基于php的雪花算法(snowflake)

 $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 nextId()
    {
        $timestamp = $this->timeGen();

        if ($timestamp < $this->lastTimestamp) {
            $diffTimestamp = bcsub($this->lastTimestamp, $timestamp);
            throw new Exception("Clock moved backwards.  Refusing to generate id for {$diffTimestamp} milliseconds");
        }

        if ($this->lastTimestamp == $timestamp) {
            $this->sequence = ($this->sequence + 1) & $this->sequenceMask;

            if (0 == $this->sequence) {
                $timestamp = $this->tilNextMillis($this->lastTimestamp);
            }
        } else {
            $this->sequence = 0;
        }

        $this->lastTimestamp = $timestamp;

        /*$gmpTimestamp    = gmp_init($this->leftShift(bcsub($timestamp, self::TWEPOCH), $this->timestampLeftShift));
        $gmpDatacenterId = gmp_init($this->leftShift($this->datacenterId, $this->datacenterIdShift));
        $gmpWorkerId     = gmp_init($this->leftShift($this->workerId, $this->workerIdShift));
        $gmpSequence     = gmp_init($this->sequence);

        return gmp_strval(gmp_or(gmp_or(gmp_or($gmpTimestamp, $gmpDatacenterId), $gmpWorkerId), $gmpSequence));*/

        return (($timestamp - self::TWEPOCH) << $this->timestampLeftShift) |
        ($this->datacenterId << $this->datacenterIdShift) |
        ($this->workerId << $this->workerIdShift) |
        $this->sequence;
    }

    protected function tilNextMillis($lastTimestamp)
    {
        $timestamp = $this->timeGen();
        while ($timestamp <= $lastTimestamp) {
            $timestamp = $this->timeGen();
        }

        return $timestamp;
    }

    protected function timeGen()
    {
        return floor(microtime(true) * 1000);
    }

    // 左移 <<
    protected function leftShift($a, $b)
    {
        return bcmul($a, bcpow(2, $b));
    }
}