Improved remote thread fetching (#10106)

* Fetch up to 5 replies when discovering a new remote status

This is used for resolving threads downwards. The originating
server must add a “replies” attributes with such replies for it to
be useful.

* Add some tests for ActivityPub::FetchRepliesWorker

* Add specs for ActivityPub::FetchRepliesService

* Serialize up to 5 public self-replies for ActivityPub notes

* Add specs for ActivityPub::NoteSerializer

* Move exponential backoff logic to a worker concern

* Fetch first page of paginated collections when fetching thread replies

* Add specs for paginated collections in replies

* Move Note replies serialization to a first CollectionPage

The collection isn't actually paginable yet as it has no id nor
a `next` field. This may come in another PR.

* Use pluck(:uri) instead of map(&:uri) to improve performances

* Fix fetching replies when they are in a CollectionPage

1 files changed, 12 insertions, 0 deletions

diff --git a/app/workers/activitypub/fetch_replies_worker.rb b/app/workers/activitypub/fetch_replies_worker.rb
new file mode 100644
index 000000000..bf466db54
--- /dev/null
+++ b/app/workers/activitypub/fetch_replies_worker.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class ActivityPub::FetchRepliesWorker
+  include Sidekiq::Worker
+  include ExponentialBackoff
+
+  sidekiq_options queue: 'pull', retry: 3
+
+  def perform(parent_status_id, replies_uri)
+    ActivityPub::FetchRepliesService.new.call(Status.find(parent_status_id), replies_uri)
+  end
+end