SessionHandler.php

<?php

/**
 * A PHP session handler to keep session data within a MySQL database
 *
 * @author 	Manuel Reinhard <manu@sprain.ch>
 * @link		https://github.com/sprain/PHP-MySQL-Session-Handler
 */

class SessionHandler{

    /**
     * a database MySQLi connection resource
     * @var resource
     */
    protected $dbConnection;


    /**
     * the name of the DB table which handles the sessions
     * @var string
     */
    protected $dbTable;

    function __construct($dbHost, $dbUser, $dbPassword, $dbDatabase) {
        // add db data
        $this->setDbDetails($dbHost, $dbUser, $dbPassword, $dbDatabase);
        $this->setDbTable('session_handler_table');
        session_set_save_handler(array($this, 'open'),
                array($this, 'close'),
                array($this, 'read'),
                array($this, 'write'),
                array($this, 'destroy'),
                array($this, 'gc'));
    }

    /**
     * Set db data if no connection is being injected
     * @param 	string	$dbHost	
     * @param	string	$dbUser
     * @param	string	$dbPassword
     * @param	string	$dbDatabase
     */	
    public function setDbDetails($dbHost, $dbUser, $dbPassword, $dbDatabase){

        //create db connection
        $this->dbConnection = new mysqli($dbHost, $dbUser, $dbPassword, $dbDatabase);

        //check connection
        if (mysqli_connect_error()) {
            throw new Exception('Connect Error (' . mysqli_connect_errno() . ') ' . mysqli_connect_error());
        }//if

    }//function



    /**
     * Inject DB connection from outside
     * @param 	object	$dbConnection	expects MySQLi object
     */
    public function setDbConnection($dbConnection){

        $this->dbConnection = $dbConnection;

    }


    /**
     * Inject DB connection from outside
     * @param 	object	$dbConnection	expects MySQLi object
     */
    public function setDbTable($dbTable){

        $this->dbTable = $dbTable;

    }


    /**
     * Open the session
     * @return bool
     */
    public function open() {

        //delete old session handlers
        $limit = time() - (3600 * 24);
        $sql = sprintf("DELETE FROM %s WHERE timestamp < %s", $this->dbTable, $limit);
        return $this->dbConnection->query($sql);

    }

    /**
     * Close the session
     * @return bool
     */
    public function close() {

        return $this->dbConnection->close();

    }

    /**
     * Read the session
     * @param int session id
     * @return string string of the sessoin
     */
    public function read($id) {

        $sql = sprintf("SELECT data FROM %s WHERE id = '%s'", $this->dbTable, $this->dbConnection->escape_string($id));
        if ($result = $this->dbConnection->query($sql)) {
            if ($result->num_rows && $result->num_rows > 0) {
                $record = $result->fetch_assoc();
                return $record['data'];
            } else {
                return false;
            }
        } else {
            return false;
        }
        return true;

    }


    /**
     * Write the session
     * @param int session id
     * @param string data of the session
     */
    public function write($id, $data) {

        //$sql = sprintf("REPLACE INTO %s VALUES('%s', '%s', '%s')",
        $sql = sprintf("INSERT INTO %s(id, data, timestamp) VALUES('%s', '%s', '%s') ON DUPLICATE KEY UPDATE data=VALUES(data), timestamp=VALUES(timestamp)",
                $this->dbTable, 
                $this->dbConnection->escape_string($id),
                $this->dbConnection->escape_string($data),
                time());
        return $this->dbConnection->query($sql);

    }

    /**
     * Destoroy the session
     * @param int session id
     * @return bool
     */
    public function destroy($id) {

        $sql = sprintf("DELETE FROM %s WHERE `id` = '%s'", $this->dbTable, $this->dbConnection->escape_string($id));
        return $this->dbConnection->query($sql);

    }



    /**
     * Garbage Collector
     * @param int life time (sec.)
     * @return bool
     * @see session.gc_divisor      100
     * @see session.gc_maxlifetime 1440
     * @see session.gc_probability    1
     * @usage execution rate 1/100
     *        (session.gc_probability/session.gc_divisor)
     */
    public function gc($max) {

        $sql = sprintf("DELETE FROM %s WHERE `timestamp` < '%s'", $this->dbTable, time() - intval($max));
        return $this->dbConnection->query($sql);

    }

}//class

?>