Fescar example解析 - TM发送逻辑

素颜马尾好姑娘i 2022-02-13 02:15 171阅读 0赞

## 开篇 ##

这篇文章的目的主要是理清楚Fescar的TM发送部分的逻辑，从时序图和源码两个层面进行分析。

文章中间会解答两个自己阅读代码中遇到的困惑（**估计大部分人看代码的时候也会遇到这个困惑**），包括**TmRpcClient的初始化过程**和**配置加载过程**。

文章的最后会附上GlobalAction相关Request的类关系图，便于理解依赖关系。

## Fescar TM发送流程 ##

![TM Sender.jpg][]

**说明：**

*  1.DefaultGlobalTransaction执行begin/commit/rollback等调用DefaultTransactionManager。
 *  2.DefaultTransactionManager内部调用syncCall()方法，进而调用TmRpcClient的sendMsgWithResponse()方法。
 *  3.TmRpcClient调用父类AbstractRpcRemoting的sendAsyncRequest()方法构建发送队列。
 *  4.AbstractRpcRemotingClient的MergedSendRunnable线程消费发送队列构建MergedWarpMessage调用sendRequest发送。
 *  5.sendRequest()方法内部调用writeAndFlush完成消息发送。

![TmRcpClient][]  
**说明：**

*  TmRpcClient的类依赖关系图如上。
 *  TmRpcClient继承自AbstractRpcRemotingClient类。

## Fescar TM发送源码分析 ##

public class DefaultTransactionManager implements TransactionManager {
    
        private static class SingletonHolder {
            private static final TransactionManager INSTANCE = new DefaultTransactionManager();
        }
    
        /**
         * Get transaction manager.
         *
         * @return the transaction manager
         */
        public static TransactionManager get() {
            return SingletonHolder.INSTANCE;
        }
    
        private DefaultTransactionManager() {
    
        }
    
        @Override
        public String begin(String applicationId, String transactionServiceGroup, String name, int timeout) 
                throws TransactionException {
            GlobalBeginRequest request = new GlobalBeginRequest();
            request.setTransactionName(name);
            request.setTimeout(timeout);
            GlobalBeginResponse response = (GlobalBeginResponse) syncCall(request);
            return response.getXid();
        }
    
        @Override
        public GlobalStatus commit(String xid) throws TransactionException {
            long txId = XID.getTransactionId(xid);
            GlobalCommitRequest globalCommit = new GlobalCommitRequest();
            globalCommit.setTransactionId(txId);
            GlobalCommitResponse response = (GlobalCommitResponse) syncCall(globalCommit);
            return response.getGlobalStatus();
        }
    
        @Override
        public GlobalStatus rollback(String xid) throws TransactionException {
            long txId = XID.getTransactionId(xid);
            GlobalRollbackRequest globalRollback = new GlobalRollbackRequest();
            globalRollback.setTransactionId(txId);
            GlobalRollbackResponse response = (GlobalRollbackResponse) syncCall(globalRollback);
            return response.getGlobalStatus();
        }
    
        @Override
        public GlobalStatus getStatus(String xid) throws TransactionException {
            long txId = XID.getTransactionId(xid);
            GlobalStatusRequest queryGlobalStatus = new GlobalStatusRequest();
            queryGlobalStatus.setTransactionId(txId);
            GlobalStatusResponse response = (GlobalStatusResponse) syncCall(queryGlobalStatus);
            return response.getGlobalStatus();
        }
    
        private AbstractTransactionResponse syncCall(AbstractTransactionRequest request) throws TransactionException {
            try {
                return (AbstractTransactionResponse) TmRpcClient.getInstance().sendMsgWithResponse(request);
            } catch (TimeoutException toe) {
                throw new TransactionException(TransactionExceptionCode.IO, toe);
            }
        }
    }

**说明：**

*  DefaultTransactionManager的beigin/commit/rollback方法内部最终调用syncCall()方法。
 *  syncCall方法内部执行TmRpcClient.getInstance().sendMsgWithResponse(request)调用TmRpcClient方法。

public final class TmRpcClient extends AbstractRpcRemotingClient {
        @Override
        public Object sendMsgWithResponse(Object msg) throws TimeoutException {
            return sendMsgWithResponse(msg, NettyClientConfig.getRpcRequestTimeout());
        }
    
