/**
* 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;
}
