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2005 Aurelien 1 
<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
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/**
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 * CodeIgniter
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 *
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 * An open source application development framework for PHP 4.3.2 or newer
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 *
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 * @package		CodeIgniter
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 * @author		ExpressionEngine Dev Team
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 * @copyright	Copyright (c) 2008, EllisLab, Inc.
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 * @license		http://codeigniter.com/user_guide/license.html
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 * @link		http://codeigniter.com
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 * @since		Version 1.0
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 * @filesource
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 */
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// ------------------------------------------------------------------------
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/**
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 * Database Cache Class
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 *
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 * @category	Database
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 * @author		ExpressionEngine Dev Team
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 * @link		http://codeigniter.com/user_guide/database/
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 */
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class CI_DB_Cache {
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	var $CI;
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	var $db;	// allows passing of db object so that multiple database connections and returned db objects can be supported
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	/**
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	 * Constructor
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	 *
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	 * Grabs the CI super object instance so we can access it.
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	 *
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	 */
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	function CI_DB_Cache(&$db)
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	{
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		// Assign the main CI object to $this->CI
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		// and load the file helper since we use it a lot
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		$this->CI =& get_instance();
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		$this->db =& $db;
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		$this->CI->load->helper('file');
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	}
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	// --------------------------------------------------------------------
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	/**
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	 * Set Cache Directory Path
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	 *
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	 * @access	public
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	 * @param	string	the path to the cache directory
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	 * @return	bool
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	 */
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	function check_path($path = '')
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	{
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		if ($path == '')
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		{
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			if ($this->db->cachedir == '')
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			{
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				return $this->db->cache_off();
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			}
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			$path = $this->db->cachedir;
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		}
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		// Add a trailing slash to the path if needed
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		$path = preg_replace("/(.+?)\/*$/", "\\1/",  $path);
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		if ( ! is_dir($path) OR ! is_really_writable($path))
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		{
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			// If the path is wrong we'll turn off caching
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			return $this->db->cache_off();
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		}
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		$this->db->cachedir = $path;
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		return TRUE;
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	}
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	// --------------------------------------------------------------------
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	/**
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	 * Retrieve a cached query
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	 *
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	 * The URI being requested will become the name of the cache sub-folder.
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	 * An MD5 hash of the SQL statement will become the cache file name
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	 *
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	 * @access	public
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	 * @return	string
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	 */
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	function read($sql)
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	{
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		if ( ! $this->check_path())
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		{
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			return $this->db->cache_off();
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		}
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		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
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		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
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		$filepath = $this->db->cachedir.$segment_one.'+'.$segment_two.'/'.md5($sql);
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		if (FALSE === ($cachedata = read_file($filepath)))
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		{
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			return FALSE;
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		}
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		return unserialize($cachedata);
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	}
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	// --------------------------------------------------------------------
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	/**
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	 * Write a query to a cache file
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	 *
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	 * @access	public
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	 * @return	bool
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	 */
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	function write($sql, $object)
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	{
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		if ( ! $this->check_path())
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		{
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			return $this->db->cache_off();
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		}
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		$segment_one = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
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		$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
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		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
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		$filename = md5($sql);
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		if ( ! @is_dir($dir_path))
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		{
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			if ( ! @mkdir($dir_path, DIR_WRITE_MODE))
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			{
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				return FALSE;
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			}
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			@chmod($dir_path, DIR_WRITE_MODE);
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		}
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		if (write_file($dir_path.$filename, serialize($object)) === FALSE)
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		{
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			return FALSE;
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		}
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		@chmod($dir_path.$filename, DIR_WRITE_MODE);
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		return TRUE;
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	}
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	// --------------------------------------------------------------------
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	/**
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	 * Delete cache files within a particular directory
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	 *
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	 * @access	public
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	 * @return	bool
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	 */
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	function delete($segment_one = '', $segment_two = '')
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	{
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		if ($segment_one == '')
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		{
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			$segment_one  = ($this->CI->uri->segment(1) == FALSE) ? 'default' : $this->CI->uri->segment(1);
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		}
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		if ($segment_two == '')
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		{
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			$segment_two = ($this->CI->uri->segment(2) == FALSE) ? 'index' : $this->CI->uri->segment(2);
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		}
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		$dir_path = $this->db->cachedir.$segment_one.'+'.$segment_two.'/';
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		delete_files($dir_path, TRUE);
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	}
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	// --------------------------------------------------------------------
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	/**
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	 * Delete all existing cache files
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	 *
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	 * @access	public
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	 * @return	bool
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	 */
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	function delete_all()
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	{
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		delete_files($this->db->cachedir, TRUE);
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	}
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}
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/* End of file DB_cache.php */
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/* Location: ./system/database/DB_cache.php */