Initial commit of Caching Driver.
diff --git a/system/libraries/Cache/Cache.php b/system/libraries/Cache/Cache.php
new file mode 100644
index 0000000..ea31942
--- /dev/null
+++ b/system/libraries/Cache/Cache.php
@@ -0,0 +1,216 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 4.3.2 or newer
+ *
+ * @package CodeIgniter
+ * @author ExpressionEngine Dev Team
+ * @copyright Copyright (c) 2006 - 2010 EllisLab, Inc.
+ * @license http://codeigniter.com/user_guide/license.html
+ * @link http://codeigniter.com
+ * @since Version 2.0
+ * @filesource
+ */
+
+// ------------------------------------------------------------------------
+
+/**
+ * CodeIgniter Caching Class
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Core
+ * @author ExpressionEngine Dev Team
+ * @link
+ */
+class Cache extends CI_Driver_Library {
+
+ protected $valid_drivers = array(
+ 'cache_apc', 'cache_file', 'cache_memcached', 'cache_dummy'
+ );
+
+ protected $_cache_path = NULL; // Path of cache files (if file-based cache)
+ protected $_adapter = 'dummy';
+ protected $_backup_driver;
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Constructor
+ *
+ * @param array
+ */
+ public function __construct($config = array())
+ {
+ if ( ! empty($config))
+ {
+ $this->_initialize($config);
+ }
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get
+ *
+ * Look for a value in the cache. If it exists, return the data
+ * if not, return FALSE
+ *
+ * @param string
+ * @return mixed value that is stored/FALSE on failure
+ */
+ public function get($id)
+ {
+ return $this->{$this->_adapter}->get($id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Save
+ *
+ * @param string Unique Key
+ * @param mixed Data to store
+ * @param int Length of time (in seconds) to cache the data
+ *
+ * @return boolean true on success/false on failure
+ */
+ public function save($id, $data, $ttl = 60)
+ {
+ return $this->{$this->_adapter}->save($id, $data, $ttl);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Delete from Cache
+ *
+ * @param mixed unique identifier of the item in the cache
+ * @return boolean true on success/false on failure
+ */
+ public function delete($id)
+ {
+ return $this->{$this->_adapter}->delete($id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Clean the cache
+ *
+ * @return boolean false on failure/true on success
+ */
+ public function clean()
+ {
+ return $this->{$this->_adapter}->clean();
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Info
+ *
+ * @param string user/filehits
+ * @return mixed array on success, false on failure
+ */
+ public function cache_info($type = 'user')
+ {
+ return $this->{$this->_adapter}->cache_info($type);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get Cache Metadata
+ *
+ * @param mixed key to get cache metadata on
+ * @return mixed return value from child method
+ */
+ public function get_metadata($id)
+ {
+ return $this->{$this->_adapter}->get_metadata($id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Initialize
+ *
+ * Initialize class properties based on the configuration array.
+ *
+ * @param array
+ * @return void
+ */
+ private function _initialize($config)
+ {
+ $default_config = array(
+ 'adapter',
+ 'memcached'
+ );
+
+ foreach ($default_config as $key)
+ {
+ if (isset($config[$key]))
+ {
+ $param = '_'.$key;
+
+ $this->{$param} = $config[$key];
+ }
+ }
+
+ if (isset($config['backup']))
+ {
+ if (in_array('cache_'.$config['backup'], $this->valid_drivers))
+ {
+ $this->_backup_driver = $config['backup'];
+ }
+ }
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Is the requested driver supported in this environment?
+ *
+ * @param string The driver to test.
+ * @return array
+ */
+ public function is_supported($driver)
+ {
+ static $support = array();
+
+ if ( ! isset($support[$driver]))
+ {
+ $support[$driver] = $this->{$driver}->is_supported();
+ }
+
+ return $support[$driver];
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * __get()
+ *
+ * @param child
+ * @return object
+ */
+ public function __get($child)
+ {
+ $obj = parent::__get($child);
+
+ if ( ! $this->is_supported($child))
+ {
+ $this->_adapter = $this->_backup_driver;
+ }
+
+ return $obj;
+ }
+
+ // ------------------------------------------------------------------------
+}
+// End Class
+
+/* End of file Cache.php */
+/* Location: ./system/libraries/Cache/Cache.php */
\ No newline at end of file
diff --git a/system/libraries/Cache/drivers/Cache_apc.php b/system/libraries/Cache/drivers/Cache_apc.php
new file mode 100644
index 0000000..9c716a9
--- /dev/null
+++ b/system/libraries/Cache/drivers/Cache_apc.php
@@ -0,0 +1,151 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.1.6 or newer
+ *
+ * @package CodeIgniter
+ * @author ExpressionEngine Dev Team
+ * @copyright Copyright (c) 2006 - 2010 EllisLab, Inc.
