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/*
* Copyright (c) 2018, 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.
*
* 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.
*/
/**
* @test
* @modules java.management java.base/java.io:+open java.base/java.net:+open
* @run main/othervm -Djava.net.preferIPv4Stack=true UnreferencedMulticastSockets
* @run main/othervm UnreferencedMulticastSockets
* @summary Check that unreferenced multicast sockets are closed
*/
import java.io.FileDescriptor;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.DatagramSocketImpl;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.UnknownHostException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.ArrayDeque;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.TimeUnit;
import com.sun.management.UnixOperatingSystemMXBean;
public class UnreferencedMulticastSockets {
/**
* The set of sockets we have to check up on.
*/
final static ArrayDeque<NamedWeak> pendingSockets = new ArrayDeque<>(5);
/**
* Queued objects when they are unreferenced.
*/
final static ReferenceQueue<Object> pendingQueue = new ReferenceQueue<>();
// Server to echo a datagram packet
static class Server implements Runnable {
MulticastSocket ss;
Server() throws IOException {
ss = new MulticastSocket(0);
System.out.printf(" DatagramServer addr: %s: %d%n",
this.getHost(), this.getPort());
pendingSockets.add(new NamedWeak(ss, pendingQueue, "serverMulticastSocket"));
extractRefs(ss, "serverMulticastSocket");
}
InetAddress getHost() throws UnknownHostException {
InetAddress localhost = InetAddress.getByName("localhost"); //.getLocalHost();
return localhost;
}
int getPort() {
return ss.getLocalPort();
}
// Receive a byte and send back a byte
public void run() {
try {
byte[] buffer = new byte[50];
DatagramPacket p = new DatagramPacket(buffer, buffer.length);
ss.receive(p);
buffer[0] += 1;
ss.send(p); // send back +1
// do NOT close but 'forget' the socket reference
ss = null;
} catch (Exception ioe) {
ioe.printStackTrace();
}
}
}
public static void main(String args[]) throws Exception {
// Create and close a MulticastSocket to warm up the FD count for side effects.
try (MulticastSocket s = new MulticastSocket(0)) {
// no-op; close immediately
s.getLocalPort(); // no-op
}
long fdCount0 = getFdCount();
listProcFD();
// start a server
Server svr = new Server();
Thread thr = new Thread(svr);
thr.start();
MulticastSocket client = new MulticastSocket(0);
client.connect(svr.getHost(), svr.getPort());
pendingSockets.add(new NamedWeak(client, pendingQueue, "clientMulticastSocket"));
extractRefs(client, "clientMulticastSocket");
byte[] msg = new byte[1];
msg[0] = 1;
DatagramPacket p = new DatagramPacket(msg, msg.length, svr.getHost(), svr.getPort());
client.send(p);
p = new DatagramPacket(msg, msg.length);
client.receive(p);
System.out.printf("echo received from: %s%n", p.getSocketAddress());
if (msg[0] != 2) {
throw new AssertionError("incorrect data received: expected: 2, actual: " + msg[0]);
}
// Do NOT close the MulticastSocket; forget it
Object ref;
int loops = 20;
while (!pendingSockets.isEmpty() && loops-- > 0) {
ref = pendingQueue.remove(1000L);
if (ref != null) {
pendingSockets.remove(ref);
System.out.printf(" ref freed: %s, remaining: %d%n", ref, pendingSockets.size());
} else {
client = null;
p = null;
msg = null;
System.gc();
}
}
thr.join();
// List the open file descriptors
long fdCount = getFdCount();
System.out.printf("Initial fdCount: %d, final fdCount: %d%n", fdCount0, fdCount);
listProcFD();
if (loops == 0) {
