心跳检测的概念

在分布式架构中,比如Hadoop集群,Storm集群等,或多或少都涉及到Master/Slave的概念,往往是一个或者多个Master和N个Slave之间进行通信。那么通常Master应该需要知道Slave的状态,Slave会定时的向Master进行发送消息,相当于告知Master:“我还活着,我现在在做什么,什么进度,我的CPU/内存情况如何”等,这就是所谓的心跳。Master根据Slave的心跳,进行协调,比如Slave的CPU/内存消耗很大,那么Master可以将任务分配给其他负载小的Slave进行处理;比如Slave一段时间没有发送心跳过来,那么Master可能会将可服务列表中暂时删除该Slave,并可能发出报警,告知运维/开发人员进行处理.如下图所示。

wKiom1iWwz-y9e5cAABXb5p25Bs315.png



Netty实现心跳检测代码实例


心跳信息对象

主要储存Slave的IP,通信PORT,时间,内存,CPU信息等。

package day4;

import java.io.Serializable;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

/**
 * Created by zhangfengzhe on 2017/2/4.
 */
public class HeartInfo implements Serializable{

    private String ip;

    private int port;

    private Date lasttime;

    private Map<String , String> cpuInfo = new HashMap<String,String>();

    private Map<String , String> memInfo = new HashMap<String, String>();

    public String getIp() {
        return ip;
    }

    public void setIp(String ip) {
        this.ip = ip;
    }

    public int getPort() {
        return port;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public Date getLasttime() {
        return lasttime;
    }

    public void setLasttime(Date lasttime) {
        this.lasttime = lasttime;
    }

    public Map<String, String> getCpuInfo() {
        return cpuInfo;
    }

    public void setCpuInfo(Map<String, String> cpuInfo) {
        this.cpuInfo = cpuInfo;
    }

    public Map<String, String> getMemInfo() {
        return memInfo;
    }

    public void setMemInfo(Map<String, String> memInfo) {
        this.memInfo = memInfo;
    }

    @Override
    public String toString() {
        return "HeartInfo{" +
                "ip='" + ip + '\'' +
                ", port=" + port +
                ", lasttime=" + lasttime +
                ", cpuInfo=" + cpuInfo +
                ", memInfo=" + memInfo +
                '}';
    }
}


JBoss Marshalling编解码处理器

package day3;

import io.netty.handler.codec.marshalling.DefaultMarshallerProvider;
import io.netty.handler.codec.marshalling.DefaultUnmarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallingDecoder;
import io.netty.handler.codec.marshalling.MarshallingEncoder;
import io.netty.handler.codec.marshalling.UnmarshallerProvider;

import org.jboss.marshalling.MarshallerFactory;
import org.jboss.marshalling.Marshalling;
import org.jboss.marshalling.MarshallingConfiguration;

/**
 * Marshalling工厂
 */
public final class MarshallingCodeCFactory {

    /**
     * 创建Jboss Marshalling解码器MarshallingDecoder
     * @return MarshallingDecoder
     */
    public static MarshallingDecoder buildMarshallingDecoder() {
       //首先通过Marshalling工具类的精通方法获取Marshalling实例对象 参数serial标识创建的是java序列化工厂对象。
      final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
      //创建了MarshallingConfiguration对象,配置了版本号为5 
      final MarshallingConfiguration configuration = new MarshallingConfiguration();
      configuration.setVersion(5);
      //根据marshallerFactory和configuration创建provider
      UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
      //构建Netty的MarshallingDecoder对象,俩个参数分别为provider和单个消息序列化后的最大长度
      MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024);
      return decoder;
    }

    /**
     * 创建Jboss Marshalling编码器MarshallingEncoder
     * @return MarshallingEncoder
     */
    public static MarshallingEncoder buildMarshallingEncoder() {
      final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
      final MarshallingConfiguration configuration = new MarshallingConfiguration();
      configuration.setVersion(5);
      MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
      //构建Netty的MarshallingEncoder对象,MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
      MarshallingEncoder encoder = new MarshallingEncoder(provider);
      return encoder;
    }
}


Client

package day4;

import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;

public class Client {

   
   public static void main(String[] args) throws Exception{
      
      EventLoopGroup group = new NioEventLoopGroup();
      Bootstrap b = new Bootstrap();

      final int port = 8765;
      final String serverIP = "127.0.0.1";

      b.group(group)
       .channel(NioSocketChannel.class)
       .handler(new ChannelInitializer<SocketChannel>() {
         @Override
         protected void initChannel(SocketChannel sc) throws Exception {
            sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
            sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
            sc.pipeline().addLast(new ClientHandler(port));
         }
      });
      
      ChannelFuture cf = b.connect(serverIP, port).sync();

      cf.channel().closeFuture().sync();
      group.shutdownGracefully();
   }
}


Client Handler

package day4;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 * Created by zhangfengzhe on 2017/2/4.
 */
public class ClientHandler extends ChannelHandlerAdapter {

    private String ip;
    private int port;
    private ScheduledExecutorService scheduledExecutorService = Executors.newScheduledThreadPool(1);
    private ScheduledFuture<?> scheduledFuture;

    private static final String SUCCESS = "OK";

    public ClientHandler(){}

    public ClientHandler(int port) {

        this.port = port;

        //获取本机IP
        try {
            this.ip = InetAddress.getLocalHost().getHostAddress();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

