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Jolokia :: Service :: Agent Discovery
package org.jolokia.service.discovery;
import java.io.IOException;
import java.net.*;
import java.util.*;
import java.util.concurrent.*;
import org.jolokia.server.core.service.api.AgentDetails;
import org.jolokia.server.core.service.api.LogHandler;
import org.jolokia.server.core.util.NetworkUtil;
/**
* Utility class for handling multicast stuff
*
* @author roland
* @since 28.01.14
*/
public final class MulticastUtil {
// IPv4 Address for Jolokia's Multicast group
public static final String JOLOKIA_MULTICAST_GROUP = "239.192.48.84";
// Multicast port where to listen for queries
public static final int JOLOKIA_MULTICAST_PORT = 24884;
// Utility class
private MulticastUtil() {
}
static MulticastSocket newMulticastSocket(InetAddress pAddress, LogHandler pLogHandler) throws IOException {
// TODO: IpV6 (not supported yet)
InetSocketAddress socketAddress =
new InetSocketAddress(JOLOKIA_MULTICAST_GROUP, JOLOKIA_MULTICAST_PORT);
MulticastSocket socket = new MulticastSocket(JOLOKIA_MULTICAST_PORT);
socket.setReuseAddress(true);
setOutgoingInterfaceForMulticastRequest(pAddress, socket);
socket.setTimeToLive(255);
if (joinMcGroupsOnAllNetworkInterfaces(socket, socketAddress, pLogHandler) == 0) {
throw new IOException("Couldn't join multicast group " + socketAddress + " on any network interfaces");
}
return socket;
}
/**
* Sent out a message to Jolokia's multicast group over all network interfaces supporting multicast request (and no
* logging is used)
*
* @param pOutMsg the message to send
* @param pTimeout timeout used for how long to wait for discovery messages
* @return list of received answers, never null
* @throws IOException if something fails during the discovery request
*/
public static List sendQueryAndCollectAnswers(DiscoveryOutgoingMessage pOutMsg, int pTimeout) throws IOException {
return sendQueryAndCollectAnswers(pOutMsg, pTimeout, LogHandler.QUIET);
}
/**
* Sent out a message to Jolokia's multicast group over all network interfaces supporting multicasts
*
* @param pOutMsg the message to send
* @param pTimeout timeout used for how long to wait for discovery messages
* @param pLogHandler a log handler for printing out logging information
* @return list of received answers, never null
* @throws IOException if something fails during the discovery request
*/
public static List sendQueryAndCollectAnswers(DiscoveryOutgoingMessage pOutMsg,
int pTimeout,
LogHandler pLogHandler) throws IOException {
final List>> futures = sendDiscoveryRequests(pOutMsg, pTimeout, pLogHandler);
return collectIncomingMessages(pTimeout, futures, pLogHandler);
}
// ==============================================================================================================
// Send requests in parallel threads, return the futures for getting the result
private static List>> sendDiscoveryRequests(DiscoveryOutgoingMessage pOutMsg,
int pTimeout,
LogHandler pLogHandler) throws SocketException, UnknownHostException {
// Note for Ipv6 support: If there are two local addresses, one with IpV6 and one with IpV4 then two discovery request
// should be sent, on each interface respectively. Currently, only IpV4 is supported.
List addresses = getMulticastAddresses();
ExecutorService executor = Executors.newFixedThreadPool(addresses.size());
final List>> futures = new ArrayList>>(addresses.size());
for (InetAddress address : addresses) {
// Discover UDP packet send to multicast address
DatagramPacket out = pOutMsg.createDatagramPacket(InetAddress.getByName(JOLOKIA_MULTICAST_GROUP), JOLOKIA_MULTICAST_PORT);
Callable> findAgentsCallable = new FindAgentsCallable(address, out, pTimeout, pLogHandler);
futures.add(executor.submit(findAgentsCallable));
}
executor.shutdownNow();
return futures;
}
// All addresses which can be used for sending multicast addresses
private static List getMulticastAddresses() throws SocketException, UnknownHostException {
List addresses = NetworkUtil.getMulticastAddresses();
if (addresses.size() == 0) {
throw new UnknownHostException("Cannot find address of local host which can be used for sending discovery request");
}
return addresses;
}
// Collect the incoming messages and filter out duplicates
private static List collectIncomingMessages(int pTimeout, List>> pFutures, LogHandler pLogHandler) throws UnknownHostException {
List ret = new ArrayList();
Set seen = new HashSet();
int nrCouldntSend = 0;
for (Future> future : pFutures) {
try {
List inMsgs = future.get(pTimeout + 500 /* some additional buffer */, TimeUnit.MILLISECONDS);
for (DiscoveryIncomingMessage inMsg : inMsgs) {
AgentDetails details = inMsg.getAgentDetails();
String id = details.getAgentId();
// There can be multiples answers with the same message id
if (!seen.contains(id)) {
ret.add(inMsg);
seen.add(id);
}
}
} catch (InterruptedException exp) {
// Try next one ...
