Subversion Repositories uuid_mac_utils

/**

 * The sorting of SQL Server is rather confusing and incompatible with UUIDv6 and UUIDv7.

 * Therefore this method generates UUID which are sortable by SQL Server.

 * Version 1: Resolution of 1 milliseconds, random part of 16 bits, local timezone, NOT UUIDv8 conform.

 * Version 2: Resolution of 1 milliseconds, random part of 18 bits, UTC time, UUIDv8 conform.

 * C# implementation: https://gist.github.com/danielmarschall/7fafd270a3bc107d38e8449ce7420c25

 * PHP implementation: https://github.com/danielmarschall/uuid_mac_utils/blob/master/includes/uuid_utils.inc.php

 *

 * @param int      $hickelUuidVersion (optional)

 * @param DateTime $dt                (optional)

 * @return string The UUID

 */

function gen_uuid_v8_sqlserver_sortable(int $hickelUuidVersion = 2, DateTime $dt = null): string {

        // The sorting in SQL Server is like this:

        if ($dt == null) $dt = new DateTime();

        // First Sort block 5, nibbles from left to right (i.e. 000000000001 < 000000000010 < ... < 010000000000 < 100000000000)

        if ($hickelUuidVersion == 1) {

                $block5 = "000000000000";

        } else if ($hickelUuidVersion == 2) {

                $block5 = "4849434B454C"/*Hex:"HICKEL"*/;

        } else {

                throw new Exception("Invalid version");

        }

        // Then: Sort block 4, nibbles from left to right

        if ($hickelUuidVersion == 1) {

                $year = $dt->format('Y');

                $block4 = substr($year, 2, 2).substr($year, 0, 2); // Example: 0x2420 = 2024

        } else {

                $variant = 0x8; // First nibble needs to be 0b10_ (0x8-0xB) for "RFC 4122bis". We use it to store 2 more random bits.

                $rnd2bits = rand(0x0, 0x3);

                $year = $dt->format('Y');

                $block4 = sprintf('%01x%03x', $variant + ($rnd2bits & 0x3), $year);

        }

        // Then: Sort block 3, bytes from right to left (i.e. 0100 < 1000 < 0001 < 0010)

        if ($hickelUuidVersion == 1) {

                $block3 = $dt->format('dm');

        } else {

                $uuidVersion = 8; // First nibble needs to be "8" for "UUIDv8 = Custom UUID"

                $dayOfYear = intval($dt->format('z')) + 1; /* 1..366 */

                $block3 = sprintf('%01x%03x', $uuidVersion, $dayOfYear);

        }

        // Then: Sort block 2, bytes from right to left

        if ($hickelUuidVersion == 1) {

                $block2 = $dt->format('ih');

        } else {

                $minuteOfDay = (intval($dt->format('i')) + intval($dt->format('h')) * 60) + 1; // 1..1440

                $block2 = sprintf('%04x', $minuteOfDay);

        }

        // Then: Sort block 1, bytes from right to left

        $millisecond8bits = ceil(($dt->format('v') / 999) * 255);

        if ($hickelUuidVersion == 1) {

                $rnd16bits = rand(0x0000, 0xFFFF-1);

                $block1 = sprintf('%04x%02x', $rnd16bits, $millisecond8bits).$dt->format('s');

        } else {

                $rnd16bits = rand(0x0000, 0xFFFF);

                $block1 = sprintf('%04x%02x%02x', $rnd16bits, $millisecond8bits, $dt->format('s'));

        }

        // Now build and parse UUID

        usleep((int)ceil(999 / 255)); // Make sure that "millisecond" is not repeated on this system

        return "$block1-$block2-$block3-$block4-$block5";

}