    }

    //通道建立初始化时  发送信息 准备握手验证
    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        String authInfo = this.ip + ":" + this.port;

        ctx.writeAndFlush(authInfo);
    }

    //当服务器发送认证信息后,开始启动心跳发送
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        if(msg instanceof String){

            //认证成功
            if(SUCCESS.equals((String)msg)){

                this.scheduledFuture = scheduledExecutorService.scheduleWithFixedDelay(new HeartTask(ctx,ip,port),2,3, TimeUnit.SECONDS);

            }else{

                System.out.println("服务器发来消息:" + msg);
            }

        }

        ReferenceCountUtil.release(msg);

    }

    //如果出现异常 取消定时
    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {

        cause.printStackTrace();
        if(this.scheduledFuture != null){
            this.scheduledFuture.cancel(true);
            this.scheduledFuture = null;
        }

    }
}

Client和Server建立通道初始化的时候,Client会向服务器发送信息用于认证。在实际开发中,Client在发送心跳前,需要和Server端进行握手验证,会涉及到加解密,这里为了简单起见,省去了这些过程。从上面的代码也可以看到,如果服务端认证成功,那么Client会开始启动定时线程去执行任务,那么接下来,我们看看这个心跳任务。


心跳任务HeartTask

package day4;

import io.netty.channel.ChannelHandlerContext;
import org.hyperic.sigar.CpuPerc;
import org.hyperic.sigar.Mem;
import org.hyperic.sigar.Sigar;

import java.util.Date;
import java.util.Random;

/**
 * Created by zhangfengzhe on 2017/2/4.
 */
public class HeartTask implements  Runnable{

    //持有引用,方便读写操作
    private ChannelHandlerContext ctx;

    private HeartInfo heartInfo = new HeartInfo();

    public HeartTask(ChannelHandlerContext ctx, String ip, int port) {

        this.ctx = ctx;

        heartInfo.setIp(ip);
        heartInfo.setPort(port);
    }

    @Override
    public void run() {

        try{
            //利用sigar获取 内存/CPU方面的信息 ; 利用CTX给服务器端发送消息
            Sigar sigar = new Sigar();

            //内存使用信息memory
            Mem mem = sigar.getMem();
            heartInfo.getMemInfo().put("total",String.valueOf(mem.getTotal()));
            heartInfo.getMemInfo().put("used",String.valueOf(mem.getUsed()));
            heartInfo.getMemInfo().put("free",String.valueOf(mem.getFree()));


            //CPU使用信息
            CpuPerc cpuPerc = sigar.getCpuPerc();
            heartInfo.getCpuInfo().put("user",String.valueOf(cpuPerc.getUser()));
            heartInfo.getCpuInfo().put("sys",String.valueOf(cpuPerc.getSys()));
            heartInfo.getCpuInfo().put("wait",String.valueOf(cpuPerc.getWait()));
            heartInfo.getCpuInfo().put("idle",String.valueOf(cpuPerc.getIdle()));

            heartInfo.setLasttime(new Date());

            ctx.writeAndFlush(heartInfo);

        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

首先,为了方便在心跳任务中进行读写操作,HeartTask持有ChannelHandlerContext的引用。其次,为了方便收集系统的内存、CPU信息,这里使用了Sigar,也是在实际中引用非常广泛的一个工具。


Server

package day4;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;

public class Server {

   public static void main(String[] args) throws Exception{
      
      EventLoopGroup pGroup = new NioEventLoopGroup();
      EventLoopGroup cGroup = new NioEventLoopGroup();
      
      ServerBootstrap b = new ServerBootstrap();
      b.group(pGroup, cGroup)
       .channel(NioServerSocketChannel.class)
       .option(ChannelOption.SO_BACKLOG, 1024)
       //设置日志
       .handler(new LoggingHandler(LogLevel.INFO))
       .childHandler(new ChannelInitializer<SocketChannel>() {
         protected void initChannel(SocketChannel sc) throws Exception {
            sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
            sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
            sc.pipeline().addLast(new ServerHandler());
         }
      });
      
      ChannelFuture cf = b.bind(8765).sync();
      
      cf.channel().closeFuture().sync();
      pGroup.shutdownGracefully();
      cGroup.shutdownGracefully();
      
   }
}


Server Handler

package day4;

import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Created by zhangfengzhe on 2017/2/4.
 */
public class ServerHandler extends ChannelHandlerAdapter {

    //KEY: ip:port VALUE: HeartInfo
    private Map<String,HeartInfo> heartInfoMap = new HashMap<String, HeartInfo>();

    private static final List<String> authList = new ArrayList<String>();

    static {
        //从其他地方加载出来的IP列表
        authList.add("192.168.99.219:8765");
    }


    //服务器会接收到2种消息 一个是客户端初始化时发送过来的认证信息 第二个是心跳信息
    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {

        if(msg instanceof String){

            if(authList.contains(msg)){ //验证通过
                ctx.writeAndFlush("OK");
            }else{
                ctx.writeAndFlush("不在认证列表中...");
            }

        }else if(msg instanceof HeartInfo){

            System.out.println((HeartInfo)msg);

            ctx.writeAndFlush("心跳接收成功!");

            HeartInfo heartInfo = (HeartInfo)msg;
            heartInfoMap.put(heartInfo.getIp() + ":" + heartInfo.getPort(),heartInfo);
        }

    }
}


运行结果


Client端

wKioL1iWyKajZ8I3AABV5IWr6XU837.png


Server端

wKiom1iWyLPTcWUcAABo90sCbsE792.png


到这里,心跳检测就实现了,就这么简单,你会了么,See U~