/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.transport.discovery.multicast;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.MulticastSocket;
import java.net.SocketAddress;
import java.net.SocketTimeoutException;
import java.net.URI;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.activemq.command.DiscoveryEvent;
import org.apache.activemq.transport.discovery.DiscoveryAgent;
import org.apache.activemq.transport.discovery.DiscoveryListener;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A {@link DiscoveryAgent} using a multicast address and heartbeat packets
* encoded using any wireformat, but openwire by default.
*
* @version $Revision$
*/
public class MulticastDiscoveryAgent implements DiscoveryAgent, Runnable {
public static final String DEFAULT_DISCOVERY_URI_STRING = "multicast://239.255.2.3:6155";
public static final String DEFAULT_HOST_STR = "default";
public static final String DEFAULT_HOST_IP = System.getProperty("activemq.partition.discovery", "239.255.2.3");
public static final int DEFAULT_PORT = 6155;
private static final Log LOG = LogFactory.getLog(MulticastDiscoveryAgent.class);
private static final String TYPE_SUFFIX = "ActiveMQ-4.";
private static final String ALIVE = "alive.";
private static final String DEAD = "dead.";
private static final String DELIMITER = "%";
private static final int BUFF_SIZE = 8192;
private static final int DEFAULT_IDLE_TIME = 500;
private static final int HEARTBEAT_MISS_BEFORE_DEATH = 10;
private long initialReconnectDelay = 1000 * 5;
private long maxReconnectDelay = 1000 * 30;
private long backOffMultiplier = 2;
private boolean useExponentialBackOff;
private int maxReconnectAttempts;
class RemoteBrokerData {
final String brokerName;
final String service;
long lastHeartBeat;
long recoveryTime;
int failureCount;
boolean failed;
public RemoteBrokerData(String brokerName, String service) {
this.brokerName = brokerName;
this.service = service;
this.lastHeartBeat = System.currentTimeMillis();
}
public synchronized void updateHeartBeat() {
lastHeartBeat = System.currentTimeMillis();
// Consider that the broker recovery has succeeded if it has not
// failed in 60 seconds.
if (!failed && failureCount > 0 && (lastHeartBeat - recoveryTime) > 1000 * 60) {
if (LOG.isDebugEnabled()) {
LOG.debug("I now think that the " + service + " service has recovered.");
}
failureCount = 0;
recoveryTime = 0;
}
}
public synchronized long getLastHeartBeat() {
return lastHeartBeat;
}
public synchronized boolean markFailed() {
if (!failed) {
failed = true;
failureCount++;
long reconnectDelay;
if (!useExponentialBackOff) {
reconnectDelay = initialReconnectDelay;
} else {
reconnectDelay = (long)Math.pow(backOffMultiplier, failureCount);
if (reconnectDelay > maxReconnectDelay) {
reconnectDelay = maxReconnectDelay;
}
}
if (LOG.isDebugEnabled()) {
LOG.debug("Remote failure of " + service + " while still receiving multicast advertisements. Advertising events will be suppressed for " + reconnectDelay
+ " ms, the current failure count is: " + failureCount);
}
recoveryTime = System.currentTimeMillis() + reconnectDelay;
return true;
}
return false;
}
/**
* @return true if this broker is marked failed and it is now the right
* time to start recovery.
*/
public synchronized boolean doRecovery() {
if (!failed) {
return false;
}
// Are we done trying to recover this guy?
if (maxReconnectAttempts > 0 && failureCount > maxReconnectAttempts) {
if (LOG.isDebugEnabled()) {
LOG.debug("Max reconnect attempts of the " + service + " service has been reached.");
}
return false;
}
// Is it not yet time?
if (System.currentTimeMillis() < recoveryTime) {
return false;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Resuming event advertisement of the " + service + " service.");
}
failed = false;
return true;
}
public boolean isFailed() {
return failed;
}
}
private int timeToLive = 1;
private boolean loopBackMode;
private Map<String, RemoteBrokerData> brokersByService = new ConcurrentHashMap<String, RemoteBrokerData>();
private String group = "default";
private URI discoveryURI;
private InetAddress inetAddress;
private SocketAddress sockAddress;
private DiscoveryListener discoveryListener;
private String selfService;
private MulticastSocket mcast;
private Thread runner;
private long keepAliveInterval = DEFAULT_IDLE_TIME;
private long lastAdvertizeTime;
private AtomicBoolean started = new AtomicBoolean(false);
private boolean reportAdvertizeFailed = true;
private final Executor executor = new ThreadPoolExecutor(1, 1, 30, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new ThreadFactory() {
public Thread newThread(Runnable runable) {
Thread t = new Thread(runable, "Multicast Discovery Agent Notifier");
t.setDaemon(true);
return t;
}
});
/**
* Set the discovery listener
*
* @param listener
*/
public void setDiscoveryListener(DiscoveryListener listener) {
this.discoveryListener = listener;
}
/**
* register a service
*/
public void registerService(String name) throws IOException {
this.selfService = name;
if (started.get()) {
doAdvertizeSelf();
}
}
/**
* @return Returns the loopBackMode.
