gh-89083: add support for UUID version 6 (RFC 9562)

Doc/library/uuid.rst

@@ -12,8 +12,8 @@
 
 This module provides immutable :class:`UUID` objects (the :class:`UUID` class)
 and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5`,
-and :func:`uuid.uuid8` for generating version 1, 3, 4, 5, and 8 UUIDs as
-specified in :rfc:`9562` (which supersedes :rfc:`4122`).
+:func:`uuid6`, and :func:`uuid8` for generating version 1, 3, 4, 5, 6,
+and 8 UUIDs as specified in :rfc:`9562` (which supersedes :rfc:`4122`).
 
 If all you want is a unique ID, you should probably call :func:`uuid1` or
 :func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates
@@ -153,8 +153,8 @@ which relays any information about the UUID's safety, using this enumeration:
  The UUID version number (1 through 8, meaningful only when the variant is
  :const:`RFC_4122`).
 
- .. versionchanged:: 3.14
- Added UUID version 8.
+ .. versionchanged:: next
+ Added UUID versions 6 and 8.
 
 
 .. attribute:: UUID.is_safe
@@ -212,6 +212,22 @@ The :mod:`uuid` module defines the following functions:
  that will be encoded using UTF-8).
 
 
+.. function:: uuid6(node=None, clock_seq=None)
+
+ Generate a UUID from a sequence number and the current time according to
+ :rfc:`9562`.
+ This is an alternative to :func:`uuid1` to improve database locality.
+
+ When *node* is not specified, :func:`getnode` is used to obtain the hardware
+ address as a 48-bit positive integer. When a sequence number *clock_seq* is
+ not specified, a pseudo-random 14-bit positive integer is generated.
+
+ If *node* or *clock_seq* exceed their expected bit count, only their least
+ significant bits are kept.
+
+ .. versionadded:: next
+
+
 .. function:: uuid8(a=None, b=None, c=None)
 
  Generate a pseudo-random UUID according to
@@ -314,7 +330,7 @@ The :mod:`uuid` module can be executed as a script from the command line.
 
 .. code-block:: sh
 
- python -m uuid [-h] [-u{uuid1,uuid3,uuid4,uuid5,uuid8}] [-n NAMESPACE] [-N NAME]
+ python -m uuid [-h] [-u{uuid1,uuid3,uuid4,uuid5,uuid6,uuid8}] [-n NAMESPACE] [-N NAME]
 
 The following options are accepted:
 
@@ -330,8 +346,8 @@ The following options are accepted:
  Specify the function name to use to generate the uuid. By default :func:`uuid4`
  is used.
 
- .. versionadded:: 3.14
- Allow generating UUID version 8.
+ .. versionchanged:: next
+ Allow generating UUID versions 6 and 8.
 
 .. option:: -n <namespace>
  --namespace <namespace>

Doc/whatsnew/3.14.rst

@@ -919,8 +919,8 @@ urllib
 uuid
 ----
 
-* Add support for UUID version 8 via :func:`uuid.uuid8` as specified
- in :rfc:`9562`.
+* Add support for UUID versions 6 and 8 via :func:`uuid.uuid6` and
+:func:`uuid.uuid8` respectively, as specified in :rfc:`9562`.
  (Contributed by Bénédikt Tran in :gh:`89083`.)
 
 * :const:`uuid.NIL` and :const:`uuid.MAX` are now available to represent the

Lib/test/test_uuid.py

@@ -1,6 +1,3 @@
-import unittest
-from test import support
-from test.support import import_helper
 import builtins
 import contextlib
 import copy
@@ -10,10 +7,14 @@
 import pickle
 import random
 import sys
+import unittest
 import weakref
 from itertools import product
 from unittest import mock
 
+from test import support
+from test.support import import_helper
+
 py_uuid = import_helper.import_fresh_module('uuid', blocked=['_uuid'])
 c_uuid = import_helper.import_fresh_module('uuid', fresh=['_uuid'])
 
@@ -724,6 +725,152 @@ def test_uuid5(self):
  equal(u, self.uuid.UUID(v))
  equal(str(u), v)
 
