feature/session (#3073): Add Memcached session driver

1 files changed, 287 insertions, 0 deletions

diff --git a/system/libraries/Session/drivers/Session_memcached_driver.php b/system/libraries/Session/drivers/Session_memcached_driver.php
new file mode 100644
index 000000000..c6ad56511
--- /dev/null
+++ b/system/libraries/Session/drivers/Session_memcached_driver.php
@@ -0,0 +1,287 @@
+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst.  It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package		CodeIgniter
+ * @author		Andrey Andreev
+ * @copyright	Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
+ * @license		http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link		http://codeigniter.com
+ * @since		Version 3.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Session Memcached Driver
+ *
+ * @package		CodeIgniter
+ * @subpackage	Libraries
+ * @category	Sessions
+ * @author		Andrey Andreev
+ * @link		http://codeigniter.com/user_guide/libraries/sessions.html
+ */
+class CI_Session_memcached_driver extends CI_Session_driver implements SessionHandlerInterface {
+
+	/**
+	 * Save path
+	 *
+	 * @var	string
+	 */
+	protected $_save_path;
+
+	/**
+	 * Memcached instance
+	 *
+	 * @var	Memcached
+	 */
+	protected $_memcached;
+
+	/**
+	 * Key prefix
+	 *
+	 * @var	string
+	 */
+	protected $_key_prefix = 'ci_session:';
+
+	/**
+	 * Lock key
+	 *
+	 * @var	string
+	 */
+	protected $_lock_key;
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Class constructor
+	 *
+	 * @param	array	$params	Configuration parameters
+	 * @return	void
+	 */
+	public function __construct(&$params)
+	{
+		parent::__construct($params);
+
+		if (empty($this->_save_path))
+		{
+			log_message('error', 'Session: No Memcached save path configured.');
+		}
+
+		if ($this->_match_ip === TRUE)
+		{
+			$this->_key_prefix .= $_SERVER['REMOTE_ADDR'].':';
+		}
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function open($save_path, $name)
+	{
+		$this->_memcached = new Memcached();
+		$server_list = array();
+		foreach ($this->_memcached->getServerList() as $server)
+		{
+			$server_list[] = $server['host'].':'.$server['port'];
+		}
+
+		if ( ! preg_match_all('#,?([^,:]+)\:(\d{1,5})(?:\:(\d+))?#', $this->_save_path, $matches, PREG_SET_ORDER))
+		{
+			$this->_memcached = NULL;
+			log_message('error', 'Session: Invalid Memcached save path format: '.$this->_save_path);
+			return FALSE;
+		}
+
+		foreach ($matches as $match)
+		{
+			// If Memcached already has this server (or if the port is invalid), skip it
+			if (in_array($match[1].':'.$match[2], $server_list, TRUE))
+			{
+				log_message('debug', 'Session: Memcached server pool already has '.$match[1].':'.$match[2]);
+				continue;
+			}
+
+			if ( ! $this->_memcached->addServer($match[1], $match[2], isset($match[3]) ? $match[3] : 0))
+			{
+				log_message('error', 'Could not add '.$match[1].':'.$match[2].' to Memcached server pool.');
+			}
+			else
+			{
+				$server_list[] = $server['host'].':'.$server['port'];
+			}
+		}
+
+		if (empty($server_list))
+		{
+			log_message('error', 'Session: Memcached server pool is empty.');
+			return FALSE;
+		}
+
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function read($session_id)
+	{
+		if (isset($this->_memcached) && $this->_get_lock($session_id))
+		{
+			$session_data = (string) $this->_memcached->get($this->_key_prefix.$session_id);
+			$this->_fingerprint = md5($session_data);
+			return $session_data;
+		}
+
+		return FALSE;
+	}
+
+	public function write($session_id, $session_data)
+	{
+		if (isset($this->_memcached, $this->_lock_key))
+		{
+			$this->_memcached->replace($this->_lock_key, time(), 5);
+			if ($this->_fingerprint !== ($fingerprint = md5($session_data)))
+			{
+				if ($this->_memcached->set($this->_key_prefix.$session_id, $session_data, $this->_expiration))
+				{
+					$this->_fingerprint = $fingerprint;
+					return TRUE;
+				}
+
+				return FALSE;
+			}
+
+			return $this->_memcached->touch($this->_key_prefix.$session_id, $this->_expiration);
+		}
+
+		return FALSE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function close()
+	{
+		if (isset($this->_memcached))
+		{
+			isset($this->_lock_key) && $this->_memcached->delete($this->_lock_key);
+			if ( ! $this->_memcached->quit())
+			{
+				return FALSE;
+			}
+
+			$this->_memcached = NULL;
+			return TRUE;
+		}
+
+		return FALSE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function destroy($session_id)
+	{
+		if (isset($this->_memcached, $this->_lock_key))
+		{
+			$this->_memcached->delete($this->_key_prefix.$session_id);
+			return ($this->_cookie_destroy() && $this->close());
+		}
+
+		return $this->close();
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function gc($maxlifetime)
+	{
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	protected function _get_lock($session_id)
+	{
+		if (isset($this->_lock_key))
+		{
+			return $this->_memcached->replace($this->_lock_key, time(), 5);
+		}
+
+		$lock_key = $this->_key_prefix.$session_id.':lock';
+		if ( ! ($ts = $this->_memcached->get($lock_key)))
+		{
+			if ( ! $this->_memcached->set($lock_key, TRUE, 5))
+			{
+				log_message('error', 'Session: Error while trying to obtain lock for '.$this->_key_prefix.$session_id);
+				return FALSE;
+			}
+
+			$this->_lock_key = $lock_key;
+			$this->_lock = TRUE;
+			return TRUE;
+		}
+
+		// Another process has the lock, we'll try to wait for it to free itself ...
+		$attempt = 0;
+		while ($attempt++ < 5)
+		{
+			usleep(((time() - $ts) * 1000000) - 20000);
+			if (($ts = $this->_memcached->get($lock_key)) < time())
+			{
+				continue;
+			}
+
+			if ( ! $this->_memcached->set($lock_key, time(), 5))
+			{
+				log_message('error', 'Session: Error while trying to obtain lock for '.$this->_key_prefix.$session_id);
+				return FALSE;
+			}
+
+			$this->_lock_key = $lock_key;
+			break;
+		}
+
+		if ($attempt === 5)
+		{
+			log_message('error', 'Session: Unable to obtain lock for '.$this->_key_prefix.$session_id.' after 5 attempts, aborting.');
+			return FALSE;
+		}
+
+		$this->_lock = TRUE;
+		return TRUE;
+	}
+
+	// ------------------------------------------------------------------------
+
+	protected function _release_lock()
+	{
+		if (isset($this->_memcached, $this->_lock_key) && $this->_lock)
+		{
+			if ( ! $this->_memcached->delete($this->_lock_key) && $this->_memcached->getResultCode() !== Memcached::RES_NOTFOUND)
+			{
+				log_message('error', 'Session: Error while trying to free lock for '.$this->_key_prefix.$session_id);
+				return FALSE;
+			}
+
+			$this->_lock_key = NULL;
+			$this->_lock = FALSE;
+		}
+
+		return TRUE;
+	}
+
+}
+
+/* End of file Session_memcached_driver.php */
+/* Location: ./system/libraries/Session/drivers/Session_memcached_driver.php */
\ No newline at end of file