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ActiveMQ example source code file (SimpleDiscoveryAgent.java)

This example ActiveMQ source code file (SimpleDiscoveryAgent.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - ActiveMQ tags/keywords

atomicboolean, atomicboolean, discovery, exception, io, ioexception, it, logger, net, network, object, object, simplediscoveryevent, simplediscoveryevent, string, string, threading, threads, util, waiting

The ActiveMQ SimpleDiscoveryAgent.java source code

/**
 * 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.simple;

import java.io.IOException;
import java.net.URI;
import java.util.Map;
import java.util.concurrent.SynchronousQueue;
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.thread.DefaultThreadPools;
import org.apache.activemq.transport.discovery.DiscoveryAgent;
import org.apache.activemq.transport.discovery.DiscoveryListener;
import org.apache.activemq.util.MDCHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A simple DiscoveryAgent that allows static configuration of the discovered
 * services.
 * 
 * 
 */
public class SimpleDiscoveryAgent implements DiscoveryAgent {

    private final static Logger LOG = LoggerFactory.getLogger(SimpleDiscoveryAgent.class);
    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;
    private DiscoveryListener listener;
    private String services[] = new String[] {};
    private final AtomicBoolean running = new AtomicBoolean(false);

    class SimpleDiscoveryEvent extends DiscoveryEvent {

        private int connectFailures;
        private long reconnectDelay = initialReconnectDelay;
        private long connectTime = System.currentTimeMillis();
        private AtomicBoolean failed = new AtomicBoolean(false);

        public SimpleDiscoveryEvent(String service) {
            super(service);
        }

    }

    public void setDiscoveryListener(DiscoveryListener listener) {
        this.listener = listener;
    }

    public void registerService(String name) throws IOException {
    }

    public void start() throws Exception {
        running.set(true);
        for (int i = 0; i < services.length; i++) {
            listener.onServiceAdd(new SimpleDiscoveryEvent(services[i]));
        }
    }

    public void stop() throws Exception {
        running.set(false);
        synchronized (sleepMutex) {
            sleepMutex.notifyAll();
        }
    }

    public String[] getServices() {
        return services;
    }

    public void setServices(String services) {
        this.services = services.split(",");
    }

    public void setServices(String services[]) {
        this.services = services;
    }

    public void setServices(URI services[]) {
        this.services = new String[services.length];
        for (int i = 0; i < services.length; i++) {
            this.services[i] = services[i].toString();
        }
    }

    public void serviceFailed(DiscoveryEvent devent) throws IOException {

        final SimpleDiscoveryEvent event = (SimpleDiscoveryEvent)devent;
        if (event.failed.compareAndSet(false, true)) {

            listener.onServiceRemove(event);
            final Map context = MDCHelper.getCopyOfContextMap();
            DefaultThreadPools.getDefaultTaskRunnerFactory().execute(new Runnable() {
                public void run() {

                    MDCHelper.setContextMap(context);

                    // We detect a failed connection attempt because the service
                    // fails right
                    // away.
                    if (event.connectTime + minConnectTime > System.currentTimeMillis()) {
                        LOG.debug("Failure occurred soon after the discovery event was generated.  It will be classified 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()) {
                                    return;
                                }

                                LOG.debug("Waiting "+event.reconnectDelay+" ms before attempting 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()) {
                        return;
                    }

                    event.connectTime = System.currentTimeMillis();
                    event.failed.set(false);
                    listener.onServiceAdd(event);
                }
            }, "Simple Discovery Agent");
        }
    }

    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 long getMinConnectTime() {
        return minConnectTime;
    }

    public void setMinConnectTime(long minConnectTime) {
        this.minConnectTime = minConnectTime;
    }

    public boolean isUseExponentialBackOff() {
        return useExponentialBackOff;
    }

    public void setUseExponentialBackOff(boolean useExponentialBackOff) {
        this.useExponentialBackOff = useExponentialBackOff;
    }
}

Other ActiveMQ examples (source code examples)

Here is a short list of links related to this ActiveMQ SimpleDiscoveryAgent.java source code file:

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