RocketMQ中Broker的启动源码分析（二）

接着上一篇博客  【RocketMQ中Broker的启动源码分析（一）】

 

在完成准备工作后，调用start方法：

 1 public static BrokerController start(BrokerController controller) {
 2     try {
 3 
 4         controller.start();
 5 
 6         String tip = "The broker[" + controller.getBrokerConfig().getBrokerName() + ", "
 7             + controller.getBrokerAddr() + "] boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();
 8 
 9         if (null != controller.getBrokerConfig().getNamesrvAddr()) {
10             tip += " and name server is " + controller.getBrokerConfig().getNamesrvAddr();
11         }
12 
13         log.info(tip);
14         System.out.printf("%s%n", tip);
15         return controller;
16     } catch (Throwable e) {
17         e.printStackTrace();
18         System.exit(-1);
19     }
20 
21     return null;
22 }

这里最主要的是通过BrokerController 的start方法来完成启动

 

BrokerController的start方法：

 1 public void start() throws Exception {
 2     if (this.messageStore != null) {
 3         this.messageStore.start();
 4     }
 5 
 6     if (this.remotingServer != null) {
 7         this.remotingServer.start();
 8     }
 9 
10     if (this.fastRemotingServer != null) {
11         this.fastRemotingServer.start();
12     }
13 
14     if (this.fileWatchService != null) {
15         this.fileWatchService.start();
16     }
17 
18     if (this.brokerOuterAPI != null) {
19         this.brokerOuterAPI.start();
20     }
21 
22     if (this.pullRequestHoldService != null) {
23         this.pullRequestHoldService.start();
24     }
25 
26     if (this.clientHousekeepingService != null) {
27         this.clientHousekeepingService.start();
28     }
29 
30     if (this.filterServerManager != null) {
31         this.filterServerManager.start();
32     }
33 
34     if (!messageStoreConfig.isEnableDLegerCommitLog()) {
35         startProcessorByHa(messageStoreConfig.getBrokerRole());
36         handleSlaveSynchronize(messageStoreConfig.getBrokerRole());
37     }
38 
39 
40 
41     this.registerBrokerAll(true, false, true);
42 
43     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
44 
45         @Override
46         public void run() {
47             try {
48                 BrokerController.this.registerBrokerAll(true, false, brokerConfig.isForceRegister());
49             } catch (Throwable e) {
50                 log.error("registerBrokerAll Exception", e);
51             }
52         }
53     }, 1000 * 10, Math.max(10000, Math.min(brokerConfig.getRegisterNameServerPeriod(), 60000)), TimeUnit.MILLISECONDS);
54 
55     if (this.brokerStatsManager != null) {
56         this.brokerStatsManager.start();
57     }
58 
59     if (this.brokerFastFailure != null) {
60         this.brokerFastFailure.start();
61     }
62 
63 
64 }

首先通过messageStore启动messageStore

DefaultMessageStore的start方法：

 1 public void start() throws Exception {
 2     lock = lockFile.getChannel().tryLock(0, 1, false);
 3     if (lock == null || lock.isShared() || !lock.isValid()) {
 4         throw new RuntimeException("Lock failed,MQ already started");
 5     }
 6 
 7     lockFile.getChannel().write(ByteBuffer.wrap("lock".getBytes()));
 8     lockFile.getChannel().force(true);
 9     {
10         /**
11          * 1. Make sure the fast-forward messages to be truncated during the recovering according to the max physical offset of the commitlog;
12          * 2. DLedger committedPos may be missing, so the maxPhysicalPosInLogicQueue maybe bigger that maxOffset returned by DLedgerCommitLog, just let it go;
13          * 3. Calculate the reput offset according to the consume queue;
14          * 4. Make sure the fall-behind messages to be dispatched before starting the commitlog, especially when the broker role are automatically changed.
15          */
16         long maxPhysicalPosInLogicQueue = commitLog.getMinOffset();
17         for (ConcurrentMap<Integer, ConsumeQueue> maps : this.consumeQueueTable.values()) {
18             for (ConsumeQueue logic : maps.values()) {
19                 if (logic.getMaxPhysicOffset() > maxPhysicalPosInLogicQueue) {
20                     maxPhysicalPosInLogicQueue = logic.getMaxPhysicOffset();
21                 }
22             }
23         }
24         if (maxPhysicalPosInLogicQueue < 0) {
25             maxPhysicalPosInLogicQueue = 0;
26         }
27         if (maxPhysicalPosInLogicQueue < this.commitLog.getMinOffset()) {
28             maxPhysicalPosInLogicQueue = this.commitLog.getMinOffset();
29             /**
30              * This happens in following conditions:
31              * 1. If someone removes all the consumequeue files or the disk get damaged.
32              * 2. Launch a new broker, and copy the commitlog from other brokers.
33              *
34              * All the conditions has the same in common that the maxPhysicalPosInLogicQueue should be 0.
35              * If the maxPhysicalPosInLogicQueue is gt 0, there maybe something wrong.
36              */
37             log.warn("[TooSmallCqOffset] maxPhysicalPosInLogicQueue={} clMinOffset={}", maxPhysicalPosInLogicQueue, this.commitLog.getMinOffset());
38         }
39         log.info("[SetReputOffset] maxPhysicalPosInLogicQueue={} clMinOffset={} clMaxOffset={} clConfirmedOffset={}",
40             maxPhysicalPosInLogicQueue, this.commitLog.getMinOffset(), this.commitLog.getMaxOffset(), this.commitLog.getConfirmOffset());
41         this.reputMessageService.setReputFromOffset(maxPhysicalPosInLogicQueue);
42         this.reputMessageService.start();
43 
44         /**
45          *  1. Finish dispatching the messages fall behind, then to start other services.
46          *  2. DLedger committedPos may be missing, so here just require dispatchBehindBytes <= 0
47          */
48         while (true) {
49             if (dispatchBehindBytes() <= 0) {
50                 break;
51             }
52             Thread.sleep(1000);
53             log.info("Try to finish doing reput the messages fall behind during the starting, reputOffset={} maxOffset={} behind={}", this.reputMessageService.getReputFromOffset(), this.getMaxPhyOffset(), this.dispatchBehindBytes());
54         }
55         this.recoverTopicQueueTable();
56     }
57 
58     if (!messageStoreConfig.isEnableDLegerCommitLog()) {
59         this.haService.start();
60         this.handleScheduleMessageService(messageStoreConfig.getBrokerRole());
61     }
62 
63     this.flushConsumeQueueService.start();
64     this.commitLog.start();
65     this.storeStatsService.start();
66 
67     this.createTempFile();
68     this.addScheduleTask();
69     this.shutdown = false;
70 }

这里首先尝试获取.../store/lock文件锁，保证磁盘上的文件只会被一个messageStore读写

然后通过commitLog的getMinOffset方法获取最小的Offset

commitLog会将消息持久化为文件，每个文件默认最大1G，当超过1G，则会新创建一个文件存储，如此反复
而commitLog会把这些文件在物理上不连续的Offset映射成逻辑上连续的Offset，以此来定位

CommitLog的getMinOffset方法：

 1 public long getMinOffset() {
 2     MappedFile mappedFile = this.mappedFileQueue.getFirstMappedFile();
 3     if (mappedFile != null) {
 4         if (mappedFile.isAvailable()) {
 5             return mappedFile.getFileFromOffset();
 6         } else {
 7             return this.rollNextFile(mappedFile.getFileFromOffset());
 8         }
 9     }
10 
11     return -1;
12 }

