instance method pubsub_adapter

# File actioncable/lib/action_cable/server/configuration.rb, line 24
      def pubsub_adapter
        adapter = (cable.fetch("adapter") { "redis" })
        path_to_adapter = "action_cable/subscription_adapter/#{adapter}"
        begin
          require path_to_adapter
        rescue Gem::LoadError => e
          raise Gem::LoadError, "Specified '#{adapter}' for Action Cable pubsub adapter, but the gem is not loaded. Add `gem '#{e.name}'` to your Gemfile (and ensure its version is at the minimum required by Action Cable)."
        rescue LoadError => e
          raise LoadError, "Could not load '#{path_to_adapter}'. Make sure that the adapter in config/cable.yml is valid. If you use an adapter other than 'postgresql' or 'redis' add the necessary adapter gem to the Gemfile.", e.backtrace
        end

        adapter = adapter.camelize
        adapter = "PostgreSQL" if adapter == "Postgresql"
        "ActionCable::SubscriptionAdapter::#{adapter}".constantize
      end