每小时获取缓存以每半小时更新一次变量

Question

I have a .net application variable cached. What I want to do it get the cache to recycle the variable every half hour on the hour, 1, 1.30, 2, 2.30 etc. I have the onRemoveCallback function set and everything works, my real question is what is the best way to generate the correct absoluteExpiration value?

DateTime time_to_expire = DateTime.Now;
            if (time_to_expire.Minute < 29)
            {
                time_to_expire = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour, 30, 0);
            }
            else
            {
                time_to_expire = new DateTime(DateTime.Now.Year, DateTime.Now.Month, DateTime.Now.Day, DateTime.Now.Hour + 1, 0, 0);
            }

The reason I test the time_to_expire value to 29 is that I am worried about boundary cases and I don't want the variable to 'go blank' for a half hour period! Ideas on how to do this better?

Thanks

Answer 1

Don't know that it is any "better" but I would be inclined to do something like this:

        DateTime time_to_expire = DateTime.Now.AddMinutes(30);
        time_to_expire = new DateTime(time_to_expire.Year, time_to_expire.Month, time_to_expire.Day, time_to_expire.Hour, time_to_expire.Minute >= 30 ? 30 : 0, 0);