在RocketMQ中，使用BrokerStartup作為啟動類，相較於NameServer的啟動，Broker作為RocketMQ的核心可複雜得多

【RocketMQ中NameServer的啟動原始碼分析】

主函式作為其啟動的入口：

1 public static void main(String[] args) {
2     start(createBrokerController(args));
3 }

首先通過createBrokerController方法生成Broker的控制器BrokerController

createBrokerController方法：

  1 public static BrokerController createBrokerController(String[] args) {
  2     System.setProperty(RemotingCommand.REMOTING_VERSION_KEY, Integer.toString(MQVersion.CURRENT_VERSION));
  3 
  4     if (null == System.getProperty(NettySystemConfig.COM_ROCKETMQ_REMOTING_SOCKET_SNDBUF_SIZE)) {
  5         NettySystemConfig.socketSndbufSize = 131072;
  6     }
  7 
  8     if (null == System.getProperty(NettySystemConfig.COM_ROCKETMQ_REMOTING_SOCKET_RCVBUF_SIZE)) {
  9         NettySystemConfig.socketRcvbufSize = 131072;
 10     }
 11 
 12     try {
 13         //PackageConflictDetect.detectFastjson();
 14         Options options = ServerUtil.buildCommandlineOptions(new Options());
 15         commandLine = ServerUtil.parseCmdLine("mqbroker", args, buildCommandlineOptions(options),
 16             new PosixParser());
 17         if (null == commandLine) {
 18             System.exit(-1);
 19         }
 20 
 21         final BrokerConfig brokerConfig = new BrokerConfig();
 22         final NettyServerConfig nettyServerConfig = new NettyServerConfig();
 23         final NettyClientConfig nettyClientConfig = new NettyClientConfig();
 24 
 25         nettyClientConfig.setUseTLS(Boolean.parseBoolean(System.getProperty(TLS_ENABLE,
 26             String.valueOf(TlsSystemConfig.tlsMode == TlsMode.ENFORCING))));
 27         nettyServerConfig.setListenPort(10911);
 28         final MessageStoreConfig messageStoreConfig = new MessageStoreConfig();
 29 
 30         if (BrokerRole.SLAVE == messageStoreConfig.getBrokerRole()) {
 31             int ratio = messageStoreConfig.getAccessMessageInMemoryMaxRatio() - 10;
 32             messageStoreConfig.setAccessMessageInMemoryMaxRatio(ratio);
 33         }
 34 
 35         if (commandLine.hasOption('c')) {
 36             String file = commandLine.getOptionValue('c');
 37             if (file != null) {
 38                 configFile = file;
 39                 InputStream in = new BufferedInputStream(new FileInputStream(file));
 40                 properties = new Properties();
 41                 properties.load(in);
 42 
 43                 properties2SystemEnv(properties);
 44                 MixAll.properties2Object(properties, brokerConfig);
 45                 MixAll.properties2Object(properties, nettyServerConfig);
 46                 MixAll.properties2Object(properties, nettyClientConfig);
 47                 MixAll.properties2Object(properties, messageStoreConfig);
 48 
 49                 BrokerPathConfigHelper.setBrokerConfigPath(file);
 50                 in.close();
 51             }
 52         }
 53 
 54         MixAll.properties2Object(ServerUtil.commandLine2Properties(commandLine), brokerConfig);
 55 
 56         if (null == brokerConfig.getRocketmqHome()) {
 57             System.out.printf("Please set the %s variable in your environment to match the location of the RocketMQ installation", MixAll.ROCKETMQ_HOME_ENV);
 58             System.exit(-2);
 59         }
 60 
 61         String namesrvAddr = brokerConfig.getNamesrvAddr();
 62         if (null != namesrvAddr) {
 63             try {
 64                 String[] addrArray = namesrvAddr.split(";");
 65                 for (String addr : addrArray) {
 66                     RemotingUtil.string2SocketAddress(addr);
 67                 }
 68             } catch (Exception e) {
 69                 System.out.printf(
 70                     "The Name Server Address[%s] illegal, please set it as follows, \"127.0.0.1:9876;192.168.0.1:9876\"%n",
 71                     namesrvAddr);
 72                 System.exit(-3);
 73             }
 74         }
 75 
 76         switch (messageStoreConfig.getBrokerRole()) {
 77             case ASYNC_MASTER:
 78             case SYNC_MASTER:
 79                 brokerConfig.setBrokerId(MixAll.MASTER_ID);
 80                 break;
 81             case SLAVE:
 82                 if (brokerConfig.getBrokerId() <= 0) {
 83                     System.out.printf("Slave's brokerId must be > 0");
 84                     System.exit(-3);
 85                 }
 86 
 87                 break;
 88             default:
 89                 break;
 90         }
 91 
 92         messageStoreConfig.setHaListenPort(nettyServerConfig.getListenPort() + 1);
 93         LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
 94         JoranConfigurator configurator = new JoranConfigurator();
 95         configurator.setContext(lc);
 96         lc.reset();
 97         configurator.doConfigure(brokerConfig.getRocketmqHome() + "/conf/logback_broker.xml");
 98 
 99         if (commandLine.hasOption('p')) {
100             InternalLogger console = InternalLoggerFactory.getLogger(LoggerName.BROKER_CONSOLE_NAME);
101             MixAll.printObjectProperties(console, brokerConfig);
102             MixAll.printObjectProperties(console, nettyServerConfig);
103             MixAll.printObjectProperties(console, nettyClientConfig);
104             MixAll.printObjectProperties(console, messageStoreConfig);
105             System.exit(0);
106         } else if (commandLine.hasOption('m')) {
107             InternalLogger console = InternalLoggerFactory.getLogger(LoggerName.BROKER_CONSOLE_NAME);
108             MixAll.printObjectProperties(console, brokerConfig, true);
109             MixAll.printObjectProperties(console, nettyServerConfig, true);
110             MixAll.printObjectProperties(console, nettyClientConfig, true);
111             MixAll.printObjectProperties(console, messageStoreConfig, true);
112             System.exit(0);
113         }
114 
115         log = InternalLoggerFactory.getLogger(LoggerName.BROKER_LOGGER_NAME);
116         MixAll.printObjectProperties(log, brokerConfig);
117         MixAll.printObjectProperties(log, nettyServerConfig);
118         MixAll.printObjectProperties(log, nettyClientConfig);
119         MixAll.printObjectProperties(log, messageStoreConfig);
120 
121         final BrokerController controller = new BrokerController(
122             brokerConfig,
123             nettyServerConfig,
124             nettyClientConfig,
125             messageStoreConfig);
126         // remember all configs to prevent discard
127         controller.getConfiguration().registerConfig(properties);
128 
129         boolean initResult = controller.initialize();
130         if (!initResult) {
131             controller.shutdown();
132             System.exit(-3);
133         }
134 
135         Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
136             private volatile boolean hasShutdown = false;
137             private AtomicInteger shutdownTimes = new AtomicInteger(0);
138 
139             @Override
140             public void run() {
141                 synchronized (this) {
142                     log.info("Shutdown hook was invoked, {}", this.shutdownTimes.incrementAndGet());
143                     if (!this.hasShutdown) {
144                         this.hasShutdown = true;
145                         long beginTime = System.currentTimeMillis();
146                         controller.shutdown();
147                         long consumingTimeTotal = System.currentTimeMillis() - beginTime;
148                         log.info("Shutdown hook over, consuming total time(ms): {}", consumingTimeTotal);
149                     }
150                 }
151             }
152         }, "ShutdownHook"));
153 
154         return controller;
155     } catch (Throwable e) {
156         e.printStackTrace();
157         System.exit(-1);
158     }
159 
160     return null;
161 }

