From 2e0089dd5c27c86488d2c68170d80d02c24135f3 Mon Sep 17 00:00:00 2001
From: Mark Felder <feld@feld.me>
Date: Sun, 13 Nov 2022 13:33:27 -0500
Subject: [PATCH] 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                                  |  1 +
 lib/pleroma/web/activity_pub/side_effects.ex  |  1 -
 lib/pleroma/web/federator.ex                  |  9 ++++-
 .../pleroma/workers/publisher_worker_test.exs | 40 +++++++++++++++++++
 4 files changed, 48 insertions(+), 3 deletions(-)
 create mode 100644 test/pleroma/workers/publisher_worker_test.exs

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 141cc2e40..56f328234 100644
--- a/CHANGELOG.md
+++ b/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
diff --git a/lib/pleroma/web/activity_pub/side_effects.ex b/lib/pleroma/web/activity_pub/side_effects.ex
index b2e15e1a0..a2152b945 100644
--- a/lib/pleroma/web/activity_pub/side_effects.ex
+++ b/lib/pleroma/web/activity_pub/side_effects.ex
@@ -282,7 +282,6 @@ defmodule Pleroma.Web.ActivityPub.SideEffects 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
diff --git a/lib/pleroma/web/federator.ex b/lib/pleroma/web/federator.ex
index 3be71c1b6..318b6cb11 100644
--- a/lib/pleroma/web/federator.ex
+++ b/lib/pleroma/web/federator.ex
@@ -47,10 +47,15 @@ defmodule Pleroma.Web.Federator 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()}
diff --git a/test/pleroma/workers/publisher_worker_test.exs b/test/pleroma/workers/publisher_worker_test.exs
new file mode 100644
index 000000000..13372bf49
--- /dev/null
+++ b/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