BankEv.java

package tutorial;
 
import umontreal.ssj.simevents.*;
import umontreal.ssj.rng.*;
import umontreal.ssj.randvar.*;
import umontreal.ssj.stat.*;
 
public class BankEv {
   static final double minute = 1.0 / 60.0;
   int nbTellers; // Number of tellers.
   int nbBusy; // Number of tellers busy.
   int nbWait; // Queue length.
   int nbServed; // Number of customers served so far
   double meanDelay; // Mean time between arrivals.
   Event nextArriv = new Arrival(); // The next arrival.
   RandomStream streamArr = new MRG32k3a(); // Customer's arrivals
   ErlangGen genServ = new ErlangConvolutionGen(new MRG32k3a(), 2, 1.0 / minute);
   RandomStream streamTeller = new MRG32k3a(); // Number of tellers
   RandomStream streamBalk = new MRG32k3a(); // Balking decisions
   Tally statServed = new Tally("Nb. served per day");
   Tally avWait = new Tally("Average wait per day (hours)");
   Accumulate wait = new Accumulate("cumulated wait for this day");
 
   Event e9h45 = new Event() {
      public void actions() {
         meanDelay = 2.0 * minute;
         nextArriv.schedule(ExponentialGen.nextDouble(streamArr, 1.0 / meanDelay));
      }
   };
 
   Event e10h = new Event() {
      public void actions() {
         double u = streamTeller.nextDouble();
         if (u >= 0.2)
            nbTellers = 3;
         else if (u < 0.05)
            nbTellers = 1;
         else
            nbTellers = 2;
         while (nbWait > 0 && nbBusy < nbTellers) {
            nbBusy++;
            nbWait--;
            new Departure().schedule(genServ.nextDouble());
         }
         wait.update(nbWait);
      }
   };
 
   Event e11h = new Event() {
      public void actions() {
         nextArriv.reschedule((nextArriv.time() - Sim.time()) / 2.0);
         meanDelay = minute;
      }
   };
 
   Event e14h = new Event() {
      public void actions() {
         nextArriv.reschedule((nextArriv.time() - Sim.time()) * 2.0);
         meanDelay = 2.0 * minute;
      }
   };
 
   Event e15h = new Event() {
      public void actions() {
         nextArriv.cancel();
      }
   };
 
   private boolean balk() {
      return (nbWait > 9) || (nbWait > 5 && (5.0 * streamBalk.nextDouble() < nbWait - 5));
   }
 
   class Arrival extends Event {
      public void actions() {
         nextArriv.schedule(ExponentialGen.nextDouble(streamArr, 1.0 / meanDelay));
         if (nbBusy < nbTellers) {
            nbBusy++;
            new Departure().schedule(genServ.nextDouble());
         } else if (!balk()) {
            nbWait++;
            wait.update(nbWait);
         }
      }
   }
 
   class Departure extends Event {
      public void actions() {
         nbServed++;
         if (nbWait > 0) {
            new Departure().schedule(genServ.nextDouble());
            nbWait--;
            wait.update(nbWait);
         } else
            nbBusy--;
      }
   };
 
   public void simulOneDay() {
      Sim.init();
      wait.init();
      nbTellers = 0;
      nbBusy = 0;
      nbWait = 0;
      nbServed = 0;
      e9h45.schedule(9.75);
      e10h.schedule(10.0);
      e11h.schedule(11.0);
      e14h.schedule(14.0);
      e15h.schedule(15.0);
      Sim.start();
      statServed.add(nbServed);
      wait.update();
      avWait.add(wait.sum());
   }
 
   public void simulateDays(int numDays) {
      for (int i = 1; i <= numDays; i++)
         simulOneDay();
      System.out.println(statServed.report());
      System.out.println(avWait.report());
   }
 
   public static void main(String[] args) {
      new BankEv().simulateDays(100);
   }
}