Stale user refreshing should be done async to prevent blocking of rendering activities

changelog.d/user-refresh.change

@@ -0,0 +1 @@
+User profile refreshes are now asynchronous

config/test.exs

@@ -183,6 +183,8 @@
 
 config :pleroma, Pleroma.Web.RichMedia.Backfill, provider: Pleroma.Web.RichMedia.Backfill
 
+config :pleroma, Pleroma.User, sync_refreshing: true
+
 if File.exists?("./config/test.secret.exs") do
   import_config "test.secret.exs"
 else

lib/pleroma/user.ex

@@ -2154,20 +2154,23 @@ def html_filter_policy(_), do: Config.get([:markup, :scrub_policy])
 
   def fetch_by_ap_id(ap_id), do: ActivityPub.make_user_from_ap_id(ap_id)
 
+  @spec get_or_fetch_by_ap_id(String.t()) :: {:ok, User.t()} | {:error, any()}
   def get_or_fetch_by_ap_id(ap_id) do
-    cached_user = get_cached_by_ap_id(ap_id)
+    with cached_user = %User{} <- get_cached_by_ap_id(ap_id),
+         _ <- maybe_refresh(cached_user) do
+      {:ok, cached_user}
+    else
+      _ -> fetch_by_ap_id(ap_id)
+    end
+  end
 
-    maybe_fetched_user = needs_update?(cached_user) && fetch_by_ap_id(ap_id)
+  defp maybe_refresh(user) do
+    fun = fn -> needs_update?(user) && fetch_by_ap_id(user.ap_id) end
 
-    case {cached_user, maybe_fetched_user} do
-      {_, {:ok, %User{} = user}} ->
-        {:ok, user}
-
-      {%User{} = user, _} ->
-        {:ok, user}
-
-      _ ->
-        {:error, :not_found}
+    if Config.get([__MODULE__, :sync_refreshing], false) do
+      fun.()
+    else
+      Task.start(fun)
     end
   end
 

test/pleroma/user_test.exs

@@ -953,9 +953,12 @@ test "updates an existing user, if stale" do
 
       {:ok, user} = User.get_or_fetch_by_ap_id("http://mastodon.example.org/users/admin")
 
-      assert user.inbox
+      # User was updated async, fetch from cache now
+      updated_user = User.get_cached_by_ap_id(user.ap_id)
 
-      refute user.last_refreshed_at == orig_user.last_refreshed_at
+      assert updated_user.inbox
+
+      refute updated_user.last_refreshed_at == orig_user.last_refreshed_at
     end
 
     test "if nicknames clash, the old user gets a prefix with the old id to the nickname" do