源码地址：https://gitee.com/a1234567891/koalas-rpc
企业生产级百亿日PV高可用可拓展的RPC框架。理论上并发数量接近服务器带宽，客户端采用thrift协议，服务端支持netty和thrift的TThreadedSelectorServer半同步半异步线程模型，支持动态扩容，服务上下线，权重动态，可用性配置，页面流量统计，支持trace跟踪等，天然接入cat支持数据大盘展示等，持续为个人以及中小型公司提供可靠的RPC框架技术方案，贴上
1 @Override
2 public void run() {
3 try {
4 if (Epoll.isAvailable ()) {
5 bossGroup = new EpollEventLoopGroup (serverPublisher.bossThreadCount==0?AbstractKoalsServerPublisher.DEFAULT_EVENT_LOOP_THREADS:serverPublisher.bossThreadCount);
6 workerGroup = new EpollEventLoopGroup ( serverPublisher.workThreadCount==0? AbstractKoalsServerPublisher.DEFAULT_EVENT_LOOP_THREADS*2:serverPublisher.workThreadCount);
7 } else {
8 bossGroup = new NioEventLoopGroup (serverPublisher.bossThreadCount==0?AbstractKoalsServerPublisher.DEFAULT_EVENT_LOOP_THREADS:serverPublisher.bossThreadCount);
9 workerGroup = new NioEventLoopGroup ( serverPublisher.workThreadCount==0? AbstractKoalsServerPublisher.DEFAULT_EVENT_LOOP_THREADS*2:serverPublisher.workThreadCount );
10 }
11 executorService = KoalasThreadedSelectorWorkerExcutorUtil.getWorkerExecutorWithQueue (serverPublisher.koalasThreadCount==0?AbstractKoalsServerPublisher.DEFAULT_KOALAS_THREADS:serverPublisher.koalasThreadCount,serverPublisher.koalasThreadCount==0?AbstractKoalsServerPublisher.DEFAULT_KOALAS_THREADS:serverPublisher.koalasThreadCount,serverPublisher.workQueue,new KoalasDefaultThreadFactory (serverPublisher.serviceInterface.getName ()));
12
13 ServerBootstrap b = new ServerBootstrap ();
14 b.group ( bossGroup, workerGroup ).channel ( workerGroup instanceof EpollEventLoopGroup ? EpollServerSocketChannel.class : NioServerSocketChannel.class )
15 .handler ( new LoggingHandler ( LogLevel.INFO ) )
16 .childHandler ( new NettyServerInitiator (serverPublisher,executorService))
17 .option ( ChannelOption.SO_BACKLOG, 1024 )
18 .option ( ChannelOption.SO_REUSEADDR, true )
19 .option ( ChannelOption.SO_KEEPALIVE, true );
20 Channel ch = b.bind ( serverPublisher.port ).sync ().channel ();
21 Runtime.getRuntime().addShutdownHook(new Thread(){
22 @Override
23 public void run(){
24 logger.info ( "Shutdown by Runtime" );
25 if(zookeeperServer != null){
26 zookeeperServer.destroy ();
27 }
28 logger.info ( "wait for service over 3000ms" );
29 try {
30 Thread.sleep ( 3000 );
31 } catch (Exception e) {
32 }
33 if(executorService!=null){
34 executorService.shutdown ();
35 }
36 if(bossGroup != null) bossGroup.shutdownGracefully ();
37 if(workerGroup != null) workerGroup.shutdownGracefully ();
38 }
39 });
40
41 if(StringUtils.isNotEmpty ( serverPublisher.zkpath )){
42 ZookServerConfig zookServerConfig = new ZookServerConfig ( serverPublisher.zkpath,serverPublisher.serviceInterface.getName (),serverPublisher.env,serverPublisher.port,serverPublisher.weight,"netty" );
43 zookeeperServer = new ZookeeperServer ( zookServerConfig );
44 zookeeperServer.init ();
45 }
46 } catch ( Exception e){
47 logger.error ( "NettyServer start faid !",e );
48 if(bossGroup != null) bossGroup.shutdownGracefully ();
49 if(workerGroup != null) workerGroup.shutdownGracefully ();
50 }
51
52 logger.info("netty server init success server={}",serverPublisher);
53
54 }首先开启NIO服务，由系统内核来判断是否支持epoll-EpollEventLoopGroup,如果不支持epoll采用IO多路复用的方式EpollEventLoopGroup，然后声明一个用户自定义线程池，这里有不清楚的读者肯定会问，netty本身支持连接线程和IO线程，为什么还要自定义声明自定义线程池，原因是假设在IO线程池中做的业务非常复杂，大量耗时，这样就会阻塞了netty线程的IO处理速度，影响吞吐量，这也就是reactor模型的设计理念，不让业务干扰连接线程和IO读写线程。NettyServerInitiator就是实际处理的业务handle了。
1 Runtime.getRuntime().addShutdownHook(new Thread(){
2 @Override
3 public void run(){
4 logger.info ( "Shutdown by Runtime" );
5 if(zookeeperServer != null){
6 zookeeperServer.destroy ();
7 }
8 logger.info ( "wait for service over 3000ms" );
9 try {
10 Thread.sleep ( 3000 );
11 } catch (Exception e) {
12 }
13 if(executorService!=null){
14 executorService.shutdown ();
15 }
16 if(bossGroup != null) bossGroup.shutdownGracefully ();
17 if(workerGroup != null) workerGroup.shutdownGracefully ();
18 }
19 });手动关闭钩子，服务关闭的时候要主动关闭节点信息。下面来看一下hander拦截器
package netty.initializer;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.socket.SocketChannel;
import netty.hanlder.KoalasDecoder;
import netty.hanlder.KoalasEncoder;
import netty.hanlder.KoalasHandler;
import org.apache.thrift.TProcessor;
