php session mysql存储

一直知道逻辑没实际用过，今天试用下！

session.gc_divisor   100
session.gc_maxlifetime 1440
session.gc_probability  1

以上三值很重要，session.gc_divisor决定了回收频率。测试时可以设置小点才有效果！

<?php
class Session
{
 /**
  * a database connection resource
  * @var resource
  */
 private static $_sess_db;

 /**
  * Open the session
  * @return bool
  */
 public static function open() {

   if (self::$_sess_db = mysql_connect('localhost:3306',
                     'root',
                     '123456')) {
     return mysql_select_db('sessions', self::$_sess_db);
   }
   return false;
 }

 /**
  * Close the session
  * @return bool
  */
 public static function close() {
   return mysql_close(self::$_sess_db);
 }

 /**
  * Read the session
  * @param int session id
  * @return string string of the sessoin
  */
 public static function read($id) {
   $id = mysql_real_escape_string($id);
   $sql = sprintf("SELECT `session_data` FROM `sessions` " .
           "WHERE `session` = '%s'", $id);
   if ($result = mysql_query($sql, self::$_sess_db)) {
     if (mysql_num_rows($result)) {
       $record = mysql_fetch_assoc($result);
       return $record['session_data'];
     }
   }
   return '';
 }

 /**
  * Write the session
  * @param int session id
  * @param string data of the session
  */
 public static function write($id, $data) {
   $sql = sprintf("REPLACE INTO `sessions` VALUES('%s', '%s', '%s')",
           mysql_real_escape_string($id),
           mysql_real_escape_string(time()),
           mysql_real_escape_string($data)
           );
   return mysql_query($sql, self::$_sess_db) or die("Invalid query: " . mysql_error());
;
 }

 /**
  * Destoroy the session
  * @param int session id
  * @return bool
  */
 public static function destroy($id) {
   $sql = sprintf("DELETE FROM `sessions` WHERE `session` = '%s'", $id);
   return mysql_query($sql, self::$_sess_db);
 }

 /**
  * Garbage Collector
  * @param int life time (sec.)
  * @return bool
  * @see session.gc_divisor   100
  * @see session.gc_maxlifetime 1440
  * @see session.gc_probability  1
  * @usage execution rate 1/100
  *    (session.gc_probability/session.gc_divisor)
  */
 public static function gc($max) {
   $sql = sprintf("DELETE FROM `sessions` WHERE `session_expires` < '%s'",
           mysql_real_escape_string(time() - $max));
   var_dump($sql);
   return mysql_query($sql, self::$_sess_db);
 }
}

ini_set('zend.enable_gc', 1);
ini_set('session.gc_probability', 1);
ini_set('session.save_handler', 'user');
session_set_save_handler(array('Session', 'open'),
            array('Session', 'close'),
            array('Session', 'read'),
            array('Session', 'write'),
            array('Session', 'destroy'),
            array('Session', 'gc')
            );

if (session_id() == "") session_start();
//session_regenerate_id(false); //also works fine
if (isset($_SESSION['counter'])) {
 $_SESSION['counter']++;
} else {
 $_SESSION['counter'] = 1;
}
echo '<br/>SessionID: '. session_id() .'<br/>Counter: '. $_SESSION['counter'];
?>