/**
* This function generates the unique index for a specific lock key.
* Once an index is assigned to a key, it never changes - so this is
* statically cached.
*
* @param string $key
* @return int
* @throws \moodle_exception
*/
protected function get_index_from_key($key)
{
if (isset(self::$lockidcache[$key])) {
return self::$lockidcache[$key];
}
$index = 0;
$record = $this->db->get_record('lock_db', array('resourcekey' => $key));
if ($record) {
$index = $record->id;
}
if (!$index) {
$record = new \stdClass();
$record->resourcekey = $key;
try {
$index = $this->db->insert_record('lock_db', $record);
} catch (\dml_exception $de) {
// Race condition - never mind - now the value is guaranteed to exist.
$record = $this->db->get_record('lock_db', array('resourcekey' => $key));
if ($record) {
$index = $record->id;
}
}
}
if (!$index) {
throw new \moodle_exception('Could not generate unique index for key');
}
self::$lockidcache[$key] = $index;
return $index;
}
/**
* 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;
}
/**
* Read session handler
*
* {@see http://php.net/manual/en/function.session-set-save-handler.php}
*
* @param string $sid
* @return string
*/
public function handler_read($sid)
{
global $CFG;
if ($this->record and $this->record->sid != $sid) {
error_log('Weird error reading database session - mismatched sid');
$this->failed = true;
return '';
}
try {
if (!($record = $this->database->get_record('sessions', array('sid' => $sid)))) {
$record = new stdClass();
$record->state = 0;
$record->sid = $sid;
$record->sessdata = null;
$record->userid = 0;
$record->timecreated = $record->timemodified = time();
$record->firstip = $record->lastip = getremoteaddr();
$record->id = $this->database->insert_record_raw('sessions', $record);
}
} catch (Exception $ex) {
// do not rethrow exceptions here, we need this to work somehow before 1.9.x upgrade and during install
error_log('Can not read or insert database sessions');
$this->failed = true;
return '';
}
try {
$this->database->get_session_lock($record->id, SESSION_ACQUIRE_LOCK_TIMEOUT);
} catch (Exception $ex) {
// This is a fatal error, better inform users.
// It should not happen very often - all pages that need long time to execute
// should close session soon after access control checks
error_log('Can not obtain session lock');
$this->failed = true;
throw $ex;
}
// verify timeout
if ($record->timemodified + $CFG->sessiontimeout < time()) {
$ignoretimeout = false;
if (!empty($record->userid)) {
// skips not logged in
if ($user = $this->database->get_record('user', array('id' => $record->userid))) {
if (!isguestuser($user)) {
$authsequence = get_enabled_auth_plugins();
// auths, in sequence
foreach ($authsequence as $authname) {
$authplugin = get_auth_plugin($authname);
if ($authplugin->ignore_timeout_hook($user, $record->sid, $record->timecreated, $record->timemodified)) {
$ignoretimeout = true;
break;
}
}
}
}
}
if ($ignoretimeout) {
//refresh session
$record->timemodified = time();
try {
$this->database->update_record('sessions', $record);
} catch (Exception $ex) {
// very unlikely error
error_log('Can not refresh database session');
$this->failed = true;
throw $ex;
}
} else {
//time out session
$record->state = 0;
$record->sessdata = null;
$record->userid = 0;
$record->timecreated = $record->timemodified = time();
$record->firstip = $record->lastip = getremoteaddr();
try {
$this->database->update_record('sessions', $record);
} catch (Exception $ex) {
// very unlikely error
error_log('Can not time out database session');
$this->failed = true;
throw $ex;
}
}
}
$data = is_null($record->sessdata) ? '' : base64_decode($record->sessdata);
unset($record->sessdata);
// conserve memory
$this->record = $record;
return $data;
}
/**
* @param stdClass $instance
* @param $name
* @param moodle_database $DB
* @return int|mixed id of the group
* @throws coding_exception
* @throws moodle_exception
*/
private function get_group(stdClass $instance, $name, moodle_database $DB)
{
$idnumber = "autoenrol|{$instance->id}|{$name}";
$group = $DB->get_record('groups', array('idnumber' => $idnumber, 'courseid' => $instance->courseid));
if ($group == null) {
$newgroupdata = new stdclass();
$newgroupdata->courseid = $instance->courseid;
$newgroupdata->name = $name;
$newgroupdata->idnumber = $idnumber;
$newgroupdata->description = get_string('auto_desc', 'enrol_autoenrol');
$group = groups_create_group($newgroupdata);
} else {
$group = $group->id;
}
return $group;
}
/**
* Destroy session handler.
*
* {@see http://php.net/manual/en/function.session-set-save-handler.php}
*
* @param string $sid
* @return bool success
*/
public function handler_destroy($sid)
{
if (!($session = $this->database->get_record('sessions', array('sid' => $sid), 'id, sid'))) {
if ($sid == session_id()) {
$this->recordid = null;
$this->lasthash = null;
}
return true;
}
if ($this->recordid and $session->id == $this->recordid) {
try {
$this->database->release_session_lock($this->recordid);
} catch (\Exception $ex) {
// Ignore problems.
}
$this->recordid = null;
$this->lasthash = null;
}
$this->database->delete_records('sessions', array('id' => $session->id));
return true;
}
