fix(Plugs.RecentlyVisited): handle task timeout

lib/dotcom_web/controllers/mode_controller.ex

@@ -6,10 +6,9 @@ defmodule DotcomWeb.ModeController do
 
   alias CMS.{Partial.Teaser, Repo}
   alias DotcomWeb.Mode
+  alias DotcomWeb.Plugs.RecentlyVisited
   alias Routes.Route
 
-  plug(DotcomWeb.Plugs.RecentlyVisited)
-
   def subway(conn, params), do: Mode.Hub.index(Mode.SubwayController, conn, params)
   def bus(conn, params), do: Mode.Hub.index(Mode.BusController, conn, params)
   def ferry(conn, params), do: Mode.Hub.index(Mode.FerryController, conn, params)
@@ -23,6 +22,7 @@ defmodule DotcomWeb.ModeController do
 
   def index(conn, _params) do
     conn
+    |> RecentlyVisited.call(RecentlyVisited.init([]))
     |> async_assign_default(:alerts, fn -> Alerts.Repo.all(conn.assigns.date_time) end, [])
     |> async_assign_default(:green_routes, fn -> green_routes() end)
     |> async_assign_default(:grouped_routes, fn -> filtered_grouped_routes([:bus]) end)

lib/dotcom_web/plugs/recently_visited.ex

@@ -29,30 +29,10 @@ defmodule DotcomWeb.Plugs.RecentlyVisited do
     route_list =
       routes
       |> String.split("|")
-      |> Task.async_stream(&get_route/1)
-      |> Enum.reduce([], &parse_route_response/2)
-      |> Enum.reverse()
+      |> Task.async_stream(&@routes_repo.get/1, max_concurrency: 4, on_timeout: :kill_task)
+      |> Stream.filter(&match?({:ok, %Route{listed?: true}}, &1))
+      |> Stream.map(fn {:ok, route} -> route end)
 
     Conn.assign(conn, :recently_visited, route_list)
   end
-
-  @spec get_route(String.t()) :: Route.t() | nil
-  defp get_route("Green") do
-    "Green-B"
-    |> @routes_repo.get()
-    |> Route.to_naive()
-  end
-
-  defp get_route(route) do
-    @routes_repo.get(route)
-  end
-
-  @spec parse_route_response({:ok, Route.t() | nil} | {:error, any}, [Route.t()]) :: [Route.t()]
-  defp parse_route_response({:ok, %Route{listed?: true} = route}, acc) do
-    [route | acc]
-  end
-
-  defp parse_route_response(_, acc) do
-    acc
-  end
 end

test/dotcom_web/plugs/recently_visited_test.exs

@@ -34,7 +34,7 @@ defmodule DotcomWeb.Plugs.RecentlyVisitedTest do
                %Route{} = green,
                %Route{} = green_b,
                %Route{} = blue
-             ] = conn.assigns.recently_visited
+             ] = conn.assigns.recently_visited |> Enum.to_list()
 
       assert red.id == "Red"
       assert green.id == "Green"
@@ -50,7 +50,7 @@ defmodule DotcomWeb.Plugs.RecentlyVisitedTest do
         |> Map.put(:cookies, cookies)
         |> RecentlyVisited.call([])
 
-      assert [%Route{id: "Red"}] = conn.assigns.recently_visited
+      assert [%Route{id: "Red"}] = conn.assigns.recently_visited |> Enum.to_list()
     end
 
     test "does not assign :recently_visited if cookie doesn't exist", %{conn: conn} do
@@ -86,7 +86,8 @@ defmodule DotcomWeb.Plugs.RecentlyVisitedTest do
         |> Map.put(:cookies, cookies)
         |> RecentlyVisited.call([])
 
-      assert {:ok, [%Route{id: "Red"}]} = Map.fetch(conn.assigns, :recently_visited)
+      assert {:ok, visited} = Map.fetch(conn.assigns, :recently_visited)
+      assert [%Route{id: "Red"}] = visited |> Enum.to_list()
     end
 
     test "does not include unlisted routes", %{conn: conn} do
@@ -103,7 +104,8 @@ defmodule DotcomWeb.Plugs.RecentlyVisitedTest do
         |> Map.put(:cookies, cookies)
         |> RecentlyVisited.call([])
 
-      assert {:ok, []} = Map.fetch(conn.assigns, :recently_visited)
+      assert {:ok, visited} = Map.fetch(conn.assigns, :recently_visited)
+      assert [] = visited |> Enum.to_list()
     end
   end
 end