Broker存储消息大体流程

DefaultMessageStore 默认消息存储

putMessage 保存消息

public PutMessageResult putMessage(MessageExtBrokerInner msg) {
    //①messageStore已经shutdown了 返回状态SERVICE_NOT_AVAILABLE
    if (this.shutdown) {
        log.warn("message store has shutdown, so putMessage is forbidden");
        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    }
    //如果是从broker，直接拒绝服务，返回状态SERVICE_NOT_AVAILABLE
    if (BrokerRole.SLAVE == this.messageStoreConfig.getBrokerRole()) {
        long value = this.printTimes.getAndIncrement();
        if ((value % 50000) == 0) {
            log.warn("message store is slave mode, so putMessage is forbidden ");
        }

        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    }
  	//判断broker是否支持写入
    if (!this.runningFlags.isWriteable()) {
        long value = this.printTimes.getAndIncrement();
        if ((value % 50000) == 0) {
            log.warn("message store is not writeable, so putMessage is forbidden " + this.runningFlags.getFlagBits());
        }

        return new PutMessageResult(PutMessageStatus.SERVICE_NOT_AVAILABLE, null);
    } else {
        this.printTimes.set(0);
    }
    //检测 主题长度是否大于127个字节
    if (msg.getTopic().length() > Byte.MAX_VALUE) {
        log.warn("putMessage message topic length too long " + msg.getTopic().length());
        return new PutMessageResult(PutMessageStatus.MESSAGE_ILLEGAL, null);
    }
 		//检查 消息的属性字段长度是否大于65535
    if (msg.getPropertiesString() != null && msg.getPropertiesString().length() > Short.MAX_VALUE) {
        log.warn("putMessage message properties length too long " + msg.getPropertiesString().length());
        return new PutMessageResult(PutMessageStatus.PROPERTIES_SIZE_EXCEEDED, null);
    }
    //判断系统是否繁忙 默认一次追加消息的时间超过1秒 就是系统繁忙
    if (this.isOSPageCacheBusy()) {
        return new PutMessageResult(PutMessageStatus.OS_PAGECACHE_BUSY, null);
    }

    long beginTime = this.getSystemClock().now();
    //核心逻辑 调用 commitLog.putMessage 保存消息
    PutMessageResult result = this.commitLog.putMessage(msg);

    long eclipseTime = this.getSystemClock().now() - beginTime;
    //存储消息花费时间超过打印warn日志
    if (eclipseTime > 500) {
        log.warn("putMessage not in lock eclipse time(ms)={}, bodyLength={}", eclipseTime, msg.getBody().length);
    }
    //统计信息 保存运行时间分布 最大运行时间等信息
    this.storeStatsService.setPutMessageEntireTimeMax(eclipseTime);

    if (null == result || !result.isOk()) {
        //统计失败次数
        this.storeStatsService.getPutMessageFailedTimes().incrementAndGet();
    }
  
    return result;
}

CommitLog

putMessage 保存消息

public PutMessageResult putMessage(final MessageExtBrokerInner msg) {
    // Set the storage time
    msg.setStoreTimestamp(System.currentTimeMillis());
    // Set the message body BODY CRC (consider the most appropriate setting
    // on the client)
    msg.setBodyCRC(UtilAll.crc32(msg.getBody()));
    // Back to Results
    AppendMessageResult result = null;

    StoreStatsService storeStatsService = this.defaultMessageStore.getStoreStatsService();

    String topic = msg.getTopic();
    int queueId = msg.getQueueId();

    final int tranType = MessageSysFlag.getTransactionValue(msg.getSysFlag());
    //事务消息处理
    if (tranType == MessageSysFlag.TRANSACTION_NOT_TYPE
        || tranType == MessageSysFlag.TRANSACTION_COMMIT_TYPE) {
        // Delay Delivery
        if (msg.getDelayTimeLevel() > 0) {
            if (msg.getDelayTimeLevel() > this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel()) {
                msg.setDelayTimeLevel(this.defaultMessageStore.getScheduleMessageService().getMaxDelayLevel());
            }

            topic = ScheduleMessageService.SCHEDULE_TOPIC;
            queueId = ScheduleMessageService.delayLevel2QueueId(msg.getDelayTimeLevel());

