dubbo-registry-multicast/src/main/java/com/alibaba/dubbo/registry/multicast/MulticastRegistry.java

/*
 * Copyright 1999-2011 Alibaba Group.
 *  
 * Licensed 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 com.alibaba.dubbo.registry.multicast;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.MulticastSocket;
import java.util.Arrays;
import java.util.List;

import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.common.logger.Logger;
import com.alibaba.dubbo.common.logger.LoggerFactory;
import com.alibaba.dubbo.common.utils.StringUtils;
import com.alibaba.dubbo.registry.NotifyListener;
import com.alibaba.dubbo.registry.support.CacheRegistry;

/**
 * MulticastRegistry
 * 
 * @author william.liangf
 */
public class MulticastRegistry extends CacheRegistry {

    // 日志输出
    private static final Logger logger = LoggerFactory.getLogger(MulticastRegistry.class);
    
    private static final String REGISTER = "register";

    private static final String UNREGISTER = "unregister";

    private static final String SUBSCRIBE = "subscribe";

    private static final String UNSUBSCRIBE = "unsubscribe";
    
    private final InetAddress mutilcastAddress;
    
    private final MulticastSocket mutilcastSocket;
    
    public MulticastRegistry(URL url) {
        super(url);
        if (! isMulticastAddress(url.getHost())) {
            throw new IllegalArgumentException("Invalid multicast address " + url.getHost() + ", scope: 224.0.0.0 - 239.255.255.255");
        }
        try {
            mutilcastAddress = InetAddress.getByName(url.getHost());
            mutilcastSocket = new MulticastSocket(url.getPort());
            mutilcastSocket.setLoopbackMode(false);
            mutilcastSocket.joinGroup(mutilcastAddress);
            Thread thread = new Thread(new Runnable() {
                public void run() {
                    byte[] buf = new byte[2048];
                    DatagramPacket recv = new DatagramPacket(buf, buf.length);
                    while (true) {
                        try {
                            mutilcastSocket.receive(recv);
                            String msg = new String(recv.getData()).trim();
                            int i = msg.indexOf('\n');
                            if (i > 0) {
                                msg = msg.substring(0, i).trim();
                            }
                            if (logger.isInfoEnabled()) {
                                logger.info("Receive multicast message: " + msg + " from " + recv.getSocketAddress());
                            }
                            MulticastRegistry.this.receive(msg, (InetSocketAddress) recv.getSocketAddress());
                            Arrays.fill(buf, (byte)0);
                        } catch (IOException e) {
                            logger.error(e.getMessage(), e);
                        }
                    }
                }
            }, "MulticastRegistryReceiver");
            thread.setDaemon(true);
            thread.start();
        } catch (IOException e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }
    
    private static boolean isMulticastAddress(String ip) {
        int i = ip.indexOf('.');
        if (i > 0) {
            String prefix = ip.substring(0, i);
            if (StringUtils.isInteger(prefix)) {
                int p = Integer.parseInt(prefix);
                return p >= 224 && p <= 239;
            }
        }
        return false;
    }

    private void receive(String msg, InetSocketAddress remoteAddress) {
        if (msg.startsWith(REGISTER)) {
            URL url = URL.valueOf(msg.substring(REGISTER.length()).trim());
            registered(url);
        } else if (msg.startsWith(UNREGISTER)) {
            URL url = URL.valueOf(msg.substring(UNREGISTER.length()).trim());
            unregistered(url);
        } else if (msg.startsWith(SUBSCRIBE)) {
            URL url = URL.valueOf(msg.substring(SUBSCRIBE.length()).trim());
            List<URL> urls = lookup(url);
            if (urls != null && urls.size() > 0) {
                for (URL u : urls) {
                    unicast(REGISTER + " " + u.toFullString(), url.getHost());
                }
            }
        } else if (msg.startsWith(UNSUBSCRIBE)) {
        }
    }
    
    private void broadcast(String msg) {
        if (logger.isInfoEnabled()) {
            logger.info("Send broadcast message: " + msg + " to " + mutilcastAddress + ":" + mutilcastSocket.getLocalPort());
        }
        try {
            byte[] data = (msg + "\n").getBytes();
            DatagramPacket hi = new DatagramPacket(data, data.length, mutilcastAddress, mutilcastSocket.getLocalPort());
            mutilcastSocket.send(hi);
        } catch (Exception e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }
    
    private void unicast(String msg, String host) {
        if (logger.isInfoEnabled()) {
            logger.info("Send unicast message: " + msg + " to " + host + ":" + mutilcastSocket.getLocalPort());
        }
        try {
            byte[] data = (msg + "\n").getBytes();
            DatagramPacket hi = new DatagramPacket(data, data.length, InetAddress.getByName(host), mutilcastSocket.getLocalPort());
            mutilcastSocket.send(hi);
        } catch (Exception e) {
            throw new IllegalStateException(e.getMessage(), e);
        }
    }
    
    protected void doRegister(URL url) {
        broadcast(REGISTER + " " + url.toFullString());
    }

    protected void doUnregister(URL url) {
        broadcast(UNREGISTER + " " + url.toFullString());
    }

    protected void doSubscribe(URL url, NotifyListener listener) {
        url = url.setProtocol("multicast").setHost(mutilcastAddress.getHostAddress()).setPort(mutilcastSocket.getLocalPort());
        broadcast(SUBSCRIBE + " " + url.toFullString());
        synchronized (listener) {
            try {
                listener.wait(5000);
            } catch (InterruptedException e) {
            }
        }
    }

    protected void doUnsubscribe(URL url, NotifyListener listener) {
        url = url.setProtocol("multicast").setHost(mutilcastAddress.getHostAddress()).setPort(mutilcastSocket.getLocalPort());
        broadcast(UNSUBSCRIBE + " " + url.toFullString());
    }

    public boolean isAvailable() {
        try {
            return mutilcastSocket.isConnected();
        } catch (Throwable t) {
            return false;
        }
    }

    public void destroy() {
        super.destroy();
        try {
            mutilcastSocket.close();
        } catch (Throwable t) {
            logger.warn(t.getMessage(), t);
        }
    }

}