71   m_stopAt = 0;

   444         //

   445         // We also want to stop the simulator at some time even if there are events 

   446         // that have been scheduled out in the future.  If we're in realtime mode, we 

   447         // actually have time passing, so we must look at the realtime clock to see if 

   448         // we're past the end time.

   449         //

   450         if (m_stopAt && m_stopAt <= m_synchronizer->GetCurrentRealtime ())

   451           {

   452             done = true;

   453           }

   540 }

   541 

   542 static void Placeholder (void) {}

   543 

   544 //

   545 // Schedule a stop for a _relative_ time in the future.  If the simulation

   546 // hasn't started yet, this will effectively be an absolute time.

   547 //

   548 void 

   549 RealtimeSimulatorImpl::Stop (Time const &time)

   550 {

   551   NS_LOG_FUNCTION (time);

   552 

   553   Time tAbsolute = Simulator::Now () + time;

   554   NS_ASSERT (tAbsolute.IsPositive ());

   555   NS_ASSERT (tAbsolute >= TimeStep (m_currentTs));

   556   m_stopAt = tAbsolute.GetTimeStep ();

   557 

   558   //

   559   // For the realtime case, we need a real event sitting out at the end of time

   560   // to keep the simulator running (sleeping) while there are no other events 

   561   // present.  If an "external" device in another thread decides to schedule an

   562   // event, the sleeping synchronizer will be awakened and the new event will

   563   // be run.

   564   //

   565   // The easiest thing to do is to call back up into the simulator to take 

   566   // advantage of all of the nice event wrappers.  This will call back down into

   567   // RealtimeSimulatorImpl::Schedule to do the work.  This path interprets the 

   568   // time as relative, so pass the relative time.

   569   //

   570   Simulator::Schedule (time, &Placeholder);