feat: use route cache in alerts filter expansion

config/config.exs

@@ -486,6 +486,7 @@ config :screens, Screens.ScreenApiResponseCache,
   allocated_memory: 250_000_000
 
 config :screens, Screens.Stops.StopsToRoutes, adapter: Nebulex.Adapters.Local
+config :screens, Screens.Routes.RoutesCache, adapter: Nebulex.Adapters.Local
 
 # Import environment specific config. This must remain at the bottom
 # of this file so it overrides the configuration defined above.

config/test.exs

@@ -27,7 +27,7 @@ config :screens,
   blue_bikes_station_status_url: [:no_api_requests_allowed_during_testing],
   blue_bikes_api_client: Screens.BlueBikes.FakeClient,
   stops_to_routes_route_mod: Screens.Routes.Route.Mock,
-  alerts_cache_filter_route_mod: Screens.Routes.Route.Mock,
+  routes_cache_route_mod: Screens.Routes.Route.Mock,
   dup_headsign_replacements: %{
     "Test 1" => "T1"
   },
@@ -164,3 +164,4 @@ config :screens, :screens_by_alert,
   screens_ttl_seconds: 1
 
 config :screens, Screens.Stops.StopsToRoutes, adapter: Nebulex.Adapters.Nil
+config :screens, Screens.Routes.RoutesCache, adapter: Nebulex.Adapters.Nil

lib/screens/alerts/cache/filter.ex

@@ -3,6 +3,7 @@ defmodule Screens.Alerts.Cache.Filter do
   Logic to apply filters to a list of `Screens.Alerts.Alert` structs.
   """
   alias Screens.Routes.Route
+  alias Screens.Routes.RoutesCache
   alias Screens.RouteType
   alias Screens.Stops.StopsToRoutes
 
@@ -125,10 +126,8 @@ defmodule Screens.Alerts.Cache.Filter do
   end
 
   defp matchers_for_route_id(route_id) do
-    route_mod = Application.get_env(:screens, :alerts_cache_filter_route_mod, Route)
-
-    case route_mod.by_id(route_id) do
-      {:ok, %Route{type: type}} ->
+    case RoutesCache.by_id(route_id) do
+      %Route{type: type} ->
         [
           %{
             route_type: RouteType.to_id(type),

lib/screens/routes/routes_cache.ex

@@ -4,7 +4,7 @@ defmodule Screens.Routes.RoutesCache do
   """
   use Nebulex.Cache,
     otp_app: :screens,
-    adapter: Nebulex.Adapters.Local
+    adapter: Application.compile_env(:screens, [__MODULE__, :adapter])
 
   alias Screens.Routes.Route
 
@@ -15,15 +15,20 @@ defmodule Screens.Routes.RoutesCache do
     if route = get(id) do
       route
     else
-      case Route.by_id(id) do
-        {:ok, %Route{} = route} ->
-          put(id, route, ttl: ttl())
+      route = fetch_by_id(id)
 
-          route
+      unless is_nil(route), do: put(id, route, ttl: ttl())
 
-        _ ->
-          nil
-      end
+      route
+    end
+  end
+
+  defp fetch_by_id(id) do
+    route_impl = Application.get_env(:screens, :routes_cache_route_mod, Route)
+
+    case route_impl.by_id(id) do
+      {:ok, %Route{} = route} -> route
+      _ -> nil
     end
   end