/** * Write session handler. * * {@see http://php.net/manual/en/function.session-set-save-handler.php} * * NOTE: Do not write to output or throw any exceptions! * Hopefully the next page is going to display nice error or it recovers... * * @param string $sid * @param string $session_data * @return bool success */ public function handler_write($sid, $session_data) { global $USER; // TODO: MDL-20625 we need to rollback all active transactions and log error if any open needed if ($this->failed) { // do not write anything back - we failed to start the session properly return false; } $userid = 0; if (!empty($USER->realuser)) { $userid = $USER->realuser; } else { if (!empty($USER->id)) { $userid = $USER->id; } } if (isset($this->record->id)) { $data = base64_encode($session_data); // There might be some binary mess :-( // Skip db update if nothing changed, // do not update the timemodified each second. $hash = sha1($data); if ($this->lasthash === $hash and $this->record->userid == $userid and time() - $this->record->timemodified < 20 and $this->record->lastip == getremoteaddr()) { // No need to update anything! return true; } $this->record->sessdata = $data; $this->record->userid = $userid; $this->record->timemodified = time(); $this->record->lastip = getremoteaddr(); try { $this->database->update_record_raw('sessions', $this->record); $this->lasthash = $hash; } catch (dml_exception $ex) { if ($this->database->get_dbfamily() === 'mysql') { try { $this->database->set_field('sessions', 'state', 9, array('id' => $this->record->id)); } catch (Exception $ignored) { } error_log('Can not write database session - please verify max_allowed_packet is at least 4M!'); } else { error_log('Can not write database session'); } return false; } catch (Exception $ex) { error_log('Can not write database session'); return false; } } else { // fresh new session try { $record = new stdClass(); $record->state = 0; $record->sid = $sid; $record->sessdata = base64_encode($session_data); // there might be some binary mess :-( $record->userid = $userid; $record->timecreated = $record->timemodified = time(); $record->firstip = $record->lastip = getremoteaddr(); $record->id = $this->database->insert_record_raw('sessions', $record); $this->record = $this->database->get_record('sessions', array('id' => $record->id)); $this->lasthash = sha1($record->sessdata); $this->database->get_session_lock($this->record->id, SESSION_ACQUIRE_LOCK_TIMEOUT); } catch (Exception $ex) { // this should not happen error_log('Can not write new database session or acquire session lock'); $this->failed = true; return false; } } return true; }
/** * Is available. * @return boolean - True if this lock type is available in this environment. */ public function is_available() { return $this->db->get_dbfamily() === 'postgres'; }