Avoid potentially slow count queries for user note count.

For a variety of reasons, posgresql won't use the available actor,
type index to do an index only scan. We now just increase the user
note count, which will lead to slightly wrong counts in some cases,
but it's better than the potentially very slow count query.

lib/pleroma/user.ex

@@ -239,6 +239,15 @@ defmodule Pleroma.User do
     {:ok, Repo.all(q)}
   end
 
+  def increase_note_count(%User{} = user) do
+    note_count = (user.info["note_count"] || 0) + 1
+    new_info = Map.put(user.info, "note_count", note_count)
+
+    cs = info_changeset(user, %{info: new_info})
+
+    Repo.update(cs)
+  end
+
   def update_note_count(%User{} = user) do
     note_count_query = from a in Object,
       where: fragment("?->>'actor' = ? and ?->>'type' = 'Note'", a.data, ^user.ap_id, a.data),

lib/pleroma/web/common_api/common_api.ex

@@ -61,7 +61,7 @@ defmodule Pleroma.Web.CommonAPI do
          context <- make_context(inReplyTo),
          object <- make_note_data(user.ap_id, to, context, content_html, attachments, inReplyTo, tags) do
       res = ActivityPub.create(to, user, context, object)
-      User.update_note_count(user)
+      User.increase_note_count(user)
       res
     end
   end

lib/pleroma/web/ostatus/handlers/note_handler.ex

@@ -112,7 +112,7 @@ defmodule Pleroma.Web.OStatus.NoteHandler do
          note <- (if inReplyTo && !inReplyToActivity, do: note |> Map.put("inReplyTo", inReplyTo), else: note)
       do
       res = ActivityPub.create(to, actor, context, note, %{}, date, false)
-      User.update_note_count(actor)
+      User.increase_note_count(actor)
       res
     else
       %Activity{} = activity -> {:ok, activity}

test/user_test.exs

@@ -246,6 +246,21 @@ defmodule Pleroma.UserTest do
       assert user.info["note_count"] == 1
     end
 
+    test "it increases the info->note_count property" do
+      note = insert(:note)
+      user = User.get_by_ap_id(note.data["actor"])
+
+      assert user.info["note_count"] == nil
+
+      {:ok, user} = User.increase_note_count(user)
+
+      assert user.info["note_count"] == 1
+
+      {:ok, user} = User.increase_note_count(user)
+
+      assert user.info["note_count"] == 2
+    end
+
     test "it sets the info->follower_count property" do
       user = insert(:user)
       follower = insert(:user)