问这个接口线程安全吗？

EN

#include "signal.h"
#include "pthread.h"

#define LOCK(mutex)     pthread_mutex_lock(&mutex)
#define UNLOCK(mutex)   pthread_mutex_unlock(&mutex)

class LoopInterface {
public:
    LoopInterface(){
        LOCK(_lock_is_signal_registered);
        bool temp = _is_signal_registered;
        UNLOCK(_lock_is_signal_registered);
        if(!temp)
        {
            register_signal();
        }
    }

    bool should_stop()
    {
        LOCK(_lock_should_stop);
        bool temp = _should_stop;
        UNLOCK(_lock_should_stop);
        return _should_stop;
    }

private:

    static void register_signal()
    {
        LOCK(_lock_is_signal_registered);
        _is_signal_registered = true;
        UNLOCK(_lock_is_signal_registered);

        signal(SIGINT, &LoopInterface::signal_handler);
    }

    static void signal_handler(int sig){
        LOCK(_lock_should_stop);
        _should_stop = true;
        UNLOCK(_lock_should_stop);
    }

    static bool _should_stop;
    static bool _is_signal_registered;
    static pthread_mutex_t _lock_should_stop, _lock_is_signal_registered;
};

#include "LoopInterface.h"
bool LoopInterface::_should_stop = false;
bool LoopInterface::_is_signal_registered = false;
pthread_mutex_t LoopInterface::_lock_should_stop;
pthread_mutex_t LoopInterface::_lock_is_signal_registered;

/************Threads*************/
#include "LoopInterface.h"
class A : public LoopInterface{

};

void threadX(){
    A a;
    while(!a.should_stop()){
        //do something...
    }
}