c# - Have a Log4Net RollingFileAppender set to roll weekly

Question

The DatePattern string needs to be something that the SimpleDateFormatter will accept.

Unfortunately this means that, out of the box, this doesn't include being able to set the boundary to be a week number. There are ways of getting this value in C#, but it's not obvious that we can extend the SimpleDateFormatter or provide a different implementation of IDateFormatter and use that instead (or even in a custom RollingFileAppender).

So how might we get a Log4Net RollingFileAppender to roll weekly?

Answer 1

I got mine rolling every week. You must set your dateformat to include the day of the month to generate unique filenames.

class RollingOverWeekFileAppender : RollingFileAppender
{
    private DateTime nextWeekendDate;

    public RollingOverWeekFileAppender()
    {
        CalcNextWeekend(DateTime.Now);
    }

    private void CalcNextWeekend(DateTime time)
    { 
        // Calc next sunday
        time = time.AddMilliseconds((double)-time.Millisecond);
        time = time.AddSeconds((double)-time.Second);
        time = time.AddMinutes((double)-time.Minute);
        time = time.AddHours((double)-time.Hour);
        nextWeekendDate = time.AddDays((double)(7 - (int)time.DayOfWeek));
    }

    protected override void AdjustFileBeforeAppend()
    {
        DateTime now = DateTime.Now;

        if (now >= nextWeekendDate)
        {
            CalcNextWeekend(now);
            // As you included the day and month AdjustFileBeforeAppend takes care of creating 
            // new file with the new name
            base.AdjustFileBeforeAppend();
        }
    }
}