config/initializers/delayed_job.rb with conditional mail delaying

delayed_job.rb

# Conditionally delay outgoing mail
class DelayedMailerBase < ActionMailer::Base
  class << self
    def method_missing(method_symbol, *parameters)
      # If this is "deliver_xx", maybe delay it; if we do, change 
      # its name so that we don't delay in the worker.
      method_name = method_symbol.to_s
      if matches_deliver_method?(method_name) and delaying_mail?
        return self.send_later("delayed_#{method_name}".to_sym, *parameters)
      end

      # If this is a delayed name (meaning we're the worker), 
      # convert it back.
      if match = matches_delayed_deliver_method?(method_name)
        return super(match[1], *parameters)
      end

      super # Nothing funny - do the normal thing.
    end

    def respond_to?(method)
      super or matches_deliver_method?(method) \
        or matches_delayed_deliver_method?(method) \
    end

    def delaying_mail?
      Rails.env.production?
    end

    private
      def matches_deliver_method?(method_symbol) #:nodoc:
        /^deliver_[_a-z]\w*/.match(method_symbol.to_s)
      end

      def matches_delayed_deliver_method?(method_symbol) #:nodoc:
        /^delayed_(deliver.*)/.match(method_symbol.to_s)
      end
  end
end