這裡和NameServer中的createNamesrvController方法作用類似，對Broker所需做了一系列的配置

先設定了Netty通訊時的緩衝區大小，這裡預設是128K

接著會建立了幾個實體類
BrokerConfig，用來封裝其絕大多數基本配置資訊
NettyServerConfig，封裝了其作為對外暴露的訊息佇列伺服器的資訊
NettyClientConfig，則封裝了其作為NameServer客戶端的資訊
這裡面封裝的資訊和NameServer一個道理，都是映射了配置檔案相應的配置

然後對NettyClientConfig的TLS進行設定
讓NettyServerConfig預設監聽10911埠

緊接著建立了一個MessageStoreConfig，這個就是用來封裝Store的資訊，

MessageStoreConfig會預設配置BrokerRole為ASYNC_MASTER
Broker有三種身份，用BrokerRole列舉來表示：

1 public enum BrokerRole {
2     ASYNC_MASTER,
3     SYNC_MASTER,
4     SLAVE;
5 }

也就是非同步Master，同步Master，以及Slave

這裡會對其身份進行檢查，若是Slave，則需要調整其允許的訊息最大記憶體佔比，預設值是40，也就是說Master允許訊息最大記憶體佔用40%，而Slave則只允許30%

接著會對”-c“指令進行相應配置的載入

往後看到對namesrvAddr進行了檢查，只是簡單地檢查NameServer叢集地址資訊是否合法

往下看到有個switch塊，其根據Broker的身份，進行設定
只要是Master，將其BrokerId設為0，而Slave的BrokerId需要大於0
（一個Master可以對應多個Slave，但是一個Slave只能對應一個Master，Master與Slave的對應關係通過指定相同的BrokerName，不同的BrokerId來定義，BrokerId為0表示Master，大於0表示Slave，Master也可以部署多個）

繼續往下，這裡會對Store設定HA的監聽埠，是NettyServer偵聽埠加1

往下是對“-p”，”-m“指令進行相應配置的載入，以及日誌的相關配置

之後就會建立了一個BrokerController：

 1 public BrokerController(
 2         final BrokerConfig brokerConfig,
 3         final NettyServerConfig nettyServerConfig,
 4         final NettyClientConfig nettyClientConfig,
 5         final MessageStoreConfig messageStoreConfig
 6     ) {
 7     this.brokerConfig = brokerConfig;
 8     this.nettyServerConfig = nettyServerConfig;
 9     this.nettyClientConfig = nettyClientConfig;
10     this.messageStoreConfig = messageStoreConfig;
11     this.consumerOffsetManager = new ConsumerOffsetManager(this);
12     this.topicConfigManager = new TopicConfigManager(this);
13     this.pullMessageProcessor = new PullMessageProcessor(this);
14     this.pullRequestHoldService = new PullRequestHoldService(this);
15     this.messageArrivingListener = new NotifyMessageArrivingListener(this.pullRequestHoldService);
16     this.consumerIdsChangeListener = new DefaultConsumerIdsChangeListener(this);
17     this.consumerManager = new ConsumerManager(this.consumerIdsChangeListener);
18     this.consumerFilterManager = new ConsumerFilterManager(this);
19     this.producerManager = new ProducerManager();
20     this.clientHousekeepingService = new ClientHousekeepingService(this);
21     this.broker2Client = new Broker2Client(this);
22     this.subscriptionGroupManager = new SubscriptionGroupManager(this);
23     this.brokerOuterAPI = new BrokerOuterAPI(nettyClientConfig);
24     this.filterServerManager = new FilterServerManager(this);
25 
26     this.slaveSynchronize = new SlaveSynchronize(this);
27 
28     this.sendThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getSendThreadPoolQueueCapacity());
29     this.pullThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getPullThreadPoolQueueCapacity());
30     this.queryThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getQueryThreadPoolQueueCapacity());
31     this.clientManagerThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getClientManagerThreadPoolQueueCapacity());
32     this.consumerManagerThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getConsumerManagerThreadPoolQueueCapacity());
33     this.heartbeatThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getHeartbeatThreadPoolQueueCapacity());
34     this.endTransactionThreadPoolQueue = new LinkedBlockingQueue<Runnable>(this.brokerConfig.getEndTransactionPoolQueueCapacity());
35 
36     this.brokerStatsManager = new BrokerStatsManager(this.brokerConfig.getBrokerClusterName());
37     this.setStoreHost(new InetSocketAddress(this.getBrokerConfig().getBrokerIP1(), this.getNettyServerConfig().getListenPort()));
38 
39     this.brokerFastFailure = new BrokerFastFailure(this);
40     this.configuration = new Configuration(
41         log,
42         BrokerPathConfigHelper.getBrokerConfigPath(),
43         this.brokerConfig, this.nettyServerConfig, this.nettyClientConfig, this.messageStoreConfig
44     );
45 }

