RocketMQ-通信层

前言

RocketMQ的网络通信是基于Netty实现的RPC框架,这些RPC框架实现的功能都具有通用性,如sofa-bolt,分布式服务框架Dubbo,实现的网络通信模型都具有协议定义,同步请求,异步请求,单向请求,负载均衡,流控,心跳,重连等机制。

 

服务端NettyRemotingServer

通信的服务端继承NettyRemotingAbstract实现RemotingServer

public class NettyRemotingServer extends NettyRemotingAbstract implements RemotingServer

   server端实现的功能:

public interface RemotingServer extends RemotingService {
   // 注册处理器
    void registerProcessor(final int requestCode, final NettyRequestProcessor processor,
        final ExecutorService executor);
  
    void registerDefaultProcessor(final NettyRequestProcessor processor, final ExecutorService executor);

    int localListenPort();

    Pair<NettyRequestProcessor, ExecutorService> getProcessorPair(final int requestCode);

    RemotingCommand invokeSync(final Channel channel, final RemotingCommand request,
        final long timeoutMillis) throws InterruptedException, RemotingSendRequestException,
        RemotingTimeoutException;

    void invokeAsync(final Channel channel, final RemotingCommand request, final long timeoutMillis,
        final InvokeCallback invokeCallback) throws InterruptedException,
        RemotingTooMuchRequestException, RemotingTimeoutException, RemotingSendRequestException;

    void invokeOneway(final Channel channel, final RemotingCommand request, final long timeoutMillis)
        throws InterruptedException, RemotingTooMuchRequestException, RemotingTimeoutException,
        RemotingSendRequestException;
View Code

server端初始化
实现Reactor主从多线程模型,初始化3个eventloop,
private final EventLoopGroup eventLoopGroupSelector;   // 用于就绪选择,可以使Epoll或者NIO的模式。默认3个线程数
private final EventLoopGroup eventLoopGroupBoss; //作为acceptor负责与client建立连接 一个线程足够了
private DefaultEventExecutorGroup defaultEventExecutorGroup; // 工作线程池用于处理handler,默认8个线程

server端启动
初始化serverBootstrap,设置TCP参数,定义handler调用链。
@Override
    public void start() {
        // 处理handler i/o 线程组
        this.defaultEventExecutorGroup = new DefaultEventExecutorGroup(
                nettyServerConfig.getServerWorkerThreads(),
                new ThreadFactory() {

                    private AtomicInteger threadIndex = new AtomicInteger(0);

                    @Override
                    public Thread newThread(Runnable r) {
                        return new Thread(r, "NettyServerCodecThread_" + this.threadIndex.incrementAndGet());
                    }
                });
        //   对于线程池的配置  可以参考一下 Reactor  主从多线程池模型
        ServerBootstrap childHandler =
                this.serverBootstrap.group(this.eventLoopGroupBoss, this.eventLoopGroupSelector)
                        .channel(useEpoll() ? EpollServerSocketChannel.class : NioServerSocketChannel.class)
                        .option(ChannelOption.SO_BACKLOG, 1024)
                        .option(ChannelOption.SO_REUSEADDR, true)
                        .option(ChannelOption.SO_KEEPALIVE, false)
                        .childOption(ChannelOption.TCP_NODELAY, true)
                        .childOption(ChannelOption.SO_SNDBUF, nettyServerConfig.getServerSocketSndBufSize())
                        .childOption(ChannelOption.SO_RCVBUF, nettyServerConfig.getServerSocketRcvBufSize())
                        .localAddress(new InetSocketAddress(this.nettyServerConfig.getListenPort()))
                        .childHandler(new ChannelInitializer<SocketChannel>() {
                            @Override
                            public void initChannel(SocketChannel ch) throws Exception {
                                ch.pipeline().addLast(
                                        defaultEventExecutorGroup,
                                        new NettyEncoder(),
                                        new NettyDecoder(),
                                        new IdleStateHandler(0, 0, nettyServerConfig.getServerChannelMaxIdleTimeSeconds()),
                                        new NettyConnectManageHandler(),
                                        new NettyServerHandler());
                            }
                        });

        // 启用字节缓冲池
        if (nettyServerConfig.isServerPooledByteBufAllocatorEnable()) {
            childHandler.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
        }
        try {
            ChannelFuture sync = this.serverBootstrap.bind().sync();
            InetSocketAddress addr = (InetSocketAddress) sync.channel().localAddress();
            this.port = addr.getPort();
        } catch (InterruptedException e1) {
            throw new RuntimeException("this.serverBootstrap.bind().sync() InterruptedException", e1);
        }

