UUID1 from UTC Timestamp in Python?

Question

The problem goes like this:

My application is deployed on a remote server with different timezone and I want to generate a uuid1 against UTC timestamp. I can't find a way to generate uuid1 from any given timestamp. The reason I want to do this is that I don't want to get into the hassle of calculating my local time where my local time does not observe Daylight saving time and the remote server does and a result the presentation logic becomes cumbersome.

The limitation is that the Timestamp needs to be stored as uuid1. Any idea or workaround for this will be higly appreciated.

Answer 1

the UUID class will do the bit-juggling if you give it the right fragments - http://docs.python.org/library/uuid.html

to get the right components you can copy the the uuid1 code from python2.7:

def uuid1(node=None, clock_seq=None):
        """Generate a UUID from a host ID, sequence number, and the current time.
        If 'node' is not given, getnode() is used to obtain the hardware
        address.  If 'clock_seq' is given, it is used as the sequence number;
        otherwise a random 14-bit sequence number is chosen."""
    # When the system provides a version-1 UUID generator, use it (but don't
    # use UuidCreate here because its UUIDs don't conform to RFC 4122).
    if _uuid_generate_time and node is clock_seq is None:
        _buffer = ctypes.create_string_buffer(16)
        _uuid_generate_time(_buffer)
        return UUID(bytes=_buffer.raw)
    global _last_timestamp
    import time
    nanoseconds = int(time.time() * 1e9)
    # 0x01b21dd213814000 is the number of 100-ns intervals between the
    # UUID epoch 1582-10-15 00:00:00 and the Unix epoch 1970-01-01 00:00:00.
    timestamp = int(nanoseconds//100) + 0x01b21dd213814000L
    if _last_timestamp is not None and timestamp <= _last_timestamp:
        timestamp = _last_timestamp + 1
    _last_timestamp = timestamp
    if clock_seq is None:
        import random
        clock_seq = random.randrange(1<<14L) # instead of stable storage
    time_low = timestamp & 0xffffffffL
    time_mid = (timestamp >> 32L) & 0xffffL
    time_hi_version = (timestamp >> 48L) & 0x0fffL
    clock_seq_low = clock_seq & 0xffL
    clock_seq_hi_variant = (clock_seq >> 8L) & 0x3fL
    if node is None:
        node = getnode()
    return UUID(fields=(time_low, time_mid, time_hi_version,
                        clock_seq_hi_variant, clock_seq_low, node), version=1)

all you need to do is copy+paste that and modify the timestamp part to use a fixed value (you can ignore the last_timestamp part if you know that your times are distinct - that is just to avoid duplicates when the clock resolution is insufficient).