Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * The core cache API.

 *

 * Pretty much just includes the mandatory classes and contains the misc classes that arn't worth separating into individual files.

 *

 * This file is part of Moodle's cache API, affectionately called MUC.

 * It contains the components that are requried in order to use caching.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

// Include the required classes.

require_once($CFG->dirroot.'/cache/classes/interfaces.php');

require_once($CFG->dirroot.'/cache/classes/config.php');

require_once($CFG->dirroot.'/cache/classes/helper.php');

require_once($CFG->dirroot.'/cache/classes/factory.php');

require_once($CFG->dirroot.'/cache/classes/loaders.php');

require_once($CFG->dirroot.'/cache/classes/store.php');

require_once($CFG->dirroot.'/cache/classes/definition.php');

/**

 * A cached object wrapper.

 *

 * This class gets used when the data is an object that has implemented the cacheable_object interface.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class cache_cached_object {

    /**

     * The class of the cacheable object

     * @var string

     */

    protected $class;

    /**

     * The data returned by the cacheable_object prepare_to_cache method.

     * @var mixed

     */

    protected $data;

    /**

     * Constructs a cached object wrapper.

     * @param cacheable_object $obj

     */

    public function __construct(cacheable_object $obj) {

        $this->class = get_class($obj);

        $this->data = $obj->prepare_to_cache();

    }

    /**

     * Restores the data as an instance of the cacheable_object class.

     * @return object

     */

    public function restore_object() {

        $class = $this->class;

        return $class::wake_from_cache($this->data);

    }

}

/**

 * A wrapper class used to handle ttl when the cache store doesn't natively support it.

 *

 * This class is exactly why you should use event driving invalidation of cache data rather than relying on ttl.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class cache_ttl_wrapper {

    /**

     * The data being stored.

     * @var mixed

     */

    public $data;

    /**

     * When the cache data expires as a timestamp.

     * @var int

     */

    public $expires;

    /**

     * Constructs a ttl cache wrapper.

     *

     * @param mixed $data

     * @param int $ttl The time to live in seconds.

     */

    public function __construct($data, $ttl) {

        $this->data = $data;

        $this->expires = cache::now() + (int)$ttl;

    }

    /**

     * Returns true if the data has expired.

     * @return int

     */

    public function has_expired() {

        return ($this->expires < cache::now());

    }

}

/**

 * A cache exception class. Just allows people to catch cache exceptions.

 *

 * @package    core

 * @category   cache

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class cache_exception extends moodle_exception {

    /**

     * Constructs a new exception

     *

     * @param string $errorcode

     * @param string $module

     * @param string $link

     * @param mixed $a

     * @param mixed $debuginfo

     */

    public function __construct($errorcode, $module = 'cache', $link = '', $a = null, $debuginfo = null) {

        // This may appear like a useless override but you will notice that we have set a MUCH more useful default for $module.

        parent::__construct($errorcode, $module, $link, $a, $debuginfo);

    }

}

/**

 * An array of cacheable objects.

 *

 * This class allows a developer to create an array of cacheable objects and store that.

 * The cache API doesn't check items within an array to see whether they are cacheable. Such a check would be very costly to both

 * arrays using cacheable object and those that don't.

 * Instead the developer must explicitly use a cacheable_object_array instance.

 *

 * The following is one example of how this class can be used.

 * <code>

 * $data = array();

 * $data[] = new cacheable_object('one');

 * $data[] = new cacheable_object('two');

 * $data[] = new cacheable_object('three');

 * $cache->set(new cacheable_object_array($data));

 * </code>

 * Another example would be

 * <code>

 * $data = new cacheable_object_array();

 * $data[] = new cacheable_object('one');

 * $data[] = new cacheable_object('two');

 * $data[] = new cacheable_object('three');

 * $cache->set($data);

 * </code>

 *

 * @copyright  2012 Sam Hemelryk

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class cacheable_object_array extends ArrayObject implements cacheable_object {

    /**

     * Constructs a new array object instance.

     * @param array $items

     */

    final public function __construct(array $items = array()) {

        parent::__construct($items, ArrayObject::STD_PROP_LIST);

    }

    /**

     * Returns the data to cache for this object.

     *

     * @return array An array of cache_cached_object instances.

     * @throws coding_exception

     */

    final public function prepare_to_cache() {

        $result = array();

        foreach ($this as $key => $value) {

            if ($value instanceof cacheable_object) {

                $value = new cache_cached_object($value);

            } else {

                throw new coding_exception('Only cacheable_object instances can be added to a cacheable_array');

            }

            $result[$key] = $value;

        }

        return $result;

    }

    /**

     * Returns the cacheable_object_array that was originally sent to the cache.

     *

     * @param array $data

     * @return cacheable_object_array

     * @throws coding_exception

     */

    final public static function wake_from_cache($data) {

        if (!is_array($data)) {

            throw new coding_exception('Invalid data type when reviving cacheable_array data');

        }

        $result = array();

        foreach ($data as $key => $value) {

            $result[$key] = $value->restore_object();

        }

        $class = __CLASS__;

        return new $class($result);

    }

}