        // 启动netty事件监听
        if (this.channelEventListener != null) {
            this.nettyEventExecutor.start();
        }

        // 定时任务处理当前响应
        this.timer.scheduleAtFixedRate(new TimerTask() {

            @Override
            public void run() {
                try {
                    NettyRemotingServer.this.scanResponseTable();
                } catch (Throwable e) {
                    log.error("scanResponseTable exception", e);
                }
            }
        }, 1000 * 3, 1000);


    }
View Code

这里面主要关注这几个handler,NettyEncoder,NettyDecoder,IdleStateHandler,NettyConnectManageHandler,NettyServerHandler,将会在下文介绍。

 

 客户端 NettyRemotingClient

public class NettyRemotingClient extends NettyRemotingAbstract implements RemotingClient 

client端实现的功能,与server端类似
public interface RemotingClient extends RemotingService {

    public void updateNameServerAddressList(final List<String> addrs);

    public List<String> getNameServerAddressList();

    public RemotingCommand invokeSync(final String addr, final RemotingCommand request,
        final long timeoutMillis) throws InterruptedException, RemotingConnectException,
        RemotingSendRequestException, RemotingTimeoutException;

    public void invokeAsync(final String addr, final RemotingCommand request, final long timeoutMillis,
        final InvokeCallback invokeCallback) throws InterruptedException, RemotingConnectException,
        RemotingTooMuchRequestException, RemotingTimeoutException, RemotingSendRequestException;

    public void invokeOneway(final String addr, final RemotingCommand request, final long timeoutMillis)
        throws InterruptedException, RemotingConnectException, RemotingTooMuchRequestException,
        RemotingTimeoutException, RemotingSendRequestException;

    public void registerProcessor(final int requestCode, final NettyRequestProcessor processor,
        final ExecutorService executor);

    public boolean isChannelWriteable(final String addr);
}
View Code

  客户端发起连接,是在发送消息的时候实时建立连接的

 

client初始化bootstrap

跟server不同的是,client需要一个eventLoopGroupWorker负责建立连接,并且初始化一个defaultEventExecutorGroup处理handler。

    @Override
    public void start() {
        this.defaultEventExecutorGroup = new DefaultEventExecutorGroup(//
            nettyClientConfig.getClientWorkerThreads(), //
            new ThreadFactory() {

                private AtomicInteger threadIndex = new AtomicInteger(0);

                @Override
                public Thread newThread(Runnable r) {
                    return new Thread(r, "NettyClientWorkerThread_" + this.threadIndex.incrementAndGet());
                }
            });

        Bootstrap handler = this.bootstrap.group(this.eventLoopGroupWorker).channel(NioSocketChannel.class)//
            .option(ChannelOption.TCP_NODELAY, true)
            .option(ChannelOption.SO_KEEPALIVE, false)
            .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, nettyClientConfig.getConnectTimeoutMillis())
            .option(ChannelOption.SO_SNDBUF, nettyClientConfig.getClientSocketSndBufSize())
            .option(ChannelOption.SO_RCVBUF, nettyClientConfig.getClientSocketRcvBufSize())
            .handler(new ChannelInitializer<SocketChannel>() {
                @Override
                public void initChannel(SocketChannel ch) throws Exception {
                    ch.pipeline().addLast(
                        defaultEventExecutorGroup,
                        new NettyEncoder(),
                        new NettyDecoder(),
                        new IdleStateHandler(0, 0, nettyClientConfig.getClientChannelMaxIdleTimeSeconds()),
                        new NettyConnectManageHandler(),
                        new NettyClientHandler());
                }
            });

        this.timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                try {
                    NettyRemotingClient.this.scanResponseTable();
                } catch (Throwable e) {
                    log.error("scanResponseTable exception", e);
                }
            }
        }, 1000 * 3, 1000);

        if (this.channelEventListener != null) {
            this.nettyEventExecutor.start();
        }
    }
View Code

相关的handler将会在下文介绍。

 

通信协议RemotingCommand

定义了远程调用的数据结构,定义了私有化协议,具体看一下这些属性:

private static final int RPC_TYPE = 0; // 0, REQUEST_COMMAND  // 1, RESPONSE_COMMAND
    private static final int RPC_ONEWAY = 1; // 0, RPC  // 1, Oneway
    /**
     * 缓存了具体的CommandCustomHeader都有哪些field
     */
    private static final Map<Class<? extends CommandCustomHeader>, Field[]> CLASS_HASH_MAP =
            new HashMap<Class<? extends CommandCustomHeader>, Field[]>();
    /**
     * 缓存具体的CommandCustomHeader对应的简单类名
     */
    private static final Map<Class, String> CANONICAL_NAME_CACHE = new HashMap<Class, String>();