CommitLog管理的这些文件是通过mappedFileQueue管理，mappedFileQueue中会通过mappedFiles映射到每一个文件：

1 private final CopyOnWriteArrayList<MappedFile> mappedFiles = new CopyOnWriteArrayList<MappedFile>();

 

MappedFileQueue的getFirstMappedFile方法：

 1 public MappedFile getFirstMappedFile() {
 2     MappedFile mappedFileFirst = null;
 3 
 4     if (!this.mappedFiles.isEmpty()) {
 5         try {
 6             mappedFileFirst = this.mappedFiles.get(0);
 7         } catch (IndexOutOfBoundsException e) {
 8             //ignore
 9         } catch (Exception e) {
10             log.error("getFirstMappedFile has exception.", e);
11         }
12     }
13 
14     return mappedFileFirst;
15 }

这里很简单，在mappedFiles不为空的情况下，会取出第一个MappedFile

MappedFile 则持有与文件有关的属性和操作：

1 public class MappedFile extends ReferenceResource {
2     protected int fileSize;
3     protected FileChannel fileChannel;
4     protected ByteBuffer writeBuffer = null;
5     private String fileName;
6     private long fileFromOffset;
7     private File file;
8     ......
9 }

MappedFile可以通过fileChannel来完成对文件的访问和修改

在得到第一个文件的MappedFile映射后，通过getFileFromOffset方法，获取该文件的Offset

在DefaultMessageStore的start方法中将这个Offset作为maxPhysicalPosInLogicQueue
然后遍历consumeQueueTable中的所有ConsumeQueue，通过ConsumeQueue可以得到消费的最大Offset
遍历完成，maxPhysicalPosInLogicQueue就会被替换为最大的那次的消费Offset，这样后续就可以通过这个Offset映射到具体哪个文件的哪个位置

 

接着调用reputMessageService的setReputFromOffset方法：

1 public void setReputFromOffset(long reputFromOffset) {
2     this.reputFromOffset = reputFromOffset;
3 }

将reputFromOffset更新为刚才得到的Offset

然后调用reputMessageService的start方法，启动ReputMessageService服务，ReputMessageService是一个Thread，所以是启动了一个线程：

 1 public void run() {
 2     DefaultMessageStore.log.info(this.getServiceName() + " service started");
 3 
 4     while (!this.isStopped()) {
 5         try {
 6             Thread.sleep(1);
 7             this.doReput();
 8         } catch (Exception e) {
 9             DefaultMessageStore.log.warn(this.getServiceName() + " service has exception. ", e);
10         }
11     }
12 
13     DefaultMessageStore.log.info(this.getServiceName() + " service end");
14 }

这个线程很简单，定时1毫秒调用doReput方法

ReputMessageService的doReput方法：

 1 private void doReput() {
 2     if (this.reputFromOffset < DefaultMessageStore.this.commitLog.getMinOffset()) {
 3         log.warn("The reputFromOffset={} is smaller than minPyOffset={}, this usually indicate that the dispatch behind too much and the commitlog has expired.",
 4             this.reputFromOffset, DefaultMessageStore.this.commitLog.getMinOffset());
 5         this.reputFromOffset = DefaultMessageStore.this.commitLog.getMinOffset();
 6     }
 7     for (boolean doNext = true; this.isCommitLogAvailable() && doNext; ) {
 8 
 9         if (DefaultMessageStore.this.getMessageStoreConfig().isDuplicationEnable()
10             && this.reputFromOffset >= DefaultMessageStore.this.getConfirmOffset()) {
11             break;
12         }
13 
14         SelectMappedBufferResult result = DefaultMessageStore.this.commitLog.getData(reputFromOffset);
15         if (result != null) {
16             try {
17                 this.reputFromOffset = result.getStartOffset();
18 
19                 for (int readSize = 0; readSize < result.getSize() && doNext; ) {
20                     DispatchRequest dispatchRequest =
21                         DefaultMessageStore.this.commitLog.checkMessageAndReturnSize(result.getByteBuffer(), false, false);
22                     int size = dispatchRequest.getBufferSize() == -1 ? dispatchRequest.getMsgSize() : dispatchRequest.getBufferSize();
23 
24                     if (dispatchRequest.isSuccess()) {
25                         if (size > 0) {
26                             DefaultMessageStore.this.doDispatch(dispatchRequest);
27 
28                             if (BrokerRole.SLAVE != DefaultMessageStore.this.getMessageStoreConfig().getBrokerRole()
29                                 && DefaultMessageStore.this.brokerConfig.isLongPollingEnable()) {
30                                 DefaultMessageStore.this.messageArrivingListener.arriving(dispatchRequest.getTopic(),
31                                     dispatchRequest.getQueueId(), dispatchRequest.getConsumeQueueOffset() + 1,
32                                     dispatchRequest.getTagsCode(), dispatchRequest.getStoreTimestamp(),
33                                     dispatchRequest.getBitMap(), dispatchRequest.getPropertiesMap());
34                             }
35 
36                             this.reputFromOffset += size;
37                             readSize += size;
38                             if (DefaultMessageStore.this.getMessageStoreConfig().getBrokerRole() == BrokerRole.SLAVE) {
39                                 DefaultMessageStore.this.storeStatsService
40                                     .getSinglePutMessageTopicTimesTotal(dispatchRequest.getTopic()).incrementAndGet();
41                                 DefaultMessageStore.this.storeStatsService
42                                     .getSinglePutMessageTopicSizeTotal(dispatchRequest.getTopic())
43                                     .addAndGet(dispatchRequest.getMsgSize());
44                             }
45                         } else if (size == 0) {
46                             this.reputFromOffset = DefaultMessageStore.this.commitLog.rollNextFile(this.reputFromOffset);
47                             readSize = result.getSize();
48                         }
49                     } else if (!dispatchRequest.isSuccess()) {
50 
51                         if (size > 0) {
52                             log.error("[BUG]read total count not equals msg total size. reputFromOffset={}", reputFromOffset);
53                             this.reputFromOffset += size;
54                         } else {
55                             doNext = false;
56                             log.error("[BUG]dispatch message to consume queue error, COMMITLOG OFFSET: {}",
57                                 this.reputFromOffset);
58 
59                             this.reputFromOffset += result.getSize() - readSize;
60                         }
61                     }
62                 }
63             } finally {
64                 result.release();
65             }
66         } else {
67             doNext = false;
68         }
69     }
70 }

首先看到这个for循环的结束条件isCommitLogAvailable

isCommitLogAvailable方法：

1 private boolean isCommitLogAvailable() {
2     return this.reputFromOffset < DefaultMessageStore.this.commitLog.getMaxOffset();
3 }

其中commitLog的getMaxOffset方法和getMinOffset方法相似：

 1 public long getMaxOffset() {
 2     MappedFile mappedFile = getLastMappedFile();
 3     if (mappedFile != null) {
 4         return mappedFile.getFileFromOffset() + mappedFile.getReadPosition();
 5     }
 6     return 0;
 7 }
 8 
 9 public MappedFile getLastMappedFile() {
10     MappedFile mappedFileLast = null;
11 
12     while (!this.mappedFiles.isEmpty()) {
13         try {
14             mappedFileLast = this.mappedFiles.get(this.mappedFiles.size() - 1);
15             break;
16         } catch (IndexOutOfBoundsException e) {
17             //continue;
18         } catch (Exception e) {
19             log.error("getLastMappedFile has exception.", e);
20             break;
21         }
22     }
23 
24     return mappedFileLast;
25 }

