Timestamp occasionally out-of-sequence

[colinangusmackay]

In rare cases when many logs are created in multiple threads the timestamps and sequence numbers can become out of order. Each should only ever increase, and ordering a set of log entries by sequence should produce the same sequence as ordering by timestamp.

This fix, ensures that timestamps are only ever increasing. The resolution of the DateTime.UtcNow function is system dependent, so can be between 0.5ms to 15ms, or 5000 to 150,000 ticks (at 10,000 ticks per millisecond). So, in some scenarios, multiple log entries can be created before the DateTime.UtcNow method produces a new value. In this event a new DateTime is produces that increments the Ticks by 1 to ensure that the value is distinct from the preceding log entry.