/**
* 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.http;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.activemq.Service;
import org.apache.activemq.command.DiscoveryEvent;
import org.apache.activemq.transport.discovery.DiscoveryAgent;
import org.apache.activemq.transport.discovery.DiscoveryListener;
import org.apache.activemq.util.IntrospectionSupport;
import org.apache.commons.httpclient.HttpClient;
import org.apache.commons.httpclient.methods.DeleteMethod;
import org.apache.commons.httpclient.methods.GetMethod;
import org.apache.commons.httpclient.methods.PutMethod;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class HTTPDiscoveryAgent implements DiscoveryAgent {
private static final Log LOG = LogFactory.getLog(HTTPDiscoveryAgent.class);
private String registryURL = "http://localhost:8080/discovery-registry/default";
private HttpClient httpClient = new HttpClient();
private AtomicBoolean running=new AtomicBoolean();
private final AtomicReference<DiscoveryListener> discoveryListener = new AtomicReference<DiscoveryListener>();
private final HashSet<String> registeredServices = new HashSet<String>();
private final HashMap<String, SimpleDiscoveryEvent> discoveredServices = new HashMap<String, SimpleDiscoveryEvent>();
private Thread thread;
private long updateInterval = 1000*10;
private String brokerName;
private boolean startEmbeddRegistry=false;
private Service jetty;
private AtomicInteger startCounter=new AtomicInteger(0);
private long initialReconnectDelay = 1000;
private long maxReconnectDelay = 1000 * 30;
private long backOffMultiplier = 2;
private boolean useExponentialBackOff=true;
private int maxReconnectAttempts;
private final Object sleepMutex = new Object();
private long minConnectTime = 5000;
class SimpleDiscoveryEvent extends DiscoveryEvent {
private int connectFailures;
private long reconnectDelay = initialReconnectDelay;
private long connectTime = System.currentTimeMillis();
private AtomicBoolean failed = new AtomicBoolean(false);
private AtomicBoolean removed = new AtomicBoolean(false);
public SimpleDiscoveryEvent(String service) {
super(service);
}
}
public String getGroup() {
return null;
}
public void registerService(String service) throws IOException {
synchronized(registeredServices) {
registeredServices.add(service);
}
doRegister(service);
}
synchronized private void doRegister(String service) {
String url = registryURL;
try {
PutMethod method = new PutMethod(url);
// method.setParams(createParams());
method.setRequestHeader("service", service);
int responseCode = httpClient.executeMethod(method);
LOG.debug("PUT to "+url+" got a "+responseCode);
} catch (Exception e) {
LOG.debug("PUT to "+url+" failed with: "+e);
}
}
synchronized private void doUnRegister(String service) {
String url = registryURL;
try {
DeleteMethod method = new DeleteMethod(url);
// method.setParams(createParams());
method.setRequestHeader("service", service);
int responseCode = httpClient.executeMethod(method);
LOG.debug("DELETE to "+url+" got a "+responseCode);
} catch (Exception e) {
LOG.debug("DELETE to "+url+" failed with: "+e);
}
}
// private HttpMethodParams createParams() {
// HttpMethodParams params = new HttpMethodParams();
// params.setParameter(HttpMethodParams.RETRY_HANDLER, new DefaultHttpMethodRetryHandler(0,false));
// return params;
// }
synchronized private Set<String> doLookup(long freshness) {
String url = registryURL+"?freshness="+freshness;
try {
GetMethod method = new GetMethod(url);
// method.setParams(createParams());
int responseCode = httpClient.executeMethod(method);
LOG.debug("GET to "+url+" got a "+responseCode);
if( responseCode == 200 ) {
Set<String> rc = new HashSet<String>();
Scanner scanner = new Scanner(method.getResponseBodyAsStream());
while( scanner.hasNextLine() ) {
String service = scanner.nextLine();
if( service.trim().length() != 0 ) {
rc.add(service);
}
}
return rc;
} else {
LOG.debug("GET to "+url+" failed with response code: "+responseCode);
return null;
}
} catch (Exception e) {
LOG.debug("GET to "+url+" failed with: "+e);
return null;
}
}
public void serviceFailed(DiscoveryEvent devent) throws IOException {
final SimpleDiscoveryEvent event = (SimpleDiscoveryEvent)devent;
if (event.failed.compareAndSet(false, true)) {
discoveryListener.get().onServiceRemove(event);
if(!event.removed.get()) {
// Setup a thread to re-raise the event...