import server.config.AbstractKoalsServerPublisher;
import java.util.concurrent.ExecutorService;
/**
* Copyright (C) 2018
* All rights reserved
* User: yulong.zhang
* Date:2018年11月23日11:13:33
*/
public class NettyServerInitiator extends ChannelInitializer<SocketChannel> {
private ExecutorService executorService;
private AbstractKoalsServerPublisher serverPublisher;
public NettyServerInitiator(AbstractKoalsServerPublisher serverPublisher,ExecutorService executorService){
this.serverPublisher = serverPublisher;
this.executorService = executorService;
}
@Override
protected void initChannel(SocketChannel ch) {
ch.pipeline ().addLast ( "decoder",new KoalasDecoder () );
ch.pipeline ().addLast ( "encoder",new KoalasEncoder ());
ch.pipeline ().addLast ( "handler",new KoalasHandler (serverPublisher,executorService) );
}
}decode负责拆包。encoder负责装包，handler是真正业务处理的逻辑，所有的业务处理都在这里的线程池中运行，结果通过ChannelHandlerContext 异步的返回给client端，通过这种方式真正的实现了reactor
下面我们看看拆包处理 1 package netty.hanlder;
2
3 import io.netty.buffer.ByteBuf;
4 import io.netty.channel.ChannelHandlerContext;
5 import io.netty.handler.codec.ByteToMessageDecoder;
6 import org.slf4j.Logger;
7 import org.slf4j.LoggerFactory;
8 import server.KoalasServerPublisher;
9
10 import java.util.List;
11 /**
12 * Copyright (C) 2018
13 * All rights reserved
14 * User: yulong.zhang
15 * Date:2018年11月23日11:13:33
16 */
17 public class KoalasDecoder extends ByteToMessageDecoder {
18
19 private final static Logger logger = LoggerFactory.getLogger ( KoalasDecoder.class );
20
21 @Override
22 protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) {
23
24 try {
25 if (in.readableBytes () < 4) {
26 return;
27 }
28
29 in.markReaderIndex ();
30 byte[] b = new byte[4];
31 in.readBytes ( b );
32
33 int length = decodeFrameSize ( b );
34
35 if (in.readableBytes () < length) {
36 //reset the readerIndex
37 in.resetReaderIndex ();
38 return;
39 }
40
41 in.resetReaderIndex ();
42 ByteBuf fream = in.readRetainedSlice ( 4 + length );
43 in.resetReaderIndex ();
44
45 in.skipBytes ( 4 + length );
46 out.add ( fream );
47 } catch (Exception e) {
48 logger.error ( "decode error",e );
49 }
50
51 }
52
53 public static final int decodeFrameSize(byte[] buf) {
54 return (buf[0] & 255) << 24 | (buf[1] & 255) << 16 | (buf[2] & 255) << 8 | buf[3] & 255;
55 }
56 }通过读取四个字节的长度来决定消息体长度，然后根据消息体长度来读取所有的字节流数据。decodeFrameSize方法将四个字节流转成int类型。KoalasHandler处理器逻辑比较复杂，我们只看核心的内容，首先通过thrift解析字节流来获取transport
ByteArrayInputStream inputStream = new ByteArrayInputStream ( b );
ByteArrayOutputStream outputStream = new ByteArrayOutputStream ( );
TIOStreamTransport tioStreamTransportInput = new TIOStreamTransport ( inputStream);
TIOStreamTransport tioStreamTransportOutput = new TIOStreamTransport ( outputStream);
TKoalasFramedTransport inTransport = new TKoalasFramedTransport ( tioStreamTransportInput,2048000 );
inTransport.setReadMaxLength_ ( maxLength );
TKoalasFramedTransport outTransport = new TKoalasFramedTransport ( tioStreamTransportOutput,2048000,ifUserProtocol );最终扔到线程池里去执行，将当前IO线程释放给下一个任务。
try {
executorService.execute ( new NettyRunable ( ctx,in,out,outputStream,localTprocessor,b,privateKey,publicKey,className,methodName,koalasTrace,cat));
} catch (RejectedExecutionException e){
logger.error ( e.getMessage ()+ErrorType.THREAD+",className:" +className,e );
handlerException(b,ctx,e,ErrorType.THREAD,privateKey,publicKey,thriftNative);
}RejectedExecutionException来负责当线程池不够用的时候返回给client端异常，因为server端的业务处理能力有限，所以这里适当的做了一下服务端保护防止雪崩的问题。当发现server端有大量的RejectedExecutionException抛出，说明单机已经无法满足业务请求了，需要横向拓展机器来进行负载均衡。用户实际的业务执行是在Runable里，我们看看他到底做了什么 1 try {
2 tprocessor.process ( in,out );
3 ctx.writeAndFlush (outputStream);
4 if(transaction!=null && cat)
5 transaction.setStatus ( Transaction.SUCCESS );
6 } catch (Exception e) {
7 if(transaction!=null && cat)
8 transaction.setStatus ( e );
9 logger.error ( e.getMessage () + ErrorType.APPLICATION+",className:"+className,e );
10 handlerException(this.b,ctx,e,ErrorType.APPLICATION,privateKey,publicKey,thriftNative);
11 }通过thrift的process来执行业务逻辑，将结果通过ctx.writeAndFlush (outputStream)，返回给client端。在catch里处理当出现异常之后返回给client端异常结果。这样netty server的实现就全部结束了，thrift服务端解析相关内容我们下一篇来说，里面当中有很多细节需要读者是跟着源码阅读，如果有问题欢迎加群825199617来交流，更多spring，spring mvc，aop，jdk等源码交流等你来！
