Added database session handling.

classes/Session.php

@@ -0,0 +1,249 @@
+<?php
+
+/**
+ * Session Handling for PICKLES
+ *
+ * PHP version 5
+ *
+ * Licensed under The MIT License
+ * Redistribution of these files must retain the above copyright notice.
+ *
+ * @author    Josh Sherman <josh@gravityblvd.com>
+ * @copyright Copyright 2007-2011, Gravity Boulevard, LLC
+ * @license   http://www.opensource.org/licenses/mit-license.html
+ * @package   PICKLES
+ * @link      http://p.ickl.es
+ */
+
+/**
+ * Session Class
+ *
+ * Provides session handling via database instead of the file based session
+ * handling built into PHP. Using this class requires an array to be defined
+ * in place of the boolean true/false (on/off). If simply array(), the
+ * datasource will default to the value in $config['pickles']['datasource'] and
+ * if the table will default to "sessions". The format is as follows:
+ *
+ *     $config = array(
+ *         'pickles' => array(
+ *             'session' => array(
+ *                 'datasource' => 'mysql',
+ *                 'table'      => 'sessions',
+ *             )
+ *         )
+ *     );
+ *
+ * In addition to the configuration variables, a table in your database must
+ * be created. The [MySQL] table schema is as follows:
+ *
+ *     CREATE TABLE sessions (
+ *         id varchar(32) COLLATE utf8_unicode_ci NOT NULL,
+ *         session text COLLATE utf8_unicode_ci NOT NULL,
+ *         expires_at datetime NOT NULL,
+ *         PRIMARY KEY (id)
+ *     ) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
+ *
+ * Note: The reason for not using a model class was to avoid a naming conflict
+ * between the Session model and the Session class itself. This will eventually
+ * be resolved when I abandon full 5.x support and migrate to 5.3+ (assuming
+ * that ever happens).
+ */
+class Session extends Object
+{
+	/**
+	 * Accessed At
+	 *
+	 * The UNIX timestamp of when the page was accessed.
+	 *
+	 * @access private
+	 * @var    integer
+	 */
+	private $accessed_at = null;
+
+	/**
+	 * Time to Live
+	 *
+	 * The number of seconds the session should remain active. Corresponds to
+	 * the INI variable session.gc_maxlifetime
+	 *
+	 * @access private
+	 * @var    integer
+	 */
+	private $time_to_live = null;
+
+	/**
+	 * Datasource
+	 *
+	 * Name of the datasource, defaults to whatever the default datasource
+	 * is defined to in config.php
+	 *
+	 * @access private
+	 * @var    string
+	 */
+	private $datasource = null;
+
+	/**
+	 * Table
+	 *
+	 * Name of the database table in the aforementioned datasource that holds
+	 * the session data. The expected schema is defined above.
+	 *
+	 * @access private
+	 * @var    string
+	 */
+	private $table = null;
+
+	/**
+	 * Database
+	 *
+	 * Our database object to interact with the aforementioned datasource and
+	 * table. This object is shared with other PICKLES internals.
+	 *
+	 * @access private
+	 * @var    object
+	 */
+	private $db = null;
+
+	/**
+	 * Constructor
+	 *
+	 * All of our set up logic for the session in contained here. This object
+	 * is initially instantiated from pickles.php and does nothing more than
+	 * the instantiation. All variables are driven from php.ini and/or the
+	 * site config. Once configured, the session is started
+	 */
+	public function __construct()
+	{
+		// Sets our access time and time to live
+		$this->accessed_at  = time();
+		$this->time_to_live = ini_get('session.gc_maxlifetime');
+
+		// Gets the config into scope
+		parent::__construct();
+
+		// Sets up our configuration variables
+		$config = $this->config->pickles['session'];
+
+		$this->datasource = (isset($config['datasource']) ? $config['datasource'] : $this->config->pickles['datasource']);
+		$this->table      = (isset($config['table'])      ? $config['table']      : 'sessions'                          );
+
+		// Gets a database instance
+		$this->db = Database::getInstance($this->datasource);
+
+		// Sets up the session handler
+		session_set_save_handler(
+			array($this, 'open'),
+			array($this, 'close'),
+			array($this, 'read'),
+			array($this, 'write'),
+			array($this, 'destroy'),
+			array($this, 'gc')
+		);
+
+		register_shutdown_function('session_write_close');
+		session_start();
+	}
+
+	/**
+	 * Destructor
+	 *
+	 * Runs garbage collection and closes the session. I'm not sure if the
+	 * garbage collection should stay as it could be accomplished via php.ini
+	 * variables. The session_write_close() is present to combat a chicken
+	 * and egg scenario in earlier versions of PHP 5.
+	 */
+	public function __destruct()
+	{
+		$this->gc($this->time_to_live);
+		session_write_close();
+	}
+
+	/**
+	 * Opens the Session
+	 *
+	 * Since the session is in the database, opens the database connection.
+	 * This step isn't really necessary as the Database object is smart enough
+	 * to open itself up upon execute.
+	 */
+	public function open()
+	{
+		return $this->db->open();
+	}
+
+	/**
+	 * Closes the Session
+	 *
+	 * Same as above, but in reverse.
+	 */
+	public function close()
+	{
+		return $this->db->close();
+	}
+
+	/**
+	 * Reads the Session
+	 *
+	 * Checks the database for the session ID and returns the session data.
+	 *
+	 * @param  string $id session ID
+	 * @return string serialized session data
+	 */
+	public function read($id)
+	{
+		$sql = 'SELECT session FROM `' . $this->table . '` WHERE id = ?;';
+
+		$session = $this->db->fetch($sql, array($id));
+
+		return isset($session[0]['session']) ? $session[0]['session'] : '';
+	}
+
+	/**
+	 * Writes the Session
+	 *
+	 * When there's changes to the session, writes the data to the database.
+	 *
+	 * @param  string $id session ID
+	 * @param  string $session serialized session data
+	 * @return boolean whether the query executed correctly
+	 */
+	public function write($id, $session)
+	{
+		$sql = 'REPLACE INTO `' . $this->table . '` VALUES (?, ? ,?);';
+
+		$parameters = array($id, $session, date('Y-m-d H:i:s', $this->accessed_at));
+
+		return $this->db->execute($sql, $parameters);
+	}
+
+	/**
+	 * Destroys the Session
+	 *
+	 * Deletes the session from the database.
+	 *
+	 * @param  string $id session ID
+	 * @return boolean whether the query executed correctly
+	 */
+	public function destroy($id)
+	{
+		$sql = 'DELETE FROM `' . $this->table . '` WHERE id = ?;';
+
+		return $this->db->execute($sql, array($id));
+	}
+
+	/**
+	 * Garbage Collector
+	 *
+	 * This is who you call when you got trash to be taken out.
+	 *
+	 * @param  integer $time_to_live number of seconds a session is active
+	 * @return boolean whether the query executed correctly
+	 */
+	public function gc($time_to_live)
+	{
+		$sql = 'DELETE FROM `' . $this->table . '` WHERE expires_at < ?;';
+
+		$parameters = array(date('Y-m-d H:i:s', $this->accessed_at - $time_to_live));
+
+		return $this->db->execute($sql, $parameters);
+	}
+}