+ * @license http://codeigniter.com/user_guide/license.html
+ * @link http://codeigniter.com
+ * @since Version 2.0
+ * @filesource
+ */
+
+// ------------------------------------------------------------------------
+
+/**
+ * CodeIgniter APC Caching Class
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Core
+ * @author ExpressionEngine Dev Team
+ * @link
+ */
+
+class Cache_apc extends CI_Driver {
+
+ /**
+ * Get
+ *
+ * Look for a value in the cache. If it exists, return the data
+ * if not, return FALSE
+ *
+ * @param string
+ * @return mixed value that is stored/FALSE on failure
+ */
+ public function get($id)
+ {
+ $data = apc_fetch($id);
+
+ return (is_array($data)) ? $data[0] : FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Save
+ *
+ * @param string Unique Key
+ * @param mixed Data to store
+ * @param int Length of time (in seconds) to cache the data
+ *
+ * @return boolean true on success/false on failure
+ */
+ public function save($id, $data, $ttl = 60)
+ {
+ return apc_store($id, array($data, time(), $ttl), $ttl);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Delete from Cache
+ *
+ * @param mixed unique identifier of the item in the cache
+ * @param boolean true on success/false on failure
+ */
+ public function delete($id)
+ {
+ return apc_delete($id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Clean the cache
+ *
+ * @return boolean false on failure/true on success
+ */
+ public function clean()
+ {
+ return apc_clear_cache('user');
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Info
+ *
+ * @param string user/filehits
+ * @return mixed array on success, false on failure
+ */
+ public function cache_info($type = NULL)
+ {
+ return apc_cache_info($type);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get Cache Metadata
+ *
+ * @param mixed key to get cache metadata on
+ * @return mixed array on success/false on failure
+ */
+ public function get_metadata($id)
+ {
+ $stored = apc_fetch($id);
+
+ if (count($stored) !== 3)
+ {
+ return FALSE;
+ }
+
+ list($value, $time, $ttl) = $stored;
+
+ return array(
+ 'expire' => $time + $ttl,
+ 'mtime' => $time,
+ 'data' => $data
+ );
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * is_supported()
+ *
+ * Check to see if APC is available on this system, bail if it isn't.
+ */
+ public function is_supported()
+ {
+ if ( ! extension_loaded('apc') OR ! function_exists('apc_store'))
+ {
+ log_message('error', 'The APC PHP extension must be loaded to use APC Cache.');
+ return FALSE;
+ }
+
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+
+}
+// End Class
+
+/* End of file Cache_apc.php */
+/* Location: ./system/libraries/Cache/drivers/Cache_apc.php */
\ No newline at end of file
diff --git a/system/libraries/Cache/drivers/Cache_dummy.php b/system/libraries/Cache/drivers/Cache_dummy.php
new file mode 100644
index 0000000..13c1f5c
--- /dev/null
+++ b/system/libraries/Cache/drivers/Cache_dummy.php
@@ -0,0 +1,129 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 4.3.2 or newer
+ *
+ * @package CodeIgniter
+ * @author ExpressionEngine Dev Team
+ * @copyright Copyright (c) 2006 - 2010 EllisLab, Inc.
+ * @license http://codeigniter.com/user_guide/license.html
+ * @link http://codeigniter.com
+ * @since Version 2.0
+ * @filesource
+ */
+
+// ------------------------------------------------------------------------
+
+/**
+ * CodeIgniter Dummy Caching Class
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Core
+ * @author ExpressionEngine Dev Team
+ * @link
+ */
+
+class Cache_dummy extends CI_Driver {
+
+ /**
+ * Get
+ *
+ * Since this is the dummy class, it's always going to return FALSE.
+ *
+ * @param string
+ * @return Boolean FALSE
+ */
+ public function get($id)
+ {
+ return FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Save
+ *
+ * @param string Unique Key
+ * @param mixed Data to store
+ * @param int Length of time (in seconds) to cache the data
+ *
+ * @return boolean TRUE, Simulating success
+ */
+ public function save($id, $data, $ttl = 60)
+ {
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Delete from Cache
+ *
+ * @param mixed unique identifier of the item in the cache
+ * @param boolean TRUE, simulating success
+ */
+ public function delete($id)
+ {
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Clean the cache
+ *
+ * @return boolean TRUE, simulating success
+ */
+ public function clean()
+ {
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Info
+ *
+ * @param string user/filehits
+ * @return boolean FALSE
+ */
+ public function cache_info($type = NULL)
+ {
+ return FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get Cache Metadata
+ *
+ * @param mixed key to get cache metadata on
+ * @return boolean FALSE
+ */
+ public function get_metadata($id)
+ {
+ return FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Is this caching driver supported on the system?
