root/trunk/framework/Web/UI/TSessionPageStatePersister.php

<?php
/**
 * TSessionPageStatePersister class file
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @link http://www.pradosoft.com/
 * @copyright Copyright &copy; 2005-2008 PradoSoft
 * @license http://www.pradosoft.com/license/
 * @version $Id$
 * @package System.Web.UI
 */

/**
 * TSessionPageStatePersister class
 *
 * TSessionPageStatePersister implements a page state persistent method based on
 * sessions. Page state are stored in user sessions and therefore, this persister
 * requires session to be started and available.
 *
 * TSessionPageStatePersister keeps limited number of history states in session,
 * mainly to preserve the precious server storage. The number is specified
 * by {@link setHistorySize HistorySize}, which defaults to 10.
 *
 * There are a couple of ways to use TSessionPageStatePersister.
 * One can override the page's {@link TPage::getStatePersister()} method and
 * create a TSessionPageStatePersister instance there.
 * Or one can configure the pages to use TSessionPageStatePersister in page configurations
 * as follows,
 * <code>
 *   <pages StatePersisterClass="System.Web.UI.TSessionPageStatePersister" />
 * </code>
 * The above configuration will affect the pages under the directory containing
 * this configuration and all its subdirectories.
 * To configure individual pages to use TSessionPageStatePersister, use
 * <code>
 *   <pages>
 *     <page id="PageID" StatePersisterClass="System.Web.UI.TSessionPageStatePersister" />
 *   </pages>
 * </code>
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id$
 * @package System.Web.UI
 * @since 3.1
 */
class TSessionPageStatePersister extends TComponent implements IPageStatePersister
{
    const STATE_SESSION_KEY='PRADO_SESSION_PAGESTATE';
    const QUEUE_SESSION_KEY='PRADO_SESSION_STATEQUEUE';

    private $_page;
    private $_historySize=10;

    /**
     * @param TPage the page that this persister works for
     */
    public function getPage()
    {
        return $this->_page;
    }

    /**
     * @param TPage the page that this persister works for.
     */
    public function setPage(TPage $page)
    {
        $this->_page=$page;
    }

    /**
     * @return integer maximum number of page states that should be kept in session. Defaults to 10.
     */
    public function getHistorySize()
    {
        return $this->_historySize;
    }

    /**
     * @param integer maximum number of page states that should be kept in session
     * @throws TInvalidDataValueException if the number is smaller than 1.
     */
    public function setHistorySize($value)
    {
        if(($value=TPropertyValue::ensureInteger($value))>0)
            $this->_historySize=$value;
        else
            throw new TInvalidDataValueException('sessionpagestatepersister_historysize_invalid');
    }
    /**
     * Saves state in session.
     * @param mixed state to be stored
     */
    public function save($state)
    {
        $session=$this->_page->getSession();
        $session->open();
        $data=serialize($state);
        $timestamp=(string)microtime(true);
        $key=self::STATE_SESSION_KEY.$timestamp;
        $session->add($key,$data);
        if(($queue=$session->itemAt(self::QUEUE_SESSION_KEY))===null)
            $queue=array();
        $queue[]=$key;
        if(count($queue)>$this->getHistorySize())
        {
            $expiredKey=array_shift($queue);
            $session->remove($expiredKey);
        }
        $session->add(self::QUEUE_SESSION_KEY,$queue);
        $this->_page->setClientState(TPageStateFormatter::serialize($this->_page,$timestamp));
    }

    /**
     * Loads page state from session.
     * @return mixed the restored state
     * @throws THttpException if page state is corrupted
     */
    public function load()
    {
        if(($timestamp=TPageStateFormatter::unserialize($this->_page,$this->_page->getRequestClientState()))!==null)
        {
            $session=$this->_page->getSession();
            $session->open();
            $key=self::STATE_SESSION_KEY.$timestamp;
            if(($data=$session->itemAt($key))!==null)
                return unserialize($data);
        }
        throw new THttpException(400,'sessionpagestatepersister_pagestate_corrupted');
    }
}

?>