Thread thread = new Thread() {
public void run() {
// We detect a failed connection attempt because the service
// fails right away.
if (event.connectTime + minConnectTime > System.currentTimeMillis()) {
LOG.debug("Failure occured soon after the discovery event was generated. It will be clasified as a connection failure: "+event);
event.connectFailures++;
if (maxReconnectAttempts > 0 && event.connectFailures >= maxReconnectAttempts) {
LOG.debug("Reconnect attempts exceeded "+maxReconnectAttempts+" tries. Reconnecting has been disabled.");
return;
}
synchronized (sleepMutex) {
try {
if (!running.get() || event.removed.get()) {
return;
}
LOG.debug("Waiting "+event.reconnectDelay+" ms before attepting to reconnect.");
sleepMutex.wait(event.reconnectDelay);
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
return;
}
}
if (!useExponentialBackOff) {
event.reconnectDelay = initialReconnectDelay;
} else {
// Exponential increment of reconnect delay.
event.reconnectDelay *= backOffMultiplier;
if (event.reconnectDelay > maxReconnectDelay) {
event.reconnectDelay = maxReconnectDelay;
}
}
} else {
event.connectFailures = 0;
event.reconnectDelay = initialReconnectDelay;
}
if (!running.get() || event.removed.get()) {
return;
}
event.connectTime = System.currentTimeMillis();
event.failed.set(false);
discoveryListener.get().onServiceAdd(event);
}
};
thread.setDaemon(true);
thread.start();
}
}
}
public void setBrokerName(String brokerName) {
this.brokerName = brokerName;
}
public void setDiscoveryListener(DiscoveryListener discoveryListener) {
this.discoveryListener.set(discoveryListener);
}
public void setGroup(String group) {
}
public void start() throws Exception {
if( startCounter.addAndGet(1)==1 ) {
if( startEmbeddRegistry ) {
jetty = createEmbeddedJettyServer();
Map props = new HashMap();
props.put("agent", this);
IntrospectionSupport.setProperties(jetty, props);
jetty.start();
}
running.set(true);
thread = new Thread("HTTPDiscovery Agent") {
@Override
public void run() {
while(running.get()) {
try {
update();
Thread.sleep(updateInterval);
} catch (InterruptedException e) {
return;
}
}
}
};
thread.setDaemon(true);
thread.start();
}
}
/**
* Create the EmbeddedJettyServer instance via reflection so that we can avoid a hard runtime dependency on
* jetty.
*
* @return
* @throws Exception
*/
private Service createEmbeddedJettyServer() throws Exception {
Class clazz = HTTPDiscoveryAgent.class.getClassLoader().loadClass("org.apache.activemq.transport.discovery.http.EmbeddedJettyServer");
return (Service)clazz.newInstance();
}
private void update() {
// Register all our services...
synchronized(registeredServices) {
for (String service : registeredServices) {
doRegister(service);
}
}
// Find new registered services...
DiscoveryListener discoveryListener = this.discoveryListener.get();
if(discoveryListener!=null) {
Set<String> activeServices = doLookup(updateInterval*3);
// If there is error talking the the central server, then activeServices == null
if( activeServices !=null ) {
synchronized(discoveredServices) {
HashSet<String> removedServices = new HashSet<String>(discoveredServices.keySet());
removedServices.removeAll(activeServices);
HashSet<String> addedServices = new HashSet<String>(activeServices);
addedServices.removeAll(discoveredServices.keySet());
addedServices.removeAll(removedServices);
for (String service : addedServices) {
SimpleDiscoveryEvent e = new SimpleDiscoveryEvent(service);
discoveredServices.put(service, e);
discoveryListener.onServiceAdd(e);
}
for (String service : removedServices) {
SimpleDiscoveryEvent e = discoveredServices.remove(service);
if( e !=null ) {
e.removed.set(true);
}
discoveryListener.onServiceRemove(e);
}
}
}
}
}
public void stop() throws Exception {
if( startCounter.decrementAndGet()==0 ) {
running.set(false);
if( thread!=null ) {
thread.join(updateInterval*3);
thread=null;
}
if( jetty!=null ) {
jetty.stop();
jetty = null;
}
}
}
public String getRegistryURL() {
return registryURL;
}
public void setRegistryURL(String discoveryRegistryURL) {
this.registryURL = discoveryRegistryURL;
}
public long getUpdateInterval() {
return updateInterval;
}
public void setUpdateInterval(long updateInterval) {
this.updateInterval = updateInterval;
}
public boolean isStartEmbeddRegistry() {
return startEmbeddRegistry;
}
public void setStartEmbeddRegistry(boolean startEmbeddRegistry) {
this.startEmbeddRegistry = startEmbeddRegistry;
}
}