dynamic config

config/config.exs

@@ -28,10 +28,7 @@ config :philomena,
   channel_banner_file_root: "priv/static/system/images",
   tag_file_root: "priv/static/system/images",
   cdn_host: "",
-  proxy_host: nil,
-  quick_tags_json: File.read!("config/quick_tag_table.json"),
-  aggregation_json: File.read!("config/aggregation.json"),
-  footer_json: File.read!("config/footer.json")
+  proxy_host: nil
 
 config :philomena, :pow,
   user: Philomena.Users.User,

lib/philomena/application.ex

@@ -10,8 +10,7 @@ defmodule Philomena.Application do
     children = [
       # Start the Ecto repository
       Philomena.Repo,
-      # Start the endpoint when the application starts
-      PhilomenaWeb.Endpoint,
+
       # Starts a worker by calling: Philomena.Worker.start_link(arg)
       # {Philomena.Worker, arg},
       Philomena.Servers.ImageProcessor,
@@ -20,8 +19,12 @@ defmodule Philomena.Application do
       Philomena.Servers.PiczelChannelUpdater,
       Philomena.Servers.UserFingerprintUpdater,
       Philomena.Servers.UserIpUpdater,
+      Philomena.Servers.Config,
       Pow.Store.Backend.MnesiaCache,
-      {Redix, name: :redix, host: Application.get_env(:philomena, :redis_host)}
+      {Redix, name: :redix, host: Application.get_env(:philomena, :redis_host)},
+
+      # Start the endpoint when the application starts
+      PhilomenaWeb.Endpoint
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html

lib/philomena/servers/config.ex

@@ -0,0 +1,55 @@
+defmodule Philomena.Servers.Config do
+  use GenServer
+
+  @process_name :philomena_config
+
+  def start_link([]) do
+    GenServer.start_link(__MODULE__, [])
+  end
+
+  def get(key) do
+    pid = Process.whereis(@process_name)
+    GenServer.call(pid, {:get, key})
+  end
+
+  def reload do
+    pid = Process.whereis(@process_name)
+    GenServer.cast(pid, :reload)
+  end
+
+  @impl true
+  def init([]) do
+    Process.register(self(), @process_name)
+    {:ok, %{}}
+  end
+
+  @impl true
+  def handle_call({:get, key}, _from, state) do
+    state = maybe_update_state(state, key, Map.has_key?(state, key))
+
+    {:reply, state[key], state}
+  end
+
+  @impl true
+  def handle_cast(:reload, _state) do
+    {:noreply, %{}}
+  end
+
+  @impl true
+  def code_change(_old_vsn, _state, _extra) do
+    {:ok, %{}}
+  end
+
+  defp maybe_update_state(state, key, false) do
+    Map.put(state, key, load_config(key))
+  end
+  defp maybe_update_state(state, _key, _true), do: state
+
+  defp load_config(name) do
+    with {:ok, text} <- File.read("config/#{name}.json"),
+         {:ok, json} <- Jason.decode(text)
+    do
+      json
+    end
+  end
+end

lib/philomena_web/controllers/stat_controller.ex

@@ -2,6 +2,7 @@ defmodule PhilomenaWeb.StatController do
   use PhilomenaWeb, :controller
 
   alias Philomena.Elasticsearch
+  alias Philomena.Servers.Config
   alias Philomena.Images.Image
   alias Philomena.Comments.Comment
   alias Philomena.Topics.Topic
@@ -48,9 +49,7 @@ defmodule PhilomenaWeb.StatController do
   end
 
   defp aggregations do
-    data =
-      Application.get_env(:philomena, :aggregation_json)
-      |> Jason.decode!()
+    data = Config.get(:aggregation)
 
     {
       Elasticsearch.search(Image, data["images"]),

lib/philomena_web/views/layout_view.ex

@@ -2,6 +2,7 @@ defmodule PhilomenaWeb.LayoutView do
   use PhilomenaWeb, :view
 
   alias PhilomenaWeb.ImageView
+  alias Philomena.Servers.Config
   alias Plug.Conn
 
   def layout_class(conn) do
@@ -62,16 +63,7 @@ defmodule PhilomenaWeb.LayoutView do
   end
 
   def footer_data do
-    case Application.get_env(:philomena, :footer) do
-      nil ->
-        footer = Jason.decode!(Application.get_env(:philomena, :footer_json))
-        Application.put_env(:philomena, :footer, footer)
-
-        footer
-
-      footer ->
-        footer
-    end
+    Config.get(:footer)
   end
 
   def stylesheet_path(conn, %{theme: "dark"}),

lib/philomena_web/views/tag_view.ex

@@ -2,6 +2,7 @@ defmodule PhilomenaWeb.TagView do
   use PhilomenaWeb, :view
 
   # this is bad practice, don't copy this.
+  alias Philomena.Servers.Config
   alias Philomena.Elasticsearch
   alias Philomena.Tags.Tag
   alias Philomena.Repo
@@ -27,8 +28,7 @@ defmodule PhilomenaWeb.TagView do
     case Application.get_env(:philomena, :quick_tags) do
       nil ->
         quick_tags =
-          Application.get_env(:philomena, :quick_tags_json)
-          |> Jason.decode!()
+          Config.get(:quick_tag_table)
           |> lookup_quick_tags()
           |> render_quick_tags(conn)