        @Override
        public Object sendMsgWithResponse(String serverAddress, Object msg, long timeout)
            throws TimeoutException {
            return sendAsyncRequestWithResponse(serverAddress, connect(serverAddress), msg, timeout);
        }
    }

**说明：**

*  TmRpcClient内部执行发送sendMsgWithResponse调用sendAsyncRequestWithResponse。
 *  sendAsyncRequestWithResponse的实现在父类AbstractRpcRemoting当中。

public abstract class AbstractRpcRemoting extends ChannelDuplexHandler {
    
        protected Object sendAsyncRequestWithResponse(String address, Channel channel, Object msg, long timeout) throws
            TimeoutException {
            if (timeout <= 0) {
                throw new FrameworkException("timeout should more than 0ms");
            }
            return sendAsyncRequest(address, channel, msg, timeout);
        }
    
        private Object sendAsyncRequest(String address, Channel channel, Object msg, long timeout)
            throws TimeoutException {
            if (channel == null) {
                LOGGER.warn("sendAsyncRequestWithResponse nothing, caused by null channel.");
                return null;
            }
    
            // 构建RpcMessage对象
            final RpcMessage rpcMessage = new RpcMessage();
            rpcMessage.setId(RpcMessage.getNextMessageId());
            rpcMessage.setAsync(false);
            rpcMessage.setHeartbeat(false);
            rpcMessage.setRequest(true);
            rpcMessage.setBody(msg);
    
            // 通过MessageFuture包装实现超时
            final MessageFuture messageFuture = new MessageFuture();
            messageFuture.setRequestMessage(rpcMessage);
            messageFuture.setTimeout(timeout);
            futures.put(rpcMessage.getId(), messageFuture);
    
            // 测试代码走的是这个分支
            if (address != null) {
                // 根据address进行hash放置到不同的Map当中
                ConcurrentHashMap<String, BlockingQueue<RpcMessage>> map = basketMap;
                BlockingQueue<RpcMessage> basket = map.get(address);
                if (basket == null) {
                    map.putIfAbsent(address, new LinkedBlockingQueue<RpcMessage>());
                    basket = map.get(address);
                }
                basket.offer(rpcMessage);
                if (LOGGER.isDebugEnabled()) {
                    LOGGER.debug("offer message: " + rpcMessage.getBody());
                }
    
                // 发送其实是另外一个线程单独执行发送操作的
                if (!isSending) {
                    synchronized (mergeLock) {
                        mergeLock.notifyAll();
                    }
                }
            } else {
                ChannelFuture future;
                channelWriteableCheck(channel, msg);
                future = channel.writeAndFlush(rpcMessage);
                future.addListener(new ChannelFutureListener() {
                    @Override
                    public void operationComplete(ChannelFuture future) {
                        if (!future.isSuccess()) {
                            MessageFuture messageFuture = futures.remove(rpcMessage.getId());
                            if (messageFuture != null) {
                                messageFuture.setResultMessage(future.cause());
                            }
                            destroyChannel(future.channel());
                        }
                    }
                });
            }
    
            // 通过Future实现限时超时机制
            if (timeout > 0) {
                try {
                    return messageFuture.get(timeout, TimeUnit.MILLISECONDS);
                } catch (Exception exx) {
                    LOGGER.error("wait response error:" + exx.getMessage() + ",ip:" + address + ",request:" + msg);
                    if (exx instanceof TimeoutException) {
                        throw (TimeoutException)exx;
                    } else {
                        throw new RuntimeException(exx);
                    }
                }
            } else {
                return null;
            }
        }
    }

**说明：**

*  构建RpcMessage对象，包装Request。
 *  构建MessageFuture对象，包装RpcMessage，实现超时等待功能。
 *  通过basket进行分桶操作，真正执行发送的代码在AbstractRpcRemotingClient类的MergedSendRunnable。
 *  Request的发送类似生成消费者模型，上述代码只是生产者部分。

public abstract class AbstractRpcRemotingClient extends AbstractRpcRemoting
        implements RemotingService, RegisterMsgListener, ClientMessageSender {
    
        public class MergedSendRunnable implements Runnable {
    
            @Override
            public void run() {
                while (true) {
                    synchronized (mergeLock) {
                        try {
                            mergeLock.wait(MAX_MERGE_SEND_MILLS);
                        } catch (InterruptedException e) {}
                    }
                    isSending = true;
                    for (String address : basketMap.keySet()) {
                        BlockingQueue<RpcMessage> basket = basketMap.get(address);
                        if (basket.isEmpty()) { continue; }
    
