english/libraries/joomla/session/session.php
/**
	 * Frees all session variables and destroys all data registered to a session
	 *
	 * This method resets the $_SESSION variable and destroys all of the data associated
	 * with the current session in its storage (file or DB). It forces new session to be
	 * started after this method is called. It does not unset the session cookie.
	 *
	 * @return  boolean  True on success
	 *
	 * @see     session_destroy()
	 * @see     session_unset()
	 * @since   11.1
	 */
Frees all session variables and destroys all data registered to a session
This method resets the $_SESSION variable and destroys all of the data associated
with the current session in its storage (file or DB). It forces new session to be
started after this method is called. It does not unset the session cookie.

@return  boolean  True on success


Frees all session variables and destroys all data registered to a session This method resets the $_SESSION variable and destroys all of the data associated with the current session in its storage ( file or DB ) . It forces new session to be started after this method is called . It does not unset the session cookie . @return boolean True on success
public function destroy()
	{
		if ($this->_state === 'destroyed') {
			return true;
		}
		if (isset($_COOKIE[session_name()])) {
			$config = JFactory::getConfig();
			$cookie_domain = $config->get('cookie_domain', '');
			$cookie_path = $config->get('cookie_path', '/');
			setcookie(session_name(), '', time()-42000, $cookie_path, $cookie_domain);
		}
		session_unset();
		session_destroy();
		$this->_state = 'destroyed';
		return true;
	}
public function destroy ( ) { if ( $ this -> _state === 'destroyed' ) { return true ; } if ( isset ( $ _COOKIE [ session_name ( ) ] ) ) { $ config = JFactory :: getConfig ( ) ; $ cookie_domain = $ config -> get ( 'cookie_domain' , '' ) ; $ cookie_path = $ config -> get ( 'cookie_path' , '/' ) ; setcookie ( session_name ( ) , '' , time ( ) - 42000 , $ cookie_path , $ cookie_domain ) ; } session_unset ( ) ; session_destroy ( ) ; $ this -> _state = 'destroyed' ; return true ; }
Frees all session variables and destroys all data registered to a session
 This method resets the $_SESSION variable and destroys all of the data associated
 with the current session in its storage (file or DB).
Frees all session variables and destroys all data registered to a session This method resets the $_SESSION variable and destroys all of the data associated with the current session in its storage ( file or DB ) .
// Session was already destroyed // In order to kill the session altogether, such as to log the user out, the session id // must also be unset. If a cookie is used to propagate the session id (default behavior), // then the session cookie must be deleted.