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SleepingBarber.java-------------------------
//Figure 2-36
import Semaphore;
public class SleepingBarber extends Thread {
// Shared objects
// Number of customers waiting for service
public static Semaphore customers = new Semaphore(0);
// Number of barbers waiting for customers
public static Semaphore barbers = new Semaphore(0);
// For mutual exclusion
public static Semaphore mutex = new Semaphore(1);
// Customers are waiting (not being cut)
public static int waiting = 0;
// Chairs for waiting customers
public static final int CHAIRS = 5;
class Barber extends Thread {
private int myNumber; // Id for the Barber
public Barber(int i) { // Constructor for the Barber
myNumber = i;
}
public void run(){ // What a barber does
while(true) {
customers.down(); // Go to sleep if no customers
mutex.down(); // Acquire access to waiting
waiting = waiting - 1; // Decrement count of waiting
// customers
barbers.up(); // One barber is now ready to cut
// hair
mutex.up(); // Release waiting
cut_hair(); // Noncritical region
}
}
public void cut_hair(){
System.out.println("Barber " + myNumber + " is cutting hair");
try {
sleep(7500);
} catch (InterruptedException ex){ }
}
} //end of Barber Class
private class Customer extends Thread {
private int myNumber; // Id for the Customer
public Customer(int i) { // Constructor for the Customer
myNumber = i;
}
public void run(){ // What a customer does
mutex.down(); // Acquire access to waiting
if(waiting ‹ CHAIRS){
waiting = waiting + 1; // Increment count of waiting
// customers
customers.up(); // Wake up barber if needed
mutex.up(); // Release waiting
barbers.down(); // Go to sleep if number of free
// barbers is 0
get_haircut(); // Noncritical region
} else {
mutex.up(); // Shop is full do not wait
}
}
public void get_haircut(){
System.out.println("Customer " + myNumber
+ " is getting his hair cut");
try {
sleep(10000);
} catch (InterruptedException ex){ }
}
} //end of Customer Class
public static void main(String args[]) {
SleepingBarber holder = new SleepingBarber();
holder.start();
}
// This thread spins off a number of customers
public void run(){
final int BARBERS = 3;
Barber aBarber;
Customer aCustomer;
for(int i=0; i‹BARBERS; i++) {
// Create the barbers
aBarber = new Barber(i);
// Start the threads running
aBarber.start();
}
int customerNumber = 0;
while(true){
aCustomer = new Customer(customerNumber++);
// Start the customer running
aCustomer.start();
// Wait a bit and make another customer
try {
sleep(1000);
} catch(InterruptedException ex) {};
}
} //end of run method for SleepingBarber
}
End of SleepingBarber.java---------------------------------------
SleepingBarberD.java---------------------------------------------
//Figure 2-36
import Semaphore;
public class SleepingBarberD extends Thread {
// Shared objects
// Number of customers waiting for service
public static Semaphore customers = new Semaphore(0);
// Number of barbers waiting for customers
public static Semaphore barbers = new Semaphore(0);
// For mutual exclusion
public static Semaphore mutex = new Semaphore(1);
// Customers are waiting (not being cut)
public static int waiting = 0;
// Chairs for waiting customers
public static final int CHAIRS = 5;
class Barber extends Thread {
private int myNumber; // Id for the Barber
public Barber(int i) { // Constructor for the Barber
myNumber = i;
}
public void run(){ // What a barber does
while(true) {
customers.down(); // Go to sleep if no customers
mutex.down(); // Acquire access to waiting
waiting = waiting - 1; // Decrement count of waiting
// customers
barbers.up(); // One barber is now ready to cut
// hair
mutex.up(); // Release waiting
cut_hair(); // Noncritical region
}
}
public void cut_hair(){
System.out.println("Barber " + myNumber + " is cutting hair");
try {
sleep(7500);
} catch (InterruptedException ex){ }
}
} //end of Barber Class
private class Customer extends Thread {
private int myNumber; // Id for the Customer
public Customer(int i) { // Constructor for the Customer
myNumber = i;
}
public void run(){
// What a customer does
mutex.down(); // Acquire access to waiting
if(waiting ‹ CHAIRS){
waiting = waiting + 1; // Increment count of waiting
// customers
customers.up(); // Wake up barber if needed
mutex.up(); // Release waiting
//added section RFC Walters 9 December 2005
try { //random sleep
sleep(10000); //
} catch (InterruptedException e) {} //
try { //random sleep
sleep(10000); //
} catch (InterruptedException e) {} //
try { //random sleep
sleep(10000); //
} catch (InterruptedException e) {} //
//end of added section RFC Walters 9 December 2005
barbers.down(); // Go to sleep if number of free
// barbers is 0
get_haircut(); // Noncritical region
} else {
mutex.up(); // Shop is full do not wait
}
}
public void get_haircut(){
System.out.println("Customer " + myNumber
+ " is getting his hair cut");
try {
sleep(10000);
} catch (InterruptedException ex){ }
}
} //end of Customer Class
public static void main(String args[]) {
SleepingBarberD holder = new SleepingBarberD();
holder.start();
}
// This thread spins off a number of customers
public void run(){
final int BARBERS = 3;
Barber aBarber;
Customer aCustomer;
for(int i=0; i // Create the barbers
aBarber = new Barber(i);
// Start the threads running
aBarber.start();
}
int customerNumber = 0;
while(true){
aCustomer = new Customer(customerNumber++);
// Start the customer running
aCustomer.start();
// Wait a bit and make another customer
try {
sleep(1000);
} catch(InterruptedException ex) {};
}
} //end of run method for SleepingBarber
}
End of SleepingBarberD.java
