minor #36077 [Uid] Add support for UUIDv6 (nicolas-grekas)

This PR was merged into the 5.1-dev branch.

Discussion
----------

[Uid] Add support for UUIDv6

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| Deprecations? | no
| Tickets       | -
| License       | MIT
| Doc PR        | -

See https://github.com/uuid6/uuid6-ietf-draft/blob/master/draft-peabody-dispatch-new-uuid-format-00.txt

A v6 UUID is a lexicographically-sortable-v1.
This makes it db-index friendly (same as ULIDs).

For reference:
- v1 has no benefits over v6 except being in the current official RFC
- v6 is order-friendly and leaks time data + stable entropy (potentially bound to a MAC address or equivalent)
- ULID is also order-friendly and leaks time data, with high entropy (crypto random source)
- v4 is pure crypto random source, aka no order and no leak of anything.

Commits
-------

b705ee1 [Uid] Add support for UUIDv6

src/Symfony/Component/Uid/Tests/UuidTest.php

@@ -18,6 +18,7 @@
 use Symfony\Component\Uid\UuidV3;
 use Symfony\Component\Uid\UuidV4;
 use Symfony\Component\Uid\UuidV5;
+use Symfony\Component\Uid\UuidV6;
 
 class UuidTest extends TestCase
 {
@@ -73,6 +74,18 @@ public function testV5()
         $this->assertInstanceOf(UuidV5::class, $uuid);
     }
 
+    public function testV6()
+    {
+        $uuid = Uuid::v6();
+
+        $this->assertInstanceOf(UuidV6::class, $uuid);
+
+        $uuid = new UuidV6(substr_replace(self::A_UUID_V1, '6', 14, 1));
+
+        $this->assertSame(85916308548.27832, $uuid->getTime());
+        $this->assertSame('3499710062d0', $uuid->getNode());
+    }
+
     public function testBinary()
     {
         $uuid = new UuidV4(self::A_UUID_V4);

src/Symfony/Component/Uid/Ulid.php

@@ -12,6 +12,8 @@
 namespace Symfony\Component\Uid;
 
 /**
+ * A ULID is lexicographically sortable and contains a 48-bit timestamp and 80-bit of crypto-random entropy.
+ *
  * @see https://github.com/ulid/spec
  *
  * @experimental in 5.1

src/Symfony/Component/Uid/Uuid.php

@@ -49,6 +49,7 @@ public static function fromString(string $uuid): self
             case UuidV3::TYPE: return new UuidV3($uuid);
             case UuidV4::TYPE: return new UuidV4($uuid);
             case UuidV5::TYPE: return new UuidV5($uuid);
+            case UuidV6::TYPE: return new UuidV6($uuid);
             case NullUuid::TYPE: return new NullUuid();
             case self::TYPE: return new self($uuid);
         }
@@ -76,6 +77,11 @@ final public static function v5(self $namespace, string $name): UuidV5
         return new UuidV5(uuid_generate_sha1($namespace->uuid, $name));
     }
 
+    final public static function v6(): UuidV6
+    {
+        return new UuidV6();
+    }
+
     public static function isValid(string $uuid): bool
     {
         if (__CLASS__ === static::class) {

src/Symfony/Component/Uid/UuidV1.php

@@ -12,7 +12,7 @@
 namespace Symfony\Component\Uid;
 
 /**
- * A v1 UUID contains a 60-bit timestamp and ~60 extra unique bits.
+ * A v1 UUID contains a 60-bit timestamp and 63 extra unique bits.
  *
  * @experimental in 5.1
  *

src/Symfony/Component/Uid/UuidV6.php

@@ -0,0 +1,60 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Uid;
+
+/**
+ * A v6 UUID is lexicographically sortable and contains a 60-bit timestamp and 63 extra unique bits.
+ *
+ * @experimental in 5.1
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class UuidV6 extends Uuid
+{
+    protected const TYPE = 6;
+
+    // https://tools.ietf.org/html/rfc4122#section-4.1.4
+    // 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.
+    private const TIME_OFFSET_INT = 0x01b21dd213814000;
+    private const TIME_OFFSET_COM = "\xfe\x4d\xe2\x2d\xec\x7e\xc0\x00";
+
+    public function __construct(string $uuid = null)
+    {
+        if (null === $uuid) {
+            $uuid = uuid_create(UUID_TYPE_TIME);
+            $this->uuid = substr($uuid, 15, 3).substr($uuid, 9, 4).$uuid[0].'-'.substr($uuid, 1, 4).'-6'.substr($uuid, 5, 3).substr($uuid, 18);
+        } else {
+            parent::__construct($uuid);
+        }
+    }
+
+    public function getTime(): float
+    {
+        $time = '0'.substr($this->uuid, 0, 8).substr($this->uuid, 9, 4).substr($this->uuid, 15, 3);
+
+        if (\PHP_INT_SIZE >= 8) {
+            return (hexdec($time) - self::TIME_OFFSET_INT) / 10000000;
+        }
+
+        $time = str_pad(hex2bin($time), 8, "\0", STR_PAD_LEFT);
+        $time = BinaryUtil::add($time, self::TIME_OFFSET_COM);
+        $time[0] = $time[0] & "\x7F";
+
+        return BinaryUtil::toBase($time, BinaryUtil::BASE10) / 10000000;
+    }
+
+    public function getNode(): string
+    {
+        return substr($this->uuid, 24);
+    }
+}