php如何生成唯一订单编号_php时间戳随机数雪花算法与重复概率分析

<?php
function generateOrderNo() {
    $timestamp = time(); // 当前时间戳
    $randStr   = str_pad(rand(0, 9999), 4, '0', STR_PAD_LEFT); // 补零到4位
    return $timestamp . $randStr;
}
echo generateOrderNo(); // 输出类似：17123456780045
?>

<?php
function generateUniqueOrderNo() {
    $microtime = explode(' ', microtime());
    $timestamp = (int)($microtime[1] % 100000000); // 取时间戳后8位
    $micro     = (int)($microtime[0] * 10000);      // 微秒部分转为整数
    $pid       = getmypid() % 1000;                 // 当前进程ID取模
    return sprintf("%d%04d%03d", $timestamp, $micro, $pid);
}
?>

<?php
class Snowflake
{
    const TWEPOCH = 1288834974657; // 起始时间戳（毫秒）
    const WORKER_ID_BITS = 5;
    const DATACENTER_ID_BITS = 5;
    const SEQUENCE_BITS = 12;
<pre class="brush:php;toolbar:false;"><pre class="brush:php;toolbar:false;">private $workerId;
private $datacenterId;
private $sequence = 0;
private $lastTimestamp = -1;

public function __construct($workerId = 1, $datacenterId = 1)
{
    $maxWorkerId = -1 ^ (-1 << self::WORKER_ID_BITS);
    if ($workerId > $maxWorkerId || $workerId < 0) {
        throw new InvalidArgumentException('workerId can\'t be greater than 31 or less than 0');
    }
    $maxDatacenterId = -1 ^ (-1 << self::DATACENTER_ID_BITS);
    if ($datacenterId > $maxDatacenterId || $datacenterId < 0) {
        throw new InvalidArgumentException('datacenterId can\'t be greater than 31 or less than 0');
    }
    $this->workerId = $workerId;
    $this->datacenterId = $datacenterId;
}

public function nextId()
{
    $timestamp = $this->timeGen();
    if ($timestamp < $this->lastTimestamp) {
        throw new RuntimeException("Clock moved backwards!");
    }
    if ($this->lastTimestamp === $timestamp) {
        $this->sequence = ($this->sequence + 1) & ((1 << self::SEQUENCE_BITS) - 1);
        if ($this->sequence === 0) {
            $timestamp = $this->tilNextMillis($this->lastTimestamp);
        }
    } else {
        $this->sequence = 0;
    }
    $this->lastTimestamp = $timestamp;

    return (($timestamp - self::TWEPOCH) << (self::WORKER_ID_BITS + self::DATACENTER_ID_BITS + self::SEQUENCE_BITS)) |
           ($this->workerId << (self::DATACENTER_ID_BITS + self::SEQUENCE_BITS)) |
           ($this->datacenterId << self::SEQUENCE_BITS) |
           $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);
}