可以看到，這裡例項化了許多成員，我就不一一分析，挑幾個重要的介紹

ConsumerOffsetManager：用來管理消費者的消費訊息的進度，主要通過一張map來快取

1 private ConcurrentMap<String/* topic@group */, ConcurrentMap<Integer, Long>> offsetTable =
2         new ConcurrentHashMap<String, ConcurrentMap<Integer, Long>>(512);

由topic@group的形式構成鍵，而值中的map的Integer代表具體的哪條訊息佇列，Long表示該訊息佇列的偏移量offset

TopicConfigManager：管理Topic和訊息佇列的資訊，主要通過一張map來快取

1 private final ConcurrentMap<String, TopicConfig> topicConfigTable =
2         new ConcurrentHashMap<String, TopicConfig>(1024);
3     private final DataVersion dataVersion = new DataVersion();

鍵就是Topic，值TopicConfig用來記錄對應的訊息佇列的個數

PullMessageProcessor、PullRequestHoldService、NotifyMessageArrivingListener這三個來管理Pull訊息請求，關於Pull訊息在後續部落格再細說

ConsumerManager：管理Consumer，主要通過一張map來快取

1 private final ConcurrentMap<String/* Group */, ConsumerGroupInfo> consumerTable =
2         new ConcurrentHashMap<String, ConsumerGroupInfo>(1024);

鍵值就是Consumer的GroupName，
而ConsumerGroupInfo由如下構成：

1 private final ConcurrentMap<String/* Topic */, SubscriptionData> subscriptionTable =
2         new ConcurrentHashMap<String, SubscriptionData>();
3 private final ConcurrentMap<Channel, ClientChannelInfo> channelInfoTable =
4 new ConcurrentHashMap<Channel, ClientChannelInfo>(16);
5 private volatile ConsumeType consumeType;
6 private volatile MessageModel messageModel;        

可以看到封裝了一個subscriptionTable ，這個map記錄Topic和訂閱內容
以及一個channelInfoTable，記錄Consumer的物理連線
ConsumeType是一個列舉，表明兩種消費方式：

1 public enum ConsumeType {
2     CONSUME_ACTIVELY("PULL"),
3     CONSUME_PASSIVELY("PUSH");
4 }

MessageModel 也是一個列舉，表明兩種消費模式：

 1 public enum MessageModel {
 2     /**
 3      * broadcast
 4      */
 5     BROADCASTING("BROADCASTING"),
 6     /**
 7      * clustering
 8      */
 9     CLUSTERING("CLUSTERING");
10 }

Broadcasting：同一個ConsumerGroup裡的每個Consumer都能消費到所訂閱Topic的全部訊息，也就是一個訊息會被多次分發，被多個Consumer消費
Clustering：同一個ConsumerGroup裡的每個Consumer只消費所訂閱訊息的一部分內容，同一個ConsumerGroup裡所有的Consumer消費的內容合起來才是所訂閱Topic內容的整體，從而達到負載均衡的目的

結合著來看，也就是說使用相同GroupName的一組Consumer，其ConsumeType和MessageModel必定相同，其訂閱的Topic會根據ConsumeType和MessageModel來完成相應的方式的訊息處理

回到BrokerController的構造

ProducerManager：管理Producer，主要通過一張map來快取

1 private final HashMap<String /* group name */, HashMap<Channel, ClientChannelInfo>> groupChannelTable =
2         new HashMap<String, HashMap<Channel, ClientChannelInfo>>();

相比ConsumerManager，對Producer的管理簡單的多，只需要記錄group name 和物理連線的對映

再回到createBrokerController方法，在完成BrokerController的建立後，會呼叫BrokerController的initialize方法：

