雪花算法的实现
最近看了下雪花算法,自己试着写了一下
<?PHPclass SNowFlake{ const TWEPOCH = 0; // 时间起始标记点,作为基准,一般取系统的最近时间(一旦确定不能变动) const WORKER_ID_BITS = 5; // 机器标识位数 const DATACENTER_ID_BITS = 5; // 数据中心标识位数 const SEQUENCE_BITS = 12; // 毫秒内自增位 private $workerID; // 工作机器ID private $datacenterID; // 数据中心ID private $sequence; // 毫秒内序列 private $maxWorkerID = -1 ^ (-1 << self::WORKER_ID_BITS); // 机器ID最大值 private $maxDatacenterID = -1 ^ (-1 << self::DATACENTER_ID_BITS); // 数据中心ID最大值 private $workerIDShift = self::SEQUENCE_BITS; // 机器ID偏左移位数 private $datacenterIDShift = self::SEQUENCE_BITS + self::WORKER_ID_BITS; // 数据中心ID左移位数 private $timestampleftShift = self::SEQUENCE_BITS + self::WORKER_ID_BITS + self::DATACENTER_ID_BITS; // 时间毫秒左移位数 private $sequenceMask = -1 ^ (-1 << self::SEQUENCE_BITS); // 生成序列的掩码 private $lastTimestamp = -1; // 上次生产ID时间戳 public function __construct($workerID, $datacenterID, $sequence = 0) { if ($workerID > $this->maxWorkerID || $workerID < 0) { throw new Exception("worker ID can't be greater than {$this->maxWorkerID} or less than 0"); } if ($datacenterID > $this->maxDatacenterID || $datacenterID < 0) { throw new Exception("datacenter ID can't be greater than {$this->maxDatacenterID} or less than 0"); } $this->workerID = $workerID; $this->datacenterID = $datacenterID; $this->sequence = $sequence; } public function createID() { $timestamp = $this->createTimestamp(); if ($timestamp < $this->lastTimestamp) {//当产生的时间戳小于上次的生成的时间戳时,报错 $diffTimestamp = bcsub($this->lastTimestamp, $timestamp); throw new Exception("Clock moved backwards. Refusing to generate ID for {$diffTimestamp} milliseconds"); } if ($this->lastTimestamp == $timestamp) {//当生成的时间戳等于上次生成的时间戳的时候 $this->sequence = ($this->sequence + 1) & $this->sequenceMask;//序列自增一次 if (0 == $this->sequence) {//当序列为0时,重新生成最新的时间戳 $timestamp = $this->createNextTimestamp($this->lastTimestamp); } } else {//当生成的时间戳不等于上次的生成的时间戳的时候,序列归0 $this->sequence = 0; } $this->lastTimestamp = $timestamp; return (($timestamp - self::TWEPOCH) << $this->timestampleftShift) | ($this->datacenterID << $this->datacenterIDShift) | ($this->workerID << $this->workerIDShift) | $this->sequence; } protected function createNextTimestamp($lastTimestamp) //生成一个大于等于 上次生成的时间戳 的时间戳 { $timestamp = $this->createTimestamp(); while ($timestamp <= $lastTimestamp) { $timestamp = $this->createTimestamp(); } return $timestamp; } protected function createTimestamp()//生成毫秒级别的时间戳 { return floor(microtime(true) * 1000); }}?>
推荐学习:《PHP视频教程》 总结
以上是内存溢出为你收集整理的用PHP捣鼓一个雪花算法全部内容,希望文章能够帮你解决用PHP捣鼓一个雪花算法所遇到的程序开发问题。
如果觉得内存溢出网站内容还不错,欢迎将内存溢出网站推荐给程序员好友。
欢迎分享,转载请注明来源:内存溢出
评论列表(0条)