PHP Snowflake（雪花算法）生成唯一ID值

<?php namespace app\user\controller; use cmf\controller\AdminBaseController; class SnowController extends AdminBaseController { //开始时间,固定一个小于当前时间的毫秒数即可 const twepoch = 1420041600000;//(2015-01-01)，具体可以自己定义 //机器标识占的位数 const workerIdBits = 10; //毫秒内自增数点的位数 const sequenceBits = 12; protected $workId = 0; //要用静态变量 static $lastTimestamp = -1; static $sequence = 0; function __construct($workId){ //机器ID范围判断 $maxWorkerId = -1 ^ (-1 << self::workerIdBits); //echo $maxWorkerId;exit(); if($workId > $maxWorkerId || $workId< 0){ //这里如果用wamp或者phpstudy可能会报错，主要是这里是用的是64位的PHP版本，确保正确即可，在Linux上测试无误 throw new Exception("workerId can't be greater than ".$this->maxWorkerId." or less than 0"); } //赋值 $this->workId = $workId; } //生成一个ID public function nextId(){ $timestamp = $this->timeGen(); $lastTimestamp = self::$lastTimestamp; //判断时钟是否正常 if ($timestamp < $lastTimestamp) { throw new Exception("Clock moved backwards. Refusing to generate id for %d milliseconds", ($lastTimestamp - $timestamp)); } //生成唯一序列 if ($lastTimestamp == $timestamp) { $sequenceMask = -1 ^ (-1 << self::sequenceBits); self::$sequence = (self::$sequence + 1) & $sequenceMask; if (self::$sequence == 0) { $timestamp = $this->tilNextMillis($lastTimestamp); } } else { self::$sequence = 0; } self::$lastTimestamp = $timestamp; // //时间毫秒/数据中心ID/机器ID,要左移的位数 $timestampLeftShift = self::sequenceBits + self::workerIdBits; $workerIdShift = self::sequenceBits; //组合3段数据返回: 时间戳.工作机器.序列 $nextId = (($timestamp - self::twepoch) << $timestampLeftShift) | ($this->workId << $workerIdShift) | self::$sequence; return $nextId; } //取当前时间毫秒 protected function timeGen(){ $timestramp = (float)sprintf("%.0f", microtime(true) * 1000); return $timestramp; } //取下一毫秒 protected function tilNextMillis($lastTimestamp) { $timestamp = $this->timeGen(); while ($timestamp <= $lastTimestamp) { $timestamp = $this->timeGen(); } return $timestamp; } } //这里是测试程序，注意，正确生成的话是18位 $snow=new SnowController(1023); for($i=0; $i<1000;$i++) { $id = $snow->nextId(); echo $id . "<br>"; }