    /**
     * 缓存一个field和对应的注解信息,用于后续解码后,数据的非空校验等
     */
    private static final Map<Field, Annotation> NOT_NULL_ANNOTATION_CACHE = new HashMap<Field, Annotation>();
    // 具体的请求编号
    private int code;
    private LanguageCode language = LanguageCode.JAVA;
    private int version = 0;
    // 一次rpc的请求ID
    private int opaque = requestId.getAndIncrement();
    private int flag = 0;
    // 异常信息记录在remark
    private String remark;

    //扩展字段,数据序列化前后存储结构
    private HashMap<String, String> extFields;
    
    //  数据编码之前 把customHeader中的属性转化成extFields 再序列化
    //   数据反序列化之后 存在在extFields 再装换成具体的customHeader
    private transient CommandCustomHeader customHeader;

    /**
     * 有rocketmq和json两种序列化方式,默认为json
     */
    private SerializeType serializeTypeCurrentRPC = serializeTypeConfigInThisServer;

    // 消息message,调用接口传入
    private transient byte[] body;

  

编解码

NettyEncoder

实际上就是把请求header与body的数据发送出去

ByteBuffer header = remotingCommand.encodeHeader();
            out.writeBytes(header);
            // body的编码是上面在message中序列化好的
            byte[] body = remotingCommand.getBody();
            if (body != null) {
                out.writeBytes(body);
            }

具体的编码过程:

header返回的缓冲字节结构如下:

|-- int 4byte 总长度(包括body长度)--|--int 4bytes 序列化信息--| -- headerData--|

private ByteBuffer encodeHeader(final int bodyLength) {
        //计算分配的内存大小   最前面需要四个字节,放一个int整型
        // 1> header length size  最前面放一个Int整型  占用四个字节
        int length = 4;

        // 2> header data length   这里面包含很多信息
        byte[] headerData;
        headerData = this.headerEncode();
        length += headerData.length;

        // 3> body data length
        length += bodyLength;


        //  放  总长度(4)  +   序列化类型(4)+ header的长度
        ByteBuffer result = ByteBuffer.allocate(4 + length - bodyLength);

        // 目前为止 length的值包含了  4 + headerData.length + body.length
        // length  这个值不包含 ProtocolType长度
        result.putInt(length);


        // header length  4个字节
        result.put(markProtocolType(headerData.length, serializeTypeCurrentRPC));

        // header data
        result.put(headerData);

        result.flip();

        return result;

    }

 4个字节的的整型int序列化信息,包含着一个字节的序列化code和3个字节保存一个4字节的headerLength

public static byte[] markProtocolType(int source, SerializeType type) {
        byte[] result = new byte[4];

        result[0] = type.getCode();
        result[1] = (byte) ((source >> 16) & 0xFF);
        result[2] = (byte) ((source >> 8) & 0xFF);
        result[3] = (byte) (source & 0xFF);
        return result;
    }

// 获取headerlength
public static int getHeaderLength(int length) {
return length & 0xFFFFFF;
}

 接下来看一下headerData = this.headerEncode(); 具体如何编码header的

private byte[] headerEncode() {
// 这个方法实际上就是  把自定义header类里面的字段,封装成map,放在extFields里面 以便后续序列化
        this.makeCustomHeaderToNet();
        if (SerializeType.ROCKETMQ == serializeTypeCurrentRPC) {
            return RocketMQSerializable.rocketMQProtocolEncode(this);
        } else {
// json序列化很好理解 就是 JSON.toJSONString(obj, prettyFormat);
            return RemotingSerializable.encode(this);
        }
    }

herderData在RocketMQ自定义序列化的条件下,结构是这样的,

private static int calTotalLen(int remark, int ext) {
        // int code(~32767)
        int length = 2
                // LanguageCode language
                + 1
                // int version(~32767)
                + 2
                // int opaque
                + 4
                // int flag
                + 4
                // String remark
                + 4 + remark
                // HashMap<String, String> extFields
                + 4 + ext;

        return length;

  其中ext的序列化方式是

// 都是长度加数据的方式追加
Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
        while (it.hasNext()) {
            int kvLength; // keylength(short 2)+ keybyte + valuelength(int 4) + valuebyte
            Map.Entry<String, String> entry = it.next();
            if (entry.getKey() != null && entry.getValue() != null) {
                kvLength = 2 + entry.getKey().getBytes(CHARSET_UTF8).length
                        + 4 + entry.getValue().getBytes(CHARSET_UTF8).length;
                totalLength += kvLength;
            }

