How Sessions in Codeigniter Work
Yes, is about the session id stored in the cookie. This is regenerated every 5 minutes. And when it's time to regenerate, first it will get current session data and than assign it to the new session id.
code from CI session library, function sess_update():
// Save the old session id so we know which record to// update in the database if we need it$old_sessid = $this->userdata['session_id'];$new_sessid = '';while (strlen($new_sessid) < 32){ $new_sessid .= mt_rand(0, mt_getrandmax());}// To make the session ID even more secure we'll combine it with the user's IP$new_sessid .= $this->CI->input->ip_address();// Turn it into a hash$new_sessid = md5(uniqid($new_sessid, TRUE));// Update the session data in the session data array$this->userdata['session_id'] = $new_sessid;$this->userdata['last_activity'] = $this->now;