先通过getLastMappedFile得到最后一个文件的映射MappedFile
进而得到fileFromOffset，通过fileFromOffset+ReadPosition定位到当前文件读取指针的位置

isCommitLogAvailable方法，就是判断reputFromOffset是否达到了最后一个文件能访问的地方

 

回到for循环，根据reputFromOffset，通过commitLog的getData方法获取SelectMappedBufferResult

CommitLog的getData方法：

 1 public SelectMappedBufferResult getData(final long offset) {
 2     return this.getData(offset, offset == 0);
 3 }
 4 
 5 public SelectMappedBufferResult getData(final long offset, final boolean returnFirstOnNotFound) {
 6     int mappedFileSize = this.defaultMessageStore.getMessageStoreConfig().getMapedFileSizeCommitLog();
 7     MappedFile mappedFile = this.mappedFileQueue.findMappedFileByOffset(offset, returnFirstOnNotFound);
 8     if (mappedFile != null) {
 9         int pos = (int) (offset % mappedFileSize);
10         SelectMappedBufferResult result = mappedFile.selectMappedBuffer(pos);
11         return result;
12     }
13 
14     return null;
15 }

这里的mappedFileSize就是文件的大小，默认1G

根据reputFromOffset通过mappedFileQueue的findMappedFileByOffset方法定位具体的MappedFile文件映射

MappedFileQueue的findMappedFileByOffset方法：

 1 public MappedFile findMappedFileByOffset(final long offset, final boolean returnFirstOnNotFound) {
 2     try {
 3         MappedFile firstMappedFile = this.getFirstMappedFile();
 4         MappedFile lastMappedFile = this.getLastMappedFile();
 5         if (firstMappedFile != null && lastMappedFile != null) {
 6             if (offset < firstMappedFile.getFileFromOffset() || offset >= lastMappedFile.getFileFromOffset() + this.mappedFileSize) {
 7                 LOG_ERROR.warn("Offset not matched. Request offset: {}, firstOffset: {}, lastOffset: {}, mappedFileSize: {}, mappedFiles count: {}",
 8                     offset,
 9                     firstMappedFile.getFileFromOffset(),
10                     lastMappedFile.getFileFromOffset() + this.mappedFileSize,
11                     this.mappedFileSize,
12                     this.mappedFiles.size());
13             } else {
14                 int index = (int) ((offset / this.mappedFileSize) - (firstMappedFile.getFileFromOffset() / this.mappedFileSize));
15                 MappedFile targetFile = null;
16                 try {
17                     targetFile = this.mappedFiles.get(index);
18                 } catch (Exception ignored) {
19                 }
20 
21                 if (targetFile != null && offset >= targetFile.getFileFromOffset()
22                     && offset < targetFile.getFileFromOffset() + this.mappedFileSize) {
23                     return targetFile;
24                 }
25 
26                 for (MappedFile tmpMappedFile : this.mappedFiles) {
27                     if (offset >= tmpMappedFile.getFileFromOffset()
28                         && offset < tmpMappedFile.getFileFromOffset() + this.mappedFileSize) {
29                         return tmpMappedFile;
30                     }
31                 }
32             }
33 
34             if (returnFirstOnNotFound) {
35                 return firstMappedFile;
36             }
37         }
38     } catch (Exception e) {
39         log.error("findMappedFileByOffset Exception", e);
40     }
41 
42     return null;
43 }

首先检查offset的有效性，然后通过：

1 int index = (int) ((offset / this.mappedFileSize) - (firstMappedFile.getFileFromOffset() / this.mappedFileSize));

这个简单的计算，得到offset对应的文件在mappedFiles这个list中的下标，进而得到文件映射MappedFile

回到getData，再通过offset得到MappedFile后
通过offset和mappedFileSize（1G）取余，得到文件指针起始位置

然后调用mappedFile的selectMappedBuffer方法，得到SelectMappedBufferResult：

 1 public SelectMappedBufferResult selectMappedBuffer(int pos) {
 2      int readPosition = getReadPosition();
 3      if (pos < readPosition && pos >= 0) {
 4          if (this.hold()) {
 5              ByteBuffer byteBuffer = this.mappedByteBuffer.slice();
 6              byteBuffer.position(pos);
 7              int size = readPosition - pos;
 8              ByteBuffer byteBufferNew = byteBuffer.slice();
 9              byteBufferNew.limit(size);
10              return new SelectMappedBufferResult(this.fileFromOffset + pos, byteBufferNew, size, this);
11          }
12      }
13 
14      return null;
15  }

这里通过JDK的NIO操作，将文件从pos起始到readPosition结束的数据（所有的消息信息）放入byteBufferNew中

然后将这些信息封装在SelectMappedBufferResult中

 

回到doReput方法，在得到SelectMappedBufferResult后，首先会跟新当前reputFromOffset

进入for循环，会将封装好的消息从头读取完，通过commitLog的checkMessageAndReturnSize方法封装成一个个的DispatchRequest