*/
public boolean isLoopBackMode() {
return loopBackMode;
}
/**
* @param loopBackMode The loopBackMode to set.
*/
public void setLoopBackMode(boolean loopBackMode) {
this.loopBackMode = loopBackMode;
}
/**
* @return Returns the timeToLive.
*/
public int getTimeToLive() {
return timeToLive;
}
/**
* @param timeToLive The timeToLive to set.
*/
public void setTimeToLive(int timeToLive) {
this.timeToLive = timeToLive;
}
/**
* @return the discoveryURI
*/
public URI getDiscoveryURI() {
return discoveryURI;
}
/**
* Set the discoveryURI
*
* @param discoveryURI
*/
public void setDiscoveryURI(URI discoveryURI) {
this.discoveryURI = discoveryURI;
}
public long getKeepAliveInterval() {
return keepAliveInterval;
}
public void setKeepAliveInterval(long keepAliveInterval) {
this.keepAliveInterval = keepAliveInterval;
}
/**
* start the discovery agent
*
* @throws Exception
*/
public void start() throws Exception {
if (started.compareAndSet(false, true)) {
if (group == null || group.length() == 0) {
throw new IOException("You must specify a group to discover");
}
String type = getType();
if (!type.endsWith(".")) {
LOG.warn("The type '" + type + "' should end with '.' to be a valid Discovery type");
type += ".";
}
if (discoveryURI == null) {
discoveryURI = new URI(DEFAULT_DISCOVERY_URI_STRING);
}
if (LOG.isTraceEnabled())
LOG.trace("start - discoveryURI = " + discoveryURI);
String myHost = discoveryURI.getHost();
int myPort = discoveryURI.getPort();
if( DEFAULT_HOST_STR.equals(myHost) )
myHost = DEFAULT_HOST_IP;
if(myPort < 0 )
myPort = DEFAULT_PORT;
if (LOG.isTraceEnabled()) {
LOG.trace("start - myHost = " + myHost);
LOG.trace("start - myPort = " + myPort);
LOG.trace("start - group = " + group );
}
this.inetAddress = InetAddress.getByName(myHost);
this.sockAddress = new InetSocketAddress(this.inetAddress, myPort);
mcast = new MulticastSocket(myPort);
mcast.setLoopbackMode(loopBackMode);
mcast.setTimeToLive(getTimeToLive());
mcast.joinGroup(inetAddress);
mcast.setSoTimeout((int)keepAliveInterval);
runner = new Thread(this);
runner.setName("MulticastDiscovery: " + selfService);
runner.setDaemon(true);
runner.start();
doAdvertizeSelf();
}
}
/**
* stop the channel
*
* @throws Exception
*/
public void stop() throws Exception {
if (started.compareAndSet(true, false)) {
doAdvertizeSelf();
if (mcast != null) {
mcast.close();
}
}
}
public String getType() {
return group + "." + TYPE_SUFFIX;
}
public void run() {
byte[] buf = new byte[BUFF_SIZE];
DatagramPacket packet = new DatagramPacket(buf, 0, buf.length);
while (started.get()) {
doTimeKeepingServices();
try {
mcast.receive(packet);
if (packet.getLength() > 0) {
String str = new String(packet.getData(), packet.getOffset(), packet.getLength());
processData(str);
}
} catch (SocketTimeoutException se) {
// ignore
} catch (IOException e) {
if (started.get()) {
LOG.error("failed to process packet: " + e);
}
}
}
}
private void processData(String str) {
if (discoveryListener != null) {
if (str.startsWith(getType())) {
String payload = str.substring(getType().length());
if (payload.startsWith(ALIVE)) {
String brokerName = getBrokerName(payload.substring(ALIVE.length()));
String service = payload.substring(ALIVE.length() + brokerName.length() + 2);
processAlive(brokerName, service);
} else {
String brokerName = getBrokerName(payload.substring(DEAD.length()));
String service = payload.substring(DEAD.length() + brokerName.length() + 2);
processDead(service);
}
}
}
}
private void doTimeKeepingServices() {
if (started.get()) {
long currentTime = System.currentTimeMillis();
if (currentTime < lastAdvertizeTime || ((currentTime - keepAliveInterval) > lastAdvertizeTime)) {
doAdvertizeSelf();
lastAdvertizeTime = currentTime;
}
doExpireOldServices();
}
}
private void doAdvertizeSelf() {
if (selfService != null) {
String payload = getType();
payload += started.get() ? ALIVE : DEAD;
payload += DELIMITER + "localhost" + DELIMITER;
payload += selfService;
try {
byte[] data = payload.getBytes();
DatagramPacket packet = new DatagramPacket(data, 0, data.length, sockAddress);
mcast.send(packet);
} catch (IOException e) {
// If a send fails, chances are all subsequent sends will fail
// too.. No need to keep reporting the
// same error over and over.
