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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
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*
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* 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).
*
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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.
Other part of code has no access to broadcast loop and have to use provided static methods startDiscoveryService and stopDiscoveryService
startDiscoveryService could be called multiple times as it stops the running service if it is necessary. Call to stopDiscoveryService ignored if service isn't run.
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.
- com.sun.management.jdp.ttl - set ttl for broadcast packet
- com.sun.management.jdp.pause - set broadcast interval in seconds
- com.sun.management.jdp.source_addr - an address of interface to use for broadcast
null parameters values are filtered out on JdpPacketWriter level and corresponding keys are not placed to packet.
/**
* 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>{@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> 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>null parameters values are filtered out on {@link JdpPacketWriter} level and
* corresponding keys are not placed to packet.
*/
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
Params: - address – - multicast group address
- port – - udp port to use
- instanceName – - name of running JVM instance
- url – - JMX service url
Throws:
/**
* 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(Integer.toString(pause));
// 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(null, controller, "JDP broadcaster", 0, false);
t.setDaemon(true);
t.start();
}
Stop running discovery service,
it's safe to attempt to stop not started service
/**
* 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;
}
}
}