            // Backup real topic, queueId
            MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_TOPIC, msg.getTopic());
            MessageAccessor.putProperty(msg, MessageConst.PROPERTY_REAL_QUEUE_ID, String.valueOf(msg.getQueueId()));
            msg.setPropertiesString(MessageDecoder.messageProperties2String(msg.getProperties()));

            msg.setTopic(topic);
            msg.setQueueId(queueId);
        }
    }

    long eclipseTimeInLock = 0;
    MappedFile unlockMappedFile = null;
    //获取最后一个文件
    MappedFile mappedFile = this.mappedFileQueue.getLastMappedFile();

    putMessageLock.lock(); //spin or ReentrantLock ,depending on store config
    try {
        long beginLockTimestamp = this.defaultMessageStore.getSystemClock().now();
        this.beginTimeInLock = beginLockTimestamp;

        // Here settings are stored timestamp, in order to ensure an orderly
        // global
        msg.setStoreTimestamp(beginLockTimestamp);

        if (null == mappedFile || mappedFile.isFull()) {
            //没有文件 则创建一个
            mappedFile = this.mappedFileQueue.getLastMappedFile(0); // Mark: NewFile may be cause noise
        }
        //文件没有创建成功
        if (null == mappedFile) {
            log.error("create mapped file1 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
            beginTimeInLock = 0;
            return new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, null);
        }
      	//核心逻辑 调用mappedFile.appendMessage保存消息
        result = mappedFile.appendMessage(msg, this.appendMessageCallback);
        //处理保存结果
        switch (result.getStatus()) {
            //保存成功
            case PUT_OK:
                break;
            //文件已被写满
            case END_OF_FILE:
                unlockMappedFile = mappedFile;
                // Create a new file, re-write the message 创建新文件 重新写入消息
                mappedFile = this.mappedFileQueue.getLastMappedFile(0);
                if (null == mappedFile) {
                    // XXX: warn and notify me
                    log.error("create mapped file2 error, topic: " + msg.getTopic() + " clientAddr: " + msg.getBornHostString());
                    beginTimeInLock = 0;
                    return new PutMessageResult(PutMessageStatus.CREATE_MAPEDFILE_FAILED, result);
                }
                result = mappedFile.appendMessage(msg, this.appendMessageCallback);
                break;
            //消息长度超了
            case MESSAGE_SIZE_EXCEEDED:
            //属性长度超了
            case PROPERTIES_SIZE_EXCEEDED:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.MESSAGE_ILLEGAL, result);
            //未知错误
            case UNKNOWN_ERROR:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result);
            default:
                beginTimeInLock = 0;
                return new PutMessageResult(PutMessageStatus.UNKNOWN_ERROR, result);
        }
        //保存消息花费的时间
        eclipseTimeInLock = this.defaultMessageStore.getSystemClock().now() - beginLockTimestamp;
        beginTimeInLock = 0;
    } finally {
        putMessageLock.unlock();
    }

    if (eclipseTimeInLock > 500) {
        log.warn("[NOTIFYME]putMessage in lock cost time(ms)={}, bodyLength={} AppendMessageResult={}", eclipseTimeInLock, msg.getBody().length, result);
    }

    if (null != unlockMappedFile && this.defaultMessageStore.getMessageStoreConfig().isWarmMapedFileEnable()) {
        this.defaultMessageStore.unlockMappedFile(unlockMappedFile);
    }

    PutMessageResult putMessageResult = new PutMessageResult(PutMessageStatus.PUT_OK, result);

    // Statistics
    storeStatsService.getSinglePutMessageTopicTimesTotal(msg.getTopic()).incrementAndGet();
    storeStatsService.getSinglePutMessageTopicSizeTotal(topic).addAndGet(result.getWroteBytes());
		//处理刷盘
    handleDiskFlush(result, putMessageResult, msg);
    //处理主从同步
    handleHA(result, putMessageResult, msg);

    return putMessageResult;
}

MappedFile

appendMessage 保存消息

public AppendMessageResult appendMessages(final MessageExtBatch messageExtBatch, final AppendMessageCallback cb) {
    return appendMessagesInner(messageExtBatch, cb);
}

public AppendMessageResult appendMessagesInner(final MessageExt messageExt, final AppendMessageCallback cb) {
    assert messageExt != null;
    assert cb != null;
    