+ def test_uuid6(self):
+ equal = self.assertEqual
+ u = self.uuid.uuid6()
+ equal(u.variant, self.uuid.RFC_4122)
+ equal(u.version, 6)
+
+ fake_nanoseconds = 0x1571_20a1_de1a_c533
+ fake_node_value = 0x54e1_acf6_da7f
+ fake_clock_seq = 0x14c5
+ with (
+ mock.patch.object(self.uuid, '_last_timestamp_v6', None),
+ mock.patch.object(self.uuid, 'getnode', return_value=fake_node_value),
+ mock.patch('time.time_ns', return_value=fake_nanoseconds),
+ mock.patch('random.getrandbits', return_value=fake_clock_seq)
+ ):
+ u = self.uuid.uuid6()
+ equal(u.variant, self.uuid.RFC_4122)
+ equal(u.version, 6)
+
+ # 32 (top) | 16 (mid) | 12 (low) == 60 (timestamp)
+ equal(u.time, 0x1e901fca_7a55_b92)
+ equal(u.fields[0], 0x1e901fca) # 32 top bits of time
+ equal(u.fields[1], 0x7a55) # 16 mid bits of time
+ # 4 bits of version + 12 low bits of time
+ equal((u.fields[2] >> 12) & 0xf, 6)
+ equal((u.fields[2] & 0xfff), 0xb92)
+ # 2 bits of variant + 6 high bits of clock_seq
+ equal((u.fields[3] >> 6) & 0xf, 2)
+ equal(u.fields[3] & 0x3f, fake_clock_seq >> 8)
+ # 8 low bits of clock_seq
+ equal(u.fields[4], fake_clock_seq & 0xff)
+ equal(u.fields[5], fake_node_value)
+
+ def test_uuid6_uniqueness(self):
+ # Test that UUIDv6-generated values are unique.
+
+ # Unlike UUIDv8, only 62 bits can be randomized for UUIDv6.
+ # In practice, however, it remains unlikely to generate two
+ # identical UUIDs for the same 60-bit timestamp if neither
+ # the node ID nor the clock sequence is specified.
+ uuids ={self.uuid.uuid6() for _ in range(1000)}
+ self.assertEqual(len(uuids), 1000)
+ versions ={u.version for u in uuids}
+ self.assertSetEqual(versions,{6})
+
+ timestamp = 0x1ec9414c_232a_b00
+ fake_nanoseconds = (timestamp - 0x1b21dd21_3814_000) * 100
+
+ with mock.patch('time.time_ns', return_value=fake_nanoseconds):
+ def gen():
+ with mock.patch.object(self.uuid, '_last_timestamp_v6', None):
+ return self.uuid.uuid6(node=0, clock_seq=None)
+
+ # By the birthday paradox, sampling N = 1024 UUIDs with identical
+ # node IDs and timestamps results in duplicates with probability
+ # close to 1 (not having a duplicate happens with probability of
+ # order 1E-15) since only the 14-bit clock sequence is randomized.
+ N = 1024
+ uuids ={gen() for _ in range(N)}
+ self.assertSetEqual({u.node for u in uuids},{0})
+ self.assertSetEqual({u.time for u in uuids},{timestamp})
+ self.assertLess(len(uuids), N, 'collision property does not hold')
+
+ def test_uuid6_node(self):
+ # Make sure the given node ID appears in the UUID.
+ #
+ # Note: when no node ID is specified, the same logic as for UUIDv1
+ # is applied to UUIDv6. In particular, there is no need to test that
+ # getnode() correctly returns positive integers of exactly 48 bits
+ # since this is done in test_uuid1_eui64().
+ self.assertLessEqual(self.uuid.uuid6().node.bit_length(), 48)
+
+ self.assertEqual(self.uuid.uuid6(0).node, 0)
+
+ # tests with explicit values
+ max_node = 0xffff_ffff_ffff
+ self.assertEqual(self.uuid.uuid6(max_node).node, max_node)
+ big_node = 0xE_1234_5678_ABCD # 52-bit node
+ res_node = 0x0_1234_5678_ABCD # truncated to 48 bits
+ self.assertEqual(self.uuid.uuid6(big_node).node, res_node)
+
+ # randomized tests
+ for _ in range(10):
+ # node with > 48 bits is truncated
+ for b in [24, 48, 72]:
+ node = (1 << (b - 1)) | random.getrandbits(b)
+ with self.subTest(node=node, bitlen=b):
+ self.assertEqual(node.bit_length(), b)
+ u = self.uuid.uuid6(node=node)
+ self.assertEqual(u.node, node & 0xffff_ffff_ffff)
+
+ def test_uuid6_clock_seq(self):
+ # Make sure the supplied clock sequence appears in the UUID.
+ #
+ # For UUIDv6, clock sequence bits are stored from bit 48 to bit 62,
+ # with the convention that the least significant bit is bit 0 and
+ # the most significant bit is bit 127.
+ get_clock_seq = lambda u: (u.int >> 48) & 0x3fff
+
+ u = self.uuid.uuid6()
+ self.assertLessEqual(get_clock_seq(u).bit_length(), 14)
+
+ # tests with explicit values
+ big_clock_seq = 0xffff # 16-bit clock sequence
+ res_clock_seq = 0x3fff # truncated to 14 bits
+ u = self.uuid.uuid6(clock_seq=big_clock_seq)
+ self.assertEqual(get_clock_seq(u), res_clock_seq)
+
+ # some randomized tests
+ for _ in range(10):
+ # clock_seq with > 14 bits is truncated
+ for b in [7, 14, 28]:
+ node = random.getrandbits(48)
+ clock_seq = (1 << (b - 1)) | random.getrandbits(b)
+ with self.subTest(node=node, clock_seq=clock_seq, bitlen=b):
+ self.assertEqual(clock_seq.bit_length(), b)
+ u = self.uuid.uuid6(node=node, clock_seq=clock_seq)
+ self.assertEqual(get_clock_seq(u), clock_seq & 0x3fff)
+
+ def test_uuid6_test_vectors(self):
+ equal = self.assertEqual
+ # https://www.rfc-editor.org/rfc/rfc9562#name-test-vectors
+ # (separators are put at the 12th and 28th bits)
+ timestamp = 0x1ec9414c_232a_b00
+ fake_nanoseconds = (timestamp - 0x1b21dd21_3814_000) * 100
+ # https://www.rfc-editor.org/rfc/rfc9562#name-example-of-a-uuidv6-value
+ node = 0x9f6bdeced846
+ clock_seq = (3 << 12) | 0x3c8
+
+ with (
+ mock.patch.object(self.uuid, '_last_timestamp_v6', None),
+ mock.patch('time.time_ns', return_value=fake_nanoseconds)
+ ):
+ u = self.uuid.uuid6(node=node, clock_seq=clock_seq)
+ equal(str(u).upper(), '1EC9414C-232A-6B00-B3C8-9F6BDECED846')
+ # 32 16 4 12 2 14 48
+ # time_hi | time_mid | ver | time_lo | var | clock_seq | node
+ equal(u.time, timestamp)
+ equal(u.int & 0xffff_ffff_ffff, node)
+ equal((u.int >> 48) & 0x3fff, clock_seq)
+ equal((u.int >> 62) & 0x3, 0b10)
+ equal((u.int >> 64) & 0xfff, 0xb00)
+ equal((u.int >> 76) & 0xf, 0x6)
+ equal((u.int >> 80) & 0xffff, 0x232a)
+ equal((u.int >> 96) & 0xffff_ffff, 0x1ec9_414c)
+
  def test_uuid8(self):
  equal = self.assertEqual
  u = self.uuid.uuid8()

