标签：netty 心跳检测
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。
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
Server端
到这里，心跳检测就实现了，就这么简单，你会了么，See U~
本文出自 “学海无涯 心境无限” 博客，请务必保留此出处http://zhangfengzhe.blog.51cto.com/8855103/1895031
标签：netty 心跳检测
原文地址：http://zhangfengzhe.blog.51cto.com/8855103/1895031