} catch (ExecutionException e) {
Throwable exp = e.getCause();
if (exp instanceof CouldntSendDiscoveryPacketException) {
nrCouldntSend++;
pLogHandler.debug("--> Couldnt send discovery message from " +
((CouldntSendDiscoveryPacketException) exp).getAddress() + ": " + exp.getCause());
}
// Didn't worked a given address, which can happen e.g. when multicast is not routed or in other cases
// throw new IOException("Error while performing a discovery call " + e,e);
pLogHandler.debug("--> Exception during lookup: " + e);
} catch (TimeoutException e) {
// Timeout occurred while waiting for the results. So we go to the next one ...
}
}
if (nrCouldntSend == pFutures.size()) {
// No a single discovery message could be send out
throw new UnknownHostException("Cannot send a single multicast recovery request on any multicast enabled interface");
}
return ret;
}
// We are using all interfaces available and try to join them
private static int joinMcGroupsOnAllNetworkInterfaces(MulticastSocket pSocket, InetSocketAddress pSocketAddress, LogHandler pLogHandler) throws IOException {
// V6: ffx8::/16
Enumeration nifs = NetworkInterface.getNetworkInterfaces();
int interfacesJoined = 0;
while (nifs.hasMoreElements()) {
NetworkInterface n = nifs.nextElement();
if (NetworkUtil.isMulticastSupported(n)) {
try {
pSocket.joinGroup(pSocketAddress, n);
interfacesJoined++;
} catch (IOException exp) {
pLogHandler.info("Cannot join multicast group on NIF " + n.getDisplayName() + ": " + exp.getMessage());
}
}
}
return interfacesJoined;
}
private static void setOutgoingInterfaceForMulticastRequest(InetAddress pAddress, MulticastSocket pSocket) throws SocketException, UnknownHostException {
NetworkInterface nif = NetworkInterface.getByInetAddress(pAddress);
if (nif != null) {
pSocket.setNetworkInterface(nif);
}
}
private static final class FindAgentsCallable implements Callable> {
private final InetAddress address;
private final DatagramPacket outPacket;
private final int timeout;
private final LogHandler logHandler;
private FindAgentsCallable(InetAddress pAddress, DatagramPacket pOutPacket, int pTimeout, LogHandler pLogHandler) {
address = pAddress;
outPacket = pOutPacket;
timeout = pTimeout;
logHandler = pLogHandler;
}
public List call() throws IOException {
final DatagramSocket socket = new DatagramSocket(0, address);
List ret = new ArrayList();
try {
socket.setSoTimeout(timeout);
logHandler.debug(address + "--> Sending");
socket.send(outPacket);
} catch (IOException exp) {
throw new CouldntSendDiscoveryPacketException(
address,
"Can't send discovery UDP packet from " + address + ": " + exp.getMessage(),
exp);
}
try {
try {
do {
byte[] buf = new byte[AbstractDiscoveryMessage.MAX_MSG_SIZE];
DatagramPacket in = new DatagramPacket(buf, buf.length);
socket.receive(in);
logHandler.debug(address + "--> Received answer from " + in.getAddress());
addIncomingMessage(ret, in);
} while (true); // Leave loop with a SocketTimeoutException in receive()
} catch (SocketTimeoutException exp) {
logHandler.debug(address + "--> Timeout");
// Expected until no responses are returned anymore
} catch (IOException exp) {
throw new IOException("Cannot receive broadcast answer on " + address + ": " + exp.getMessage(),exp);
}
return ret;
} finally {
socket.close();
}
}
private void addIncomingMessage(List ret, DatagramPacket in) {
try {
DiscoveryIncomingMessage inMsg = new DiscoveryIncomingMessage(in);
if (!inMsg.isQuery()) {
ret.add(inMsg);
}
} catch (Exception exp) {
logHandler.debug("Invalid incoming package from " + in.getAddress() + " --> " + exp + ". Ignoring");
}
}
}
private static class CouldntSendDiscoveryPacketException extends IOException {
private final InetAddress address;
public CouldntSendDiscoveryPacketException(InetAddress pAddress, String pMessage, IOException pNested) {
super(pMessage,pNested);
this.address = pAddress;
}
public InetAddress getAddress() {
return address;
}
}
}
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