database/DB_cache.php

   1 <?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
   2 /**
   3  * CodeIgniter
   4  *
   5  * An open source application development framework for PHP 4.3.2 or newer
   6  *
   7  * @package             CodeIgniter
   8  * @author              ExpressionEngine Dev Team
   9  * @copyright   Copyright (c) 2008, EllisLab, Inc.
  10  * @license             http://codeigniter.com/user_guide/license.html
  11  * @link                http://codeigniter.com
  12  * @since               Version 1.0
  13  * @filesource
  14  */
  15
  16 // ------------------------------------------------------------------------
  17
  18 /**
  19  * Database Cache Class
  20  *
  21  * @category    Database
  22  * @author              ExpressionEngine Dev Team
  23  * @link                http://codeigniter.com/user_guide/database/
  24  */
  25 class CI_DB_Cache {
  26
  27         var $CI;
  28         var $db;        // allows passing of db object so that multiple database connections and returned db objects can be supported
  29
  30         /**
  31          * Constructor
  32          *
  33          * Grabs the CI super object instance so we can access it.
  34          *
  35          */
  36         function CI_DB_Cache(&$db)
  37         {
  38                 // Assign the main CI object to $this->CI
  39                 // and load the file helper since we use it a lot
  40                 $this->CI =& get_instance();
  41                 $this->db =& $db;
  42                 $this->CI->load->helper('file');
  43         }
  44
  45         // --------------------------------------------------------------------
  46
  47         /**
  48          * Set Cache Directory Path
  49          *
  50          * @access      public
  51          * @param       string  the path to the cache directory
  52          * @return      bool
  53          */
  54         function check_path($path = '')
  55         {
  56                 if ($path == '')
  57                 {
  58                         if ($this->db->cachedir == '')
  59                         {
  60                                 return $this->db->cache_off();
  61                         }
  62
  63                         $path = $this->db->cachedir;
  64                 }
  65
  66                 // Add a trailing slash to the path if needed
  67                 $path = preg_replace("/(.+?)\/*$/", "\\1/",  $path);
  68
  69                 if ( ! is_dir($path) OR ! is_really_writable($path))
  70                 {
  71                         // If the path is wrong we'll turn off caching
  72                         return $this->db->cache_off();
  73                 }
  74
  75                 $this->db->cachedir = $path;
  76                 return TRUE;
  77         }
  78
  79         // --------------------------------------------------------------------
  80
  81         /**
  82          * Retrieve a cached query
  83          *
  84          * The URI being requested will become the name of the cache sub-folder.
  85          * An MD5 hash of the SQL statement will become the cache file name
  86          *
  87          * @access      public
  88          * @return      string
  89          */
  90         function read($sql)
  91         {
  92                 if ( ! $this->check_path())
  93                 {
  94                         return $this->db->cache_off();
  95                 }
  96
  97                 $segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
  98
  99                 $segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
 100
 101                 $filepath = $this->db->cachedir.$segment_one.'+'.$segment_two.'/'.md5($sql);
 102
 103                 if (FALSE === ($cachedata = read_file($filepath)))
 104                 {
 105                         return FALSE;
 106                 }
 107
 108                 return unserialize($cachedata);
 109         }
 110
 111         // --------------------------------------------------------------------
 112
 113         /**
 114          * Write a query to a cache file
 115          *
 116          * @access      public
 117          * @return      bool
 118          */
 119         function write($sql, $object)
 120         {
 121                 if ( ! $this->check_path())
 122                 {
 123                         return $this->db->cache_off();
 124                 }
 125
 126                 $segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
 127
 128                 $segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
 129
 130                 $dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
 131
 132                 $filename = md5($sql);
 133
 134                 if ( ! @is_dir($dir_path))
 135                 {
 136                         if ( ! @mkdir($dir_path, DIR_WRITE_MODE))
 137                         {
 138                                 return FALSE;
 139                         }
 140
 141                         @chmod($dir_path, DIR_WRITE_MODE);
 142                 }
 143
 144                 if (write_file($dir_path.$filename, serialize($object)) === FALSE)
 145                 {
 146                         return FALSE;
 147                 }
 148
 149                 @chmod($dir_path.$filename, DIR_WRITE_MODE);
 150                 return TRUE;
 151         }
 152
 153         // --------------------------------------------------------------------
 154
 155         /**
 156          * Delete cache files within a particular directory
 157          *
 158          * @access      public
 159          * @return      bool
 160          */
 161         function delete($segment_one = '', $segment_two = '')
 162         {
 163                 if ($segment_one == '')
 164                 {
 165                         $segment_one  = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
 166                 }
 167
 168                 if ($segment_two == '')
 169                 {
 170                         $segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
 171                 }
 172
 173                 $dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
 174
 175                 delete_files($dir_path, TRUE);
 176         }
 177
 178         // --------------------------------------------------------------------
 179
 180         /**
 181          * Delete all existing cache files
 182          *
 183          * @access      public
 184          * @return      bool
 185          */
 186         function delete_all()
 187         {
 188                 delete_files($this->db->cachedir, TRUE);
 189         }
 190
 191 }
 192
 193
 194 /* End of file DB_cache.php */
 195 /* Location: ./system/database/DB_cache.php */