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<?php

/**

 * Smarty Internal Plugin

 *

 * @package    Smarty

 * @subpackage Cacher

 */

/**

 * Cache Handler API

 *

 * @package    Smarty

 * @subpackage Cacher

 * @author     Rodney Rehm

 */

abstract class Smarty_CacheResource

{

    /**

     * resource types provided by the core

     *

     * @var array

     */

    protected static $sysplugins = array('file' => 'smarty_internal_cacheresource_file.php',);

    /**

     * populate Cached Object with meta data from Resource

     *

     * @param \Smarty_Template_Cached  $cached    cached object

     * @param Smarty_Internal_Template $_template template object

     *

     * @return void

     */

    abstract public function populate(\Smarty_Template_Cached $cached, Smarty_Internal_Template $_template);

    /**

     * populate Cached Object with timestamp and exists from Resource

     *

     * @param Smarty_Template_Cached $cached

     *

     * @return void

     */

    abstract public function populateTimestamp(Smarty_Template_Cached $cached);

    /**

     * Read the cached template and process header

     *

     * @param Smarty_Internal_Template $_template template object

     * @param Smarty_Template_Cached   $cached    cached object

     * @param boolean                  $update    flag if called because cache update

     *

     * @return boolean true or false if the cached content does not exist

     */

    abstract public function process(

        Smarty_Internal_Template $_template,

        Smarty_Template_Cached $cached = null,

        $update = false

    );

    /**

     * Write the rendered template output to cache

     *

     * @param Smarty_Internal_Template $_template template object

     * @param string                   $content   content to cache

     *

     * @return boolean success

     */

    abstract public function writeCachedContent(Smarty_Internal_Template $_template, $content);

    /**

     * Read cached template from cache

     *

     * @param Smarty_Internal_Template $_template template object

     *

     * @return string  content

     */

    abstract public function readCachedContent(Smarty_Internal_Template $_template);

    /**

     * Return cached content

     *

     * @param Smarty_Internal_Template $_template template object

     *

     * @return null|string

     */

    public function getCachedContent(Smarty_Internal_Template $_template)

    {

        if ($_template->cached->handler->process($_template)) {

            ob_start();

            $unifunc = $_template->cached->unifunc;

            $unifunc($_template);

            return ob_get_clean();

        }

        return null;

    }

    /**

     * Empty cache

     *

     * @param Smarty  $smarty   Smarty object

     * @param integer $exp_time expiration time (number of seconds, not timestamp)

     *

     * @return integer number of cache files deleted

     */

    abstract public function clearAll(Smarty $smarty, $exp_time = null);

    /**

     * Empty cache for a specific template

     *

     * @param Smarty  $smarty        Smarty object

     * @param string  $resource_name template name

     * @param string  $cache_id      cache id

     * @param string  $compile_id    compile id

     * @param integer $exp_time      expiration time (number of seconds, not timestamp)

     *

     * @return integer number of cache files deleted

     */

    abstract public function clear(Smarty $smarty, $resource_name, $cache_id, $compile_id, $exp_time);

    /**

     * @param Smarty                 $smarty

     * @param Smarty_Template_Cached $cached

     *

     * @return bool|null

     */

    public function locked(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        // theoretically locking_timeout should be checked against time_limit (max_execution_time)

        $start = microtime(true);

        $hadLock = null;

        while ($this->hasLock($smarty, $cached)) {

            $hadLock = true;

            if (microtime(true) - $start > $smarty->locking_timeout) {

                // abort waiting for lock release

                return false;

            }

            sleep(1);

        }

        return $hadLock;

    }

    /**

     * Check is cache is locked for this template

     *

     * @param Smarty                 $smarty

     * @param Smarty_Template_Cached $cached

     *

     * @return bool

     */

    public function hasLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        // check if lock exists

        return false;

    }

    /**

     * Lock cache for this template

     *

     * @param Smarty                 $smarty

     * @param Smarty_Template_Cached $cached

     *

     * @return bool

     */

    public function acquireLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        // create lock

        return true;

    }

    /**

     * Unlock cache for this template

     *

     * @param Smarty                 $smarty

     * @param Smarty_Template_Cached $cached

     *

     * @return bool

     */

    public function releaseLock(Smarty $smarty, Smarty_Template_Cached $cached)

    {

        // release lock

        return true;

    }

    /**

     * Load Cache Resource Handler

     *

     * @param Smarty $smarty Smarty object

     * @param string $type   name of the cache resource

     *

     * @throws SmartyException

     * @return Smarty_CacheResource Cache Resource Handler

     */

    public static function load(Smarty $smarty, $type = null)

    {

        if (!isset($type)) {

            $type = $smarty->caching_type;

        }

        // try smarty's cache

        if (isset($smarty->_cache[ 'cacheresource_handlers' ][ $type ])) {

            return $smarty->_cache[ 'cacheresource_handlers' ][ $type ];

        }

        // try registered resource

        if (isset($smarty->registered_cache_resources[ $type ])) {

            // do not cache these instances as they may vary from instance to instance

            return $smarty->_cache[ 'cacheresource_handlers' ][ $type ] = $smarty->registered_cache_resources[ $type ];

        }

        // try sysplugins dir

        if (isset(self::$sysplugins[ $type ])) {

            $cache_resource_class = 'Smarty_Internal_CacheResource_' . ucfirst($type);

            return $smarty->_cache[ 'cacheresource_handlers' ][ $type ] = new $cache_resource_class();

        }

        // try plugins dir

        $cache_resource_class = 'Smarty_CacheResource_' . ucfirst($type);

        if ($smarty->loadPlugin($cache_resource_class)) {

            return $smarty->_cache[ 'cacheresource_handlers' ][ $type ] = new $cache_resource_class();

        }

        // give up

        throw new SmartyException("Unable to load cache resource '{$type}'");

    }

}