【PHP】一致性hash-php实现

原理

参考 https://www.bilibili.com/video/av25184175?from=search&seid=5169155263985611919 讲的非常清晰

代码

class consistencyHash
{
    protected $serverNodes = array();
    protected $virtualNum = 64;
    protected $virtualNodes = array();

    /**
     * hash实现
     * @param $str
     * @return int
     */
    public function _hash($str)
    {
        return sprintf('%u', crc32($str));
    }

    /**
     * 查找key所属的节点
     * @param $key
     * @return mixed
     */
    public function lookup($key)
    {
        $point = $this->_hash($key);
        $current = current($this->serverNodes);
        foreach ($this->virtualNodes as $key => $value) {
            if ($point <= $key) {
                $current = $value;
                break;
            }
        }
        return $current;
    }

    /**
     * 添加节点
     * @param $node
     */
    public function addNode($node)
    {
        for ($i = 0; $i <= $this->virtualNum; $i++) {
            $virtualNode = $node . "-" . $i;
            $this->virtualNodes[$this->_hash($virtualNode)] = $node;
        }
        $this->sortNodes();
    }

    /**
     * 对node进行排序
     */
    private function sortNodes()
    {
        ksort($this->serverNodes);
    }

    public function debug(){
        echo "virtualNodes :" . json_encode($this->virtualNodes);
        echo "\n\r";
    }
}