<?php
    /**
     * session使用memcached Aboc QQ:9986584
     */


     class Session{

          //过期时间
          private $_LEFT_TIME = 3600;
          
          //当前时间
          private $_nowtime = 0;
          
          //过期的确切时间
          private $_expiry = 0;

          private $_sessionid = '';
          
          private $_memcached_host = MEMCACHEDHOST;
          private $_memcached_port = MEMCACHEDPORT;
          public $mem;
          
          public function open() {
              $this->_nowtime = time();
              $this->_expiry = $this->_nowtime+$this->_LEFT_TIME;
              if (isset($_COOKIE['PHPSESSID'])){
                $this->_sessionid = $_COOKIE['PHPSESSID'];
                //session_id($this->_sessionid);
                $this->write_sessionid($this->_sessionid);
            } else {
                /**
                 * 要弄一个唯一的值才可以
                 */
                $tempsessionid = md5($_SERVER['REMOTE_ADDR'].$this->getIp().$_SERVER['HTTP_USER_AGENT'].rand(100000,999999));
                $this->write_sessionid($tempsessionid);
                $this->_sessionid = $tempsessionid;
                session_id($this->_sessionid);
            }
            $this->mem = new Memcache;
            $this->mem->connect($this->_memcached_host,$this->_memcached_port);      
         }
         
         /**
          * 设置过期时间，秒
          * Enter description here ...
          * @param unknown_type $seconds
          */
        public function setLefttime($seconds=3600){
            $this->_LEFT_TIME = $seconds;
        }
          
         private function getIp() {
        if (isset ( $_SERVER )) {
            if (isset ( $_SERVER ["HTTP_X_FORWARDED_FOR"] )) {
                $realip = $_SERVER ["HTTP_X_FORWARDED_FOR"];
            } else if (isset ( $_SERVER ["HTTP_CLIENT_IP"] )) {
                $realip = $_SERVER ["HTTP_CLIENT_IP"];
            } else {
                $realip = $_SERVER ["REMOTE_ADDR"];
            }
        } else {
            if (getenv ( "HTTP_X_FORWARDED_FOR" )) {
                $realip = getenv ( "HTTP_X_FORWARDED_FOR" );
            } else if (getenv ( "HTTP_CLIENT_IP" )) {
                $realip = getenv ( "HTTP_CLIENT_IP" );
            } else {
                $realip = getenv ( "REMOTE_ADDR" );
            }
        }
        if(isset($realip[16]))$realip = substr($realip,0,15);
        return $realip;
        }
          
          /**
           * 将自定义的sessionid写入cookie
           *
           * @param unknown_type $sessionid
           */
          private function write_sessionid($sessionid){
              setcookie('PHPSESSID',$sessionid,$this->_expiry,'/');              
          }

          public function close(){

          }

          /**
           * 读
           */
          public function read() {
              //echo $this->_sessionid;
              $content =$this->mem->get($this->_sessionid);
              if ($content){
                  return $content;
              }else{
                  $this->mem->set($this->_sessionid,'',0,$this->_LEFT_TIME);
                  return false;
              }
          }

          /**
           * 写
           */
          public function write( $sessionid , $sessdata ) {
             $this->mem->replace($this->_sessionid,$sessdata,0,$this->_LEFT_TIME);
               return true;
          }
          
          /**
           * 指定销毁
           */
          public function destroy() {
              $this->mem->delete($this->_sessionid);
          }

          /**
           * 销毁过期的数据
           */
          public function gc() {
                  //         
          }
          
          
          public function __destruct(){
              //$this->gc();
          }

     }

     $session  = new Session();
     session_set_save_handler(
                 array(&$session,'open'),
                 array(&$session,'close'),
                 array(&$session,'read'),
                 array(&$session,'write'),
                 array(&$session,'destroy'),
                 array(&$session,'gc')
     );
     session_start();
?>