+ * Of course this one is.
+ *
+ * @return TRUE;
+ */
+ public function is_supported()
+ {
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+}
+// End Class
+
+/* End of file Cache_apc.php */
+/* Location: ./system/libraries/Cache/drivers/Cache_apc.php */
\ No newline at end of file
diff --git a/system/libraries/Cache/drivers/Cache_file.php b/system/libraries/Cache/drivers/Cache_file.php
new file mode 100644
index 0000000..bedbfaf
--- /dev/null
+++ b/system/libraries/Cache/drivers/Cache_file.php
@@ -0,0 +1,196 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 4.3.2 or newer
+ *
+ * @package CodeIgniter
+ * @author ExpressionEngine Dev Team
+ * @copyright Copyright (c) 2006 - 2010 EllisLab, Inc.
+ * @license http://codeigniter.com/user_guide/license.html
+ * @link http://codeigniter.com
+ * @since Version 2.0
+ * @filesource
+ */
+
+// ------------------------------------------------------------------------
+
+/**
+ * CodeIgniter Memcached Caching Class
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Core
+ * @author ExpressionEngine Dev Team
+ * @link
+ */
+
+class Cache_file extends CI_Driver {
+
+ protected $_cache_path;
+
+ /**
+ * Constructor
+ */
+ public function __construct()
+ {
+ $CI =& get_instance();
+ $CI->load->helper('file');
+
+ $path = $CI->config->item('cache_path');
+
+ $this->_cache_path = ($path == '') ? BASEPATH.'cache/' : $path;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Fetch from cache
+ *
+ * @param mixed unique key id
+ * @return mixed data on success/false on failure
+ */
+ public function get($id)
+ {
+ if ( ! file_exists($this->_cache_path.$id))
+ {
+ return FALSE;
+ }
+
+ $data = read_file($this->_cache_path.$id);
+ $data = unserialize($data);
+
+ if (time() > $data['time'] + $data['ttl'])
+ {
+ unlink($this->_cache_path.$id);
+ return FALSE;
+ }
+
+ return $data['data'];
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Save into cache
+ *
+ * @param string unique key
+ * @param mixed data to store
+ * @param int length of time (in seconds) the cache is valid
+ * - Default is 60 seconds
+ * @return boolean true on success/false on failure
+ */
+ public function save($id, $data, $ttl = 60)
+ {
+ $contents = array(
+ 'time' => time(),
+ 'ttl' => $ttl,
+ 'data' => $data
+ );
+
+ if (write_file($this->_cache_path.$id, serialize($contents)))
+ {
+ @chmod($this->_cache_path.$id, 0777);
+ return TRUE;
+ }
+
+ return FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Delete from Cache
+ *
+ * @param mixed unique identifier of item in cache
+ * @return boolean true on success/false on failure
+ */
+ public function delete($id)
+ {
+ return unlink($this->_cache_path.$id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Clean the Cache
+ *
+ * @return boolean false on failure/true on success
+ */
+ public function clean()
+ {
+ return delete_files($this->_cache_path);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Info
+ *
+ * Not supported by file-based caching
+ *
+ * @param string user/filehits
+ * @return mixed FALSE
+ */
+ public function cache_info($type = NULL)
+ {
+ return get_dir_file_info($this->_cache_path);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get Cache Metadata
+ *
+ * @param mixed key to get cache metadata on
+ * @return mixed FALSE on failure, array on success.
