基于php雪花算法工具类Snowflake -来自chatGPT

<?php
 
class Snowflake {
    // 定义Snowflake算法的各个参数
    private $workerIdBits = 5;
    private $datacenterIdBits = 5;
    private $sequenceBits = 12;
 
    private $workerIdShift;
    private $datacenterIdShift;
    private $timestampLeftShift;
 
    private $maxWorkerId;
    private $maxDatacenterId;
    private $sequenceMask;
 
    private $workerId;
    private $datacenterId;
    private $sequence = 0;
    private $lastTimestamp = -1;
 
    public function __construct($workerId, $datacenterId) {
        // 计算位偏移量
        $this->workerIdShift = $this->sequenceBits;
        $this->datacenterIdShift = $this->sequenceBits + $this->workerIdBits;
        $this->timestampLeftShift = $this->sequenceBits + $this->workerIdBits + $this->datacenterIdBits;
 
        // 计算最大ID
        $this->maxWorkerId = -1 ^ (-1 << $this->workerIdBits);
        $this->maxDatacenterId = -1 ^ (-1 << $this->datacenterIdBits);
        $this->sequenceMask = -1 ^ (-1 << $this->sequenceBits);
 
        // 初始化参数
        $this->workerId = $workerId;
        $this->datacenterId = $datacenterId;
    }
 
    // 生成下一个唯一ID
    public function generateId() {
        // 获取当前时间戳（毫秒级）
        $timestamp = floor(microtime(true) * 1000);
 
        // 如果当前时间小于上次生成ID的时间戳，则抛出异常
        if ($timestamp < $this->lastTimestamp) {
            throw new Exception("Invalid system clock!");
        }
 
        // 如果当前时间戳与上次时间戳相同，则自增序列号
        if ($timestamp == $this->lastTimestamp) {
            $this->sequence = ($this->sequence + 1) & $this->sequenceMask;
 
            // 如果序列号等于0，则需要进入下一毫秒重新生成ID
            if ($this->sequence == 0) {
                $timestamp = $this->waitNextMillis($this->lastTimestamp);
            }
        } else {
            $this->sequence = 0;
        }
 
        // 保存最后生成ID的时间戳
        $this->lastTimestamp = $timestamp;
 
        // 生成最终的唯一ID
        $uniqueId = (($timestamp << $this->timestampLeftShift) |
                     ($this->datacenterId << $this->datacenterIdShift) |
                     ($this->workerId << $this->workerIdShift) |
                     $this->sequence);
 
        return $uniqueId;
    }
 
    // 阻塞到下一个毫秒，直到获得新的时间戳
    private function waitNextMillis($lastTimestamp) {
        $timestamp = floor(microtime(true) * 1000);
        while ($timestamp <= $lastTimestamp) {
            usleep(1000);
            $timestamp = floor(microtime(true) * 1000);
        }
        return $timestamp;
    }
}
 
// 测试方法
$snowflake = new Snowflake(1, 1);
for ($i = 0; $i < 10; $i++) {
    $uniqueId = $snowflake->generateId();
    echo $uniqueId . "\n";
}
 
?>