add 1 min fallback poll to recheck servers w/o instances

lib/farside/application.ex

@@ -6,6 +6,7 @@ defmodule Farside.Application do
   require Logger
 
   alias Farside.LastUpdated
+  alias Farside.Check
   alias Farside.Sync
   alias Farside.Http
 
@@ -22,7 +23,7 @@ defmodule Farside.Application do
     maybe_loaded_children =
       case is_nil(System.get_env("FARSIDE_TEST")) do
         true ->
-          [{Sync, []}]
+          [{Check, []}, {Sync, []}]
 
         false ->
           Logger.info("Skipping sync job setup...")
@@ -82,5 +83,4 @@ defmodule Farside.Application do
 
     response
   end
-
 end

lib/farside/check.ex

@@ -0,0 +1,28 @@
+defmodule Farside.Check do
+  use Task
+
+  def child_spec(args) do
+    %{
+      id: __MODULE__,
+      start: {__MODULE__, :start_link, [args]},
+      type: :worker
+    }
+  end
+
+  def start_link(_arg) do
+    Task.start_link(&poll/0)
+  end
+
+  def poll() do
+    receive do
+    after
+      60_000 ->
+        run()
+        poll()
+    end
+  end
+
+  defp run() do
+    Farside.Instance.Supervisor.sync_empty_instances()
+  end
+end

lib/farside/instance.ex

@@ -76,6 +76,25 @@ defmodule Farside.Instance do
     {:noreply, state}
   end
 
+  def handle_cast(
+        :check,
+        state
+      ) do
+    service = :ets.lookup(String.to_atom(state.type), :default)
+
+    {_, service} = List.first(service)
+
+    if Enum.count(service.instances) == 0 do
+      service = Http.fetch_instances(service)
+
+      :ets.delete(String.to_atom(state.type), :data)
+
+      :ets.insert(state.ref, {:data, service})
+    end
+
+    {:noreply, state}
+  end
+
   @doc false
   def via_tuple(data, registry \\ @registry_name) do
     {:via, Registry, {registry, data}}

lib/farside/instance.supervisor.ex

@@ -90,4 +90,12 @@ defmodule Farside.Instance.Supervisor do
       _ -> true
     end
   end
+
+  def sync_empty_instances() do
+    list()
+    |> Enum.each(fn x ->
+      SERVER.via_tuple(x)
+      |> GenServer.cast(:check)
+    end)
+  end
 end