CommitLog的checkMessageAndReturnSize方法：

  1 public DispatchRequest checkMessageAndReturnSize(java.nio.ByteBuffer byteBuffer, final boolean checkCRC,
  2     final boolean readBody) {
  3     try {
  4         // 1 TOTAL SIZE
  5         int totalSize = byteBuffer.getInt();
  6 
  7         // 2 MAGIC CODE
  8         int magicCode = byteBuffer.getInt();
  9         switch (magicCode) {
 10             case MESSAGE_MAGIC_CODE:
 11                 break;
 12             case BLANK_MAGIC_CODE:
 13                 return new DispatchRequest(0, true /* success */);
 14             default:
 15                 log.warn("found a illegal magic code 0x" + Integer.toHexString(magicCode));
 16                 return new DispatchRequest(-1, false /* success */);
 17         }
 18 
 19         byte[] bytesContent = new byte[totalSize];
 20 
 21         int bodyCRC = byteBuffer.getInt();
 22 
 23         int queueId = byteBuffer.getInt();
 24 
 25         int flag = byteBuffer.getInt();
 26 
 27         long queueOffset = byteBuffer.getLong();
 28 
 29         long physicOffset = byteBuffer.getLong();
 30 
 31         int sysFlag = byteBuffer.getInt();
 32 
 33         long bornTimeStamp = byteBuffer.getLong();
 34 
 35         ByteBuffer byteBuffer1 = byteBuffer.get(bytesContent, 0, 8);
 36 
 37         long storeTimestamp = byteBuffer.getLong();
 38 
 39         ByteBuffer byteBuffer2 = byteBuffer.get(bytesContent, 0, 8);
 40 
 41         int reconsumeTimes = byteBuffer.getInt();
 42 
 43         long preparedTransactionOffset = byteBuffer.getLong();
 44 
 45         int bodyLen = byteBuffer.getInt();
 46         if (bodyLen > 0) {
 47             if (readBody) {
 48                 byteBuffer.get(bytesContent, 0, bodyLen);
 49 
 50                 if (checkCRC) {
 51                     int crc = UtilAll.crc32(bytesContent, 0, bodyLen);
 52                     if (crc != bodyCRC) {
 53                         log.warn("CRC check failed. bodyCRC={}, currentCRC={}", crc, bodyCRC);
 54                         return new DispatchRequest(-1, false/* success */);
 55                     }
 56                 }
 57             } else {
 58                 byteBuffer.position(byteBuffer.position() + bodyLen);
 59             }
 60         }
 61 
 62         byte topicLen = byteBuffer.get();
 63         byteBuffer.get(bytesContent, 0, topicLen);
 64         String topic = new String(bytesContent, 0, topicLen, MessageDecoder.CHARSET_UTF8);
 65 
 66         long tagsCode = 0;
 67         String keys = "";
 68         String uniqKey = null;
 69 
 70         short propertiesLength = byteBuffer.getShort();
 71         Map<String, String> propertiesMap = null;
 72         if (propertiesLength > 0) {
 73             byteBuffer.get(bytesContent, 0, propertiesLength);
 74             String properties = new String(bytesContent, 0, propertiesLength, MessageDecoder.CHARSET_UTF8);
 75             propertiesMap = MessageDecoder.string2messageProperties(properties);
 76 
 77             keys = propertiesMap.get(MessageConst.PROPERTY_KEYS);
 78 
 79             uniqKey = propertiesMap.get(MessageConst.PROPERTY_UNIQ_CLIENT_MESSAGE_ID_KEYIDX);
 80 
 81             String tags = propertiesMap.get(MessageConst.PROPERTY_TAGS);
 82             if (tags != null && tags.length() > 0) {
 83                 tagsCode = MessageExtBrokerInner.tagsString2tagsCode(MessageExt.parseTopicFilterType(sysFlag), tags);
 84             }
 85 
 86             // Timing message processing
 87             {
 88                 String t = propertiesMap.get(MessageConst.PROPERTY_DELAY_TIME_LEVEL);
 89                 if (ScheduleMessageService.SCHEDULE_TOPIC.equals(topic) && t != null) {
 90                     int delayLevel = Integer.parseInt(t);
 91 
 92                     if (delayLevel > this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel()) {
 93                         delayLevel = this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel();
 94                     }
 95 
 96                     if (delayLevel > 0) {
 97                         tagsCode = this.defaultMessageStore.getScheduleMessageService().computeDeliverTimestamp(delayLevel,
 98                             storeTimestamp);
 99                     }
100                 }
101             }
102         }
103 
104         int readLength = calMsgLength(bodyLen, topicLen, propertiesLength);
105         if (totalSize != readLength) {
106             doNothingForDeadCode(reconsumeTimes);
107             doNothingForDeadCode(flag);
108             doNothingForDeadCode(bornTimeStamp);
109             doNothingForDeadCode(byteBuffer1);
110             doNothingForDeadCode(byteBuffer2);
111             log.error(
112                 "[BUG]read total count not equals msg total size. totalSize={}, readTotalCount={}, bodyLen={}, topicLen={}, propertiesLength={}",
113                 totalSize, readLength, bodyLen, topicLen, propertiesLength);
114             return new DispatchRequest(totalSize, false/* success */);
115         }
116 
117         return new DispatchRequest(
118             topic,
119             queueId,
120             physicOffset,
121             totalSize,
122             tagsCode,
123             storeTimestamp,
124             queueOffset,
125             keys,
126             uniqKey,
127             sysFlag,
128             preparedTransactionOffset,
129             propertiesMap
130         );
131     } catch (Exception e) {
132     }
133 
134     return new DispatchRequest(-1, false /* success */);
135 }

这里的操作其实不难，根据刚才存放在缓冲区ByteBuffer中的消息数据，按CommitLog存储消息的结构顺序读取数据，将比特信息转换为对应的消息结构中的值

消息结构如下：

然后将所需信息封装为DispatchRequest

得到DispatchRequest后，调用DefaultMessageStore的doDispatch方法，将消息分发

DefaultMessageStore的doDispatch方法：

1 public void doDispatch(DispatchRequest req) {
2     for (CommitLogDispatcher dispatcher : this.dispatcherList) {
3         dispatcher.dispatch(req);
4     }
5 }

这里的dispatcherList，在DefaultMessageStore初始化的时候添加了CommitLogDispatcherBuildConsumeQueue和CommitLogDispatcherBuildIndex实例

所以这里实际执行CommitLogDispatcherBuildConsumeQueue和CommitLogDispatcherBuildIndex的dispatch方法

CommitLogDispatcherBuildConsumeQueue的dispatch方法：

 1 public void dispatch(DispatchRequest request) {
 2     final int tranType = MessageSysFlag.getTransactionValue(request.getSysFlag());
 3     switch (tranType) {
 4         case MessageSysFlag.TRANSACTION_NOT_TYPE:
 5         case MessageSysFlag.TRANSACTION_COMMIT_TYPE:
 6             DefaultMessageStore.this.putMessagePositionInfo(request);
 7             break;
 8         case MessageSysFlag.TRANSACTION_PREPARED_TYPE:
 9         case MessageSysFlag.TRANSACTION_ROLLBACK_TYPE:
10             break;
11     }
12 }

当消息满足TRANSACTION_NOT_TYPE和TRANSACTION_COMMIT_TYPE时，调用putMessagePositionInfo方法

DefaultMessageStore的putMessagePositionInfo方法：

1 public void putMessagePositionInfo(DispatchRequest dispatchRequest) {
2     ConsumeQueue cq = this.findConsumeQueue(dispatchRequest.getTopic(), dispatchRequest.getQueueId());
3     cq.putMessagePositionInfoWrapper(dispatchRequest);
4 }

首先根据dispatchRequest封装的Topic和QueueId查找对应的ConsumeQueue

findConsumeQueue方法：

 1 public ConsumeQueue findConsumeQueue(String topic, int queueId) {
 2     ConcurrentMap<Integer, ConsumeQueue> map = consumeQueueTable.get(topic);
 3     if (null == map) {
 4         ConcurrentMap<Integer, ConsumeQueue> newMap = new ConcurrentHashMap<Integer, ConsumeQueue>(128);
 5         ConcurrentMap<Integer, ConsumeQueue> oldMap = consumeQueueTable.putIfAbsent(topic, newMap);
 6         if (oldMap != null) {
 7             map = oldMap;
 8         } else {
 9             map = newMap;
10         }
11     }
12 
13     ConsumeQueue logic = map.get(queueId);
14     if (null == logic) {
15         ConsumeQueue newLogic = new ConsumeQueue(
16             topic,
17             queueId,
18             StorePathConfigHelper.getStorePathConsumeQueue(this.messageStoreConfig.getStorePathRootDir()),
19             this.getMessageStoreConfig().getMapedFileSizeConsumeQueue(),
20             this);
21         ConsumeQueue oldLogic = map.putIfAbsent(queueId, newLogic);
22         if (oldLogic != null) {
23             logic = oldLogic;
24         } else {
25             logic = newLogic;
26         }
27     }
28 
29     return logic;
30 }

