def length
      (@client.redis.multi do
        %w[ locks work scheduled depends ].each do |suffix|
          @client.redis.zcard("ql:q:#{@name}-#{suffix}")
        end
      end).inject(0, :+)
    end
def length
      (@client.redis.multi do
        %w[ locks work scheduled depends ].each do |suffix|
          @client.redis.zcard("ql:q:#{@name}-#{suffix}")
        end
      end).inject(0, :+)
    end
How many items in the queue?