core.php

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<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to [e-mail] so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Cache
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */


/**
 * @package    Zend_Cache
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Cache_Core
{
    /**
     * Backend Object
     *
     * @var object $_backend
     */
    private $_backend = null;

    /**
     * Available options
     *
     * ====> (boolean) write_control :
     * - Enable / disable write control (the cache is read just after writing to detect corrupt entries)
     * - Enable write control will lightly slow the cache writing but not the cache reading
     * Write control can detect some corrupt cache files but maybe it's not a perfect control
     *
     * ====> (boolean) caching :
     * - Enable / disable caching
     * (can be very useful for the debug of cached scripts)
     *
     * =====> (string) cache_id_prefix :
     * - prefix for cache ids (namespace)
     * 
     * ====> (boolean) automatic_serialization :
     * - Enable / disable automatic serialization
     * - It can be used to save directly datas which aren't strings (but it's slower)
     *
     * ====> (int) automatic_cleaning_factor :
     * - Disable / Tune the automatic cleaning process
     * - The automatic cleaning process destroy too old (for the given life time)
     *   cache files when a new cache file is written :
     *     0               => no automatic cache cleaning
     *     1               => systematic cache cleaning
     *     x (integer) > 1 => automatic cleaning randomly 1 times on x cache write
     *
     * ====> (int) lifetime :
     * - Cache lifetime (in seconds)
     * - If null, the cache is valid forever.
     *
     * ====> (boolean) logging :
     * - If set to true, logging is activated (but the system is slower)
     * 
     * ====> (boolean) ignore_user_abort
     * - If set to true, the core will set the ignore_user_abort PHP flag inside the
     *   save() method to avoid cache corruptions in some cases (default false)
     *
     * @var array $_options available options
     */
    protected $_options = array(
        'write_control'             => true,
        'caching'                   => true,
        'cache_id_prefix'           => null,
        'automatic_serialization'   => false,
        'automatic_cleaning_factor' => 10,
        'lifetime'                  => 3600,
        'logging'                   => false,
        'logger'                    => null,
        'ignore_user_abort'		    => false
    );

    /**
     * Array of options which have to be transfered to backend
     *
     * @var array $_directivesList
     */
    protected static $_directivesList = array('lifetime', 'logging', 'logger');

    /**
     * Not used for the core, just a sort a hint to get a common setOption() method (for the core and for frontends)
     *
     * @var array $_specificOptions
     */
    protected $_specificOptions = array();

    /**
     * Last used cache id
     *
     * @var string $_lastId
     */
    private $_lastId = null;

    /**
     * Constructor
     *
     * @param  array $options Associative array of options
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function __construct($options = array())
    {
        if (!is_array($options)) {
            Zend_Cache::throwException('Options parameter must be an array');
        }
        while (list($name, $value) = each($options)) {
            $this->setOption($name, $value);
        }
        $this->_loggerSanity();
    }

    /**
     * Set the backend
     *
     * @param  object $backendObject
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function setBackend($backendObject)
    {
        if (!is_object($backendObject)) {
            Zend_Cache::throwException('Incorrect backend object !');
        }
        $this->_backend= $backendObject;
        // some options (listed in $_directivesList) have to be given
        // to the backend too (even if they are not "backend specific")
        $directives = array();
        foreach (Zend_Cache_Core::$_directivesList as $directive) {
            $directives[$directive] = $this->_options[$directive];
        }
        $this->_backend->setDirectives($directives);
    }

    /**
     * Public frontend to set an option
     *
     * There is an additional validation (relatively to the protected _setOption method)
     *
     * @param  string $name  Name of the option
     * @param  mixed  $value Value of the option
     * @throws Zend_Cache_Exception
     * @return void
     */
    public function setOption($name, $value)
    {
        if (is_string($name)) {
            $name = strtolower($name);
            if (array_key_exists($name, $this->_options)) {
                // This is a Core option
                $this->_setOption($name, $value);
                return;
            }
            if (array_key_exists($name, $this->_specificOptions)) {
                // This a specic option of this frontend
                $this->_specificOptions[$name] = $value;
                return;
            }
        }
        Zend_Cache::throwException("Incorrect option name : $name");
    }

    /**
     * Set an option
     *
     * @param  string $name  Name of the option
     * @param  mixed  $value Value of the option
     * @throws Zend_Cache_Exception
     * @return void
     */
    private function _setOption($name, $value)
    {
        if (!is_string($name) || !array_key_exists($name, $this->_options)) {
            Zend_Cache::throwException("Incorrect option name : $name");
        }
        $this->_options[$name] = $value;
    }

    /**
     * Force a new lifetime
     *
     * The new value is set for the core/frontend but for the backend too (directive)
     *
     * @param  int $newLifetime New lifetime (in seconds)
     * @return void
     */
    public function setLifetime($newLifetime)
    {
        $this->_options['lifetime'] = $newLifetime;
        $this->_backend->setDirectives(array(
            'lifetime' => $newLifetime
        ));
    }

    /**
     * Test if a cache is available for the given id and (if yes) return it (false else)
     *
     * @param  string  $id                     Cache id
     * @param  boolean $doNotTestCacheValidity If set to true, the cache validity won't be tested
     * @param  boolean $doNotUnserialize       Do not serialize (even if automatic_serialization is true) => for internal use
     * @return mixed|false Cached datas
     */
    public function load($id, $doNotTestCacheValidity = false, $doNotUnserialize = false)
    {
        if (!$this->_options['caching']) {
            return false;
        }
        $id = $this->_id($id); // cache id may need prefix
        $this->_lastId = $id;
        self::_validateIdOrTag($id);
        $data = $this->_backend->load($id, $doNotTestCacheValidity);
        if ($data===false) {
            // no cache available
            return false;
        }
        if ((!$doNotUnserialize) && $this->_options['automatic_serialization']) {
            // we need to unserialize before sending the result
            return unserialize($data);
        }
        return $data;
    }

    /**
     * Test if a cache is available for the given id