Alter priority of Delete activities to be lowest

This will prevent a user with a large number of posts from negatively affecting performance of the outgoing federation queue if they delete their account.

CHANGELOG.md

@@ -17,6 +17,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - **Breaking**: `/api/v1/pleroma/backups` endpoints now requires `read:backups` scope instead of `read:accounts`
 - Updated the recommended pleroma.vcl configuration for Varnish to target Varnish 7.0+
 - Set timeout values for Oban queues. The default is infinity and some operations may not time out on their own.
+- Delete activities are federated at lowest priority
 
 ### Added
 - `activeMonth` and `activeHalfyear` fields in NodeInfo usage.users object

lib/pleroma/web/activity_pub/side_effects.ex

@@ -282,7 +282,6 @@ def handle(%{data: %{"type" => "EmojiReact"}} = object, meta) do
   # Tasks this handles:
   # - Delete and unpins the create activity
   # - Replace object with Tombstone
-  # - Set up notification
   # - Reduce the user note count
   # - Reduce the reply count
   # - Stream out the activity

lib/pleroma/web/federator.ex

@@ -47,10 +47,15 @@ def publish(%{id: "pleroma:fakeid"} = activity) do
   end
 
   @impl true
-  def publish(activity) do
-    PublisherWorker.enqueue("publish", %{"activity_id" => activity.id})
+  def publish(%Pleroma.Activity{data: %{"type" => type}} = activity) do
+    PublisherWorker.enqueue("publish", %{"activity_id" => activity.id},
+      priority: publish_priority(type)
+    )
   end
 
+  defp publish_priority("Delete"), do: 3
+  defp publish_priority(_), do: 0
+
   # Job Worker Callbacks
 
   @spec perform(atom(), module(), any()) :: {:ok, any()} | {:error, any()}

test/pleroma/workers/publisher_worker_test.exs

@@ -0,0 +1,40 @@
+# Pleroma: A lightweight social networking server
+# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
+# SPDX-License-Identifier: AGPL-3.0-only
+
+defmodule Pleroma.Workers.PublisherWorkerTest do
+  use Pleroma.DataCase, async: true
+  use Oban.Testing, repo: Pleroma.Repo
+
+  import Pleroma.Factory
+
+  alias Pleroma.Object
+  alias Pleroma.Web.ActivityPub.ActivityPub
+  alias Pleroma.Web.ActivityPub.Builder
+  alias Pleroma.Web.CommonAPI
+  alias Pleroma.Web.Federator
+
+  describe "Oban job priority:" do
+    setup do
+      user = insert(:user)
+
+      {:ok, post} = CommonAPI.post(user, %{status: "Regrettable post"})
+      object = Object.normalize(post, fetch: false)
+      {:ok, delete_data, _meta} = Builder.delete(user, object.data["id"])
+      {:ok, delete, _meta} = ActivityPub.persist(delete_data, local: true)
+
+      %{
+        post: post,
+        delete: delete
+      }
+    end
+
+    test "Deletions are lower priority", %{delete: delete} do
+      assert {:ok, %Oban.Job{priority: 3}} = Federator.publish(delete)
+    end
+
+    test "Creates are normal priority", %{post: post} do
+      assert {:ok, %Oban.Job{priority: 0}} = Federator.publish(post)
+    end
+  end
+end