Function uuid6

Lib/uuid.py:796–830

Similar to :func:`uuid1` but where fields are ordered differently for improved DB locality. More precisely, given a 60-bit timestamp value as specified for UUIDv1, for UUIDv6 the first 48 most significant bits are stored first, followed by the 4-bit version (same position), followed

(node=None, clock_seq=None)

_last_timestamp_v6 = None

def uuid6(node=None, clock_seq=None):
    """Similar to :func:`uuid1` but where fields are ordered differently
    for improved DB locality.

    More precisely, given a 60-bit timestamp value as specified for UUIDv1,
    for UUIDv6 the first 48 most significant bits are stored first, followed
    by the 4-bit version (same position), followed by the remaining 12 bits
    of the original 60-bit timestamp.
    """
    global _last_timestamp_v6
    import time
    nanoseconds = time.time_ns()
    # 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 = nanoseconds // 100 + 0x01b21dd213814000
    if _last_timestamp_v6 is not None and timestamp <= _last_timestamp_v6:
        timestamp = _last_timestamp_v6 + 1
    _last_timestamp_v6 = timestamp
    if clock_seq is None:
        import random
        clock_seq = random.getrandbits(14)  # instead of stable storage
    time_hi_and_mid = (timestamp >> 12) & 0xffff_ffff_ffff
    time_lo = timestamp & 0x0fff  # keep 12 bits and clear version bits
    clock_s = clock_seq & 0x3fff  # keep 14 bits and clear variant bits
    if node is None:
        node = getnode()
    # --- 32 + 16 ---   -- 4 --   -- 12 --  -- 2 --   -- 14 ---    48
    # time_hi_and_mid | version | time_lo | variant | clock_seq | node
    int_uuid_6 = time_hi_and_mid << 80
    int_uuid_6 |= time_lo << 64
    int_uuid_6 |= clock_s << 48
    int_uuid_6 |= node & 0xffff_ffff_ffff
    # by construction, the variant and version bits are already cleared
    int_uuid_6 |= _RFC_4122_VERSION_6_FLAGS
    return UUID._from_int(int_uuid_6)


_last_timestamp_v7 = None