ServiceMain.java

package aQute.jpm.service;

import static java.nio.charset.StandardCharsets.UTF_8;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketTimeoutException;
import java.util.Date;
import java.util.UUID;

import aQute.lib.io.IO;
import aQute.lib.io.IOConstants;
public class ServiceMain extends Thread {
	static final int		BUFFER_SIZE	= IOConstants.PAGE_SIZE * 16;

	static File				lock;
	Date					last		= new Date();
	String					message		= "<>";
	static DatagramSocket	socket;
	static Class< ? >		mainClass;
	static Method			serviceMethod;
	static Thread			mainThread;
	static final UUID		uuid		= UUID.randomUUID();
	private boolean			trace		= false;

	public static void main(String args[]) throws Exception, SecurityException, NoSuchMethodException {
		System.out.println(args.length);
		System.out.println(args[0]);
		lock = new File(args[0]).getAbsoluteFile();
		// lock.deleteOnExit();

		if (!lock.exists())
			throw new IllegalArgumentException("Must start with a valid lock file " + lock);

		socket = new DatagramSocket();
		ServiceMain main = new ServiceMain();

		main.trace("Port " + socket.getLocalPort());

		write(lock, socket.getLocalPort() + ":" + System.getProperty("pid") + ":" + uuid.toString());

		main.start();

		mainClass = ServiceMain.class.getClassLoader().loadClass(args[1]);

		try {
			serviceMethod = mainClass.getDeclaredMethod("daemon", boolean.class);
			serviceMethod.invoke(null, true);
		} catch (NoSuchMethodException e) {
			String[] args2 = new String[args.length - 2];
			System.arraycopy(args, 2, args2, 0, args2.length);

			Method m = mainClass.getDeclaredMethod("main", String[].class);
			m.invoke(null, (Object) args2);
		}
	}

	ServiceMain() {
		super("jpm main service thread");
	}

	@Override
	public void run() {
		try {
			byte[] buffer = new byte[BUFFER_SIZE];
			DatagramPacket dp = new DatagramPacket(buffer, BUFFER_SIZE);

			boolean stopped = false;
			socket.setSoTimeout(5000);

			while (!isInterrupted() && !stopped) {
				try {
					trace("Listening for messages");
					socket.receive(dp);
					trace("Received message " + dp.getAddress());
					if (dp.getAddress().isLoopbackAddress()) {

						String s = new String(dp.getData(), dp.getOffset(), dp.getLength(), UTF_8);
						trace("Received message " + s);
						String parts[] = s.split(":");
						String reply;

						if (parts[0].equals("STOP")) {
							stopped = true;
							reply = "200 STOPPING";

							if (serviceMethod != null) {
								try {
									serviceMethod.invoke(null, false);
								} catch (Exception e) {
									// Ignore
								}
								mainThread.interrupt();
								mainThread.join(2000);
							}

						} else if (parts[0].equals("STATUS")) {
							reply = "200 OK " + last + " " + message;
						} else if (parts[0].equals("TRACE-ON")) {
							trace = true;
							reply = "200 Trace on";
						} else if (parts[0].equals("TRACE-OFF")) {
							trace = false;
							reply = "200 Trace off";
						} else
							reply = "404 UNKNOWN REQUEST " + s;

						byte data[] = reply.getBytes(UTF_8);
						DatagramPacket p = new DatagramPacket(data, 0, data.length, dp.getAddress(), dp.getPort());
						trace("Sending reply message " + reply);
						socket.send(p);
					} else
						System.err.println("Received UDP from external source");
				} catch (SocketTimeoutException stoe) {
					trace("checking lock " + lock + " " + lock.exists());
					if (!lock.exists())
						break;
				}
			}
		} catch (Throwable t) {
			t.printStackTrace();
		} finally {
			try {
				socket.close();
			} finally {
				try {
					IO.delete(lock);
				} finally {
					System.exit(1);
				}
			}
		}
	}

	private void trace(String string) {
		if (trace)
			System.err.println("JPM: " + string);
	}

	private static void write(File f, String response) throws IOException {
		try (PrintWriter fw = IO.writer(f)) {
			fw.append(response);
		}
	}

	public synchronized void setMessage(String m) {
		trace(m);
		last = new Date();
		message = m;
	}
}