Provides database mutex that can be used to prevent race conditions
between two processes that affect the same data.
/**
* Run the upgrade process
*
* @return array $result Associative array containing possible errors
*/
public function run()
{
$result = array('failure' => false, 'reason' => '');
// prevent someone from running the upgrade script in parallel (see #4643)
if (!$this->mutex->lock('upgrade')) {
$result['failure'] = true;
$result['reason'] = $this->translator->translate('upgrade:locked');
return $result;
}
// disable the system log for upgrades to avoid exceptions when the schema changes.
$this->events->unregisterHandler('log', 'systemlog', 'system_log_default_logger');
$this->events->unregisterHandler('all', 'all', 'system_log_listener');
// turn off time limit
set_time_limit(0);
if ($this->getUnprocessedUpgrades()) {
$this->processUpgrades();
}
$this->events->trigger('upgrade', 'system', null);
elgg_flush_caches();
$this->mutex->unlock('upgrade');
return $result;
}