这里的实现还是比较简单的，根据Topic和queueId在consumeQueueTable中查找，若是不存在直接创建

得到ConsumeQueue后，调用其putMessagePositionInfoWrapper方法

ConsumeQueue的putMessagePositionInfoWrapper方法：

 1 public void putMessagePositionInfoWrapper(DispatchRequest request) {
 2    final int maxRetries = 30;
 3     boolean canWrite = this.defaultMessageStore.getRunningFlags().isCQWriteable();
 4     for (int i = 0; i < maxRetries && canWrite; i++) {
 5         long tagsCode = request.getTagsCode();
 6         if (isExtWriteEnable()) {
 7             ConsumeQueueExt.CqExtUnit cqExtUnit = new ConsumeQueueExt.CqExtUnit();
 8             cqExtUnit.setFilterBitMap(request.getBitMap());
 9             cqExtUnit.setMsgStoreTime(request.getStoreTimestamp());
10             cqExtUnit.setTagsCode(request.getTagsCode());
11 
12             long extAddr = this.consumeQueueExt.put(cqExtUnit);
13             if (isExtAddr(extAddr)) {
14                 tagsCode = extAddr;
15             } else {
16                 log.warn("Save consume queue extend fail, So just save tagsCode! {}, topic:{}, queueId:{}, offset:{}", cqExtUnit,
17                     topic, queueId, request.getCommitLogOffset());
18             }
19         }
20         boolean result = this.putMessagePositionInfo(request.getCommitLogOffset(),
21             request.getMsgSize(), tagsCode, request.getConsumeQueueOffset());
22         if (result) {
23             this.defaultMessageStore.getStoreCheckpoint().setLogicsMsgTimestamp(request.getStoreTimestamp());
24             return;
25         } else {
26             // XXX: warn and notify me
27             log.warn("[BUG]put commit log position info to " + topic + ":" + queueId + " " + request.getCommitLogOffset()
28                 + " failed, retry " + i + " times");
29 
30             try {
31                 Thread.sleep(1000);
32             } catch (InterruptedException e) {
33                 log.warn("", e);
34             }
35         }
36     }
37 
38     // XXX: warn and notify me
39     log.error("[BUG]consume queue can not write, {} {}", this.topic, this.queueId);
40     this.defaultMessageStore.getRunningFlags().makeLogicsQueueError();
41 }

这个方法主要是在重试次数内完成对putMessagePositionInfo的调用

putMessagePositionInfo方法：

 1 private boolean putMessagePositionInfo(final long offset, final int size, final long tagsCode,
 2    final long cqOffset) {
 3 
 4     if (offset + size <= this.maxPhysicOffset) {
 5         log.warn("Maybe try to build consume queue repeatedly maxPhysicOffset={} phyOffset={}", maxPhysicOffset, offset);
 6         return true;
 7     }
 8 
 9     this.byteBufferIndex.flip();
10     this.byteBufferIndex.limit(CQ_STORE_UNIT_SIZE);
11     this.byteBufferIndex.putLong(offset);
12     this.byteBufferIndex.putInt(size);
13     this.byteBufferIndex.putLong(tagsCode);
14 
15     final long expectLogicOffset = cqOffset * CQ_STORE_UNIT_SIZE;
16 
17     MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile(expectLogicOffset);
18     if (mappedFile != null) {
19 
20         if (mappedFile.isFirstCreateInQueue() && cqOffset != 0 && mappedFile.getWrotePosition() == 0) {
21             this.minLogicOffset = expectLogicOffset;
22             this.mappedFileQueue.setFlushedWhere(expectLogicOffset);
23             this.mappedFileQueue.setCommittedWhere(expectLogicOffset);
24             this.fillPreBlank(mappedFile, expectLogicOffset);
25             log.info("fill pre blank space " + mappedFile.getFileName() + " " + expectLogicOffset + " "
26                 + mappedFile.getWrotePosition());
27         }
28 
29         if (cqOffset != 0) {
30             long currentLogicOffset = mappedFile.getWrotePosition() + mappedFile.getFileFromOffset();
31 
32             if (expectLogicOffset < currentLogicOffset) {
33                 log.warn("Build  consume queue repeatedly, expectLogicOffset: {} currentLogicOffset: {} Topic: {} QID: {} Diff: {}",
34                     expectLogicOffset, currentLogicOffset, this.topic, this.queueId, expectLogicOffset - currentLogicOffset);
35                 return true;
36             }
37 
38             if (expectLogicOffset != currentLogicOffset) {
39                 LOG_ERROR.warn(
40                     "[BUG]logic queue order maybe wrong, expectLogicOffset: {} currentLogicOffset: {} Topic: {} QID: {} Diff: {}",
41                     expectLogicOffset,
42                     currentLogicOffset,
43                     this.topic,
44                     this.queueId,
45                     expectLogicOffset - currentLogicOffset
46                 );
47             }
48         }
49         this.maxPhysicOffset = offset + size;
50         return mappedFile.appendMessage(this.byteBufferIndex.array());
51     }
52     return false;
53 }

将DispatchRequest中封装的CommitLogOffset、MsgSize以及tagsCode这 20字节的信息byteBufferIndex这个ByteBuffer中

根据ConsumeQueueOffset即cqOffset*CQ_STORE_UNIT_SIZE（20）计算expectLogicOffset

ConsumeQueue文件是通过20字节来存放对应CommitLog文件中的消息映射
其原理和CommitLog的相同

expectLogicOffset就是ConsumeQueue文件逻辑Offset，由此可以通过getLastMappedFile找到对应的文件映射MappedFile

在得到MappedFile后通过appendMessage方法，将byteBufferIndex中的数据追加在对应的ConsumeQueue文件中

MappedFile的appendMessage方法：

 1 public boolean appendMessage(final byte[] data) {
 2     int currentPos = this.wrotePosition.get();
 3 
 4     if ((currentPos + data.length) <= this.fileSize) {
 5         try {
 6             this.fileChannel.position(currentPos);
 7             this.fileChannel.write(ByteBuffer.wrap(data));
 8         } catch (Throwable e) {
 9             log.error("Error occurred when append message to mappedFile.", e);
10         }
11         this.wrotePosition.addAndGet(data.length);
12         return true;
13     }
14 
15     return false;
16 }

这里就通过JDK的NIO提供的API完成20字节数据从currentPos起始位置的追加

 

CommitLogDispatcherBuildIndex的dispatch方法：

1 public void dispatch(DispatchRequest request) {
2     if (DefaultMessageStore.this.messageStoreConfig.isMessageIndexEnable()) {
3         DefaultMessageStore.this.indexService.buildIndex(request);
4     }
5 }

根据messageIndexEnable属性的设置，调用indexService的buildIndex方法，实际上就是向Index文件的追加，原理类似，就不再说了

（IndexFile：CommitLog的另外一种形式的索引文件，只是索引的是messageKey，每个MsgKey经过hash后计算存储的slot，然后将offset存到IndexFile的相应slot上，根据msgKey来查询消息时，可以先到IndexFile中查询offset，然后根据offset去commitLog中查询消息详情）

在完成doDispatch后
如果当前是Master并且设置了长轮询的话，则需要通过messageArrivingListener通知消费队列有新的消息，后续博客再分析

对于SLAVE会进行相应的统计工作

也就是说doReput根据CommitLog文件中的数据，不断地进行消息分配

 

回到DefaultMessageStore的start方法，启动完reputMessageService后，用了一个while循环，一直等待消息分配完毕

其中dispatchBehindBytes方法：

1 public long dispatchBehindBytes() {
2     return this.reputMessageService.behind();
3 }
4 
5 public long behind() {
6     return DefaultMessageStore.this.commitLog.getMaxOffset() - this.reputFromOffset;
7 }

