Add retention policy for cached content and media (#19232)

app/lib/vacuum/statuses_vacuum.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+class Vacuum::StatusesVacuum
+  include Redisable
+
+  def initialize(retention_period)
+    @retention_period = retention_period
+  end
+
+  def perform
+    vacuum_statuses! if retention_period?
+  end
+
+  private
+
+  def vacuum_statuses!
+    statuses_scope.find_in_batches do |statuses|
+      # Side-effects not covered by foreign keys, such
+      # as the search index, must be handled first.
+
+      remove_from_account_conversations(statuses)
+      remove_from_search_index(statuses)
+
+      # Foreign keys take care of most associated records
+      # for us. Media attachments will be orphaned.
+
+      Status.where(id: statuses.map(&:id)).delete_all
+    end
+  end
+
+  def statuses_scope
+    Status.unscoped.kept.where(account: Account.remote).where(Status.arel_table[:id].lt(retention_period_as_id)).select(:id, :visibility)
+  end
+
+  def retention_period_as_id
+    Mastodon::Snowflake.id_at(@retention_period.ago, with_random: false)
+  end
+
+  def analyze_statuses!
+    ActiveRecord::Base.connection.execute('ANALYZE statuses')
+  end
+
+  def remove_from_account_conversations(statuses)
+    Status.where(id: statuses.select(&:direct_visibility?).map(&:id)).includes(:account, mentions: :account).each(&:unlink_from_conversations)
+  end
+
+  def remove_from_search_index(statuses)
+    with_redis { |redis| redis.sadd('chewy:queue:StatusesIndex', statuses.map(&:id)) } if Chewy.enabled?
+  end
+
+  def retention_period?
+    @retention_period.present?
+  end
+end