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#include <iostream>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <semaphore.h>
using namespace std;
sem_t customerReady;
sem_t barberReady;
sem_t accessWRSeats;
unsigned int numberOfAvailableSeats = 0;
unsigned int numberOfCustomers = 0;
int HOURS = 1;
int amountTime = 0;
void *barber(void*){
while(amountTime < HOURS*60){
sem_wait(&customerReady);//Check to see if there are any customers ready and if not, sleep
sem_wait(&accessWRSeats); //Wake up and and try to access the # of available seats and if not, sleep
//Enter Critical Section
//If there are any customers in the waiting room
//If there aren't any customers in the waiting room
cout << "\nBarber: number of customers: " << numberOfCustomers;
numberOfCustomers--;
numberOfAvailableSeats++;//Take a customer from the wait room to the barber chair
//Cut hair here
sem_post(&accessWRSeats);//Release lock on available seats; chairs are unlocked
sem_post(&barberReady);//Finish cutting hair and is ready to cut again
amountTime++;
}
cout << "EXITING BARBER!" << endl;
pthread_exit(NULL);
}
void *customer(void *){
while(amountTime < HOURS* 60){
sem_wait(&accessWRSeats); //Request access to the number of available seats in the waiting room
//If there are seats available, do not leave (wait)
if(numberOfAvailableSeats > 0){
numberOfCustomers++;//customer enters the barber shop
cout << "\n\tCustomer: number of Customers: " << numberOfCustomers;
numberOfAvailableSeats--;//Sit down in a chair
sem_post(&customerReady);//Signal that there is a customer ready to be served
sem_post(&accessWRSeats);//release lock on seats; lock not needed
sem_wait(&barberReady);//Wait until the barber is ready
}
//no free seats
else{
cout << "\nCustomer:no fucking seats , number of available seats is:" << numberOfAvailableSeats << endl;
cout << "\n\tNumber of available seats:" << numberOfAvailableSeats;
cout << "\tNumber of Customers:%d\n" << numberOfCustomers << endl;
sem_post(&accessWRSeats); //release the lock on the seats and leave without a haircut
}
amountTime++;
}
cout << "EXITING CUSTOMER!" << endl;
pthread_exit(NULL);
}
//***********************************************************************************************************************
/* NOTES
//condition for barber
1.) customer in the WR and takes him to the barber chair, freeing up one of the occupied WR seats
2.) no customers in the WR and the barber goes back to his chair to sleep
//conditions for WR
I. checks to see what the barber is doing
A. barber is sleeping
-customer wakes up the barber and the barber cuts the hair
B. barber is cutting someone's hair
-then you must check the WR
1.) the number of available WR seats < to the number of customers (ex: seats=0, customers=1 or more)
a. customer leaves
2.) the number of available WR seats >= to the number of customers (ex: seats=2, customers=1,0)
a. customer takes a seat in the WR and the number of WR seats decreases by one
*/
//***********************************************************************************************************************
int main(int argc, char** argv){
//get the number of seats available from the command line
if(argc == 2){
numberOfAvailableSeats = atoi(argv[1]);
}
else {
cout << "Please enter the number of seats you would like to simulate." << endl;
cin >> numberOfAvailableSeats;
}
/*Semaphore initialization*/
sem_init(&barberReady,0,1);
sem_init(&customerReady,0,0);
sem_init(&accessWRSeats,0,1);
pthread_t barberThread;
pthread_t customerThread;
int rc1 = 0; int rc2 = 0;
rc1 = pthread_create(&barberThread, NULL, barber, NULL);
rc2 = pthread_create(&customerThread, NULL, customer, NULL);
if(rc1 != 0)
cout << "Unable to create barber thread." << endl;
if(rc2 != 0)
cout << "Unable to create customer thread." << endl;
/*Customer_thread first blocked*/
rc2 = pthread_join(customerThread,NULL);
rc1 = pthread_join(barberThread,NULL);
printf("rc1: %d, rc2: %d\n", rc1, rc2);
cout << "EXITING PROGRAM" << endl;
return 0;
}
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