Mist.php
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<?php
/**
+-----------------------------------------------------------------------------------------------------------------------
* 工具类：薄雾算法
+-----------------------------------------------------------------------------------------------------------------------
* PHP version 7
*
* @category App\Util
* @package App\Util
* @author Richer <yangzi1028@163.com>
* @date 2021年9月1日15:44:32
* @copyright 2021-2022 Richer (http://www.Richer.com/)
* @license http://www.Richer.com/ License
* @link http://www.Richer.com/
*/
namespace App\Util;
/*
* 薄雾算法
*
* 1 2 48 56 64
* +------+-----------------------------------------------------+----------+----------+
* retain | increas | salt | sequence |
* +------+-----------------------------------------------------+----------+----------+
* 0 | 0000000000 0000000000 0000000000 0000000000 0000000 | 00000000 | 00000000 |
* +------+-----------------------------------------------------+------------+--------+
*
* 0. 最高位，占 1 位，保持为 0，使得值永远为正数；
* 1. 自增数，占 47 位，自增数在高位能保证结果值呈递增态势，遂低位可以为所欲为；
* 2. 随机因子一，占 8 位，上限数值 255，使结果值不可预测；
* 3. 随机因子二，占 8 位，上限数值 255，使结果值不可预测；
*
* 编号上限为百万亿级，上限值计算为 140737488355327 即 int64(1 << 47 - 1)，假设每天取值 10 亿，能使用 385+ 年
*/
class Mist
{
const saltBit = 8; // 随机因子二进制位数
public const saltShift = 8; // 随机因子移位数
public const increasShift = self::saltBit + self::saltShift; // 自增数移位数
public $increas = 0; // 自增数
public $saltA = 0; // 随机因子一
public $saltB = 0; // 随机因子二
public function __construct($increas = 1)
{
$this->increas = $increas;
}
public function generate(): int
{
$this->increas = ++$this->increas;
// 获取随机因子数值
try {
$this->saltA = random_int($this->saltA, 255);
} catch (\Exception $e) {
$this->saltA = $this->saltA++;
}
try {
$this->saltB = random_int($this->saltB, 255);
} catch (\Exception $e) {
$this->saltB = $this->saltB++;
}
return (int) ($this->increas << self::increasShift) | ($this->saltA << self::saltShift) | $this->saltB;
}
}