BrokerController的initialize方法：

  1 public boolean initialize() throws CloneNotSupportedException {
  2     boolean result = this.topicConfigManager.load();
  3 
  4     result = result && this.consumerOffsetManager.load();
  5     result = result && this.subscriptionGroupManager.load();
  6     result = result && this.consumerFilterManager.load();
  7 
  8     if (result) {
  9         try {
 10             this.messageStore =
 11                 new DefaultMessageStore(this.messageStoreConfig, this.brokerStatsManager, this.messageArrivingListener,
 12                     this.brokerConfig);
 13             if (messageStoreConfig.isEnableDLegerCommitLog()) {
 14                 DLedgerRoleChangeHandler roleChangeHandler = new DLedgerRoleChangeHandler(this, (DefaultMessageStore) messageStore);
 15                 ((DLedgerCommitLog)((DefaultMessageStore) messageStore).getCommitLog()).getdLedgerServer().getdLedgerLeaderElector().addRoleChangeHandler(roleChangeHandler);
 16             }
 17             this.brokerStats = new BrokerStats((DefaultMessageStore) this.messageStore);
 18             //load plugin
 19             MessageStorePluginContext context = new MessageStorePluginContext(messageStoreConfig, brokerStatsManager, messageArrivingListener, brokerConfig);
 20             this.messageStore = MessageStoreFactory.build(context, this.messageStore);
 21             this.messageStore.getDispatcherList().addFirst(new CommitLogDispatcherCalcBitMap(this.brokerConfig, this.consumerFilterManager));
 22         } catch (IOException e) {
 23             result = false;
 24             log.error("Failed to initialize", e);
 25         }
 26     }
 27 
 28     result = result && this.messageStore.load();
 29 
 30     if (result) {
 31         this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.clientHousekeepingService);
 32         NettyServerConfig fastConfig = (NettyServerConfig) this.nettyServerConfig.clone();
 33         fastConfig.setListenPort(nettyServerConfig.getListenPort() - 2);
 34         this.fastRemotingServer = new NettyRemotingServer(fastConfig, this.clientHousekeepingService);
 35         this.sendMessageExecutor = new BrokerFixedThreadPoolExecutor(
 36             this.brokerConfig.getSendMessageThreadPoolNums(),
 37             this.brokerConfig.getSendMessageThreadPoolNums(),
 38             1000 * 60,
 39             TimeUnit.MILLISECONDS,
 40             this.sendThreadPoolQueue,
 41             new ThreadFactoryImpl("SendMessageThread_"));
 42 
 43         this.pullMessageExecutor = new BrokerFixedThreadPoolExecutor(
 44             this.brokerConfig.getPullMessageThreadPoolNums(),
 45             this.brokerConfig.getPullMessageThreadPoolNums(),
 46             1000 * 60,
 47             TimeUnit.MILLISECONDS,
 48             this.pullThreadPoolQueue,
 49             new ThreadFactoryImpl("PullMessageThread_"));
 50 
 51         this.queryMessageExecutor = new BrokerFixedThreadPoolExecutor(
 52             this.brokerConfig.getQueryMessageThreadPoolNums(),
 53             this.brokerConfig.getQueryMessageThreadPoolNums(),
 54             1000 * 60,
 55             TimeUnit.MILLISECONDS,
 56             this.queryThreadPoolQueue,
 57             new ThreadFactoryImpl("QueryMessageThread_"));
 58 
 59         this.adminBrokerExecutor =
 60             Executors.newFixedThreadPool(this.brokerConfig.getAdminBrokerThreadPoolNums(), new ThreadFactoryImpl(
 61                 "AdminBrokerThread_"));
 62 
 63         this.clientManageExecutor = new ThreadPoolExecutor(
 64             this.brokerConfig.getClientManageThreadPoolNums(),
 65             this.brokerConfig.getClientManageThreadPoolNums(),
 66             1000 * 60,
 67             TimeUnit.MILLISECONDS,
 68             this.clientManagerThreadPoolQueue,
 69             new ThreadFactoryImpl("ClientManageThread_"));
 70 
 71         this.heartbeatExecutor = new BrokerFixedThreadPoolExecutor(
 72             this.brokerConfig.getHeartbeatThreadPoolNums(),
 73             this.brokerConfig.getHeartbeatThreadPoolNums(),
 74             1000 * 60,
 75             TimeUnit.MILLISECONDS,
 76             this.heartbeatThreadPoolQueue,
 77             new ThreadFactoryImpl("HeartbeatThread_", true));
 78 
 79         this.endTransactionExecutor = new BrokerFixedThreadPoolExecutor(
 80             this.brokerConfig.getEndTransactionThreadPoolNums(),
 81             this.brokerConfig.getEndTransactionThreadPoolNums(),
 82             1000 * 60,
 83             TimeUnit.MILLISECONDS,
 84             this.endTransactionThreadPoolQueue,
 85             new ThreadFactoryImpl("EndTransactionThread_"));
 86 
 87         this.consumerManageExecutor =
 88             Executors.newFixedThreadPool(this.brokerConfig.getConsumerManageThreadPoolNums(), new ThreadFactoryImpl(
 89                 "ConsumerManageThread_"));
 90 
 91         this.registerProcessor();
 92 
 93         final long initialDelay = UtilAll.computNextMorningTimeMillis() - System.currentTimeMillis();
 94         final long period = 1000 * 60 * 60 * 24;
 95         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
 96             @Override
 97             public void run() {
 98                 try {
 99                     BrokerController.this.getBrokerStats().record();
100                 } catch (Throwable e) {
101                     log.error("schedule record error.", e);
102                 }
103             }
104         }, initialDelay, period, TimeUnit.MILLISECONDS);
105 
106         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
107             @Override
108             public void run() {
109                 try {
110                     BrokerController.this.consumerOffsetManager.persist();
111                 } catch (Throwable e) {
112                     log.error("schedule persist consumerOffset error.", e);
113                 }
114             }
115         }, 1000 * 10, this.brokerConfig.getFlushConsumerOffsetInterval(), TimeUnit.MILLISECONDS);
116 
117         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
118             @Override
119             public void run() {
120                 try {
121                     BrokerController.this.consumerFilterManager.persist();
122                 } catch (Throwable e) {
123                     log.error("schedule persist consumer filter error.", e);
124                 }
125             }
126         }, 1000 * 10, 1000 * 10, TimeUnit.MILLISECONDS);
127 
128         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
129             @Override
130             public void run() {
131                 try {
132                     BrokerController.this.protectBroker();
133                 } catch (Throwable e) {
134                     log.error("protectBroker error.", e);
135                 }
136             }
137         }, 3, 3, TimeUnit.MINUTES);
138 
139         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
140             @Override
141             public void run() {
142                 try {
143                     BrokerController.this.printWaterMark();
144                 } catch (Throwable e) {
145                     log.error("printWaterMark error.", e);
146                 }
147             }
148         }, 10, 1, TimeUnit.SECONDS);
149 
150         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
151 
152             @Override
153             public void run() {
154                 try {
155                     log.info("dispatch behind commit log {} bytes", BrokerController.this.getMessageStore().dispatchBehindBytes());
156                 } catch (Throwable e) {
157                     log.error("schedule dispatchBehindBytes error.", e);
158                 }
159             }
160         }, 1000 * 10, 1000 * 60, TimeUnit.MILLISECONDS);
161 
162         if (this.brokerConfig.getNamesrvAddr() != null) {
163             this.brokerOuterAPI.updateNameServerAddressList(this.brokerConfig.getNamesrvAddr());
164             log.info("Set user specified name server address: {}", this.brokerConfig.getNamesrvAddr());
165         } else if (this.brokerConfig.isFetchNamesrvAddrByAddressServer()) {
166             this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
167 
168                 @Override
169                 public void run() {
170                     try {
171                         BrokerController.this.brokerOuterAPI.fetchNameServerAddr();
172                     } catch (Throwable e) {
173                         log.error("ScheduledTask fetchNameServerAddr exception", e);
174                     }
175                 }
176             }, 1000 * 10, 1000 * 60 * 2, TimeUnit.MILLISECONDS);
177         }
178 
179         if (!messageStoreConfig.isEnableDLegerCommitLog()) {
180             if (BrokerRole.SLAVE == this.messageStoreConfig.getBrokerRole()) {
181                 if (this.messageStoreConfig.getHaMasterAddress() != null && this.messageStoreConfig.getHaMasterAddress().length() >= 6) {
182                     this.messageStore.updateHaMasterAddress(this.messageStoreConfig.getHaMasterAddress());
183                     this.updateMasterHAServerAddrPeriodically = false;
184                 } else {
185                     this.updateMasterHAServerAddrPeriodically = true;
186                 }
187             } else {
188                 this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
189                     @Override
190                     public void run() {
191                         try {
192                             BrokerController.this.printMasterAndSlaveDiff();
193                         } catch (Throwable e) {
194                             log.error("schedule printMasterAndSlaveDiff error.", e);
195                         }
196                     }
197                 }, 1000 * 10, 1000 * 60, TimeUnit.MILLISECONDS);
198             }
199         }
200 
201         if (TlsSystemConfig.tlsMode != TlsMode.DISABLED) {
202             // Register a listener to reload SslContext
203             try {
204                 fileWatchService = new FileWatchService(
205                     new String[] {
206                         TlsSystemConfig.tlsServerCertPath,
207                         TlsSystemConfig.tlsServerKeyPath,
208                         TlsSystemConfig.tlsServerTrustCertPath
209                     },
210                     new FileWatchService.Listener() {
211                         boolean certChanged, keyChanged = false;
212 
213                         @Override
214                         public void onChanged(String path) {
215                             if (path.equals(TlsSystemConfig.tlsServerTrustCertPath)) {
216                                 log.info("The trust certificate changed, reload the ssl context");
217                                 reloadServerSslContext();
218                             }
219                             if (path.equals(TlsSystemConfig.tlsServerCertPath)) {
220                                 certChanged = true;
221                             }
222                             if (path.equals(TlsSystemConfig.tlsServerKeyPath)) {
223                                 keyChanged = true;
224                             }
225                             if (certChanged && keyChanged) {
226                                 log.info("The certificate and private key changed, reload the ssl context");
227                                 certChanged = keyChanged = false;
228                                 reloadServerSslContext();
229                             }
230                         }
231 
232                         private void reloadServerSslContext() {
233                             ((NettyRemotingServer) remotingServer).loadSslContext();
234                             ((NettyRemotingServer) fastRemotingServer).loadSslContext();
235                         }
236                     });
237             } catch (Exception e) {
238                 log.warn("FileWatchService created error, can't load the certificate dynamically");
239             }
240         }
241         initialTransaction();
242         initialAcl();
243         initialRpcHooks();
244     }
245     return result;
246 }

