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<?php |
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|
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/** |
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* This file is part of the ramsey/uuid library |
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* |
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* For the full copyright and license information, please view the LICENSE |
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* file that was distributed with this source code. |
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* |
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* @copyright Copyright (c) Ben Ramsey <[email protected]> |
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* @license http://opensource.org/licenses/MIT MIT |
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*/ |
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|
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declare(strict_types=1); |
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|
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namespace Ramsey\Uuid\Generator; |
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|
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use Ramsey\Uuid\Converter\NumberConverterInterface; |
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use Ramsey\Uuid\Exception\InvalidArgumentException; |
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|
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use function bin2hex; |
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use function explode; |
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use function hex2bin; |
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use function microtime; |
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use function str_pad; |
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use function substr; |
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|
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use const STR_PAD_LEFT; |
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|
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/** |
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* CombGenerator generates COMBs (combined UUID/timestamp) |
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* |
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* The CombGenerator, when used with the StringCodec (and, by proxy, the |
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* TimestampLastCombCodec) or the TimestampFirstCombCodec, combines the current |
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* timestamp with a UUID (hence the name "COMB"). The timestamp either appears |
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* as the first or last 48 bits of the COMB, depending on the codec used. |
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* |
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* By default, COMBs will have the timestamp set as the last 48 bits of the |
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* identifier. |
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* |
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* ``` php |
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* $factory = new UuidFactory(); |
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* |
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* $factory->setRandomGenerator(new CombGenerator( |
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* $factory->getRandomGenerator(), |
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* $factory->getNumberConverter() |
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* )); |
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* |
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* $comb = $factory->uuid4(); |
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* ``` |
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* |
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* To generate a COMB with the timestamp as the first 48 bits, set the |
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* TimestampFirstCombCodec as the codec. |
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* |
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* ``` php |
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* $factory->setCodec(new TimestampFirstCombCodec($factory->getUuidBuilder())); |
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* ``` |
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* |
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* @link https://www.informit.com/articles/printerfriendly/25862 The Cost of GUIDs as Primary Keys |
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*/ |
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class CombGenerator implements RandomGeneratorInterface |
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{ |
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public const TIMESTAMP_BYTES = 6; |
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|
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/** |
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* @var RandomGeneratorInterface |
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*/ |
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private $randomGenerator; |
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|
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/** |
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* @var NumberConverterInterface |
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*/ |
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private $converter; |
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|
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public function __construct( |
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RandomGeneratorInterface $generator, |
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NumberConverterInterface $numberConverter |
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) { |
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$this->converter = $numberConverter; |
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$this->randomGenerator = $generator; |
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} |
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|
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/** |
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* @throws InvalidArgumentException if $length is not a positive integer |
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* greater than or equal to CombGenerator::TIMESTAMP_BYTES |
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* |
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* @inheritDoc |
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*/ |
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public function generate(int $length): string |
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{ |
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if ($length < self::TIMESTAMP_BYTES || $length < 0) { |
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throw new InvalidArgumentException( |
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'Length must be a positive integer greater than or equal to ' . self::TIMESTAMP_BYTES |
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); |
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} |
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|
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$hash = ''; |
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if (self::TIMESTAMP_BYTES > 0 && $length > self::TIMESTAMP_BYTES) { |
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$hash = $this->randomGenerator->generate($length - self::TIMESTAMP_BYTES); |
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} |
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|
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$lsbTime = str_pad( |
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$this->converter->toHex($this->timestamp()), |
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self::TIMESTAMP_BYTES * 2, |
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'0', |
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STR_PAD_LEFT |
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); |
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|
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return (string) hex2bin( |
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str_pad( |
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bin2hex($hash), |
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$length - self::TIMESTAMP_BYTES, |
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'0' |
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) |
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. $lsbTime |
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); |
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} |
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|
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/** |
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* Returns current timestamp a string integer, precise to 0.00001 seconds |
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*/ |
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private function timestamp(): string |
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{ |
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$time = explode(' ', microtime(false)); |
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|
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return $time[1] . substr($time[0], 2, 5); |
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} |
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} |
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|