 

NettyDecoder

public class NettyDecoder extends LengthFieldBasedFrameDecoder
public NettyDecoder() {
        /**
         * 1.从消息开头偏移lengthFieldOffset长度, 到达A位置
         *
         * 2.再从A位置读取lengthFieldLength长度, 到达B位置, 内容是d
         *
         * 3.再从B位置读取(d+lengthAdjustment)长度, 达到D位置
         *
         * 4.从消息开头跳过initialBytesToStrip长度到达C位置
         *
         * 5.将C位置-D位置之间的内容传送给接下来的处理器进行后续处理
         *
         * 根据编码器定义  实际上一个数据包是 4字节的序列化信息 + headerData + body
         */
        super(FRAME_MAX_LENGTH, 0, 4, 0, 4);

主要关注 RemotingCommand.decode(byteBuffer);逻辑,

public static RemotingCommand decode(final ByteBuffer byteBuffer) {
        int length = byteBuffer.limit();  // 4+ headerlength + bodylength
        int oriHeaderLen = byteBuffer.getInt();  // 4个字节   序列化方式信息
        // HeaderData长度
        int headerLength = getHeaderLength(oriHeaderLen);
        byte[] headerData = new byte[headerLength];
        byteBuffer.get(headerData);
        // 反序列化headerData
        RemotingCommand cmd = headerDecode(headerData, getProtocolType(oriHeaderLen));
        // 获取body字节
        int bodyLength = length - 4 - headerLength;
        byte[] bodyData = null;
        if (bodyLength > 0) {
            bodyData = new byte[bodyLength];
            byteBuffer.get(bodyData);
        }
        cmd.body = bodyData;

        return cmd;
    }
private static RemotingCommand headerDecode(byte[] headerData, SerializeType type) {
        switch (type) {
            case JSON: // 相对简单  这边不详细介绍了
                RemotingCommand resultJson = RemotingSerializable.decode(headerData, RemotingCommand.class);
                resultJson.setSerializeTypeCurrentRPC(type);
                return resultJson;
            case ROCKETMQ:  // 主要看一下
                RemotingCommand resultRMQ = RocketMQSerializable.rocketMQProtocolDecode(headerData);
                resultRMQ.setSerializeTypeCurrentRPC(type);
                return resultRMQ;
            default:
                break;
        }
public static RemotingCommand rocketMQProtocolDecode(final byte[] headerArray) {
        RemotingCommand cmd = new RemotingCommand();
        ByteBuffer headerBuffer = ByteBuffer.wrap(headerArray);
        // int code(~32767)
        cmd.setCode(headerBuffer.getShort());
        // LanguageCode language
        cmd.setLanguage(LanguageCode.valueOf(headerBuffer.get()));
        // int version(~32767)
        cmd.setVersion(headerBuffer.getShort());
        // int opaque
        cmd.setOpaque(headerBuffer.getInt());
        // int flag
        cmd.setFlag(headerBuffer.getInt());
        // String remark
        int remarkLength = headerBuffer.getInt();
        if (remarkLength > 0) {
            byte[] remarkContent = new byte[remarkLength];
            headerBuffer.get(remarkContent);
            cmd.setRemark(new String(remarkContent, CHARSET_UTF8));
        }

        // HashMap<String, String> extFields
        int extFieldsLength = headerBuffer.getInt();
        if (extFieldsLength > 0) {
            byte[] extFieldsBytes = new byte[extFieldsLength];
            headerBuffer.get(extFieldsBytes);
            //mapDeserialize方法会把extmap逐个解码
            cmd.setExtFields(mapDeserialize(extFieldsBytes));
        }
        return cmd;
    }

 

 

网络事件处理机制

这里主要介绍IdleStateHandler 和 NettyConnectManageHandler

IdleStateHandler

// IdleStateHandler  是netty提供的心跳机制 其本身不会发送心跳数据
// 用来检测读空闲 写空闲 还是读写空闲,根据设置的时间来触发对应的事件
// 用户自定义的handler的userEventTriggered会捕捉到空闲超时类型,用户可以
//自定义处理逻辑 比如写空闲了 可以发送心跳数据
// 设置0表示不启用设置
new IdleStateHandler(0, 0, nettyClientConfig.getClientChannelMaxIdleTimeSeconds()),