首先完成對.../store/config/topics.json、.../store/config/consumerOffset.json、
.../store/config/subscriptionGroup.json、.../store/config/consumerFilter.json這幾個檔案的載入

接著建立一個DefaultMessageStore，這是Broker的核心儲存

DefaultMessageStore的構造：

 1 private final ConcurrentMap<String/* topic */, ConcurrentMap<Integer/* queueId */, ConsumeQueue>> consumeQueueTable;
 2 ......
 3 public DefaultMessageStore(final MessageStoreConfig messageStoreConfig, final BrokerStatsManager brokerStatsManager,
 4         final MessageArrivingListener messageArrivingListener, final BrokerConfig brokerConfig) throws IOException {
 5     this.messageArrivingListener = messageArrivingListener;
 6     this.brokerConfig = brokerConfig;
 7     this.messageStoreConfig = messageStoreConfig;
 8     this.brokerStatsManager = brokerStatsManager;
 9     // 請求定位服務
10     this.allocateMappedFileService = new AllocateMappedFileService(this);
11     // 儲存服務
12     if (messageStoreConfig.isEnableDLegerCommitLog()) {
13         this.commitLog = new DLedgerCommitLog(this);
14     } else {
15         this.commitLog = new CommitLog(this);
16     }
17     // 消費佇列資訊
18     this.consumeQueueTable = new ConcurrentHashMap<>(32);
19     // 重新整理佇列服務
20     this.flushConsumeQueueService = new FlushConsumeQueueService();
21     // 清除CommitLog資料服務
22     this.cleanCommitLogService = new CleanCommitLogService();
23     // 清除消費佇列服務
24     this.cleanConsumeQueueService = new CleanConsumeQueueService();
25     this.storeStatsService = new StoreStatsService();
26     // 索引服務
27     this.indexService = new IndexService(this);
28     
29     // HA服務，主從複製
30     if (!messageStoreConfig.isEnableDLegerCommitLog()) {
31         this.haService = new HAService(this);
32     } else {
33         this.haService = null;
34     }
35     this.reputMessageService = new ReputMessageService();
36     this.scheduleMessageService = new ScheduleMessageService(this);
37 
38     this.transientStorePool = new TransientStorePool(messageStoreConfig);
39 
40     if (messageStoreConfig.isTransientStorePoolEnable()) {
41         this.transientStorePool.init();
42     }
43 
44     this.allocateMappedFileService.start();
45 
46     this.indexService.start();
47 
48     this.dispatcherList = new LinkedList<>();
49     this.dispatcherList.addLast(new CommitLogDispatcherBuildConsumeQueue());
50     this.dispatcherList.addLast(new CommitLogDispatcherBuildIndex());
51 
52     File file = new File(StorePathConfigHelper.getLockFile(messageStoreConfig.getStorePathRootDir()));
53     MappedFile.ensureDirOK(file.getParent());
54     lockFile = new RandomAccessFile(file, "rw");
55 }

