DESim Example, C++ (clang)

DESim Example

#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <unordered_map>

using namespace std;

// define the time data type
#define TimeType int

// define constants used in our simulation
#define TEST_SIZE 15
#define NUM_NAMES 6
string firstNames[NUM_NAMES] = {"Alice","Ambroise","Bert","Denise","Larry","Emily"};
string lastNames[NUM_NAMES] = {"Ghosh","Jones","Lee","Smith","Zhang","Zuckerman"};
#define SIM_LENGTH 100
#define MAX_DURATION 20
#define NUM_TELLERS 2

// define event types
typedef enum {ARRIVAL, DEPARTURE} EventType;

// define an event struct to store events
typedef struct {
	string customerName;
	TimeType eventTime;
	TimeType duration;
    TimeType waitTime; 
	EventType event;
} EventStruct;

// a standard way of printing events
void printEvent(const EventStruct & event)
{
	cout << event.customerName;
	cout << ", Time: " << event.eventTime;
	cout << ", Duration: " << event.duration;
    cout << ", Event type: ";
    if (event.event==ARRIVAL) cout << "ARRIVAL";
    else{ 
        cout << "DEPARTURE";
        cout << "Wait Time: " << event.waitTime; 
    }
}

// how to compare event times for the priority queue
struct compareEventTime
{
	bool operator()(const EventStruct& lhs, const EventStruct& rhs) const
	{
		return lhs.eventTime > rhs.eventTime;
	}
};

// our Discrete Event Simulation class
class DESim
{
private:
	// event queue -- priority queue with events queued by event time
	priority_queue<EventStruct,vector<EventStruct>,compareEventTime> eventQueue;
	// wait queue -- priority queue with waiting customers queued by arrival time
	queue<EventStruct> bankQueue;
	TimeType currentTime = 0;
	bool debugOn = false;
	int tellersAvailable = NUM_TELLERS;
public:
	void addEvent(const EventStruct & event);
    void addBankQueueCustomer(const EventStruct & event);
	void setDebugOn(bool value) {debugOn = value;};
    void printTellerNumberChange();
	void runSim();
}; // end DESim

// add a priority queue event
void DESim::addEvent(const EventStruct & event)
{
	if (debugOn) {cout << "[" << currentTime <<"] Adding event: "; printEvent(event); cout << endl;}
	eventQueue.push(event);
}

// add a bank queue customer (not really an event)
void DESim::addBankQueueCustomer(const EventStruct & event)
{
	if (debugOn) {cout << "[" << currentTime <<"] Adding bank queue customer: "; printEvent(event); cout << endl;}
	bankQueue.push(event);
}

// indicate that the number of available tellers has changed
void DESim::printTellerNumberChange()
{
	if (debugOn) {cout << "[" << currentTime <<"] Current number of tellers available: " << tellersAvailable << endl;}
}

// run the simulation
void DESim::runSim()
{
	while (!eventQueue.empty()) {
		EventStruct nextEvent = eventQueue.top(); // get next event in priority queue
		currentTime = nextEvent.eventTime;
		eventQueue.pop();
		switch (nextEvent.event) {
		case ARRIVAL:
			if (tellersAvailable) {
				// enter departure event in eventQueue
                nextEvent.eventTime = currentTime + nextEvent.duration;
                nextEvent.event = DEPARTURE;
                nextEvent.waitTime = 0; 
                addEvent(nextEvent);
                tellersAvailable--;
                printTellerNumberChange();
			} else {
				// no tellers available, put customer in bank queue
                addBankQueueCustomer(nextEvent);
			}
			break;
		case DEPARTURE:
			if(!bankQueue.empty()) {
				EventStruct nextCustomer = bankQueue.front();
                bankQueue.pop();
                nextCustomer.eventTime = currentTime + nextEvent.duration;
                nextCustomer.event = DEPARTURE;
                nextCustomer.waitTime = currentTime - 
                addEvent(nextCustomer);
			} else {
				tellersAvailable++;
                printTellerNumberChange();
			}
			break;
		default:
			cout << "ERROR: Should never get here! " << endl;
		}
	}
}

int main()
{
    cout << "*** Discrete Event Simulation Example for ECE 2574 ***\n\n";
	DESim mySim;
	mySim.setDebugOn(true);
	EventStruct myEvent;
	srand(123321);
    cout << "Adding " << TEST_SIZE << " events.\n\n";
	for (int i=0; i<TEST_SIZE; i++) {
		myEvent.customerName = firstNames[rand()%NUM_NAMES] + string(" ")
            + lastNames[rand()%NUM_NAMES];
		myEvent.eventTime = rand()%SIM_LENGTH+1;
		myEvent.duration = rand()%MAX_DURATION+1;
		myEvent.event = ARRIVAL;
		mySim.addEvent(myEvent);
	}
    cout << "\nRunning simulation...\n";
	mySim.runSim();
	return 0;
}


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