Mastodon API: Preloading and normalization optimizations

- Try to normalize the activity instead of object wherever possible
- Put the `user` key on non-home timelines as well so bookmarks and
thread mutes are preloaded there as well
- Skip trying to get the user when rendering mentions if the id ==
as:Public or user's follower collection
- Preload the object when getting replied to activities and do not crash
if it's not present

This almost solves the problem of Pleroma hammering the db with a lot
of queries when rendering timelines, the things left are
1. When rendering mentions and the user is not in cache, save it for
later and request all uncached users in one go
2. Somehow get rid of needing to get the latest follow activity to
detect the value of `requested` in a relationship. (create a database
view for user relationship and cache it maybe?)

lib/pleroma/activity.ex

@@ -224,6 +224,29 @@ def get_create_by_object_ap_id(ap_id) when is_binary(ap_id) do
 
   def get_create_by_object_ap_id(_), do: nil
 
+  def create_by_object_ap_id_with_object(ap_ids) when is_list(ap_ids) do
+    from(
+      activity in Activity,
+      where:
+        fragment(
+          "coalesce((?)->'object'->>'id', (?)->>'object') = ANY(?)",
+          activity.data,
+          activity.data,
+          ^ap_ids
+        ),
+      where: fragment("(?)->>'type' = 'Create'", activity.data),
+      inner_join: o in Object,
+      on:
+        fragment(
+          "(?->>'id') = COALESCE(?->'object'->>'id', ?->>'object')",
+          o.data,
+          activity.data,
+          activity.data
+        ),
+      preload: [object: o]
+    )
+  end
+
   def create_by_object_ap_id_with_object(ap_id) when is_binary(ap_id) do
     from(
       activity in Activity,
@@ -263,8 +286,8 @@ defp get_in_reply_to_activity_from_object(%Object{data: %{"inReplyTo" => ap_id}}
 
   defp get_in_reply_to_activity_from_object(_), do: nil
 
-  def get_in_reply_to_activity(%Activity{data: %{"object" => object}}) do
+  def get_in_reply_to_activity(%Activity{} = activity) do
-    get_in_reply_to_activity_from_object(Object.normalize(object))
+    get_in_reply_to_activity_from_object(Object.normalize(activity))
   end
 
   def normalize(obj) when is_map(obj), do: get_by_ap_id_with_object(obj["id"])

lib/pleroma/web/mastodon_api/mastodon_api_controller.ex

@@ -435,6 +435,7 @@ def public_timeline(%{assigns: %{user: user}} = conn, params) do
       |> Map.put("local_only", local_only)
       |> Map.put("blocking_user", user)
       |> Map.put("muting_user", user)
+      |> Map.put("user", user)
       |> ActivityPub.fetch_public_activities()
       |> Enum.reverse()
 
@@ -885,8 +886,8 @@ def get_mascot(%{assigns: %{user: user}} = conn, _params) do
   end
 
   def favourited_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
-    with %Activity{data: %{"object" => object}} <- Activity.get_by_id(id),
+    with %Activity{} = activity <- Activity.get_by_id_with_object(id),
-         %Object{data: %{"likes" => likes}} <- Object.normalize(object) do
+         %Object{data: %{"likes" => likes}} <- Object.normalize(activity) do
       q = from(u in User, where: u.ap_id in ^likes)
 
       users =
@@ -902,8 +903,8 @@ def favourited_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
   end
 
   def reblogged_by(%{assigns: %{user: user}} = conn, %{"id" => id}) do
-    with %Activity{data: %{"object" => object}} <- Activity.get_by_id(id),
+    with %Activity{} = activity <- Activity.get_by_id_with_object(id),
-         %Object{data: %{"announcements" => announces}} <- Object.normalize(object) do
+         %Object{data: %{"announcements" => announces}} <- Object.normalize(activity) do
       q = from(u in User, where: u.ap_id in ^announces)
 
       users =
@@ -944,6 +945,7 @@ def hashtag_timeline(%{assigns: %{user: user}} = conn, params) do
       |> Map.put("local_only", local_only)
       |> Map.put("blocking_user", user)
       |> Map.put("muting_user", user)
+      |> Map.put("user", user)
       |> Map.put("tag", tags)
       |> Map.put("tag_all", tag_all)
       |> Map.put("tag_reject", tag_reject)
@@ -1350,6 +1352,7 @@ def list_timeline(%{assigns: %{user: user}} = conn, %{"list_id" => id} = params)
         params
         |> Map.put("type", "Create")
         |> Map.put("blocking_user", user)
+        |> Map.put("user", user)
         |> Map.put("muting_user", user)
 
       # we must filter the following list for the user to avoid leaking statuses the user

lib/pleroma/web/mastodon_api/views/status_view.ex

@@ -5,6 +5,8 @@
 defmodule Pleroma.Web.MastodonAPI.StatusView do
   use Pleroma.Web, :view
 
+  require Pleroma.Constants
+
   alias Pleroma.Activity
   alias Pleroma.HTML
   alias Pleroma.Object
@@ -24,19 +26,19 @@ defp get_replied_to_activities([]), do: %{}
   defp get_replied_to_activities(activities) do
     activities
     |> Enum.map(fn
-      %{data: %{"type" => "Create", "object" => object}} ->
+      %{data: %{"type" => "Create"}} = activity ->
-        object = Object.normalize(object)
+        object = Object.normalize(activity)
-        object.data["inReplyTo"] != "" && object.data["inReplyTo"]
+        object && object.data["inReplyTo"] != "" && object.data["inReplyTo"]
 
       _ ->
         nil
     end)
     |> Enum.filter(& &1)
-    |> Activity.create_by_object_ap_id()
+    |> Activity.create_by_object_ap_id_with_object()
     |> Repo.all()
     |> Enum.reduce(%{}, fn activity, acc ->
       object = Object.normalize(activity)
-      Map.put(acc, object.data["id"], activity)
+      if object, do: Map.put(acc, object.data["id"], activity), else: acc
     end)
   end
 
@@ -88,6 +90,7 @@ def render(
     reblogged_activity =
       Activity.create_by_object_ap_id(activity_object.data["id"])
       |> Activity.with_preloaded_bookmark(opts[:for])
+      |> Activity.with_set_thread_muted_field(opts[:for])
       |> Repo.one()
 
     reblogged = render("status.json", Map.put(opts, :activity, reblogged_activity))
@@ -142,6 +145,7 @@ def render("status.json", %{activity: %{data: %{"object" => _object}} = activity
     object = Object.normalize(activity)
 
     user = get_user(activity.data["actor"])
+    user_follower_address = user.follower_address
 
     like_count = object.data["like_count"] || 0
     announcement_count = object.data["announcement_count"] || 0
@@ -157,7 +161,11 @@ def render("status.json", %{activity: %{data: %{"object" => _object}} = activity
     mentions =
       (object.data["to"] ++ tag_mentions)
       |> Enum.uniq()
-      |> Enum.map(fn ap_id -> User.get_cached_by_ap_id(ap_id) end)
+      |> Enum.map(fn
+        Pleroma.Constants.as_public() -> nil
+        ^user_follower_address -> nil
+        ap_id -> User.get_cached_by_ap_id(ap_id)
+      end)
       |> Enum.filter(& &1)
       |> Enum.map(fn user -> AccountView.render("mention.json", %{user: user}) end)