    //写指针
    int currentPos = this.wrotePosition.get();
  
    if (currentPos < this.fileSize) {
        //writeBuffer不为空 则使用writeBuffer 如果为空使用mappedByteBuffer 这里slice创建了一个副本，单独维护自身的limit、position指针，从而不改变原来的buffer
        ByteBuffer byteBuffer = writeBuffer != null ? writeBuffer.slice() : this.mappedByteBuffer.slice();
        byteBuffer.position(currentPos);
        AppendMessageResult result = null;
        if (messageExt instanceof MessageExtBrokerInner) {
            //调用AppendMessageCallback.doAppend存储信息
            result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos, (MessageExtBrokerInner) messageExt);
        } else if (messageExt instanceof MessageExtBatch) {
            //批量消息
            result = cb.doAppend(this.getFileFromOffset(), byteBuffer, this.fileSize - currentPos, (MessageExtBatch) messageExt);
        } else {
            return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
        }
        //修改写指针
        this.wrotePosition.addAndGet(result.getWroteBytes());
        //跟新存储消息时间
        this.storeTimestamp = result.getStoreTimestamp();
        return result;
    }
    log.error("MappedFile.appendMessage return null, wrotePosition: {} fileSize: {}", currentPos, this.fileSize);
    return new AppendMessageResult(AppendMessageStatus.UNKNOWN_ERROR);
}

AppendMessageCallback

public AppendMessageResult doAppend(final long fileFromOffset, final ByteBuffer byteBuffer, final int maxBlank,
    final MessageExtBrokerInner msgInner) {
    // STORETIMESTAMP + STOREHOSTADDRESS + OFFSET <br>

    // PHY OFFSET 消息全局偏移量
    long wroteOffset = fileFromOffset + byteBuffer.position();
    //重置hostHolder
    this.resetByteBuffer(hostHolder, 8);
    //创建消息id 16个字节， 4字节ip+4字节端口号+8字节偏移量wroteOffset
    String msgId = MessageDecoder.createMessageId(this.msgIdMemory, msgInner.getStoreHostBytes(hostHolder), wroteOffset);

    // Record ConsumeQueue information 记录消息队列偏移量
    keyBuilder.setLength(0);
    keyBuilder.append(msgInner.getTopic());
    keyBuilder.append('-');
    keyBuilder.append(msgInner.getQueueId());
    String key = keyBuilder.toString();
    Long queueOffset = CommitLog.this.topicQueueTable.get(key);
    if (null == queueOffset) {
        queueOffset = 0L;
        CommitLog.this.topicQueueTable.put(key, queueOffset);
    }

    // Transaction messages that require special handling 事务类型消息处理 暂不关注
    final int tranType = MessageSysFlag.getTransactionValue(msgInner.getSysFlag());
    switch (tranType) {
        // Prepared and Rollback message is not consumed, will not enter the
        // consumer queuec
        case MessageSysFlag.TRANSACTION_PREPARED_TYPE:
        case MessageSysFlag.TRANSACTION_ROLLBACK_TYPE:
            queueOffset = 0L;
            break;
        case MessageSysFlag.TRANSACTION_NOT_TYPE:
        case MessageSysFlag.TRANSACTION_COMMIT_TYPE:
        default:
            break;
    }

    /**
     * Serialize message
     */
    final byte[] propertiesData =
        msgInner.getPropertiesString() == null ? null : msgInner.getPropertiesString().getBytes(MessageDecoder.CHARSET_UTF8);

    final int propertiesLength = propertiesData == null ? 0 : propertiesData.length;
  	//检测属性长度
    if (propertiesLength > Short.MAX_VALUE) {
        log.warn("putMessage message properties length too long. length={}", propertiesData.length);
        return new AppendMessageResult(AppendMessageStatus.PROPERTIES_SIZE_EXCEEDED);
    }

    final byte[] topicData = msgInner.getTopic().getBytes(MessageDecoder.CHARSET_UTF8);
    final int topicLength = topicData.length;

    final int bodyLength = msgInner.getBody() == null ? 0 : msgInner.getBody().length;

    final int msgLen = calMsgLength(bodyLength, topicLength, propertiesLength);