用来检查是否分配完毕

然后调用recoverTopicQueueTable方法：

 1 public void recoverTopicQueueTable() {
 2     HashMap<String/* topic-queueid */, Long/* offset */> table = new HashMap<String, Long>(1024);
 3     long minPhyOffset = this.commitLog.getMinOffset();
 4     for (ConcurrentMap<Integer, ConsumeQueue> maps : this.consumeQueueTable.values()) {
 5         for (ConsumeQueue logic : maps.values()) {
 6             String key = logic.getTopic() + "-" + logic.getQueueId();
 7             table.put(key, logic.getMaxOffsetInQueue());
 8             logic.correctMinOffset(minPhyOffset);
 9         }
10     }
11 
12     this.commitLog.setTopicQueueTable(table);
13 }

由于前面的消息分配，这里将ConsumeQueue的Topic和QueueId，以及MaxOffset保存在table中，同时调用correctMinOffset方法根据物理队列最小offset计算修正逻辑队列最小offset

 

当所有的ConsumeQueue遍历完成后，更新commitLog的topicQueueTable：

1 protected HashMap<String/* topic-queueid */, Long/* offset */> topicQueueTable = new HashMap<String, Long>(1024);

 

在完成这些过后，会开启HA服务（非DLeger情况下），关于HA后续博客再详细介绍
接着开启flushConsumeQueueService服务
和reputMessageService类似，这里也会启动一个线程，使用doFlush方法定时刷新ConsumeQueue

FlushConsumeQueueService的doFlush方法：

 1 private void doFlush(int retryTimes) {
 2     int flushConsumeQueueLeastPages = DefaultMessageStore.this.getMessageStoreConfig().getFlushConsumeQueueLeastPages();
 3 
 4     if (retryTimes == RETRY_TIMES_OVER) {
 5         flushConsumeQueueLeastPages = 0;
 6     }
 7 
 8     long logicsMsgTimestamp = 0;
 9 
10     int flushConsumeQueueThoroughInterval = DefaultMessageStore.this.getMessageStoreConfig().getFlushConsumeQueueThoroughInterval();
11     long currentTimeMillis = System.currentTimeMillis();
12     if (currentTimeMillis >= (this.lastFlushTimestamp + flushConsumeQueueThoroughInterval)) {
13         this.lastFlushTimestamp = currentTimeMillis;
14         flushConsumeQueueLeastPages = 0;
15         logicsMsgTimestamp = DefaultMessageStore.this.getStoreCheckpoint().getLogicsMsgTimestamp();
16     }
17 
18     ConcurrentMap<String, ConcurrentMap<Integer, ConsumeQueue>> tables = DefaultMessageStore.this.consumeQueueTable;
19 
20     for (ConcurrentMap<Integer, ConsumeQueue> maps : tables.values()) {
21         for (ConsumeQueue cq : maps.values()) {
22             boolean result = false;
23             for (int i = 0; i < retryTimes && !result; i++) {
24                 result = cq.flush(flushConsumeQueueLeastPages);
25             }
26         }
27     }
28 
29     if (0 == flushConsumeQueueLeastPages) {
30         if (logicsMsgTimestamp > 0) {
31             DefaultMessageStore.this.getStoreCheckpoint().setLogicsMsgTimestamp(logicsMsgTimestamp);
32         }
33         DefaultMessageStore.this.getStoreCheckpoint().flush();
34     }
35 }

这里通过遍历consumeQueueTable中所有的ConsumeQueue，执行其flush方法

ConsumeQueue的flush方法：

1 public boolean flush(final int flushLeastPages) {
2     boolean result = this.mappedFileQueue.flush(flushLeastPages);
3     if (isExtReadEnable()) {
4         result = result & this.consumeQueueExt.flush(flushLeastPages);
5     }
6 
7     return result;
8 }

调用mappedFileQueue的flush方法：

 1 public boolean flush(final int flushLeastPages) {
 2     boolean result = true;
 3     MappedFile mappedFile = this.findMappedFileByOffset(this.flushedWhere, this.flushedWhere == 0);
 4     if (mappedFile != null) {
 5         long tmpTimeStamp = mappedFile.getStoreTimestamp();
 6         int offset = mappedFile.flush(flushLeastPages);
 7         long where = mappedFile.getFileFromOffset() + offset;
 8         result = where == this.flushedWhere;
 9         this.flushedWhere = where;
10         if (0 == flushLeastPages) {
11             this.storeTimestamp = tmpTimeStamp;
12         }
13     }
14 
15     return result;
16 }

根据flushedWhere，通过findMappedFileByOffset获取要刷新的文件映射MappedFile

调用其MappedFile的flush方法

 1 public int flush(final int flushLeastPages) {
 2     if (this.isAbleToFlush(flushLeastPages)) {
 3         if (this.hold()) {
 4             int value = getReadPosition();
 5 
 6             try {
 7                 //We only append data to fileChannel or mappedByteBuffer, never both.
 8                 if (writeBuffer != null || this.fileChannel.position() != 0) {
 9                     this.fileChannel.force(false);
10                 } else {
11                     this.mappedByteBuffer.force();
12                 }
13             } catch (Throwable e) {
14                 log.error("Error occurred when force data to disk.", e);
15             }
16 
17             this.flushedPosition.set(value);
18             this.release();
19         } else {
20             log.warn("in flush, hold failed, flush offset = " + this.flushedPosition.get());
21             this.flushedPosition.set(getReadPosition());
22         }
23     }
24     return this.getFlushedPosition();
25 }

这里就通过NIO的force，将更新的数据强制写入MappedFile对应的ConsumeQueue文件

完成写入后，更新flushedWhere值，方便下一次刷新的定位

 

在启动完ConsumeQueue的刷新服务后，启动commitLog

1 public void start() {
2     this.flushCommitLogService.start();
3 
4     if (defaultMessageStore.getMessageStoreConfig().isTransientStorePoolEnable()) {
5         this.commitLogService.start();
6     }
7 }

首先会启动CommitLog的刷盘服务，分为同步刷盘和异步刷盘两种模式

在采用内存池缓存消息的时候需要启动commitLogService，在使用内存池的时候，这个服务会定时将内存池中的数据刷新到FileChannel中

关于这两个后续博客再详细介绍

 

接着还会启动storeStatsService服务，监控Store

通过addScheduleTask方法，会设置几个定时任务

 1 private void addScheduleTask() {
 2     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
 3         @Override
 4         public void run() {
 5             DefaultMessageStore.this.cleanFilesPeriodically();
 6         }
 7     }, 1000 * 60, this.messageStoreConfig.getCleanResourceInterval(), TimeUnit.MILLISECONDS);
 8 
 9     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
10         @Override
11         public void run() {
12             DefaultMessageStore.this.checkSelf();
13         }
14     }, 1, 10, TimeUnit.MINUTES);
15 
16     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
17         @Override
18         public void run() {
19             if (DefaultMessageStore.this.getMessageStoreConfig().isDebugLockEnable()) {
20                 try {
21                     if (DefaultMessageStore.this.commitLog.getBeginTimeInLock() != 0) {
22                         long lockTime = System.currentTimeMillis() - DefaultMessageStore.this.commitLog.getBeginTimeInLock();
23                         if (lockTime > 1000 && lockTime < 10000000) {
24 
25                             String stack = UtilAll.jstack();
26                             final String fileName = System.getProperty("user.home") + File.separator + "debug/lock/stack-"
27                                 + DefaultMessageStore.this.commitLog.getBeginTimeInLock() + "-" + lockTime;
28                             MixAll.string2FileNotSafe(stack, fileName);
29                         }
30                     }
31                 } catch (Exception e) {
32                 }
33             }
34         }
35     }, 1, 1, TimeUnit.SECONDS);
36 }

