hash 分表

class HashServer{    private $servers = array();    private $serverNum = 0;    public function add_server($serverArr){        $this->serverNum = count($serverArr);        $servers = array();        foreach($serverArr as $k => $v){            $servers[$v] = $this->get_hash_index($v);        }        arsort($servers);        echo "<pre>";        print_r($servers);        echo "<hr>";        $this->servers = $servers;    }    private function get_hash_index($str){        $hash = 0;        $s    = md5($str);        $seed = 5;        $len  = 32;        for ($i = 0; $i < $len; $i++) {            $hash = ($hash << $seed) + $hash + ord($s{$i});        }        return $hash & 0x7FFFFFFF;    }    public function findServ($key){        foreach($this->servers as $k =>$v) {            if($this->get_hash_index($key) > $v){                return $k;                break;            }        }        foreach($this->servers as $k=>$v){            return $k;            break;        }    }}$serverArr = array(    "127.0.0.1",    "127.0.0.2",    "127.0.0.3",    "127.0.0.4",);//例如这里增加的一台服务器127.0.0.5,只要将127.0.0.4中大于127.0.0.5的数据转移给127.0.0.5即可/* 画圆更清楚 hash的位置大小排列 * 127.0.0.4 * 127.0.0.2 * 127.0.0.3 * 127.0.0.1 * 127.0.0.5 * */$hashServer = new HashServer();$hashServer->add_server($serverArr);echo "key0 : ". $hashServer->findServ("key0")."<br>";echo "key1 : ". $hashServer->findServ("key1")."<br>";echo "key2 : ". $hashServer->findServ("key2")."<br>";echo "key3 : ". $hashServer->findServ("key3")."<br>";echo "key4 : ". $hashServer->findServ("key4")."<br>";echo "key5 : ". $hashServer->findServ("key5")."<br>";echo "key6 : ". $hashServer->findServ("key6")."<br>";echo "key7 : ". $hashServer->findServ("key7")."<br>";echo "key8 : ". $hashServer->findServ("key8")."<br>";echo "key9 : ". $hashServer->findServ("key9")."<br>";