Back to index...

	/*
	* Copyright (c) 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package sun.management.jdp;

	import java.io.IOException;
	import java.net.InetAddress;
	import java.net.UnknownHostException;
	import java.util.UUID;

	import java.lang.management.ManagementFactory;
	import java.lang.management.RuntimeMXBean;
	import java.lang.reflect.Field;
	import java.lang.reflect.Method;
	import sun.management.VMManagement;

	/**
	* JdpController is responsible to create and manage a broadcast loop
	*
	* <p> Other part of code has no access to broadcast loop and have to use
	* provided static methods
	* {@link #startDiscoveryService(InetAddress,int,String,String) startDiscoveryService}
	* and {@link #stopDiscoveryService() stopDiscoveryService}</p>
	* <p>{@link #startDiscoveryService(InetAddress,int,String,String) startDiscoveryService} could be called multiple
	* times as it stops the running service if it is necessary. Call to {@link #stopDiscoveryService() stopDiscoveryService}
	* ignored if service isn't run</p>
	*
	*
	* </p>
	*
	* <p> System properties below could be used to control broadcast loop behavior.
	* Property below have to be set explicitly in command line. It's not possible to
	* set it in management.config file. Careless changes of these properties could
	* lead to security or network issues.
	* <ul>
	* <li>com.sun.management.jdp.ttl - set ttl for broadcast packet</li>
	* <li>com.sun.management.jdp.pause - set broadcast interval in seconds</li>
	* <li>com.sun.management.jdp.source_addr - an address of interface to use for broadcast</li>
	* </ul>
	</p>
	* <p>null parameters values are filtered out on {@link JdpPacketWriter} level and
	* corresponding keys are not placed to packet.</p>
	*/
	public final class JdpController {

	private static class JDPControllerRunner implements Runnable {

	private final JdpJmxPacket packet;
	private final JdpBroadcaster bcast;
	private final int pause;
	private volatile boolean shutdown = false;

	private JDPControllerRunner(JdpBroadcaster bcast, JdpJmxPacket packet, int pause) {
	this.bcast = bcast;
	this.packet = packet;
	this.pause = pause;
	}

	@Override
	public void run() {
	try {
	while (!shutdown) {
	bcast.sendPacket(packet);
	try {
	Thread.sleep(this.pause);
	} catch (InterruptedException e) {
	// pass
	}
	}

	} catch (IOException e) {
	// pass;
	}

	// It's not possible to re-use controller,
	// nevertheless reset shutdown variable
	try {
	stop();
	bcast.shutdown();
	} catch (IOException ex) {
	// pass - ignore IOException during shutdown
	}
	}

	public void stop() {
	shutdown = true;
	}
	}
	private static JDPControllerRunner controller = null;

	private JdpController(){
	// Don't allow to instantiate this class.
	}

	// Utility to handle optional system properties
	// Parse an integer from string or return default if provided string is null
	private static int getInteger(String val, int dflt, String msg) throws JdpException {
	try {
	return (val == null) ? dflt : Integer.parseInt(val);
	} catch (NumberFormatException ex) {
	throw new JdpException(msg);
	}
	}

	// Parse an inet address from string or return default if provided string is null
	private static InetAddress getInetAddress(String val, InetAddress dflt, String msg) throws JdpException {
	try {
	return (val == null) ? dflt : InetAddress.getByName(val);
	} catch (UnknownHostException ex) {
	throw new JdpException(msg);
	}
	}

	// Get the process id of the current running Java process
	private static Integer getProcessId() {
	try {
	// Get the current process id using a reflection hack
	RuntimeMXBean runtime = ManagementFactory.getRuntimeMXBean();
	Field jvm = runtime.getClass().getDeclaredField("jvm");
	jvm.setAccessible(true);

	VMManagement mgmt = (sun.management.VMManagement) jvm.get(runtime);
	Method pid_method = mgmt.getClass().getDeclaredMethod("getProcessId");
	pid_method.setAccessible(true);
	Integer pid = (Integer) pid_method.invoke(mgmt);
	return pid;
	} catch(Exception ex) {
	return null;
	}
	}


	/**
	* Starts discovery service
	*
	* @param address - multicast group address
	* @param port - udp port to use
	* @param instanceName - name of running JVM instance
	* @param url - JMX service url
	* @throws IOException
	*/
	public static synchronized void startDiscoveryService(InetAddress address, int port, String instanceName, String url)
	throws IOException, JdpException {

	// Limit packet to local subnet by default
	int ttl = getInteger(
	System.getProperty("com.sun.management.jdp.ttl"), 1,
	"Invalid jdp packet ttl");

	// Broadcast once a 5 seconds by default
	int pause = getInteger(
	System.getProperty("com.sun.management.jdp.pause"), 5,
	"Invalid jdp pause");

	// Converting seconds to milliseconds
	pause = pause * 1000;

	// Allow OS to choose broadcast source
	InetAddress sourceAddress = getInetAddress(
	System.getProperty("com.sun.management.jdp.source_addr"), null,
	"Invalid source address provided");

	// Generate session id
	UUID id = UUID.randomUUID();

	JdpJmxPacket packet = new JdpJmxPacket(id, url);

	// Don't broadcast whole command line for security reason.
	// Strip everything after first space
	String javaCommand = System.getProperty("sun.java.command");
	if (javaCommand != null) {
	String[] arr = javaCommand.split(" ", 2);
	packet.setMainClass(arr[0]);
	}

	// Put optional explicit java instance name to packet, if user doesn't specify
	// it the key is skipped. PacketWriter is responsible to skip keys having null value.
	packet.setInstanceName(instanceName);

	// Set rmi server hostname if it explicitly specified by user with
	// java.rmi.server.hostname
	String rmiHostname = System.getProperty("java.rmi.server.hostname");
	packet.setRmiHostname(rmiHostname);

	// Set broadcast interval
	packet.setBroadcastInterval(new Integer(pause).toString());

	// Set process id
	Integer pid = getProcessId();
	if (pid != null) {
	packet.setProcessId(pid.toString());
	}

	JdpBroadcaster bcast = new JdpBroadcaster(address, sourceAddress, port, ttl);

	// Stop discovery service if it's already running
	stopDiscoveryService();

	controller = new JDPControllerRunner(bcast, packet, pause);

	Thread t = new Thread(controller, "JDP broadcaster");
	t.setDaemon(true);
	t.start();
	}

	/**
	* Stop running discovery service,
	* it's safe to attempt to stop not started service
	*/
	public static synchronized void stopDiscoveryService() {
	if ( controller != null ){
	controller.stop();
	controller = null;
	}
	}
	}

Back to index...