: cb_(cb), dispatcher_(dispatcher) {

  ASSERT(cb_);

  evtimer_assign(

      &raw_event_, libevent.get(),

      [](evutil_socket_t, short, void* arg) -> void {

        TimerImpl* timer = static_cast<TimerImpl*>(arg);

        if (timer->object_ == nullptr) {

          timer->cb_();

          return;

        }

        ScopeTrackerScopeState scope(timer->object_, timer->dispatcher_);

        timer->object_ = nullptr;

        timer->cb_();

      },

      this);

}

void TimerImpl::disableTimer() {

  ASSERT(dispatcher_.isThreadSafe());

  event_del(&raw_event_);

}

void TimerImpl::enableTimer(const std::chrono::milliseconds d, const ScopeTrackedObject* object) {

  timeval tv;

  TimerUtils::durationToTimeval(d, tv);

  internalEnableTimer(tv, object);

}

                              const ScopeTrackedObject* object = nullptr) {

  timeval tv;

  TimerUtils::durationToTimeval(d, tv);

  internalEnableTimer(tv, object);

}

void TimerImpl::internalEnableTimer(const timeval& tv, const ScopeTrackedObject* object) {

  ASSERT(dispatcher_.isThreadSafe());

  object_ = object;

  event_add(&raw_event_, &tv);

}

bool TimerImpl::enabled() {

  ASSERT(dispatcher_.isThreadSafe());

  return 0 != evtimer_pending(&raw_event_, nullptr);

}