memcache分布式 [一致性hash算法] 的php实现

<?php/*** 一致性哈希memcache分布式，采用的是虚拟节点的方式解决分布均匀性问题,查找节点采用二分法快速查找* the last known user to change this file in the repository  <$LastChangedBy: nash.xiong [        DISCUZ_CODE_0        ]gt;* @author nash.xiong <nash.xiong@gmail.com>* @copyright Copyright &copy; 2003-2012 phpd.cn* @license */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() {                /* 放入配置文件 */                $config = array(                                                '127.0.0.1:11211',                                                '127.0.0.1:11212',                                                '127.0.0.1:11213',                                                '127.0.0.1:11214',                                                '127.0.0.1:11215'                                        );                                                        if (!$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 . '_' . $i;                        }                }                ksort($this->_node);        }        private function __clone(){}                /**         * 单例，保证只有一个实例         */        static public function getInstance() {                static $memcacheObj = null;                if (!is_object($memcacheObj)) {                        $memcacheObj = new self();                }                return $memcacheObj;        }                /**         * 根据key做一致性hash后连接到一台物理memcache服务器         * @param string $key         */        private function _connectMemcache($key) {                $this->_nodeData = array_keys($this->_node);                $this->_keyNode = sprintf("%u", crc32($key));                $nodeKey = $this->_findServerNode();                //如果超出环，从头再用二分法查找一个最近的，然后环的头尾做判断，取最接近的节点                if ($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];        }                /**         * 采用二分法从虚拟memcache节点中查找最近的节点         * @param unknown_type $m         * @param unknown_type $b         */        private function _findServerNode($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), 0, $expire);        }                public function add($key, $value, $expire = 0) {                return $this->_connectMemcache($key)->add($key, json_encode($value), 0, $expire);        }                public function get($key) {                return json_decode($this->_connectMemcache($key)->get($key), true);        }                public function delete($key) {                return $this->_connectMemcache($key)->delete($key);        }        }

$runData['BEGIN_TIME'] = microtime(true);//测试一万次set加getfor($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, time(), 0, 10);}var_dump(number_format(microtime(true) - $runData['BEGIN_TIME'],6));