Ticket #314: Shmop.php

<?php defined('SYSPATH') or die('No direct script access.');
/**
 * Shmop-based Cache driver.
 *
 * @package    Cache
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
class Cache_Shmop_Driver implements Cache_Driver {

    protected $key;
    protected $index;
    protected $segment;

    public function __construct()
    {
        if ( ! extension_loaded('shmop'))
            throw new Kohana_Exception('cache.extension_not_loaded', 'shmop');

        $this->key = Config::item('cache_shmop.key');
        $this->index = Config::item('cache_shmop.index');
        $this->segment = Config::item('cache_shmop.segment');

    }

    public function get($key)
    {
        if ($shm_id = @shmop_open($this->key, "a", 0, 0))
        {
            // Get the size of the structure
            $size = @shmop_read ($shm_id, 0, 4);
            $size = hexdec ($size);

            if ($size > 0)
            {
            // Read the structure
            $structure = @shmop_read ($shm_id, 4, $size);
            $structure = unserialize($structure);
            @shmop_close ($shm_id);

            if (isset($structure[$key]))
            {
                $seg_id = @shmop_open($this->key + $structure[$key], "a", 0, 0);

                if ($seg_id)
                {
                    // Get the size of the structure
                    $cache_size = @shmop_read ($seg_id, 0, 4);
                    $cache_size = hexdec ($cache_size);
                    $cache_data = @shmop_read ($seg_id, 4, $cache_size);
                    @shmop_close($seg_id);

                    return $cache_data;
                }
            }
            }
            @shmop_close ($shm_id);
        }
        return false;
    }

    public function set($id, $data, $tags, $expiration)
    {
        count($tags) and Log::add('error', 'Cache: tags are unsupported by the APC driver');

        if ($struc_id = shmop_open($this->key, "c", 0644, $this->index))
        {
            // Get the size of the structure
            $size = @shmop_read ($struc_id, 0, 4);
            $size = hexdec ($size);

            // Fetch the structure
            $structure = array();

            if ($size > 0)
            {
            $structure = shmop_read ($struc_id, 4, $size);
            $structure = unserialize($structure);
            }

            $highest = 0;
            reset ($structure);
            while (list($k, $v) = each ($structure))
            {
            if ($v > $highest) 
            {
                $highest = $v;
            }
            }

            for ($i = 1; $i <= $highest + 1; $i++)
            {
            if ( ! in_array($i, $structure))
            {
                $segment = $i;
                break;
            }
            }

            $delete =  (isset($structure[$id])) ? $structure[$id] : false;

            if ($seg_id = shmop_open($this->key + $segment, "c", 0644, $this->segment))
            {
            // Store data
            $seg_size = strlen($data);
            $seg_size = sprintf ('%04X', $seg_size);

            shmop_write($seg_id, $seg_size, 0);
            shmop_write($seg_id, $data, 4);
            shmop_close($seg_id);

            // Update structure
            $structure[$id] = $segment;

            // Store the structure
            $struc_data = serialize ($structure);
            $struc_size = strlen($struc_data);
            $struc_size = sprintf ('%04X', $struc_size);

            shmop_write($struc_id, $struc_size, 0);
            shmop_write($struc_id, $struc_data, 4);
            shmop_close($struc_id);

            // Delete old segment
            if ($delete)
            {
                $del_id = shmop_open($this->key + $delete, "w", 0, 0);
                shmop_delete($del_id);
                shmop_close($del_id);
            }
            return true;
            }
            shmop_close($struc_id);
        }
        return false;
    }

    public function find($tag)
    {
        return FALSE;
    }

    public function delete($id, $tag = FALSE)
    {
        if($struc_id = shmop_open($this->key, "c", 0644, $this->index))
        {
            $size = @shmop_read ($struc_id, 0, 4);
            $size = hexdec ($size);
            
            if($size > 0)
            {
            $structure = shmop_read ($struc_id, 4, $size);
            $structure = unserialize($structure);
            
            if ($id === true)
            {    
                while(list($k, $v) = each($structure))
                {
                // Delete old segment
                $del_id = shmop_open($this->key + $v, "w", 0, 0);
                shmop_delete($del_id);
                shmop_close($del_id);
                }
                $structure = array();
                // Store the structure
                $struc_data = serialize($structure);
                $struc_size = strlen($struc_data);
                $struc_size = sprintf ('%04X', $struc_size);
                shmop_write($struc_id, $struc_size, 0);
                shmop_write($struc_id, $struc_data, 4);
                shmop_close($struc_id);
                
                return true;
            }
            elseif ($tag == false and isset($structure[$id]))
            {
                $delete = $structure[$id];
                // Update structure
                unset($structure[$id]);
                // Store the structure
                $struc_data = serialize($structure);
                $struc_size = strlen($struc_data);
                $struc_size = sprintf('%04X', $struc_size);
                shmop_write($struc_id, $struc_size, 0);
                shmop_write($struc_id, $struc_data, 4);
                shmop_close($struc_id);
                // Delete old segment
                $del_id = shmop_open($this->key + $delete, "w", 0, 0);
                shmop_delete($del_id);
                shmop_close($del_id);

                return true;
            }
            else
            {
                    return true;
            }
            }
        }
        return false;
    }

    public function delete_expired()
    {
        return TRUE;
    }

} // End Cache Shmop Driver