                        MergedWarpMessage mergeMessage = new MergedWarpMessage();
                        while (!basket.isEmpty()) {
                            RpcMessage msg = basket.poll();
                            mergeMessage.msgs.add((AbstractMessage)msg.getBody());
                            mergeMessage.msgIds.add(msg.getId());
                        }
                        if (mergeMessage.msgIds.size() > 1) {
                            printMergeMessageLog(mergeMessage);
                        }
                        Channel sendChannel = connect(address);
                        try {
                            sendRequest(sendChannel, mergeMessage);
                        } catch (FrameworkException e) {
                            if (e.getErrcode() == FrameworkErrorCode.ChannelIsNotWritable
                                && address != null) {
                                destroyChannel(address, sendChannel);
                            }
                            LOGGER.error("", "client merge call failed", e);
                        }
                    }
                    isSending = false;
                }
            }
    }

**说明：**

*  MergedSendRunnable 负责消费待发送消息体并组装成MergedWarpMessage对象。
 *  sendRequest()方法内部将MergedWarpMessage再次包装成RpcMessage进行发送。

public abstract class AbstractRpcRemoting extends ChannelDuplexHandler {
    
        protected void sendRequest(Channel channel, Object msg) {
            RpcMessage rpcMessage = new RpcMessage();
            rpcMessage.setAsync(true);
            rpcMessage.setHeartbeat(msg instanceof HeartbeatMessage);
            rpcMessage.setRequest(true);
            rpcMessage.setBody(msg);
            rpcMessage.setId(RpcMessage.getNextMessageId());
            if (msg instanceof MergeMessage) {
                mergeMsgMap.put(rpcMessage.getId(), (MergeMessage)msg);
            }
            channelWriteableCheck(channel, msg);
            if (LOGGER.isDebugEnabled()) {
                LOGGER.debug("write message:" + rpcMessage.getBody() + ", channel:" + channel + ",active?"
                    + channel.isActive() + ",writable?" + channel.isWritable() + ",isopen?" + channel.isOpen());
            }
            channel.writeAndFlush(rpcMessage);
        }
    }

**说明：**

*  RpcMessage再次包装MergeMessage进行发送。

## TmRpcClient初始化 ##

public class GlobalTransactionScanner extends AbstractAutoProxyCreator implements InitializingBean {
    
        public GlobalTransactionScanner(String applicationId, String txServiceGroup, int mode,
                                        FailureHandler failureHandlerHook) {
            setOrder(ORDER_NUM);
            setProxyTargetClass(true);
            this.applicationId = applicationId;
            this.txServiceGroup = txServiceGroup;
            this.mode = mode;
            this.failureHandlerHook = failureHandlerHook;
        }
    
        private void initClient() {
    
            TMClient.init(applicationId, txServiceGroup);
            if ((AT_MODE & mode) > 0) {
                RMClientAT.init(applicationId, txServiceGroup);
            }
        }
    
        public void afterPropertiesSet() {
            initClient();
        }
    }

**说明：**

*  GlobalTransactionScanner的构造函数执行后执行afterPropertiesSet并执行initClient()操作。
 *  initClient()内部执行TMClient.init(applicationId, txServiceGroup)进行TMClient的初始化。

public class TMClient {
        public static void init(String applicationId, String transactionServiceGroup) {
            TmRpcClient tmRpcClient = TmRpcClient.getInstance(
                     applicationId, transactionServiceGroup);
            tmRpcClient.init();
        }
    }
    
    public final class TmRpcClient extends AbstractRpcRemotingClient {
        public void init() {
            if (initialized.compareAndSet(false, true)) {
                init(SCHEDULE_INTERVAL_MILLS, SCHEDULE_INTERVAL_MILLS);
            }
        }
    
    
        public void init(long healthCheckDelay, long healthCheckPeriod) {
            // 注意initVars()方法
            initVars();
    