+ */
+ public function get_metadata($id)
+ {
+ if ( ! file_exists($this->_cache_path.$id))
+ {
+ return FALSE;
+ }
+
+ $data = read_file($this->_cache_path.$id);
+ $data = unserialize($data);
+
+ if (is_array($data))
+ {
+ $data = $data['data'];
+ $mtime = filemtime($this->_cache_path.$id);
+
+ if ( ! isset($data['ttl']))
+ {
+ return FALSE;
+ }
+
+ return array(
+ 'expire' => $mtime + $data['ttl'],
+ 'mtime' => $mtime
+ );
+ }
+
+ return FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Is supported
+ *
+ * In the file driver, check to see that the cache directory is indeed writable
+ *
+ * @return boolean
+ */
+ public function is_supported()
+ {
+ return is_really_writable($this->_cache_path);
+ }
+
+ // ------------------------------------------------------------------------
+}
+// End Class
+
+/* End of file Cache_file.php */
+/* Location: ./system/libraries/Cache/drivers/Cache_file.php */
\ No newline at end of file
diff --git a/system/libraries/Cache/drivers/Cache_memcached.php b/system/libraries/Cache/drivers/Cache_memcached.php
new file mode 100644
index 0000000..adc7fbf
--- /dev/null
+++ b/system/libraries/Cache/drivers/Cache_memcached.php
@@ -0,0 +1,209 @@
+<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 4.3.2 or newer
+ *
+ * @package CodeIgniter
+ * @author ExpressionEngine Dev Team
+ * @copyright Copyright (c) 2006 - 2010 EllisLab, Inc.
+ * @license http://codeigniter.com/user_guide/license.html
+ * @link http://codeigniter.com
+ * @since Version 2.0
+ * @filesource
+ */
+
+// ------------------------------------------------------------------------
+
+/**
+ * CodeIgniter Memcached Caching Class
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Core
+ * @author ExpressionEngine Dev Team
+ * @link
+ */
+
+class Cache_memcached extends CI_Driver {
+
+ private $_memcached; // Holds the memcached object
+
+ protected $_memcache_conf = array(
+ 'default' => array(
+ 'default_host' => '127.0.0.1',
+ 'default_port' => 11211,
+ 'default_weight' => 1
+ )
+ );
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Fetch from cache
+ *
+ * @param mixed unique key id
+ * @return mixed data on success/false on failure
+ */
+ public function get($id)
+ {
+ $data = $this->_memcached->get($id);
+
+ return (is_array($data)) ? $data[0] : FALSE;
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Save
+ *
+ * @param string unique identifier
+ * @param mixed data being cached
+ * @param int time to live
+ * @return boolean true on success, false on failure
+ */
+ public function save($id, $data, $ttl = 60)
+ {
+ return $this->_memcached->add($id, array($data, time(), $ttl), $ttl);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Delete from Cache
+ *
+ * @param mixed key to be deleted.
+ * @return boolean true on success, false on failure
+ */
+ public function delete($id)
+ {
+ return $this->_memcached->delete($id);
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Clean the Cache
+ *
+ * @return boolean false on failure/true on success
+ */
+ public function clean()
+ {
+ return $this->_memcached->flush();
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Cache Info
+ *
+ * @param null type not supported in memcached
+ * @return mixed array on success, false on failure
+ */
+ public function cache_info($type = NULL)
+ {
+ return $this->_memcached->getStats();
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Get Cache Metadata
+ *
+ * @param mixed key to get cache metadata on
+ * @return mixed FALSE on failure, array on success.
+ */
+ public function get_metadata($id)
+ {
+ $stored = $this->_memcached->get($id);
+
+ if (count($stored) !== 3)
+ {
+ return FALSE;
+ }
+
+ list($value, $time, $ttl) = $stored;
+
+ return array(
+ 'expire' => $time + $ttl,
+ 'mtime' => $time,
+ 'data' => $data
+ );
+ }
+
+ // ------------------------------------------------------------------------
+
+ /**
+ * Setup memcached.
+ */
+ private function _setup_memcached()
+ {
+ // Try to load memcached server info from the config file.
+ $CI =& get_instance();
+ if ($CI->config->load('memcached', TRUE, TRUE))
+ {
+ if (is_array($CI->config->config['memcached']))
+ {
+ $this->_memcache_conf = NULL;
+
+ foreach ($CI->config->config['memcached'] as $name => $conf)
+ {
+ $this->_memcache_conf[$name] = $conf;
+ }
+ }
+ }
+
+ $this->_memcached = new Memcached();
+
+ foreach ($this->_memcache_conf as $name => $cache_server)
+ {
+ if ( ! array_key_exists('hostname', $cache_server))
+ {
+ $cache_server['hostname'] = $this->_default_options['default_host'];
+ }
+
+ if ( ! array_key_exists('port', $cache_server))
+ {
+ $cache_server['port'] = $this->_default_options['default_port'];
+ }
+
+ if ( ! array_key_exists('weight', $cache_server))
+ {
+ $cache_server['weight'] = $this->_default_options['default_weight'];
+ }
+
+ $this->_memcached->addServer(
+ $cache_server['hostname'], $cache_server['port'], $cache_server['weight']
+ );
+ }
+ }
+
+ // ------------------------------------------------------------------------
+
+
+ /**
+ * Is supported
+ *
+ * Returns FALSE if memcached is not supported on the system.