可以看到DefaultMessageStore的構造會建立很多服務，來管理store的儲存

其中isEnableDLegerCommitLog用來判斷是否使用DLeger，預設false是關閉的
所以在預設情況下使用CommitLog + HAService

關於DLeger可參考這篇部落格 【Dledger-RocketMQ 基於Raft協議的commitlog儲存庫】

後續的主從複製還是以CommitLog + HAService為主

回到initialize方法，接著會呼叫DefaultMessageStore的load方法：

 1 public boolean load() {
 2     boolean result = true;
 3 
 4     try {
 5         boolean lastExitOK = !this.isTempFileExist();
 6         log.info("last shutdown {}", lastExitOK ? "normally" : "abnormally");
 7 
 8         if (null != scheduleMessageService) {
 9             result = result && this.scheduleMessageService.load();
10         }
11 
12         // load Commit Log
13         result = result && this.commitLog.load();
14 
15         // load Consume Queue
16         result = result && this.loadConsumeQueue();
17 
18         if (result) {
19             this.storeCheckpoint =
20                 new StoreCheckpoint(StorePathConfigHelper.getStoreCheckpoint(this.messageStoreConfig.getStorePathRootDir()));
21 
22             this.indexService.load(lastExitOK);
23 
24             this.recover(lastExitOK);
25 
26             log.info("load over, and the max phy offset = {}", this.getMaxPhyOffset());
27         }
28     } catch (Exception e) {
29         log.error("load exception", e);
30         result = false;
31     }
32 
33     if (!result) {
34         this.allocateMappedFileService.shutdown();
35     }
36 
37     return result;
38 }

這裡會載入CommitLog和ConsumeQueue對應的檔案

接著建立熟悉的NettyRemotingServer，在前面部落格中介紹過了，就不再展開
這裡會根據nettyServerConfig克隆一份服務端配置，以此建立fastRemotingServer服務端，只不過這個服務端偵聽的是上面服務端埠減2的埠號

