关于php:PHP实现Hash环Hash一致性原理

援用大佬文章：Hash 环

class consisTenHash{public $serverList = [];    // 服务器列表

    public $virtualPos = [];    // 虚构节点地位

    public $virtualPosNum = 2;    // 每个节点下有 2 个虚节点

    /**
     应用循环冗余算法计算出十进制校验值
    **/ 
    public function cHash($str){$str = md5($str);
        return sprintf('%u',crc32($str));
    }

    /**
     从以后的服务器列表中找到适合的服务器进行寄存
    **/
    public function lookup($key){$point = $this->cHash($key);
        $finalServer = current($this->virtualPos);
        foreach ($this->virtualPos as $pos => $server) {if($point <= $pos){
                $finalServer = $server;
                break;
            }
        }
        reset($this->virtualPos);
        return $finalServer;
    }

    /**
     增加一台服务器节点
    **/
    public function addServer($server){if (!isset($this->serverList[$server])) {for ($i=0; $i < $this->virtualPosNum; $i++) {$pos = $this->cHash($server.'_'.$i);
                $this->virtualPos[$pos]         = $server;
                $this->serverList[$server][]     = $pos;}
            ksort($this->virtualPos,SORT_NUMERIC);
        }
        return true;
    }

    /**
     删除一台服务器节点
    **/
    public function delServer($key){if(isset($this->serverList[$key])){
            // 删除节点
            foreach ($this->serverList[$key] as $pos) {unset($this->virtualPos[$pos]);
            }
            // 删除对应服务器
            unset($this->serverList[$key]);
        }
        return true;
    }
}

测试代码：

// 增加五台服务器
$consisTenHash  = new consisTenHash();
$consisTenHash->addServer('127.0.0.1');
$consisTenHash->addServer('127.0.0.2');
$consisTenHash->addServer('127.0.0.3');
$consisTenHash->addServer('127.0.0.4');
$consisTenHash->addServer('127.0.0.5');

// 展现服务器的地位
var_dump($consisTenHash->serverList);

// 增加 Key, 找到其寄存的服务器地位
var_dump($consisTenHash->lookup("zxxxxx"));
var_dump($consisTenHash->lookup("rrrrrrrrr-c-1i312"));
var_dump($consisTenHash->lookup("shhjjaaaaaaa"));
var_dump($consisTenHash->lookup("blue-ssallllllkk"));
var_dump($consisTenHash->lookup("unset-bjhujka"));
var_dump($consisTenHash->lo