memcache一致性hash的php实现方法

<?php
class memcacheHashMap {
??????? private $_node = array();
??????? private $_nodeData = array();
??????? private $_keyNode = 0;
??????? private $_memcache = null;
??????? //每个物理服务器生成虚拟节点个数 [注：节点数越多,cache分布的均匀性越好,同时set get操作时,也更耗资源,10台物理服务器,采用200较为合理]
??????? private $_virtualNodeNum = 200;
??????? private function __construct() {
??????????????? $config = array(//五个memcache服务器
??????????????????????????????????????????????? '127.0.0.1:11211',
??????????????????????????????????????????????? '127.0.0.1:11212',
??????????????????????????????????????????????? '127.0.0.1:11213',
??????????????????????????????????????????????? '127.0.0.1:11214',
??????????????????????????????????????????????? '127.0.0.1:11215'
??????????????????????????????????????? );
??????????????? if (!$config) throw new Exception('Cache config NULL');
??????????????? foreach ($config as $key => $value) {
??????????????????????? for ($i = 0; $i < $this->_virtualNodeNum; $i++) {
??????????????????????????????? $this->_node[sprintf("%u",crc32($value . '_' . $i))] = $value . '_' . $i;//循环为每个memcache服务器创建200个虚拟节点
??????????????????????? }
??????????????? }
??????????????? ksort($this->_node);//创建出来的1000个虚拟节点依照键名从小到大排序
??????? }
??????? //实例化该类
??????? static public function getInstance() {
??????????????? static $memcacheObj = null;
??????????????? if (!is_object($memcacheObj)) {
??????????????????????? $memcacheObj = new self();
??????????????? }
??????????????? return $memcacheObj;
??????? }
??????? //根据传来的键查找到对应虚拟节点的位置
??????? private function _connectMemcache($key) {
??????????????? $this->_nodeData = array_keys($this->_node);//所有的虚拟节点的键的数组
??????????????? $this->_keyNode = sprintf("%u",crc32($key));//算出键的hash值
??????????????? $nodeKey = $this->_findServerNode();//找出对应的虚拟节点
??????????????? //如果超出环,从头再用二分法查找一个最近的,然后环的头尾做判断,取最接近的节点
??????????????? if ($this->_keyNode > end($this->_nodeData)) {
??????????????????????? $this->_keyNode -= end($this->_nodeData);
??????????????????????? $nodeKey2 = $this->_findServerNode();
??????????????????????? if (abs($nodeKey2 - $this->_keyNode) < abs($nodeKey - $this->_keyNode))? $nodeKey = $nodeKey2;
??????????????? }
??????????????? var_dump($this->_node[$nodeKey]);
??????????????? list($config,$num) = explode('_',$this->_node[$nodeKey]);
??????????????? if (!$config) throw new Exception('Cache config Error');
??????????????? if (!isset($this->_memcache[$config])) {
??????????????????????? $this->_memcache[$config] = new Memcache;
??????????????????????? list($host,$port) = explode(':',$config);
??????????????????????? $this->_memcache[$config]->connect($host,$port);
??????????????? }
??????????????? return $this->_memcache[$config];
??????? }
??????? //二分法根据给出的值找出最近的虚拟节点位置
??????? private function _findServerNode($m = 0,$b = 0) {
??????????? $total = count($this->_nodeData);
??????????? if ($total != 0 && $b == 0) $b = $total - 1;
??????????? if ($m < $b){
??????????????? $avg = intval(($m+$b) / 2);
??????????????? if ($this->_nodeData[$avg] == $this->_keyNode) return $this->_nodeData[$avg];
??????????????? elseif ($this->_keyNode < $this->_nodeData[$avg] && ($avg-1 >= 0)) return $this->_findServerNode($m,$avg-1);
??????????????? else return $this->_findServerNode($avg+1,$b);
??????????? }
??????????????? if (abs($this->_nodeData[$b] - $this->_keyNode) < abs($this->_nodeData[$m] - $this->_keyNode))? return $this->_nodeData[$b];
??????????????? else return $this->_nodeData[$m];
??????? }
??????? public function set($key,$value,$expire = 0) {
??????????????? return $this->_connectMemcache($key)->set($key,json_encode($value),$expire);
??????? }
??????? public function add($key,$expire = 0) {
??????????????? return $this->_connectMemcache($key)->add($key,$expire);
??????? }
??????? public function get($key) {
??????????????? return json_decode($this->_connectMemcache($key)->get($key),true);
??????? }
??????? public function delete($key) {
??????????????? return $this->_connectMemcache($key)->delete($key);
??????? }
}
$runData['BEGIN_TIME'] = microtime(true);
//测试一万次set加get
for($i=0;$i<10000;$i++) {
??????? $key = md5(mt_rand());
??????? $b = memcacheHashMap::getInstance()->set($key,time(),10);
}
var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));
$runData['BEGIN_TIME'] = microtime(true); $m= new Memcache;
$m->connect('127.0.0.1',11211);
for($i=0;$i<10000;$i++) {
??????? $key = md5(mt_rand());
??????? $b = $m->set($key,6));
?>