看過我前面的部落格就會發現這個fastRemotingServer的埠號其實就是之前提到過的VIP通道
詳見：

【RocketMQ中Producer的啟動原始碼分析】

【RocketMQ中Producer訊息的傳送原始碼分析】

接著會根據不同的需求建立很多不同的執行緒池

然後呼叫registerProcessor方法：

registerProcessor方法：

 1 public void registerProcessor() {
 2    /**
 3      * SendMessageProcessor
 4      */
 5     SendMessageProcessor sendProcessor = new SendMessageProcessor(this);
 6     sendProcessor.registerSendMessageHook(sendMessageHookList);
 7     sendProcessor.registerConsumeMessageHook(consumeMessageHookList);
 8 
 9     this.remotingServer.registerProcessor(RequestCode.SEND_MESSAGE, sendProcessor, this.sendMessageExecutor);
10     this.remotingServer.registerProcessor(RequestCode.SEND_MESSAGE_V2, sendProcessor, this.sendMessageExecutor);
11     this.remotingServer.registerProcessor(RequestCode.SEND_BATCH_MESSAGE, sendProcessor, this.sendMessageExecutor);
12     this.remotingServer.registerProcessor(RequestCode.CONSUMER_SEND_MSG_BACK, sendProcessor, this.sendMessageExecutor);
13     this.fastRemotingServer.registerProcessor(RequestCode.SEND_MESSAGE, sendProcessor, this.sendMessageExecutor);
14     this.fastRemotingServer.registerProcessor(RequestCode.SEND_MESSAGE_V2, sendProcessor, this.sendMessageExecutor);
15     this.fastRemotingServer.registerProcessor(RequestCode.SEND_BATCH_MESSAGE, sendProcessor, this.sendMessageExecutor);
16     this.fastRemotingServer.registerProcessor(RequestCode.CONSUMER_SEND_MSG_BACK, sendProcessor, this.sendMessageExecutor);
17     /**
18      * PullMessageProcessor
19      */
20     this.remotingServer.registerProcessor(RequestCode.PULL_MESSAGE, this.pullMessageProcessor, this.pullMessageExecutor);
21     this.pullMessageProcessor.registerConsumeMessageHook(consumeMessageHookList);
22 
23     /**
24      * QueryMessageProcessor
25      */
26     NettyRequestProcessor queryProcessor = new QueryMessageProcessor(this);
27     this.remotingServer.registerProcessor(RequestCode.QUERY_MESSAGE, queryProcessor, this.queryMessageExecutor);
28     this.remotingServer.registerProcessor(RequestCode.VIEW_MESSAGE_BY_ID, queryProcessor, this.queryMessageExecutor);
29 
30     this.fastRemotingServer.registerProcessor(RequestCode.QUERY_MESSAGE, queryProcessor, this.queryMessageExecutor);
31     this.fastRemotingServer.registerProcessor(RequestCode.VIEW_MESSAGE_BY_ID, queryProcessor, this.queryMessageExecutor);
32 
33     /**
34      * ClientManageProcessor
35      */
36     ClientManageProcessor clientProcessor = new ClientManageProcessor(this);
37     this.remotingServer.registerProcessor(RequestCode.HEART_BEAT, clientProcessor, this.heartbeatExecutor);
38     this.remotingServer.registerProcessor(RequestCode.UNREGISTER_CLIENT, clientProcessor, this.clientManageExecutor);
39     this.remotingServer.registerProcessor(RequestCode.CHECK_CLIENT_CONFIG, clientProcessor, this.clientManageExecutor);
40 
41     this.fastRemotingServer.registerProcessor(RequestCode.HEART_BEAT, clientProcessor, this.heartbeatExecutor);
42     this.fastRemotingServer.registerProcessor(RequestCode.UNREGISTER_CLIENT, clientProcessor, this.clientManageExecutor);
43     this.fastRemotingServer.registerProcessor(RequestCode.CHECK_CLIENT_CONFIG, clientProcessor, this.clientManageExecutor);
44 
45     /**
46      * ConsumerManageProcessor
47      */
48     ConsumerManageProcessor consumerManageProcessor = new ConsumerManageProcessor(this);
49     this.remotingServer.registerProcessor(RequestCode.GET_CONSUMER_LIST_BY_GROUP, consumerManageProcessor, this.consumerManageExecutor);
50     this.remotingServer.registerProcessor(RequestCode.UPDATE_CONSUMER_OFFSET, consumerManageProcessor, this.consumerManageExecutor);
51     this.remotingServer.registerProcessor(RequestCode.QUERY_CONSUMER_OFFSET, consumerManageProcessor, this.consumerManageExecutor);
52 
53     this.fastRemotingServer.registerProcessor(RequestCode.GET_CONSUMER_LIST_BY_GROUP, consumerManageProcessor, this.consumerManageExecutor);
54     this.fastRemotingServer.registerProcessor(RequestCode.UPDATE_CONSUMER_OFFSET, consumerManageProcessor, this.consumerManageExecutor);
55     this.fastRemotingServer.registerProcessor(RequestCode.QUERY_CONSUMER_OFFSET, consumerManageProcessor, this.consumerManageExecutor);
56 
57     /**
58      * EndTransactionProcessor
59      */
60     this.remotingServer.registerProcessor(RequestCode.END_TRANSACTION, new EndTransactionProcessor(this), this.endTransactionExecutor);
61     this.fastRemotingServer.registerProcessor(RequestCode.END_TRANSACTION, new EndTransactionProcessor(this), this.endTransactionExecutor);
62 
63     /**
64      * Default
65      */
66     AdminBrokerProcessor adminProcessor = new AdminBrokerProcessor(this);
67     this.remotingServer.registerDefaultProcessor(adminProcessor, this.adminBrokerExecutor);
68     this.fastRemotingServer.registerDefaultProcessor(adminProcessor, this.adminBrokerExecutor);
69 }

這裡會建立好幾種Processor，通過registerProcessor方法同時註冊到remotingServer和fastRemotingServer中

registerProcessor方法：

1 public void registerProcessor(int requestCode, NettyRequestProcessor processor, ExecutorService executor) {
2         ExecutorService executorThis = executor;
3     if (null == executor) {
4         executorThis = this.publicExecutor;
5     }
6 
7     Pair<NettyRequestProcessor, ExecutorService> pair = new Pair<NettyRequestProcessor, ExecutorService>(processor, executorThis);
8     this.processorTable.put(requestCode, pair);
9 }

這裡實際上就是向processorTable進行了記錄的新增，為的是後續收到請求能做出對應的處理

processorTable：

1 protected final HashMap<Integer/* request code */, Pair<NettyRequestProcessor, ExecutorService>> processorTable =
2         new HashMap<Integer, Pair<NettyRequestProcessor, ExecutorService>>(64);

這裡的SendMessageProcessor很重要，後續會詳細介紹

在完成registerProcessor後，會建立8個定時任務

①

1 BrokerController.this.getBrokerStats().record();

定時列印Broker的狀態

②

1 BrokerController.this.consumerOffsetManager.persist();

定時向consumerOffset.json檔案中寫入消費者偏移量

③

1 BrokerController.this.consumerFilterManager.persist();

定時向consumerFilter.json檔案寫入消費者過濾器資訊

④

1 BrokerController.this.protectBroker();

定時禁用消費慢的consumer，保護Broker，需要設定disableConsumeIfConsumerReadSlowly屬性，預設false

⑤

1 BrokerController.this.printWaterMark();

定時列印Send、Pull、Query、Transaction佇列資訊

⑥

1 public void run() {
2     try {
3         log.info("dispatch behind commit log {} bytes", BrokerController.this.getMessageStore().dispatchBehindBytes());
4     } catch (Throwable e) {
5         log.error("schedule dispatchBehindBytes error.", e);
6     }
7 }

定時列印已儲存在提交日誌中但尚未排程到消費佇列的位元組數

⑦

 1 if (this.brokerConfig.getNamesrvAddr() != null) {
 2     this.brokerOuterAPI.updateNameServerAddressList(this.brokerConfig.getNamesrvAddr());
 3     log.info("Set user specified name server address: {}", this.brokerConfig.getNamesrvAddr());
 4 } else if (this.brokerConfig.isFetchNamesrvAddrByAddressServer()) {
 5     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
 6 
 7         @Override
 8         public void run() {
 9             try {
10                 BrokerController.this.brokerOuterAPI.fetchNameServerAddr();
11             } catch (Throwable e) {
12                 log.error("ScheduledTask fetchNameServerAddr exception", e);
13             }
14         }
15     }, 1000 * 10, 1000 * 60 * 2, TimeUnit.MILLISECONDS);
16 }

