Minion::UUID

This struct wraps up a UUID that encodes a timestamp measured as seconds from the epoch (0001-01-01 00:00:00.0 UTC) observed at the location where the timestamp was generated, plus nanoseconds in the current second, plus 6 bytes for unique identification of the source -- this could be an IPV4 address with two null bytes, a MAC address, or some other sequence that will fit in 6 bytes.

Nanoseconds will fit in an Int32 (4 bytes), but seconds since the epoch will not. The current number of seconds leaks a short distance into a 5th byte, meaning that in this class, it has to be represented by an Int64. This is problematic because a UID allows for 16 bytes, so the use of 8 for seconds and 4 for nanoseconds leaves only 4 four system identification. It also leaves three bytes in the UUID as zeros.

One solution is to combine the seconds and the nanoseconds into a single Int64 number. This requires math operations to do efficiently: (seconds * 1000000000) + nanoseconds and then more math to extract the original numbers in order to reconstruct the original timestamp. This leaves 8 bytes for identification or other uniqueness information.

The other options is to truncate 2 bytes off of the seconds, storing 6 bytes of seconds data. This leaves 6 bytes for identification.

The current implementation chose option #2, as it is less work to generate a UUID if math is not involved.

+-------------+-----------------+------------+ | nanoseconds | seconds | identifier | | 0..3 | 4..10 | 11..15 | +-------------+-----------------+------------+