NettyConnectManageHandler

class NettyConnectManageHandler extends ChannelDuplexHandler {
        @Override
        public void connect(ChannelHandlerContext ctx, SocketAddress remoteAddress, SocketAddress localAddress,
                            ChannelPromise promise) throws Exception {
            final String local = localAddress == null ? "UNKNOWN" : RemotingHelper.parseSocketAddressAddr(localAddress);
            final String remote = remoteAddress == null ? "UNKNOWN" : RemotingHelper.parseSocketAddressAddr(remoteAddress);
            log.info("NETTY CLIENT PIPELINE: CONNECT  {} => {}", local, remote);

            super.connect(ctx, remoteAddress, localAddress, promise);

            if (NettyRemotingClient.this.channelEventListener != null) {
                NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CONNECT, remote, ctx.channel()));
            }
        }

        @Override
        public void disconnect(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY CLIENT PIPELINE: DISCONNECT {}", remoteAddress);
            closeChannel(ctx.channel());
            super.disconnect(ctx, promise);

            if (NettyRemotingClient.this.channelEventListener != null) {
                NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CLOSE, remoteAddress, ctx.channel()));
            }
        }

        @Override
        public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.info("NETTY CLIENT PIPELINE: CLOSE {}", remoteAddress);
            closeChannel(ctx.channel());
            super.close(ctx, promise);

            if (NettyRemotingClient.this.channelEventListener != null) {
                NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.CLOSE, remoteAddress, ctx.channel()));
            }
        }

        /**
         * 空闲时,客户端会主动断开连接
         * @param ctx
         * @param evt
         * @throws Exception
         */
        @Override
        public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
            if (evt instanceof IdleStateEvent) {
                IdleStateEvent event = (IdleStateEvent) evt;
                if (event.state().equals(IdleState.ALL_IDLE)) {
                    final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
                    log.warn("NETTY CLIENT PIPELINE: IDLE exception [{}]", remoteAddress);
                    closeChannel(ctx.channel());
                    if (NettyRemotingClient.this.channelEventListener != null) {
                        NettyRemotingClient.this
                                .putNettyEvent(new NettyEvent(NettyEventType.IDLE, remoteAddress, ctx.channel()));
                    }
                }
            }

            ctx.fireUserEventTriggered(evt);
        }

        @Override
        public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
            final String remoteAddress = RemotingHelper.parseChannelRemoteAddr(ctx.channel());
            log.warn("NETTY CLIENT PIPELINE: exceptionCaught {}", remoteAddress);
            log.warn("NETTY CLIENT PIPELINE: exceptionCaught exception.", cause);
            closeChannel(ctx.channel());
            if (NettyRemotingClient.this.channelEventListener != null) {
                NettyRemotingClient.this.putNettyEvent(new NettyEvent(NettyEventType.EXCEPTION, remoteAddress, ctx.channel()));
            }
        }
    }
View Code

 

读者可以发现,在每一次网络事件都会去组装一个NettyEvent的事件信息放到一个网络事件处理队列中

                        NettyRemotingClient.this
                                .putNettyEvent(new NettyEvent(NettyEventType.IDLE, remoteAddress, ctx.channel()));

这边是典型的生产者和消费者线程模型

/**
     * 这个内部类的作用:
     * 当nettyclient监听到Netty事件,比如连接  断开  异常等情况 执行客户端自定义的事件处理
     */
    class NettyEventExecutor extends ServiceThread {
        private final LinkedBlockingQueue<NettyEvent> eventQueue = new LinkedBlockingQueue<>();
        private final int maxSize = 10000;

        public void putNettyEvent(final NettyEvent event) {
            if (this.eventQueue.size() <= maxSize) {
                this.eventQueue.add(event);
            } else {
                log.warn("event queue size[{}] enough, so drop this event {}", this.eventQueue.size(), event.toString());
            }
        }

        @Override
        public String getServiceName() {
            return NettyEventExecutor.class.getSimpleName();
        }

        @Override
        public void run() {
            log.info(this.getServiceName() + " service started");
            final ChannelEventListener listener = NettyRemotingAbstract.this.getChannelEventListener();
            while (!this.isStopped()) {
                try {
                    NettyEvent event = this.eventQueue.poll(3000, TimeUnit.MILLISECONDS);
                    if (event != null && listener != null) {
                        switch (event.getType()) {
                            case IDLE:
                                listener.onChannelIdle(event.getRemoteAddr(), event.getChannel());
                                break;
                            case CLOSE:
                                listener.onChannelClose(event.getRemoteAddr(), event.getChannel());
                                break;
                            case CONNECT:
                                listener.onChannelConnect(event.getRemoteAddr(), event.getChannel());
                                break;
                            case EXCEPTION:
                                listener.onChannelException(event.getRemoteAddr(), event.getChannel());
                                break;
                            default:
                                break;

