/*
 * Dining Philosophers in AtomJava!
 * Nels Beckman
 *
 */
public class DiningPhilosophers {
	
	class Fork {

		private boolean available;

		public Fork(boolean available) { 
			this.available = available; 
		}

		void put() {
			atomic {
				this.available = true;
			}
		}

		void get() {
			atomic {
				this.available = false;
			}
		}

		boolean isAvailable() {
			return this.available;
		}
	}
	
	class PhilosopherState {
		public static final int THINKING = 1;
		public static final int HUNGRY = 2;
		public static final int HASFORKS = 3;
		public static final int EATING = 4;
		public static final int IDLE = 5;
	}

	
	
	class Philosopher extends Thread {
		
		/*
		 * states thinking, hungry, eating, idle;
		 */
		
		Fork leftFork;
		Fork rightFork;
		
		int myState;
		
		public Philosopher(Fork leftFork, Fork rightFork) {
			this.leftFork = leftFork;
			this.rightFork = rightFork;
			this.myState = PhilosopherState.IDLE;
		}
		
		public void run() {
			this.beAPhilosopher();
		}
		
		void beAPhilosopher() {
			for(int i=0; i<10; i++) {
				this.think();
				this.getForks();
				this.eat();				
				this.releaseForks();
			}
		}
		
		void think() {
			this.myState = PhilosopherState.THINKING;
			System.out.println("Philosopher " + this.hashCode() + " is thinking.");
			try {Thread.sleep(10);} catch(InterruptedException e){}
			this.myState = PhilosopherState.HUNGRY;
			System.out.println("Philosopher " + this.hashCode() + " is hungry.");
		}
		
		
		void getForks() {
			while( this.myState != PhilosopherState.HASFORKS ) {
				atomic {
					if( this.leftFork.isAvailable() &&
							this.rightFork.isAvailable() ) {
						this.leftFork.get();
						this.rightFork.get();
						this.myState = PhilosopherState.HASFORKS;
					}
				}
			}
			
			System.out.println("Philosopher " + this.hashCode() + " got the forks.");
		}
		
		void releaseForks() {
			atomic {
				this.leftFork.put();
				this.rightFork.put();
			}
			
			System.out.println("Philosopher " + this.hashCode() + " dropped the forks.");
		}
		
		void eat() {
			this.myState = PhilosopherState.EATING;
			System.out.println("Philosopher " + this.hashCode() + " eating.");
			try {Thread.sleep(10);} catch(InterruptedException e){}
			this.myState = PhilosopherState.IDLE;
		}
	}
	
	public static void main(String[] args) {
		(new DiningPhilosophers()).begin();
	}
	
	public void begin() {
		Fork f1 = new Fork(true);
		Fork f2 = new Fork(true);
		Fork f3 = new Fork(true);
		Fork f4 = new Fork(true);
		Fork f5 = new Fork(true);
		
		Philosopher p1 = new Philosopher(f1,f2);
		Philosopher p2 = new Philosopher(f2,f3);
		Philosopher p3 = new Philosopher(f3,f4);
		Philosopher p4 = new Philosopher(f4,f5);
		Philosopher p5 = new Philosopher(f5,f1);
		
		p1.start();
		p2.start();
		p3.start();
		p4.start();
		p5.start();		
	}
}