prototype-string.rb

task :build_top_fans do |_, args|
  user_id = args[:user_id]
  
  redis_client = Redis.new(configurations)
  top_fan_ids = (
                  bookmarker_fan_ids(user_id) + 
                  commenters_fan_ids(user_id) + 
                  cooker_fan_ids(user_id)
                ).uniq
  
  # top-fans:user_1: [17, 15, 11, 8, 14, 12, 2, 16, 5, 13]
  redis_client.set("top-fans:#{user_id}", top_fan_ids.join(","))
end


class User
  def top_fan_ids
    redis_client.get("top-fans:#{id}".sample(10)).split(",")
  end
  
  def top_fans
    User.where(id: top_fan_ids)
  end
end