                        }
                    }
                } catch (Exception e) {
                    log.warn(this.getServiceName() + " service has exception. ", e);
                }
            }

        }
    }

这边延伸介绍一下后台线程基类ServiceThread,本身是一个runnable对象,stop方法和shutdown方法 与 waitForRunning方法 实现等待通知的模型。在后面的刷盘,数据同步等都采用这种方式

/*
 * 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.rocketmq.remoting.common;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Base class for background thread
 */
public abstract class ServiceThread implements Runnable {
    private static final Logger log = LoggerFactory.getLogger(RemotingHelper.ROCKETMQ_REMOTING);

    private static final long JOIN_TIME = 90 * 1000;
    protected final Thread thread;
    protected volatile boolean hasNotified = false;
    protected volatile boolean stopped = false;

    public ServiceThread() {
        this.thread = new Thread(this, this.getServiceName());
    }

    public abstract String getServiceName();

    public void start() {
        this.thread.start();
    }

    public void shutdown() {
        this.shutdown(false);
    }

    public void shutdown(final boolean interrupt) {
        this.stopped = true;
        log.info("shutdown thread " + this.getServiceName() + " interrupt " + interrupt);
        synchronized (this) {
            if (!this.hasNotified) {
                this.hasNotified = true;
                this.notify();
            }
        }

        try {
            if (interrupt) {
                this.thread.interrupt();
            }

            long beginTime = System.currentTimeMillis();
            this.thread.join(this.getJointime());
            long eclipseTime = System.currentTimeMillis() - beginTime;
            log.info("join thread " + this.getServiceName() + " eclipse time(ms) " + eclipseTime + " "
                    + this.getJointime());
        } catch (InterruptedException e) {
            log.error("Interrupted", e);
        }
    }

    public long getJointime() {
        return JOIN_TIME;
    }

    public void stop() {
        this.stop(false);
    }

    public void stop(final boolean interrupt) {
        this.stopped = true;
        log.info("stop thread " + this.getServiceName() + " interrupt " + interrupt);
        synchronized (this) {
            if (!this.hasNotified) {
                this.hasNotified = true;
                this.notify();
            }
        }

        if (interrupt) {
            this.thread.interrupt();
        }
    }

    public void makeStop() {
        this.stopped = true;
        log.info("makestop thread " + this.getServiceName());
    }

    public void wakeup() {
        synchronized (this) {
            if (!this.hasNotified) {
                this.hasNotified = true;
                this.notify();
            }
        }
    }

    protected void waitForRunning(long interval) {
        synchronized (this) {
            if (this.hasNotified) {
                this.hasNotified = false;
                this.onWaitEnd();
                return;
            }

            try {
                this.wait(interval);
            } catch (InterruptedException e) {
                log.error("Interrupted", e);
            } finally {
                this.hasNotified = false;
                this.onWaitEnd();
            }
        }
    }

    protected void onWaitEnd() {
    }

    public boolean isStopped() {
        return stopped;
    }
}
View Code

 

超时请求定时清除

 在client和server端还维护了一个timer的定时任务

this.timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                try {
                    NettyRemotingClient.this.scanResponseTable();
                } catch (Throwable e) {
                    log.error("scanResponseTable exception", e);
                }
            }
        }, 1000 * 3, 1000);
/**
     * <p>
     *    This method is periodically invoked to scan and expire deprecated request.
     * </p>
     */
    public void scanResponseTable() {
        final List<ResponseFuture> rfList = new LinkedList<ResponseFuture>();
        Iterator<Entry<Integer, ResponseFuture>> it = this.responseTable.entrySet().iterator();
        while (it.hasNext()) {
            Entry<Integer, ResponseFuture> next = it.next();
            ResponseFuture rep = next.getValue();
            // 停止等待超时响应 并删除缓存
            if ((rep.getBeginTimestamp() + rep.getTimeoutMillis() + 1000) <= System.currentTimeMillis()) {
                rep.release();
                it.remove();
                rfList.add(rep);
                log.warn("remove timeout request, " + rep);
            }
        }

        // 同时对超时的异步请求 执行回调
        for (ResponseFuture rf : rfList) {
            try {
                executeInvokeCallback(rf);
            } catch (Throwable e) {
                log.warn("scanResponseTable, operationComplete Exception", e);
            }
        }
    }