Lib/uuid.py

@@ -1,8 +1,8 @@
 r"""UUID objects (universally unique identifiers) according to RFC 4122/9562.
 
 This module provides immutable UUID objects (class UUID) and the functions
-uuid1(), uuid3(), uuid4(), uuid5(), and uuid8() for generating version 1, 3,
-4, 5, and 8 UUIDs as specified in RFC 4122/9562.
+uuid1(), uuid3(), uuid4(), uuid5(), uuid6(), and uuid8() for generating
+version 1, 3, 4, 5, 6, and 8 UUIDs as specified in RFC 4122/9562.
 
 If all you want is a unique ID, you should probably call uuid1() or uuid4().
 Note that uuid1() may compromise privacy since it creates a UUID containing
@@ -101,6 +101,7 @@ class SafeUUID:
 _RFC_4122_VERSION_3_FLAGS = ((3 << 76) | (0x8000 << 48))
 _RFC_4122_VERSION_4_FLAGS = ((4 << 76) | (0x8000 << 48))
 _RFC_4122_VERSION_5_FLAGS = ((5 << 76) | (0x8000 << 48))
+_RFC_4122_VERSION_6_FLAGS = ((6 << 76) | (0x8000 << 48))
 _RFC_4122_VERSION_8_FLAGS = ((8 << 76) | (0x8000 << 48))
 
 
@@ -127,7 +128,9 @@ class UUID:
 
  fields a tuple of the six integer fields of the UUID,
  which are also available as six individual attributes
- and two derived attributes:
+ and two derived attributes. The time_* attributes are
+ only relevant to version 1, while the others are only
+ relevant to versions 1 and 6:
 
  time_low the first 32 bits of the UUID
  time_mid the next 16 bits of the UUID
@@ -353,8 +356,19 @@ def clock_seq_low(self):
 
  @property
  def time(self):
- return (((self.time_hi_version & 0x0fff) << 48) |
- (self.time_mid << 32) | self.time_low)
+ if self.version == 6:
+ # time_hi (32) | time_mid (16) | ver (4) | time_lo (12) | ... (64)
+ time_hi = self.int >> 96
+ time_lo = (self.int >> 64) & 0x0fff
+ return time_hi << 28 | (self.time_mid << 12) | time_lo
+ else:
+ # time_lo (32) | time_mid (16) | ver (4) | time_hi (12) | ... (64)
+ #
+ # For compatibility purposes, we do not warn or raise when the
+ # version is not 1 (timestamp is irrelevant to other versions).
+ time_hi = (self.int >> 64) & 0x0fff
+ time_lo = self.int >> 96
+ return time_hi << 48 | (self.time_mid << 32) | time_lo
 
  @property
  def clock_seq(self):
@@ -756,6 +770,44 @@ def uuid5(namespace, name):
  int_uuid_5 |= _RFC_4122_VERSION_5_FLAGS
  return UUID._from_int(int_uuid_5)
 
+_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)
+
 def uuid8(a=None, b=None, c=None):
  """Generate a UUID from three custom blocks.
 
@@ -788,6 +840,7 @@ def main():
  "uuid3": uuid3,
  "uuid4": uuid4,
  "uuid5": uuid5,
+ "uuid6": uuid6,
  "uuid8": uuid8,
  }
  uuid_namespace_funcs = ("uuid3", "uuid5")

Misc/NEWS.d/next/Library/2024-06-17-17-31-27.gh-issue-89083.nW00Yq.rst

@@ -0,0 +1,2 @@
+Add :func:`uuid.uuid6` for generating UUIDv6 objects as specified in
+:rfc:`9562`. Patch by Bénédikt Tran.