Periodic timer

ptimer.h

class lp_timer_t {

private:
    timer_t timerid;
    bool started;
    void* data;
    struct sigevent sev;
    struct sigaction sa;
    struct sigaction prev;
    struct itimerspec its;

protected:

    static void on_timer(int sig, siginfo_t *si, void *uc) {
        lp_timer_t * t = reinterpret_cast<lp_timer_t *>(si->si_value.sival_ptr);
        t->on_timer(t->data);
    }

public:
    lp_timer_t() : timerid(0), started(false), data(nullptr) {
    };

    virtual ~lp_timer_t() {
        stop();
    }

    void start(uint32_t seconds, void* ptr = nullptr) {
        if(!started && seconds) {
            data = ptr;
            sigaction(SIGRTMIN, NULL, &prev);
            sa.sa_flags = SA_SIGINFO;
            sa.sa_sigaction = on_timer;
            sigemptyset(&sa.sa_mask);
            sigaction(SIGRTMIN, &sa, NULL);
            sev.sigev_notify = SIGEV_SIGNAL;
            sev.sigev_signo = SIGRTMIN;
            sev.sigev_value.sival_ptr = this;
            timer_create(CLOCK_MONOTONIC, &sev, &timerid);
            its.it_value.tv_sec = 0;
            its.it_value.tv_nsec = 1;
            its.it_interval.tv_sec = seconds;
            its.it_interval.tv_nsec = 0;
            timer_settime(timerid, 0, &its, NULL);
            started = true;
        }
    }

    void stop() {
        if(started) {
            timer_delete(timerid);
            sigaction(SIGRTMIN, &prev, NULL);
            started = false;
        }
    }

    virtual void on_timer(void* data) = 0;
};