+ * If it is, we setup the memcached object & return TRUE
+ */
+ public function is_supported()
+ {
+ if ( ! extension_loaded('memcached'))
+ {
+ log_message('error', 'The Memcached Extension must be loaded to use Memcached Cache.');
+
+ return FALSE;
+ }
+
+ $this->_setup_memcached();
+ return TRUE;
+ }
+
+ // ------------------------------------------------------------------------
+
+}
+// End Class
+
+/* End of file Cache_memcached.php */
+/* Location: ./system/libraries/Cache/drivers/Cache_memcached.php */
\ No newline at end of file
diff --git a/user_guide/libraries/caching.html b/user_guide/libraries/caching.html
new file mode 100644
index 0000000..e4651dc
--- /dev/null
+++ b/user_guide/libraries/caching.html
@@ -0,0 +1,193 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<head>
+
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+<title>Caching Driver : CodeIgniter User Guide</title>
+
+<style type='text/css' media='all'>@import url('../userguide.css');</style>
+<link rel='stylesheet' type='text/css' media='all' href='../userguide.css' />
+
+<script type="text/javascript" src="../nav/nav.js"></script>
+<script type="text/javascript" src="../nav/prototype.lite.js"></script>
+<script type="text/javascript" src="../nav/moo.fx.js"></script>
+<script type="text/javascript" src="../nav/user_guide_menu.js"></script>
+
+<meta http-equiv='expires' content='-1' />
+<meta http-equiv= 'pragma' content='no-cache' />
+<meta name='robots' content='all' />
+<meta name='author' content='ExpressionEngine Dev Team' />
+<meta name='description' content='CodeIgniter User Guide' />
+
+</head>
+<body>
+
+<!-- START NAVIGATION -->
+<div id="nav"><div id="nav_inner"><script type="text/javascript">create_menu('../');</script></div></div>
+<div id="nav2"><a name="top"></a><a href="javascript:void(0);" onclick="myHeight.toggle();"><img src="../images/nav_toggle_darker.jpg" width="154" height="43" border="0" title="Toggle Table of Contents" alt="Toggle Table of Contents" /></a></div>
+<div id="masthead">
+<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
+<tr>
+<td><h1>CodeIgniter User Guide Version 2.0.0</h1></td>
+<td id="breadcrumb_right"><a href="../toc.html">Table of Contents Page</a></td>
+</tr>
+</table>
+</div>
+<!-- END NAVIGATION -->
+
+
+<!-- START BREADCRUMB -->
+<table cellpadding="0" cellspacing="0" border="0" style="width:100%">
+<tr>
+<td id="breadcrumb">
+<a href="http://codeigniter.com/">CodeIgniter Home</a> ›
+<a href="../index.html">User Guide Home</a> ›
+<a href="../general/drivers.html">Drivers</a> ›
+Caching Driver
+</td>
+<td id="searchbox"><form method="get" action="http://www.google.com/search"><input type="hidden" name="as_sitesearch" id="as_sitesearch" value="codeigniter.com/user_guide/" />Search User Guide <input type="text" class="input" style="width:200px;" name="q" id="q" size="31" maxlength="255" value="" /> <input type="submit" class="submit" name="sa" value="Go" /></form></td>
+</tr>
+</table>
+<!-- END BREADCRUMB -->
+
+<br clear="all" />
+
+
+<!-- START CONTENT -->
+<div id="content">
+
+<h1>Caching Driver</h1>
+
+<p>CodeIgniter features wrappers around some of the most popular forms of fast and dynamic caching. All but file-based caching require specific server requirements, and a Fatal Exception will be thrown if server requirements are not met.</p>
+
+<h2>Table of Contents</h2>
+<ul>
+ <li><a href="#example_usage" title="Example Usage">Example Usage</a></li>
+ <li><a href="#function_reference" title="Function Reference">Function Reference</a></li>
+</ul>
+
+<h3>Available Drivers</h3>
+<ul>
+ <li><a href="#apc" title="APC Cache">Alternative PHP Cache (APC) Caching</a></li>
+ <li><a href="#file" title="File Caching">File-based Caching</a></li>
+ <li><a href="#memcached" title="Memcached">Memcached Caching</a></li>
+ <li><a href="#dummy" title="Dummy Caching">Dummy Cache</a></li>
+</ul>
+
+<h2 id="example_usage">Example Usage</h2>
+
+<p>The following example will load the cache driver, specify <a href="#apc" title="APC">APC</a> as the driver to use, and fall back to file-based caching if APC is not available in the hosting environment.</p>
