Call once to initialize MariaDB.

analytics/operators/persystsql/MariaDB.cpp

@@ -63,6 +63,7 @@ public:
 
 MariaDB * MariaDB::instance = nullptr;
 std::mutex MariaDB::mut;
+std::once_flag MariaDB::init_once;
 
 void MariaDB::print_error(){
     	LOG(error) << "Error(" << mysql_errno(_mysql) << ") [" << mysql_sqlstate(_mysql) << "] \""<< mysql_error(_mysql) << "\"" ;
@@ -75,14 +76,13 @@ void MariaDB::print_error(){
 MariaDB::MariaDB(): _mysql(NULL), _rotation(EVERY_MONTH), _every_x_days(0), _end_aggregate_timestamp(0), _initialized(false) {
 }
 
-MariaDB * MariaDB::getInstance(){
-		// no lock here
-		if (instance) return instance;
-
-		std::lock_guard<std::mutex>  lock(mut);
-		if (instance) return instance;
+void MariaDB::initialize(){
+	instance = new MariaDB();
+}
 
-		return instance = new MariaDB();
+MariaDB * MariaDB::getInstance(){
+	std::call_once(init_once, &MariaDB::initialize);
+	return instance;
 }
 
 bool MariaDB::initializeConnection(const std::string & host, const std::string & user,

analytics/operators/persystsql/MariaDB.h

@@ -62,6 +62,7 @@ protected:
 
 	MariaDB();
 	virtual ~MariaDB();
+	static void initialize();
 
 	MYSQL *_mysql;
 	Rotation_t _rotation;
@@ -72,6 +73,7 @@ protected:
 
 	static MariaDB * instance;
 	static std::mutex mut;
+	static std::once_flag init_once;
 	bool _initialized;
 	std::map<std::string, Job_info_t> _jobCache;
 	const std::size_t JOB_CACHE_MAX_SIZE = 10000;