When list is deleted, remove feed from redis

app/models/list.rb

@@ -19,4 +19,23 @@ class List < ApplicationRecord
   has_many :accounts, through: :list_accounts
 
   validates :title, presence: true
+
+  before_destroy :clean_feed_manager
+
+  private
+
+  def clean_feed_manager
+    reblog_key       = Redis.current.key(:list, id, 'reblogs')
+    reblogged_id_set = Redis.current.zrange(reblog_key, 0, -1)
+
+    redis.pipelined do
+      Redis.current.del(FeedManager.instance.key(:list, id))
+      Redis.current.del(reblog_key)
+
+      reblogged_id_set.each do |reblogged_id|
+        reblog_set_key = FeedManager.instance.key(:list, id, "reblogs:#{reblogged_id}")
+        Redis.current.del(reblog_set_key)
+      end
+    end
+  end
 end