+
+<code>
+$this->load->driver('cache', array('adapter' => 'apc', 'backup' => 'file'));<br />
+<br />
+if ( ! $foo = $this->cache->get('foo'))<br />
+{<br />
+ echo 'Saving to the cache!<br />';<br />
+ $foo = 'foobarbaz!';<br />
+<br />
+ // Save into the cache for 5 minutes<br />
+ $this->cache->save('foo', $foo, 300);<br />
+}<br />
+<br />
+echo $foo;
+</code>
+
+<h1 id="function_reference">Function Reference</h1>
+
+<h2>is_supported(<var>driver</var>['string'])</h2>
+
+<p>This function is automatically called when accessing drivers via <samp>$this->cache->get()</samp>. However, if the individual drivers are used, make sure to call this function to ensure the driver is supported in the hosting environment.</p>
+
+<code>
+if ($this->cache->apc->is_supported())<br />
+{<br />
+ if ($data = $this->cache->apc->get('my_cache'))<br />
+ {<br />
+ // do things.<br />
+ }<br />
+}
+</code>
+
+<h2>get(<var>id</var>['string'])</h2>
+
+<p>This function will attempt to fetch an item from the cache store. If the item does not exist, the function will return <samp>FALSE</samp>.</p>
+<code>$foo = $this->cache->get('my_cached_item');</code>
+
+<h2>save(<var>id</var>['string'], <var>data</var>['mixed'], <var>ttl</var>['int'])</h2>
+
+<p>This function will save an item to the cache store. If saving fails, the function will return <samp>FALSE</samp>.</p>
+<p>The optional third parameter (Time To Live) defaults to 60 seconds.</p>
+<code>$this->cache->save('cache_item_id', 'data_to_cache');</code>
+
+<h2>delete(<var>id</var>['string'])</h2>
+
+<p>This function will delete a specific item from the cache store. If item deletion fails, the function will return <samp>FALSE</samp>.</p>
+<code>$this->cache->delete('cache_item_id');</code>
+
+<h2>clean()</h2>
+
+<p>This function will 'clean' the entire cache. If the deletion of the cache files fails, the function will return <samp>FALSE</samp>.</p>
+
+<code>$this->cache->clean();</code>
+
+<h2>cache_info()</h2>
+
+<p>This function will return information on the entire cache.</p>
+
+<code>var_dump($this->cache->cache_info());</code>
+
+<h2>get_metadata(<var>id</var>['string'])</h2>
+
+<p>This function will return detailed information on a specific item in the cache.</p>
+
+<code>var_dump($this->cache->get_metadata('my_cached_item'));</code>
+
+<h1>Drivers</h1>
+
+<h2 id="apc">Alternative PHP Cache (APC) Caching</h2>
+
+<p>All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:</p>
+<code>$this->load->driver('cache');<br />
+ $this->cache->apc->save('foo', 'bar', 10);</code>
+<p>For more information on APC, please see <a href="http://php.net/apc">http://php.net/apc</a></p>
+
+<h2 id="file">File-based Caching</h2>
+
+<p>Unlike caching from the Output Class, the driver file-based caching allows for pieces of view files to be cached. Use this with care, and make sure to benchmark your application, as a point can come where disk I/O will negate positive gains by caching.</p>
+
+<p>All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:</p>
+<code>$this->load->driver('cache');<br />
+ $this->cache->file->save('foo', 'bar', 10);</code>
+
+<h2 id="memcached">Memcached Caching</h2>
+
+<p>Multiple Memcached servers can be specified in the memcached.php configuration file, located in the <samp>application/config/</samp> directory.
+
+<p>All of the functions listed above can be accessed without passing a specific adapter to the driver loader as follows:</p>
+<code>$this->load->driver('cache');<br />
+ $this->cache->memcached->save('foo', 'bar', 10);</code>
+
+<p>For more information on Memcached, please see <a href="http://php.net/memcached">http://php.net/memcached</a></p>
+
+<h2 id="dummy">Dummy Cache</h2>
+
+<p>This is a caching backend that will always 'miss.' It stores no data, but lets you keep your caching code in place in environments that don't support your chosen cache.</p>
+
+</div>
+<!-- END CONTENT -->
+
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