Stabilize.java

import java.net.InetSocketAddress;

/**
 * Stabilize thread that periodically asks successor for its predecessor
 * and determine if current node should update or delete its successor.
 * @author Chuan Xia
 *
 */

public class Stabilize extends Thread {
	
	private Node local;
	private boolean alive;

	public Stabilize(Node _local) {
		local = _local;
		alive = true;
	}

	@Override
	public void run() {
		while (alive) {
			InetSocketAddress successor = local.getSuccessor();
			if (successor == null || successor.equals(local.getAddress())) {
				local.updateFingers(-3, null); //fill
			}
			successor = local.getSuccessor();
			if (successor != null && !successor.equals(local.getAddress())) {

				// try to get my successor's predecessor
				InetSocketAddress x = Helper.requestAddress(successor, "YOURPRE");

				// if bad connection with successor! delete successor
				if (x == null) {
					local.updateFingers(-1, null);
				}

				// else if successor's predecessor is not itself
				else if (!x.equals(successor)) {
					long local_id = Helper.hashSocketAddress(local.getAddress());
					long successor_relative_id = Helper.computeRelativeId(Helper.hashSocketAddress(successor), local_id);
					long x_relative_id = Helper.computeRelativeId(Helper.hashSocketAddress(x),local_id);
					if (x_relative_id>0 && x_relative_id < successor_relative_id) {
						local.updateFingers(1,x);
					}
				}
				
				// successor's predecessor is successor itself, then notify successor
				else {
					local.notify(successor);
				}
			}

			try {
				Thread.sleep(60);
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
		}

	}

	public void toDie() {
		alive = false;
	}





}