/*
	ForkControl.java - monitor to keep control of the forks
	in the Dining Philosophers' problem.
	Written by Robert Sheehan.
	01/09/97
*/

public class ForkControl {
		
	private boolean[] forkAvailable;
	
	public ForkControl() {
		forkAvailable = new boolean[DiningPhilosophers.NUMBER];
		for (int i = 0; i < DiningPhilosophers.NUMBER; i++)
			forkAvailable[i] = true;
	}
	
	public synchronized void getBothForks(int name) throws InterruptedException {
		while (!forkAvailable[name])
			wait();
		forkAvailable[name] = false;
		
		while (!forkAvailable[(name + 1) % DiningPhilosophers.NUMBER])
			wait();
		forkAvailable[name] =  false;
	}
	
	public synchronized void putBackBothForks(int name) {
		forkAvailable[name] = true;
		forkAvailable[(name + 1) % DiningPhilosophers.NUMBER] = true;
		notifyAll();	// try it with notify()
	}
	
}