online_user_count.rb

online_user_count.rb

class ApplicationController < ActionController:Base
  before_action :update_online_status
  
  def update_online_status
    now = DateTime.now
    expire_time = now + 5.minutes
    
    current_time_key = "online_users:#{now.minute}"
    $redis.sadd(current_time_key, current_user.id)
    $redis.expireat(current_time_key, expire_time) 
  end
  
  def online_users_num
    now = DateTime.now.minute
    ($redis.sunion (now-5..now).map{|time| "online_users#{time}"}).length
  end
end