 

处理接收的远程数据  NettyClientHandler 和 NettyServerHandler

客户端或者服务端对接收的数据可以分两类,一个是远程服务请求操作,另外一个是远程服务响应返回。

REQUEST_COMMAND

public void processMessageReceived(ChannelHandlerContext ctx, RemotingCommand msg) throws Exception {
        final RemotingCommand cmd = msg;
        if (cmd != null) {
            switch (cmd.getType()) {
                case REQUEST_COMMAND:
                    processRequestCommand(ctx, cmd);
                    break;
                case RESPONSE_COMMAND:
                    processResponseCommand(ctx, cmd);
                    break;
                default:
                    break;
            }
        }
    }

REQUEST_COMMAND

    public void processRequestCommand(final ChannelHandlerContext ctx, final RemotingCommand cmd) {
        // 根据请求code,获取已经注册的处理器与线程池配对组
        final Pair<NettyRequestProcessor, ExecutorService> matched = this.processorTable.get(cmd.getCode());
        // 如果找不到 则使用默认处理器  在server端使用adminprocess作为默认处理器
        final Pair<NettyRequestProcessor, ExecutorService> pair = null == matched ? this.defaultRequestProcessor : matched;
        final int opaque = cmd.getOpaque();

        if (pair != null) {
            Runnable run = new Runnable() {
                @Override
                public void run() {
                    try {
                        // rpchook
                        RPCHook rpcHook = NettyRemotingAbstract.this.getRPCHook();
                        if (rpcHook != null) {
                            rpcHook.doBeforeRequest(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd);
                        }

                        // 处理请求的具体逻辑,返回RemotingCommand响应数据
                        final RemotingCommand response = pair.getObject1().processRequest(ctx, cmd);
                        if (rpcHook != null) {
                            rpcHook.doAfterResponse(RemotingHelper.parseChannelRemoteAddr(ctx.channel()), cmd, response);
                        }

                        // 对于远程过来的请求类型不是单向请求的话  则设置opaque  ResponseType
                        if (!cmd.isOnewayRPC()) {
                            if (response != null) {
                                response.setOpaque(opaque);
                                response.markResponseType();
                                try {
                                    ctx.writeAndFlush(response);
                                } catch (Throwable e) {
                                    log.error("process request over, but response failed", e);
                                    log.error(cmd.toString());
                                    log.error(response.toString());
                                }
                            } else {

                            }
                        }
                    } catch (Throwable e) {
                        log.error("process request exception", e);
                        log.error(cmd.toString());

                        if (!cmd.isOnewayRPC()) {
                            final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_ERROR, //
                                RemotingHelper.exceptionSimpleDesc(e));
                            response.setOpaque(opaque);
                            ctx.writeAndFlush(response);
                        }
                    }
                }
            };

            if (pair.getObject1().rejectRequest()) {
                final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_BUSY,
                    "[REJECTREQUEST]system busy, start flow control for a while");
                response.setOpaque(opaque);
                ctx.writeAndFlush(response);
                return;
            }

            try {
                // 把任务包装成RequestTask  submit给对应的线程池
                final RequestTask requestTask = new RequestTask(run, ctx.channel(), cmd);
                pair.getObject2().submit(requestTask);
            } catch (RejectedExecutionException e) {
                if ((System.currentTimeMillis() % 10000) == 0) {
                    log.warn(RemotingHelper.parseChannelRemoteAddr(ctx.channel()) //
                        + ", too many requests and system thread pool busy, RejectedExecutionException " //
                        + pair.getObject2().toString() //
                        + " request code: " + cmd.getCode());
                }

                if (!cmd.isOnewayRPC()) {
                    final RemotingCommand response = RemotingCommand.createResponseCommand(RemotingSysResponseCode.SYSTEM_BUSY,
                        "[OVERLOAD]system busy, start flow control for a while");
                    response.setOpaque(opaque);
                    ctx.writeAndFlush(response);
                }
            }
        } else {
            String error = " request type " + cmd.getCode() + " not supported";
            final RemotingCommand response =
                RemotingCommand.createResponseCommand(RemotingSysResponseCode.REQUEST_CODE_NOT_SUPPORTED, error);
            response.setOpaque(opaque);
            ctx.writeAndFlush(response);
            log.error(RemotingHelper.parseChannelRemoteAddr(ctx.channel()) + error);
        }
    }

