spymemcached的set方法

 public OperationFuture<Boolean> set(String key, int exp, Object o) {
    return asyncStore(StoreType.set, key, exp, o, transcoder);
  }

这是set方法  注释中有这样一段

  * <p>
   * The actual value sent may either be Unix time (number of seconds since
   * January 1, 1970, as a 32-bit value), or a number of seconds starting from
   * current time. In the latter case, this number of seconds may not exceed
   * 60*60*24*30 (number of seconds in 30 days); if the number sent by a client
   * is larger than that, the server will consider it to be real Unix time value
   * rather than an offset from current time.
   * </p>

意思是过期时间这个值或者是unix绝对时间 或者是一个相对时间
相对时间的取值不能大于60*60*24*30
如果大于会认为是unix绝对时间