discourse/lib/discourse_bus.rb

# Proxies MessageBus and noops READONLY errors.
module DiscourseBus

  def self.start!
    MessageBus.site_id_lookup do
      RailsMultisite::ConnectionManagement.current_db
    end

    MessageBus.extra_response_headers_lookup do |env|
      {
        "Access-Control-Allow-Origin" => Discourse.base_url_no_prefix,
        "Access-Control-Allow-Methods" => "GET, POST",
        "Access-Control-Allow-Headers" => "X-SILENCE-LOGGER, X-Shared-Session-Key"
      }
    end

    MessageBus.user_id_lookup do |env|
      user = CurrentUser.lookup_from_env(env)
      user.id if user
    end

    MessageBus.group_ids_lookup do |env|
      user = CurrentUser.lookup_from_env(env)
      user.groups.select('groups.id').map{|g| g.id} if user
    end

    MessageBus.on_connect do |site_id|
      RailsMultisite::ConnectionManagement.establish_connection(db: site_id)
    end

    MessageBus.on_disconnect do |site_id|
      ActiveRecord::Base.connection_handler.clear_active_connections!
    end

    # Point at our redis
    MessageBus.redis_config = YAML.load(ERB.new(File.new("#{Rails.root}/config/redis.yml").read).result)[Rails.env].symbolize_keys

    MessageBus.long_polling_enabled = SiteSetting.enable_long_polling
    MessageBus.long_polling_interval = SiteSetting.long_polling_interval

    MessageBus.is_admin_lookup do |env|
      user = CurrentUser.lookup_from_env(env)
      if user && user.admin
        true
      else
        false
      end
    end

    MessageBus.cache_assets = !Rails.env.development?
    MessageBus.enable_diagnostics
  end

  def self.proxy_readonly(*methods)
    methods.each do |name|
      define_singleton_method(name) do |*args, &block|
        DiscourseRedis.ignore_readonly { MessageBus.send(name, *args, &block) }
      end
    end
  end

  proxy_readonly :publish,
                 :subscribe,
                 :unsubscribe,
                 :last_id,
                 :last_message,
                 :backlog,
                 :after_fork,
                 :on_connect,
                 :on_disconnect,
                 :track_publish

end