def lock_id(locker_uid, id_to_lock, expire_in_sec = 5)
      now = redis_time
      @con.multi do
        @con.zadd("#{LOCK_MAP_KEY}_z", (now + expire_in_sec), id_to_lock)
        @con.hset("#{LOCK_MAP_KEY}_h", id_to_lock, locker_uid)
      end
    end
def lock_id(locker_uid, id_to_lock, expire_in_sec = 5)
      now = redis_time
      @con.multi do
        @con.zadd("#{LOCK_MAP_KEY}_z", (now + expire_in_sec), id_to_lock)
        @con.hset("#{LOCK_MAP_KEY}_h", id_to_lock, locker_uid)
      end
    end
Locking mechanisem is based on sorted set, sorted set is used to allow a simulation
 of expiration time on the keys in the map