            ExecutorService mergeSendExecutorService = new ThreadPoolExecutor(
               MAX_MERGE_SEND_THREAD, MAX_MERGE_SEND_THREAD,
               KEEP_ALIVE_TIME, TimeUnit.MILLISECONDS, 
               new LinkedBlockingQueue<Runnable>(),
               new NamedThreadFactory(getThreadPrefix(MERGE_THREAD_PREFIX), 
                            MAX_MERGE_SEND_THREAD));
            mergeSendExecutorService.submit(new MergedSendRunnable());
            timerExecutor.scheduleAtFixedRate(new Runnable() {
                @Override
                public void run() {
                    try {
                        reconnect();
                    } catch (Exception ignore) {
                        LOGGER.error(ignore.getMessage());
                    }
                }
            }, healthCheckDelay, healthCheckPeriod, TimeUnit.SECONDS);
        }
    
    
        private void initVars() {
            enableDegrade = CONFIG.getBoolean(
            ConfigurationKeys.SERVICE_PREFIX + ConfigurationKeys.ENABLE_DEGRADE_POSTFIX);
            super.init();
        }
    }

**说明：**

*  核心在于关注initVars()方法。

public abstract class AbstractRpcRemotingClient extends AbstractRpcRemoting
        implements RemotingService, RegisterMsgListener, ClientMessageSender {
    
        public void init() {
            NettyPoolableFactory keyPoolableFactory = new NettyPoolableFactory(this);
            // 核心构建发送的对象的连接池
            nettyClientKeyPool = new GenericKeyedObjectPool(keyPoolableFactory);
            nettyClientKeyPool.setConfig(getNettyPoolConfig());
            serviceManager = new ServiceManagerStaticConfigImpl();
            super.init();
        }
    }
    
    
    public abstract class AbstractRpcRemoting extends ChannelDuplexHandler {
        public void init() {
            timerExecutor.scheduleAtFixedRate(new Runnable() {
                @Override
                public void run() {
                    List<MessageFuture> timeoutMessageFutures = new ArrayList<MessageFuture>(futures.size());
    
                    for (MessageFuture future : futures.values()) {
                        if (future.isTimeout()) {
                            timeoutMessageFutures.add(future);
                        }
                    }
    
                    for (MessageFuture messageFuture : timeoutMessageFutures) {
                        futures.remove(messageFuture.getRequestMessage().getId());
                        messageFuture.setResultMessage(null);
                        if (LOGGER.isDebugEnabled()) {
                            LOGGER.debug("timeout clear future : " + messageFuture.getRequestMessage().getBody());
                        }
                    }
                    nowMills = System.currentTimeMillis();
                }
            }, TIMEOUT_CHECK_INTERNAL, TIMEOUT_CHECK_INTERNAL, TimeUnit.MILLISECONDS);
        }
    }

**说明：**

*  AbstractRpcRemotingClient的init()方法核心构建nettyClientKeyPool工厂。
 *  nettyClientKeyPool用于获取连接TC的对象的工厂池。

## 配置加载分析 ##

![Config][]

public class FileConfiguration implements Configuration {
    
        private static final Logger LOGGER = LoggerFactory.getLogger(FileConfiguration.class);
    
        private static final Config CONFIG = ConfigFactory.load();
    }
    
    
    package com.typesafe.config;
    public final class ConfigFactory {
        private ConfigFactory() {
        }
    
        public static Config load() {
            return load(ConfigParseOptions.defaults());
        }
    }

**说明：**

*  配置加载使用了[JAVA 配置管理库 typesafe.config][JAVA _ typesafe.config]
 *  默认加载classpath下的application.conf,application.json和application.properties文件。通过ConfigFactory.load()加载。

## Request的类关系图 ##

![GlobalActionRequest.png][]

[TM Sender.jpg]: /images/20220213/9c0c498bb0b949e59d0523b485dad8e4.png
[TmRcpClient]: /images/20220213/122cbd096bdb4ae19e137050b60a37b0.png
[Config]: /images/20220213/b6a4bdbd4f804566bab4f11fc4482b2f.png
[JAVA _ typesafe.config]: https://blog.csdn.net/u010039929/article/details/76215687
[GlobalActionRequest.png]: /images/20220213/d40b4e13117b429197c1eb2814a9ab70.png