①定期清除文件，会定期删除掉长时间（默认72小时）未被引用的CommitLog文件

②定期检查CommitLog和ConsumeQueue文件有否损坏、丢失，做日志打印

③定期虚拟机堆栈使用日志记录

 

DefaultMessageStore的启动完毕，回到BrokerController的start方法
接着启动remotingServer和fastRemotingServer，建立物理层的网络侦听，这在NameServer中介绍过了，不要忘记对serverBootstrap绑定了一个NettyServerHandler，这是后续博客的基础

brokerOuterAPI的start，其实调用了Netty客户端的方法：

1 public void start() {
2     this.remotingClient.start();
3 }

这在分析Producer的启动时也详细说过

之后会启动pullRequestHoldService，分析消息拉取时再说

clientHousekeepingService的start方法会设置一个定时任务：

 1 public void start() {
 2     this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
 3         @Override
 4         public void run() {
 5             try {
 6                 ClientHousekeepingService.this.scanExceptionChannel();
 7             } catch (Throwable e) {
 8                 log.error("Error occurred when scan not active client channels.", e);
 9             }
10         }
11     }, 1000 * 10, 1000 * 10, TimeUnit.MILLISECONDS);
12 }
13 
14 private void scanExceptionChannel() {
15     this.brokerController.getProducerManager().scanNotActiveChannel();
16     this.brokerController.getConsumerManager().scanNotActiveChannel();
17     this.brokerController.getFilterServerManager().scanNotActiveChannel();
18 }

用于扫描并清除产生异常的Channel缓存

接着启动filterServerManager服务

之后在非DLeger模式下，
Master会启动事务消息检查，遍历未提交、未回滚的部分消息并向生产者发送检查请求以获取事务状态
进行偏移量的检查和计算等操作，并移除掉需要丢弃的消息
Slave会启动同步操作
后续详细介绍

 

接着会调用registerBrokerAll，向Master的注册
registerBrokerAll方法：

 1 public synchronized void registerBrokerAll(final boolean checkOrderConfig, boolean oneway, boolean forceRegister) {
 2    TopicConfigSerializeWrapper topicConfigWrapper = this.getTopicConfigManager().buildTopicConfigSerializeWrapper();
 3 
 4     if (!PermName.isWriteable(this.getBrokerConfig().getBrokerPermission())
 5         || !PermName.isReadable(this.getBrokerConfig().getBrokerPermission())) {
 6         ConcurrentHashMap<String, TopicConfig> topicConfigTable = new ConcurrentHashMap<String, TopicConfig>();
 7         for (TopicConfig topicConfig : topicConfigWrapper.getTopicConfigTable().values()) {
 8             TopicConfig tmp =
 9                 new TopicConfig(topicConfig.getTopicName(), topicConfig.getReadQueueNums(), topicConfig.getWriteQueueNums(),
10                     this.brokerConfig.getBrokerPermission());
11             topicConfigTable.put(topicConfig.getTopicName(), tmp);
12         }
13         topicConfigWrapper.setTopicConfigTable(topicConfigTable);
14     }
15 
16     if (forceRegister || needRegister(this.brokerConfig.getBrokerClusterName(),
17         this.getBrokerAddr(),
18         this.brokerConfig.getBrokerName(),
19         this.brokerConfig.getBrokerId(),
20         this.brokerConfig.getRegisterBrokerTimeoutMills())) {
21         doRegisterBrokerAll(checkOrderConfig, oneway, topicConfigWrapper);
22     }
23 }

这里通过TopicConfigManager的buildTopicConfigSerializeWrapper方法，把其topicConfigTable

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

这张记录Topic信息的表封装在TopicConfigSerializeWrapper中

在注册前会通过needRegister检查是否需要注册
needRegister方法：

 1 private boolean needRegister(final String clusterName,
 2    final String brokerAddr,
 3     final String brokerName,
 4     final long brokerId,
 5     final int timeoutMills) {
 6 
 7     TopicConfigSerializeWrapper topicConfigWrapper = this.getTopicConfigManager().buildTopicConfigSerializeWrapper();
 8     List<Boolean> changeList = brokerOuterAPI.needRegister(clusterName, brokerAddr, brokerName, brokerId, topicConfigWrapper, timeoutMills);
 9     boolean needRegister = false;
10     for (Boolean changed : changeList) {
11         if (changed) {
12             needRegister = true;
13             break;
14         }
15     }
16     return needRegister;
17 }

这里通过brokerOuterAPI的needRegister方法：

 1 public List<Boolean> needRegister(
 2     final String clusterName,
 3     final String brokerAddr,
 4     final String brokerName,
 5     final long brokerId,
 6     final TopicConfigSerializeWrapper topicConfigWrapper,
 7     final int timeoutMills) {
 8     final List<Boolean> changedList = new CopyOnWriteArrayList<>();
 9     List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
10     if (nameServerAddressList != null && nameServerAddressList.size() > 0) {
11         final CountDownLatch countDownLatch = new CountDownLatch(nameServerAddressList.size());
12         for (final String namesrvAddr : nameServerAddressList) {
13             brokerOuterExecutor.execute(new Runnable() {
14                 @Override
15                 public void run() {
16                     try {
17                         QueryDataVersionRequestHeader requestHeader = new QueryDataVersionRequestHeader();
18                         requestHeader.setBrokerAddr(brokerAddr);
19                         requestHeader.setBrokerId(brokerId);
20                         requestHeader.setBrokerName(brokerName);
21                         requestHeader.setClusterName(clusterName);
22                         RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.QUERY_DATA_VERSION, requestHeader);
23                         request.setBody(topicConfigWrapper.getDataVersion().encode());
24                         RemotingCommand response = remotingClient.invokeSync(namesrvAddr, request, timeoutMills);
25                         DataVersion nameServerDataVersion = null;
26                         Boolean changed = false;
27                         switch (response.getCode()) {
28                             case ResponseCode.SUCCESS: {
29                                 QueryDataVersionResponseHeader queryDataVersionResponseHeader =
30                                     (QueryDataVersionResponseHeader) response.decodeCommandCustomHeader(QueryDataVersionResponseHeader.class);
31                                 changed = queryDataVersionResponseHeader.getChanged();
32                                 byte[] body = response.getBody();
33                                 if (body != null) {
34                                     nameServerDataVersion = DataVersion.decode(body, DataVersion.class);
35                                     if (!topicConfigWrapper.getDataVersion().equals(nameServerDataVersion)) {
36                                         changed = true;
37                                     }
38                                 }
39                                 if (changed == null || changed) {
40                                     changedList.add(Boolean.TRUE);
41                                 }
42                             }
43                             default:
44                                 break;
45                         }
46                         log.warn("Query data version from name server {} OK,changed {}, broker {},name server {}", namesrvAddr, changed, topicConfigWrapper.getDataVersion(), nameServerDataVersion == null ? "" : nameServerDataVersion);
47                     } catch (Exception e) {
48                         changedList.add(Boolean.TRUE);
49                         log.error("Query data version from name server {}  Exception, {}", namesrvAddr, e);
50                     } finally {
51                         countDownLatch.countDown();
52                     }
53                 }
54             });
55 
56         }
57         try {
58             countDownLatch.await(timeoutMills, TimeUnit.MILLISECONDS);
59         } catch (InterruptedException e) {
60             log.error("query dataversion from nameserver countDownLatch await Exception", e);
61         }
62     }
63     return changedList;
64 }

