Utiliser PHP pour bricoler un algorithme de flocon de neige

Cet article parlera de l'implémentation PHP de l'algorithme de flocon de neige. J'espère qu'il sera utile aux amis dans le besoin !

Implémentation de l'algorithme Snowflake

J'ai récemment lu l'algorithme Snowflake et j'ai essayé de l'écrire moi-même

<?php
class 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 || $workerId < 0) {
            throw new Exception("worker Id can&#39;t be greater than {$this->maxWorkerId} or less than 0");
        }
        if ($datacenterId > $this->maxDatacenterId || $datacenterId < 0) {
            throw new Exception("datacenter Id can&#39;t be greater than {$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);
    }
}
?>

Apprentissage recommandé : "Tutoriel vidéo PHP"

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