Using Redis EXPIRE to Track Rails Online Audiences

To whom

• Those who are on Ruby on Rails
• Who wants to know which users are online, but have not yet thought about how
• For whom it is not a problem to use Redis (for the reason of hosting for example)

Actually implementation

Init

 # config/initializers/redis.rb $redis_onlines = Redis.new 

 # config/initializers/redis.rb $redis_onlines = Redis.new path: "/tmp/redis.sock", db: 15, driver: :hiredis 

• path: "/tmp/redis.sock" - use the socket if possible
• driver: :hiredis - hiredis driver faster
• db: 15 - use a specific database, the default is zero, but I recommend leaving it for testing, application tasks, something else. There are no problems in using the zero database - the point is that it was strictly defined for online users and for nothing else.

Gemfile

 # Gemfile gem 'redis' gem 'hiredis' # optional 

Install online

 def current_user @current_user ||= User.find_by_id( session[ :user_id ] ) end 

 # app/controllers/application_controller.rb after_filter :set_online #  Rails 4 : # after_action :set_online #     set_online private def set_online if !!current_user #   ,    $redis_onlines.set( current_user.id, nil, ex: 10*60 ) # `ex: 10*60` -     - 10 ,  10    end end 

Online?

  # app/models/user.rb def online? #      -   false,  true $redis_onlines.exists( self.id ) end 

Small bonus - list of online users

 # app/cpntrollers/application_controller.rb def all_who_are_in_touch $redis_onlines.keys # => [ "123", "234", "1", "23" ] #    id   end 

Some processing for anonymous

  # app/controllers/application_controller.rb def set_online if !!current_user #       "user:"  id $redis_onlines.set( "user:#{current_user.id}", nil, ex: 10*60 ) else #      "ip:"    id  $redis_onlines.set( "ip:#{request.remote_ip}", nil, ex: 10*60 ) end end 

 # app/models/user.rb def online? $redis_onlines.exists( "user:#{self.id}" ) end 

 # app/cpntrollers/application_controller.rb #     (   id) def all_signed_in_in_touch ids = [] $redis_onlines.scan_each( match: 'user*' ){|u| ids << u.gsub("user:", "") } ids end #      def all_anonymous_in_touch $redis_onlines.scan_each( match: 'ip*' ).to_a.size end #     def all_who_are_in_touch $redis_onlines.dbsize end 

Well, just a little bit about the size of the database

#UDP 1

#UDP 2

1. Use before_filter instead of after_filter - then the logged-in user will see himself on the list online during the first (in the next 10 minutes) visit. But then the choice depends on your needs / wishes.
2. If an anonymous audience is being counted and at the same time logged in users - then when a user logs in / out, by and large it would not be bad to clean the user from the opposite list. For example, a user logs on to the site (an entry by ip is in progress), and then becomes authorized (the second entry by id) - as a result, in the near future (conditional 10 minutes) one user will be considered as two. Example implementation in the spoiler below.

 # app/cpntrollers/session_controller.rb #   #  -  create #  - destroy before_filter :clear_from_signed_in_touch, only: :destroy before_filter :clear_from_anonymous_in_touch, only: :create # ... private #   -      ip def clear_from_anonymous_in_touch $redis_onlines.del( "ip:#{request.remote_ip}" ) end #   id      - session[:user_id] #   -      id def clear_from_signed_in_touch $redis_onlines.del( "user:#{session[:user_id]}" ) end 

• Redis
• about pipelined
• set | exists | expire | scan
• scan_each
• redis-rb
• good article for beginners on Rails + Redis