throw new AssertionError("Not all references reclaimed");
}
}
// Get the count of open file descriptors, or -1 if not available
private static long getFdCount() {
OperatingSystemMXBean mxBean = ManagementFactory.getOperatingSystemMXBean();
return (mxBean instanceof UnixOperatingSystemMXBean)
? ((UnixOperatingSystemMXBean) mxBean).getOpenFileDescriptorCount()
: -1L;
}
// Reflect to find references in the socket implementation that will be gc'd
private static void extractRefs(MulticastSocket s, String name) {
try {
Field socketImplField = DatagramSocket.class.getDeclaredField("impl");
socketImplField.setAccessible(true);
Object socketImpl = socketImplField.get(s);
Field fileDescriptorField = DatagramSocketImpl.class.getDeclaredField("fd");
fileDescriptorField.setAccessible(true);
FileDescriptor fileDescriptor = (FileDescriptor) fileDescriptorField.get(socketImpl);
extractRefs(fileDescriptor, name);
Class<?> socketImplClass = socketImpl.getClass();
System.out.printf("socketImplClass: %s%n", socketImplClass);
if (socketImplClass.getName().equals("java.net.TwoStacksPlainDatagramSocketImpl")) {
Field fileDescriptor1Field = socketImplClass.getDeclaredField("fd1");
fileDescriptor1Field.setAccessible(true);
FileDescriptor fileDescriptor1 = (FileDescriptor) fileDescriptor1Field.get(socketImpl);
extractRefs(fileDescriptor1, name + "::twoStacksFd1");
} else {
System.out.printf("socketImpl class name not matched: %s != %s%n",
socketImplClass.getName(), "java.net.TwoStacksPlainDatagramSocketImpl");
}
} catch (NoSuchFieldException | IllegalAccessException ex) {
ex.printStackTrace();
throw new AssertionError("missing field", ex);
}
}
private static void extractRefs(FileDescriptor fileDescriptor, String name) {
Object cleanup = null;
int rawfd = -1;
try {
if (fileDescriptor != null) {
Field fd1Field = FileDescriptor.class.getDeclaredField("fd");
fd1Field.setAccessible(true);
rawfd = fd1Field.getInt(fileDescriptor);
Field cleanupfdField = FileDescriptor.class.getDeclaredField("cleanup");
cleanupfdField.setAccessible(true);
cleanup = cleanupfdField.get(fileDescriptor);
pendingSockets.add(new NamedWeak(fileDescriptor, pendingQueue,
name + "::fileDescriptor: " + rawfd));
pendingSockets.add(new NamedWeak(cleanup, pendingQueue, name + "::fdCleanup: " + rawfd));
}
} catch (NoSuchFieldException | IllegalAccessException ex) {
ex.printStackTrace();
throw new AssertionError("missing field", ex);
} finally {
System.out.print(String.format(" %s:: fd: %s, fd: %d, cleanup: %s%n",
name, fileDescriptor, rawfd, cleanup));
}
}
/**
* Method to list the open file descriptors (if supported by the 'lsof' command).
*/
static void listProcFD() {
List<String> lsofDirs = List.of("/usr/bin", "/usr/sbin");
Optional<Path> lsof = lsofDirs.stream()
.map(s -> Paths.get(s, "lsof"))
.filter(f -> Files.isExecutable(f))
.findFirst();
lsof.ifPresent(exe -> {
try {
System.out.printf("Open File Descriptors:%n");
long pid = ProcessHandle.current().pid();
ProcessBuilder pb = new ProcessBuilder(exe.toString(), "-p", Integer.toString((int) pid));
pb.inheritIO();
Process p = pb.start();
p.waitFor(10, TimeUnit.SECONDS);
} catch (IOException | InterruptedException ie) {
ie.printStackTrace();
}
});
}
// Simple class to identify which refs have been queued
static class NamedWeak extends WeakReference<Object> {
private final String name;
NamedWeak(Object o, ReferenceQueue<Object> queue, String name) {
super(o, queue);
this.name = name;
}
public String toString() {
return name + "; " + super.toString();
}
}
}
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