load dependencies in application start callback (#151)

When using the new PLUG_EDITOR integration, there was a problem where
not all dependencies were available when the code reloader recompiled
the code.
This lead to missing dependencies when the live reloader joined the
channel.
This change ensures that all we initially load the deps when the
application starts, so that later recompiles don't affect the deps list.

lib/phoenix_live_reload/application.ex

@@ -9,6 +9,10 @@ defmodule Phoenix.LiveReloader.Application do
     # be started in dev via user's `only: :dev` entry.
     WebConsoleLogger.attach_logger()
 
+    # the deps paths are read by the channel when getting the full_path for
+    # opening the configured PLUG_EDITOR
+    :persistent_term.put(:phoenix_live_reload_deps_paths, deps_paths())
+
     children = [
       WebConsoleLogger,
       %{id: __MODULE__, start: {__MODULE__, :start_link, []}}
@@ -48,4 +52,13 @@ defmodule Phoenix.LiveReloader.Application do
         other
     end
   end
+
+  defp deps_paths do
+    # TODO: Use `Code.loaded?` on Elixir v1.15+
+    if :erlang.module_loaded(Mix.Project) do
+      for {app, path} <- Mix.Project.deps_paths(), into: %{}, do: {to_string(app), path}
+    else
+      %{}
+    end
+  end
 end

lib/phoenix_live_reload/channel.ex

@@ -26,7 +26,6 @@ defmodule Phoenix.LiveReloader.Channel do
         |> assign(:patterns, config[:patterns] || [])
         |> assign(:debounce, config[:debounce] || 0)
         |> assign(:notify_patterns, config[:notify] || [])
-        |> assign(:deps_paths, deps_paths())
 
       {:ok, join_info(), socket}
     else
@@ -76,7 +75,7 @@ defmodule Phoenix.LiveReloader.Channel do
   end
 
   def handle_in("full_path", %{"rel_path" => rel_path, "app" => app}, socket) do
-    case socket.assigns.deps_paths do
+    case :persistent_term.get(:phoenix_live_reload_deps_paths) do
       %{^app => dep_path} ->
         {:reply, {:ok, %{full_path: Path.join(dep_path, rel_path)}}, socket}
 
@@ -130,13 +129,4 @@ defmodule Phoenix.LiveReloader.Channel do
       %{}
     end
   end
-
-  defp deps_paths do
-    # TODO: Use `Code.loaded?` on Elixir v1.15+
-    if :erlang.module_loaded(Mix.Project) do
-      for {app, path} <- Mix.Project.deps_paths(), into: %{}, do: {to_string(app), path}
-    else
-      %{}
-    end
-  end
 end