首先获取NameServer的地址列表

遍历所有NameServer地址

封装QueryDataVersionRequestHeader请求头
通过remotingClient的invokeSync方法（【RocketMQ中Producer消息的发送源码分析】）

以同步方式向NameServe发送QUERY_DATA_VERSION请求，将DataVersion信息发送过去，在NameServe端进行比对，进行相应响应

在收到成功的响应后，检查回送的nameServerDataVersion是否相等，若不相等，在changedList中添加一个true
直至和所有NameServe比对完成

若是返回的List中有true，则代表需要向NameServe注册

调用doRegisterBrokerAll方法：

 1 private void doRegisterBrokerAll(boolean checkOrderConfig, boolean oneway,
 2         TopicConfigSerializeWrapper topicConfigWrapper) {
 3     List<RegisterBrokerResult> registerBrokerResultList = this.brokerOuterAPI.registerBrokerAll(
 4         this.brokerConfig.getBrokerClusterName(),
 5         this.getBrokerAddr(),
 6         this.brokerConfig.getBrokerName(),
 7         this.brokerConfig.getBrokerId(),
 8         this.getHAServerAddr(),
 9         topicConfigWrapper,
10         this.filterServerManager.buildNewFilterServerList(),
11         oneway,
12         this.brokerConfig.getRegisterBrokerTimeoutMills(),
13         this.brokerConfig.isCompressedRegister());
14 
15     if (registerBrokerResultList.size() > 0) {
16         RegisterBrokerResult registerBrokerResult = registerBrokerResultList.get(0);
17         if (registerBrokerResult != null) {
18             if (this.updateMasterHAServerAddrPeriodically && registerBrokerResult.getHaServerAddr() != null) {
19                 this.messageStore.updateHaMasterAddress(registerBrokerResult.getHaServerAddr());
20             }
21 
22             this.slaveSynchronize.setMasterAddr(registerBrokerResult.getMasterAddr());
23 
24             if (checkOrderConfig) {
25                 this.getTopicConfigManager().updateOrderTopicConfig(registerBrokerResult.getKvTable());
26             }
27         }
28     }
29 }

从这可以看到，会向NameServer注册很多信息，调用brokerOuterAPI的registerBrokerAll方法：

 1 public List<RegisterBrokerResult> registerBrokerAll(
 2     final String clusterName,
 3     final String brokerAddr,
 4     final String brokerName,
 5     final long brokerId,
 6     final String haServerAddr,
 7     final TopicConfigSerializeWrapper topicConfigWrapper,
 8     final List<String> filterServerList,
 9     final boolean oneway,
10     final int timeoutMills,
11     final boolean compressed) {
12 
13     final List<RegisterBrokerResult> registerBrokerResultList = Lists.newArrayList();
14     List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
15     if (nameServerAddressList != null && nameServerAddressList.size() > 0) {
16 
17         final RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
18         requestHeader.setBrokerAddr(brokerAddr);
19         requestHeader.setBrokerId(brokerId);
20         requestHeader.setBrokerName(brokerName);
21         requestHeader.setClusterName(clusterName);
22         requestHeader.setHaServerAddr(haServerAddr);
23         requestHeader.setCompressed(compressed);
24 
25         RegisterBrokerBody requestBody = new RegisterBrokerBody();
26         requestBody.setTopicConfigSerializeWrapper(topicConfigWrapper);
27         requestBody.setFilterServerList(filterServerList);
28         final byte[] body = requestBody.encode(compressed);
29         final int bodyCrc32 = UtilAll.crc32(body);
30         requestHeader.setBodyCrc32(bodyCrc32);
31         final CountDownLatch countDownLatch = new CountDownLatch(nameServerAddressList.size());
32         for (final String namesrvAddr : nameServerAddressList) {
33             brokerOuterExecutor.execute(new Runnable() {
34                 @Override
35                 public void run() {
36                     try {
37                         RegisterBrokerResult result = registerBroker(namesrvAddr,oneway, timeoutMills,requestHeader,body);
38                         if (result != null) {
39                             registerBrokerResultList.add(result);
40                         }
41 
42                         log.info("register broker[{}]to name server {} OK", brokerId, namesrvAddr);
43                     } catch (Exception e) {
44                         log.warn("registerBroker Exception, {}", namesrvAddr, e);
45                     } finally {
46                         countDownLatch.countDown();
47                     }
48                 }
49             });
50         }
51 
52         try {
53             countDownLatch.await(timeoutMills, TimeUnit.MILLISECONDS);
54         } catch (InterruptedException e) {
55         }
56     }
57 
58     return registerBrokerResultList;
59 }

和前面的方法类似，构建RegisterBrokerRequestHeader请求头，然后通过registerBroker向列表中的所有NameServer注册

registerBroker：

 1 private RegisterBrokerResult registerBroker(
 2     final String namesrvAddr,
 3     final boolean oneway,
 4     final int timeoutMills,
 5     final RegisterBrokerRequestHeader requestHeader,
 6     final byte[] body
 7 ) throws RemotingCommandException, MQBrokerException, RemotingConnectException, RemotingSendRequestException, RemotingTimeoutException,
 8     InterruptedException {
 9     RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.REGISTER_BROKER, requestHeader);
10     request.setBody(body);
11 
12     if (oneway) {
13         try {
14             this.remotingClient.invokeOneway(namesrvAddr, request, timeoutMills);
15         } catch (RemotingTooMuchRequestException e) {
16             // Ignore
17         }
18         return null;
19     }
20 
21     RemotingCommand response = this.remotingClient.invokeSync(namesrvAddr, request, timeoutMills);
22     assert response != null;
23     switch (response.getCode()) {
24         case ResponseCode.SUCCESS: {
25             RegisterBrokerResponseHeader responseHeader =
26                 (RegisterBrokerResponseHeader) response.decodeCommandCustomHeader(RegisterBrokerResponseHeader.class);
27             RegisterBrokerResult result = new RegisterBrokerResult();
28             result.setMasterAddr(responseHeader.getMasterAddr());
29             result.setHaServerAddr(responseHeader.getHaServerAddr());
30             if (response.getBody() != null) {
31                 result.setKvTable(KVTable.decode(response.getBody(), KVTable.class));
32             }
33             return result;
34         }
35         default:
36             break;
37     }
38 
39     throw new MQBrokerException(response.getCode(), response.getRemark());
40 }

这里会构建REGISTER_BROKER的请求

由于传入的oneway是false，所以这里依然使用invokeSync同步的方式

在响应成功后，可以看到NameServer会回送MasterAddr、HaServerAddr以及KvTable等信息

回到doRegisterBrokerAll方法，当向所有NameServer注册完毕后，会得到一张List

由于Master和Slave是一对多的关系，所以接下来只需要从List中得到第一个RegisterBrokerResult就行了

然后根据updateMasterHAServerAddrPeriodically，这个在我前一篇博客提了下，若是此时updateMasterHAServerAddrPeriodically为false，说明之前完成过updateMasterAddress操作，否则现在完成updateHaMasterAddress

还要向slaveSynchronize，Slave的同步操作更新Master地址

 

回到start，在registerBrokerAll结束后，还会设置一个定时任务，定时调用registerBrokerAll，以便及时更新相关信息

最后后开启brokerStatsManager和brokerFastFailure

至此Broker的启动结束

原文链接:https://www.cnblogs.com/a526583280/p/11300861.html
如有疑问请与原作者联系

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