prototype-set.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)
    
  top_fan_ids.each do |id|
    redis_client.sadd("top-fans:#{user_id}", id)
  end
end


class User
  def top_fan_ids
    # top-fans:user_1: [17, 15, 11, 8, 14, 12, 2, 16, 5, 13]
    redis_client.smembers(top_fan_key).sample(10)
  end
  
  def top_fans
    User.where(id: top_fan_ids)
  end
  
  def is_fan?(other_id)
    redis_client.sismember(top_fan_key, other_id)
  end
  
  private
    
    def top_fan_key
      "top-fans:#{id}"
    end
end