/*
 * Copyright (c) 2001 Matthew Feldt. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided the copyright notice above is
 * retained.
 *
 * THIS SOFTWARE IS PROVIDED ''AS IS'' AND WITHOUT ANY EXPRESSED OR
 * IMPLIED WARRANTIES.
 */

/**
 * DeadlockMethods.java
 *
 * Java Examples In A Nutshell Copyright (c) 2000 David Flanagan
 * Exercise 4-3:
 * Example 4-3 uses the synchronized statement to demonstrate deadlock. Write
 * a similar program that causes two threads to deadlock, but use synchronized
 * methods instead of the synchronized statement. This sort of deadlock is a
 * little more subtle and harder to detect.
 *
 * @author Matthew Feldt <developer@feldt.com>
 * @version 1.0, 2/15/2001 16:37
 */

package com.feldt.examples.thread;

class DeadlockMethods extends Thread {
	public synchronized void one(DeadlockMethods dl) {
		System.out.println("Begin DeadlockMethods.one(): " + this + ".");

		// simulate work
		try { Thread.sleep(500); }
		catch (InterruptedException e) {}

		System.out.println("DeadlockMethods.one() wants DeadlockMethods.two().");
		dl.two(this);
		System.out.println("End DeadlockMethods.one().");
	}

	public synchronized void two(DeadlockMethods dl) {
		System.out.println("Begin DeadlockMethods.two(): " + this + ".");

		// simulate work
		try { Thread.sleep(500); }
		catch (InterruptedException e) {}

		System.out.println("DeadlockMethods.two() wants DeadlockMethods.one().");
		dl.one(this);
		System.out.println("End DeadlockMethods.two().");
	}

	static class Test {
		static final DeadlockMethods dl1 = new DeadlockMethods();
		static final DeadlockMethods dl2 = new DeadlockMethods();

		public static void main(String[] args) {
			Thread thread1 = new Thread() {
				public void run() {
					dl1.one(dl2);
				}
			};

			Thread thread2 = new Thread() {
				public void run() {
					dl2.two(dl1);
				}
			};

			System.out.println("thread1.start()");
			thread1.start();
			System.out.println("thread2.start()");
			thread2.start();
		}
	}
}