/**
* Deletes all unused entries from the log_action table. This method uses a temporary table to store used
* actions, and then deletes rows from log_action that are not in this temporary table.
*
* Table locking is required to avoid concurrency issues.
*
* @throws \Exception If table locking permission is not granted to the current MySQL user.
*/
public function deleteUnusedLogActions()
{
if (!Db::isLockPrivilegeGranted()) {
throw new \Exception("RawLogDao.deleteUnusedLogActions() requires table locking permission in order to complete without error.");
}
// get current max ID in log tables w/ idaction references.
$maxIds = $this->getMaxIdsInLogTables();
$this->createTempTableForStoringUsedActions();
// do large insert (inserting everything before maxIds) w/o locking tables...
$this->insertActionsToKeep($maxIds, $deleteOlderThanMax = true);
// ... then do small insert w/ locked tables to minimize the amount of time tables are locked.
$this->lockLogTables();
$this->insertActionsToKeep($maxIds, $deleteOlderThanMax = false);
// delete before unlocking tables so there's no chance a new log row that references an
// unused action will be inserted.
$this->deleteUnusedActions();
Db::unlockAllTables();
}
/**
* Safely delete all unused log_action rows.
*/
private function purgeUnusedLogActions()
{
$this->createTempTable();
// get current max ID in log tables w/ idaction references.
$maxIds = $this->getMaxIdsInLogTables();
// do large insert (inserting everything before maxIds) w/o locking tables...
$this->insertActionsToKeep($maxIds, $deleteOlderThanMax = true);
// ... then do small insert w/ locked tables to minimize the amount of time tables are locked.
$this->lockLogTables();
$this->insertActionsToKeep($maxIds, $deleteOlderThanMax = false);
// delete before unlocking tables so there's no chance a new log row that references an
// unused action will be inserted.
$this->deleteUnusedActions();
Db::unlockAllTables();
}
/**
* Checks whether the database user is allowed to lock tables.
*
* @return bool
*/
public static function isLockPrivilegeGranted()
{
if (is_null(self::$lockPrivilegeGranted)) {
try {
Db::lockTables(Common::prefixTable('log_visit'));
Db::unlockAllTables();
self::$lockPrivilegeGranted = true;
} catch (Exception $ex) {
self::$lockPrivilegeGranted = false;
}
}
return self::$lockPrivilegeGranted;
}