RESPONSE_COMMAND

返回响应数据相对简单一些,同步本地请求的话,就直接设置返回值,如果本地是异步请求的话,使用回调线程池处理回调函数,最后在缓存中删除对应的responseFuture

public void processResponseCommand(ChannelHandlerContext ctx, RemotingCommand cmd) {
        final int opaque = cmd.getOpaque();
        final ResponseFuture responseFuture = responseTable.get(opaque);
        if (responseFuture != null) {
            responseFuture.setResponseCommand(cmd);

            responseFuture.release();

            responseTable.remove(opaque);

            if (responseFuture.getInvokeCallback() != null) {
                executeInvokeCallback(responseFuture);
            } else {
                responseFuture.putResponse(cmd);
            }
        } else {
            log.warn("receive response, but not matched any request, " + RemotingHelper.parseChannelRemoteAddr(ctx.channel()));
            log.warn(cmd.toString());
        }
    }

 

 

同步请求

1 客户端主动发起连接,如果没传addr,请求namesrv,否则获取addr对应的channel,如果channel没有在缓存中找到,则创建channel。

2 执行RpcHook

3 同步请求会创建一个ResponseFuture,并缓存起来,等到数据发送成功之后,设置发送请求成功并立刻返回。如果发送失败,则设置异常信息,并返回。

final ResponseFuture responseFuture = new ResponseFuture(opaque, timeoutMillis, null, null);
            this.responseTable.put(opaque, responseFuture);
            final SocketAddress addr = channel.remoteAddress();
            channel.writeAndFlush(request).addListener(new ChannelFutureListener() {
                @Override
                public void operationComplete(ChannelFuture f) throws Exception {
                    if (f.isSuccess()) {
                        responseFuture.setSendRequestOK(true);
                        return;
                    } else {
                        responseFuture.setSendRequestOK(false);
                    }

                    responseTable.remove(opaque);
                    responseFuture.setCause(f.cause());
                    responseFuture.putResponse(null);
                    log.warn("send a request command to channel <" + addr + "> failed.");
                }
            });

 

那么如何实现同步的呢?

接着调用下面的代码,

RemotingCommand responseCommand = responseFuture.waitResponse(timeoutMillis);

这个就得益于ResponseFuture中的countDownLatch,实现同步等待,每一个response都有有一个独立的countDownLatch,当前调用线程执行完waitResponse会等待中,等到响应回调的时候(见RESPONSE_COMMAND中的代码),会调用putResponse,将会设置返回结果,同步等待得到唤醒。

public RemotingCommand waitResponse(final long timeoutMillis) throws InterruptedException {
        this.countDownLatch.await(timeoutMillis, TimeUnit.MILLISECONDS);
        return this.responseCommand;
    }

    public void putResponse(final RemotingCommand responseCommand) {
        this.responseCommand = responseCommand;
        this.countDownLatch.countDown();
    }

最后在缓存中删除对应的ResponseFuture

 

异步请求

相对于同步请求,异步请求只有前置的rpchook,同时实现异步流控,并在发送完数据之后,释放信号量。另外调用线程不需要调用waitResponse方法同步等待,

等到响应回调的时候(见RESPONSE_COMMAND中的代码),会调用executeInvokeCallback(responseFuture);

private void executeInvokeCallback(final ResponseFuture responseFuture) {
        boolean runInThisThread = false;
        ExecutorService executor = this.getCallbackExecutor();
        if (executor != null) {
            try {
                executor.submit(new Runnable() {
                    @Override
                    public void run() {
                        try {
                            responseFuture.executeInvokeCallback();
                        } catch (Throwable e) {
                            log.warn("execute callback in executor exception, and callback throw", e);
                        }
                    }
                });
            } catch (Exception e) {
                runInThisThread = true;
                log.warn("execute callback in executor exception, maybe executor busy", e);
            }
        } else {
            runInThisThread = true;
        }

        if (runInThisThread) {
            try {
                responseFuture.executeInvokeCallback();
            } catch (Throwable e) {
                log.warn("executeInvokeCallback Exception", e);
            }
        }
    }
    /**
     * 包装回调只处理一次 ,可能存在网络回调和定时调度并行处理 使用布尔原子类能保证对个线程只处理一次
     */
    public void executeInvokeCallback() {
        if (invokeCallback != null) {
            if (this.executeCallbackOnlyOnce.compareAndSet(false, true)) {
                invokeCallback.operationComplete(this);
            }
        }
    }

 

 

单向请求

单向请求不需要同步等待,也不需要回调,其他与异步请求调用类似。

 

posted @ 2021-07-31 15:52  gaojy  阅读(153)  评论(0编辑  收藏  举报