若是設定了NamesrvAddr，需要通過updateNameServerAddressList完成一次NameServer地址的跟新（updateNameServerAddressList在前面部落格介紹過了）
若是設定了NamesrvAddr，並且設定了fetchNamesrvAddrByAddressServer屬性（預設關閉），需要定時獲取更新NameServer地址（fetchNameServerAddr方法在之前部落格也介紹過）

⑧

 1 if (!messageStoreConfig.isEnableDLegerCommitLog()) {
 2     if (BrokerRole.SLAVE == this.messageStoreConfig.getBrokerRole()) {
 3         if (this.messageStoreConfig.getHaMasterAddress() != null && this.messageStoreConfig.getHaMasterAddress().length() >= 6) {
 4             this.messageStore.updateHaMasterAddress(this.messageStoreConfig.getHaMasterAddress());
 5             this.updateMasterHAServerAddrPeriodically = false;
 6         } else {
 7             this.updateMasterHAServerAddrPeriodically = true;
 8         }
 9     } else {
10         this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
11             @Override
12             public void run() {
13                 try {
14                     BrokerController.this.printMasterAndSlaveDiff();
15                 } catch (Throwable e) {
16                     log.error("schedule printMasterAndSlaveDiff error.", e);
17                 }
18             }
19         }, 1000 * 10, 1000 * 60, TimeUnit.MILLISECONDS);
20     }
21 }

在非DLeger模式下
若是SLAVE，則需要檢查是否設定了HA的Master地址
若設定了Master地址要通過updateHaMasterAddress方法向更新Master地址
updateHaMasterAddress方法實則是在HAClient中實現的：

1 public void updateMasterAddress(final String newAddr) {
2     String currentAddr = this.masterAddress.get();
3     if (currentAddr == null || !currentAddr.equals(newAddr)) {
4         this.masterAddress.set(newAddr);
5         log.info("update master address, OLD: " + currentAddr + " NEW: " + newAddr);
6     }
7 }

非常簡單，只是一個比較替換的操作

若沒有設定需要更改updateMasterHAServerAddrPeriodically為true，在後面會有用

若是MASTER，則需要定時列印slave落後的位元組數

設定完定時任務後，和NameServer中一樣設定了對SslContext的監聽

接著通過initialTransaction方法，載入事務需要的例項
initialTransaction方法：

 1 private void initialTransaction() {
 2     this.transactionalMessageService = ServiceProvider.loadClass(ServiceProvider.TRANSACTION_SERVICE_ID, TransactionalMessageService.class);
 3     if (null == this.transactionalMessageService) {
 4         this.transactionalMessageService = new TransactionalMessageServiceImpl(new TransactionalMessageBridge(this, this.getMessageStore()));
 5         log.warn("Load default transaction message hook service: {}", TransactionalMessageServiceImpl.class.getSimpleName());
 6     }
 7     this.transactionalMessageCheckListener = ServiceProvider.loadClass(ServiceProvider.TRANSACTION_LISTENER_ID, AbstractTransactionalMessageCheckListener.class);
 8     if (null == this.transactionalMessageCheckListener) {
 9         this.transactionalMessageCheckListener = new DefaultTransactionalMessageCheckListener();
10         log.warn("Load default discard message hook service: {}", DefaultTransactionalMessageCheckListener.class.getSimpleName());
11     }
12     this.transactionalMessageCheckListener.setBrokerController(this);
13     this.transactionalMessageCheckService = new TransactionalMessageCheckService(this);
14 }

這裡動態載入了TransactionalMessageService和AbstractTransactionalMessageCheckListener的實現類，位於如下
"META-INF/service/org.apache.rocketmq.broker.transaction.TransactionalMessageService"
"META-INF/service/org.apache.rocketmq.broker.transaction.AbstractTransactionalMessageCheckListener"
還建立了TransactionalMessageCheckService

initialAcl會建立ACL許可權檢查：

 1 private void initialAcl() {
 2    if (!this.brokerConfig.isAclEnable()) {
 3         log.info("The broker dose not enable acl");
 4         return;
 5     }
 6 
 7     List<AccessValidator> accessValidators = ServiceProvider.load(ServiceProvider.ACL_VALIDATOR_ID, AccessValidator.class);
 8     if (accessValidators == null || accessValidators.isEmpty()) {
 9         log.info("The broker dose not load the AccessValidator");
10         return;
11     }
12 
13     for (AccessValidator accessValidator: accessValidators) {
14         final AccessValidator validator = accessValidator;
15         this.registerServerRPCHook(new RPCHook() {
16 
17             @Override
18             public void doBeforeRequest(String remoteAddr, RemotingCommand request) {
19                 //Do not catch the exception
20                 validator.validate(validator.parse(request, remoteAddr));
21             }
22 
23             @Override
24             public void doAfterResponse(String remoteAddr, RemotingCommand request, RemotingCommand response) {
25             }
26         });
27     }
28 }

需要設定aclEnable屬性，預設關閉
若是設定了，同樣會載入"META-INF/service/org.apache.rocketmq.acl.AccessValidator"配置的AccessValidator實體類
然後將其包裝成RPC鉤子，註冊到remotingServer和fastRemotingServer中，用於請求的呼叫validate方法進行ACL許可權檢查

initialRpcHooks方法則會註冊配置了的RPC鉤子：

1 private void initialRpcHooks() {
2     List<RPCHook> rpcHooks = ServiceProvider.load(ServiceProvider.RPC_HOOK_ID, RPCHook.class);
3     if (rpcHooks == null || rpcHooks.isEmpty()) {
4         return;
5     }
6     for (RPCHook rpcHook: rpcHooks) {
7         this.registerServerRPCHook(rpcHook);
8     }
9 }

載入"META-INF/service/org.apache.rocketmq.remoting.RPCHook"下的配置的實體類

到此Broker啟動前的準備工作已經完成，後面start方法會進行真正的啟動，在下一篇部落格繼續