<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Cache
 *
 * @copyright   Copyright (C) 2005 - 2011 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * APC cache storage handler
 *
 * @package     Joomla.Platform
 * @subpackage  Cache
 * @since       11.1
 */
class JCacheStorageApc extends JCacheStorage
{
    /**
     * Get cached data from APC by id and group
     *
     * @param   string  $id         The cache data id
     * @param   string  $group      The cache data group
     * @param   boolean $checkTime  True to verify cache time expiration threshold
     * @return  mixed   Boolean false on failure or a cached data string
     * @since   11.1
     */
    public function get($id, $group, $checkTime = true)
    {
        $cache_id = $this->_getCacheId($id, $group);
        return apc_fetch($cache_id);
    }

    /**
     * Get all cached data
     *
     * @return  array data
     * @since   11.1
     */
    public function getAll()
    {
        parent::getAll();

        $allinfo    = apc_cache_info('user');
        $keys       = $allinfo['cache_list'];
        $secret     = $this->_hash;

        $data = array();

        foreach ($keys as $key) {

            $name       = $key['info'];
            $namearr    = explode('-', $name);

            if ($namearr !== false && $namearr[0] == $secret &&  $namearr[1] == 'cache') {
                $group = $namearr[2];

                if (!isset($data[$group])) {
                    $item = new JCacheStorageHelper($group);
                } else {
                    $item = $data[$group];
                }

                $item->updateSize($key['mem_size']/1024);

                $data[$group] = $item;
            }
        }

        return $data;
    }

    /**
     * Store the data to APC by id and group
     *
     * @param   string  $id     The cache data id
     * @param   string  $group  The cache data group
     * @param   string  $data   The data to store in cache
     * @return  boolean True on success, false otherwise
     * @since   11.1
     */
    public function store($id, $group, $data)
    {
        $cache_id = $this->_getCacheId($id, $group);
        return apc_store($cache_id, $data, $this->_lifetime);
    }

    /**
     * Remove a cached data entry by id and group
     *
     * @param   string  $id     The cache data id
     * @param   string  $group  The cache data group
     * @return  boolean True on success, false otherwise
     * @since   11.1
     */
    public function remove($id, $group)
    {
        $cache_id = $this->_getCacheId($id, $group);
        return apc_delete($cache_id);
    }

    /**
     * Clean cache for a group given a mode.
     *
     * group mode       : cleans all cache in the group
     * notgroup mode    : cleans all cache not in the group
     *
     * @param   string  $group  The cache data group
     * @param   string  $mode   The mode for cleaning cache [group|notgroup]
     * @return  boolean True on success, false otherwise
     * @since   11.1
     */
    public function clean($group, $mode = null)
    {
        $allinfo    = apc_cache_info('user');
        $keys       = $allinfo['cache_list'];
        $secret     = $this->_hash;

        foreach ($keys as $key) {

            if (strpos($key['info'], $secret.'-cache-'.$group.'-') === 0 xor $mode != 'group') {
                apc_delete($key['info']);
            }
        }
        return true;
    }

    /**
     * Force garbage collect expired cache data as items are removed only on fetch!
     *
     * @return boolean  True on success, false otherwise.
     * @since   11.1
     */
    public function gc()
    {
        $lifetime   = $this->_lifetime;
        $allinfo    = apc_cache_info('user');
        $keys       = $allinfo['cache_list'];
        $secret     = $this->_hash;

        foreach ($keys as $key) {
            if (strpos($key['info'], $secret.'-cache-')) {
                apc_fetch($key['info']);
            }
        }
    }

    /**
     * Test to see if the cache storage is available.
     *
     * @return boolean  True on success, false otherwise.
     */
    public static function test()
    {
        return extension_loaded('apc');
    }

    /**
     * Lock cached item - override parent as this is more efficient
     *
     * @param   string  $id     The cache data id
     * @param   string  $group  The cache data group
     * @param   integer $locktime Cached item max lock time
     * @return  boolean True on success, false otherwise.
     * @since   11.1
     */
    public function lock($id,$group,$locktime)
    {
        $returning = new stdClass();
        $returning->locklooped = false;

        $looptime = $locktime * 10;

        $cache_id = $this->_getCacheId($id, $group).'_lock';

        $data_lock = apc_add( $cache_id, 1, $locktime );

        if ( $data_lock === FALSE ) {

            $lock_counter = 0;

            // loop until you find that the lock has been released.  that implies that data get from other thread has finished
            while ( $data_lock === FALSE ) {

                if ( $lock_counter > $looptime ) {
                    $returning->locked      = false;
                    $returning->locklooped  = true;
                    break;
                }

                usleep(100);
                $data_lock = apc_add( $cache_id, 1, $locktime );
                $lock_counter++;
            }

        }
        $returning->locked = $data_lock;

        return $returning;
    }

    /**
     * Unlock cached item - override parent for cacheid compatibility with lock
     *
     * @param   string  $id     The cache data id
     * @param   string  $group  The cache data group
     * @param   integer $locktime Cached item max lock time
     * @return  boolean True on success, false otherwise.
     * @since   11.1
     */
    public function unlock($id,$group=null)
    {
        $unlock = false;

        $cache_id = $this->_getCacheId($id, $group).'_lock';

        $unlock = apc_delete($cache_id);
        return $unlock;
    }
}