if (reportAdvertizeFailed) {
reportAdvertizeFailed = false;
LOG.error("Failed to advertise our service: " + payload, e);
if ("Operation not permitted".equals(e.getMessage())) {
LOG.error("The 'Operation not permitted' error has been know to be caused by improper firewall/network setup. "
+ "Please make sure that the OS is properly configured to allow multicast traffic over: " + mcast.getLocalAddress());
}
}
}
}
}
private void processAlive(String brokerName, String service) {
if (selfService == null || !service.equals(selfService)) {
RemoteBrokerData data = brokersByService.get(service);
if (data == null) {
data = new RemoteBrokerData(brokerName, service);
brokersByService.put(service, data);
fireServiceAddEvent(data);
doAdvertizeSelf();
} else {
data.updateHeartBeat();
if (data.doRecovery()) {
fireServiceAddEvent(data);
}
}
}
}
private void processDead(String service) {
if (!service.equals(selfService)) {
RemoteBrokerData data = brokersByService.remove(service);
if (data != null && !data.isFailed()) {
fireServiceRemovedEvent(data);
}
}
}
private void doExpireOldServices() {
long expireTime = System.currentTimeMillis() - (keepAliveInterval * HEARTBEAT_MISS_BEFORE_DEATH);
for (Iterator<RemoteBrokerData> i = brokersByService.values().iterator(); i.hasNext();) {
RemoteBrokerData data = i.next();
if (data.getLastHeartBeat() < expireTime) {
processDead(data.service);
}
}
}
private String getBrokerName(String str) {
String result = null;
int start = str.indexOf(DELIMITER);
if (start >= 0) {
int end = str.indexOf(DELIMITER, start + 1);
result = str.substring(start + 1, end);
}
return result;
}
public void serviceFailed(DiscoveryEvent event) throws IOException {
RemoteBrokerData data = brokersByService.get(event.getServiceName());
if (data != null && data.markFailed()) {
fireServiceRemovedEvent(data);
}
}
private void fireServiceRemovedEvent(RemoteBrokerData data) {
if (discoveryListener != null) {
final DiscoveryEvent event = new DiscoveryEvent(data.service);
event.setBrokerName(data.brokerName);
// Have the listener process the event async so that
// he does not block this thread since we are doing time sensitive
// processing of events.
executor.execute(new Runnable() {
public void run() {
DiscoveryListener discoveryListener = MulticastDiscoveryAgent.this.discoveryListener;
if (discoveryListener != null) {
discoveryListener.onServiceRemove(event);
}
}
});
}
}
private void fireServiceAddEvent(RemoteBrokerData data) {
if (discoveryListener != null) {
final DiscoveryEvent event = new DiscoveryEvent(data.service);
event.setBrokerName(data.brokerName);
// Have the listener process the event async so that
// he does not block this thread since we are doing time sensitive
// processing of events.
executor.execute(new Runnable() {
public void run() {
DiscoveryListener discoveryListener = MulticastDiscoveryAgent.this.discoveryListener;
if (discoveryListener != null) {
discoveryListener.onServiceAdd(event);
}
}
});
}
}
public long getBackOffMultiplier() {
return backOffMultiplier;
}
public void setBackOffMultiplier(long backOffMultiplier) {
this.backOffMultiplier = backOffMultiplier;
}
public long getInitialReconnectDelay() {
return initialReconnectDelay;
}
public void setInitialReconnectDelay(long initialReconnectDelay) {
this.initialReconnectDelay = initialReconnectDelay;
}
public int getMaxReconnectAttempts() {
return maxReconnectAttempts;
}
public void setMaxReconnectAttempts(int maxReconnectAttempts) {
this.maxReconnectAttempts = maxReconnectAttempts;
}
public long getMaxReconnectDelay() {
return maxReconnectDelay;
}
public void setMaxReconnectDelay(long maxReconnectDelay) {
this.maxReconnectDelay = maxReconnectDelay;
}
public boolean isUseExponentialBackOff() {
return useExponentialBackOff;
}
public void setUseExponentialBackOff(boolean useExponentialBackOff) {
this.useExponentialBackOff = useExponentialBackOff;
}
public void setGroup(String group) {
this.group = group;
}
}