue) (require ns-sym :reload)))
+            (recur)))))))
+
+(defn hotreload
+  "Function to hotreload the system. Add it after server-start at configuration phase \"->system\".
+  (-> (config/config app-cfg)
+      ...
+      xiana.webserver/start
+      xiana.hotreload/hotreload)
+  If a :xiana/hotreload config key is provided it needs:
+  :restart-fn \"the function to restart the system\" if none 'user/start-dev-system
+  :tracker {:dirs \"the directories vector list to search for changes\" :reload-compile-errors? \"true\"}."
+  [cfg]
+  (let [{:keys [restart-fn tracker]} (:xiana/hotreload cfg {:restart-fn 'user/start-dev-system})
+        dirs (:dirs tracker ["src"])
+        retry? (:reload-compile-errors? tracker true)
+        track-fn (ns-tracker dirs)
+        reload! (reloader dirs retry?)
+        restart-fn (resolve restart-fn)]
+    (go-loop []
+      (if (track-fn)
+        (do
+          (reload!)
+          (restart-fn))
+        (recur)))))