    // Exceeds the maximum message 检测消息长度
    if (msgLen > this.maxMessageSize) {
        CommitLog.log.warn("message size exceeded, msg total size: " + msgLen + ", msg body size: " + bodyLength
            + ", maxMessageSize: " + this.maxMessageSize);
        return new AppendMessageResult(AppendMessageStatus.MESSAGE_SIZE_EXCEEDED);
    }

    // Determines whether there is sufficient free space 如果文件不够写入了 填满剩余文件
    if ((msgLen + END_FILE_MIN_BLANK_LENGTH) > maxBlank) {
        this.resetByteBuffer(this.msgStoreItemMemory, maxBlank);
        // 1 TOTALSIZE 文件剩余的字节数
        this.msgStoreItemMemory.putInt(maxBlank);
        // 2 MAGICCODE 魔数
        this.msgStoreItemMemory.putInt(CommitLog.BLANK_MAGIC_CODE);
        // 3 The remaining space may be any value
        // Here the length of the specially set maxBlank
        final long beginTimeMills = CommitLog.this.defaultMessageStore.now();
        byteBuffer.put(this.msgStoreItemMemory.array(), 0, maxBlank);
        //返回END_OF_FILE结果，后续将新创建一个文件
        return new AppendMessageResult(AppendMessageStatus.END_OF_FILE, wroteOffset, maxBlank, msgId, msgInner.getStoreTimestamp(),
            queueOffset, CommitLog.this.defaultMessageStore.now() - beginTimeMills);
    }

    // Initialization of storage space
    this.resetByteBuffer(msgStoreItemMemory, msgLen);
    // 1 TOTALSIZE 消息总长度
    this.msgStoreItemMemory.putInt(msgLen);
    // 2 MAGICCODE 魔数
    this.msgStoreItemMemory.putInt(CommitLog.MESSAGE_MAGIC_CODE);
    // 3 BODYCRC crc
    this.msgStoreItemMemory.putInt(msgInner.getBodyCRC());
    // 4 QUEUEID 队列id
    this.msgStoreItemMemory.putInt(msgInner.getQueueId());
    // 5 FLAG
    this.msgStoreItemMemory.putInt(msgInner.getFlag());
    // 6 QUEUEOFFSET
    this.msgStoreItemMemory.putLong(queueOffset);
    // 7 PHYSICALOFFSET 全局偏移量
    this.msgStoreItemMemory.putLong(fileFromOffset + byteBuffer.position());
    // 8 SYSFLAG
    this.msgStoreItemMemory.putInt(msgInner.getSysFlag());
    // 9 BORNTIMESTAMP 消息生成时间
    this.msgStoreItemMemory.putLong(msgInner.getBornTimestamp());
    // 10 BORNHOST 消息的发送ip和端口
    this.resetByteBuffer(hostHolder, 8);
    this.msgStoreItemMemory.put(msgInner.getBornHostBytes(hostHolder));
    // 11 STORETIMESTAMP 消息存储的时间戳
    this.msgStoreItemMemory.putLong(msgInner.getStoreTimestamp());
    // 12 STOREHOSTADDRESS 消息保存的ip和端口
    this.resetByteBuffer(hostHolder, 8);
    this.msgStoreItemMemory.put(msgInner.getStoreHostBytes(hostHolder));
    //this.msgBatchMemory.put(msgInner.getStoreHostBytes());
    // 13 RECONSUMETIMES 重新消费次数
    this.msgStoreItemMemory.putInt(msgInner.getReconsumeTimes());
    // 14 Prepared Transaction Offset
    this.msgStoreItemMemory.putLong(msgInner.getPreparedTransactionOffset());
    // 15 BODY 消息体长度
    this.msgStoreItemMemory.putInt(bodyLength);
    if (bodyLength > 0) // 消息体
        this.msgStoreItemMemory.put(msgInner.getBody());
    // 16 TOPIC 主题
    this.msgStoreItemMemory.put((byte) topicLength);
    this.msgStoreItemMemory.put(topicData);
    // 17 PROPERTIES 属性
    this.msgStoreItemMemory.putShort((short) propertiesLength);
    if (propertiesLength > 0)
        this.msgStoreItemMemory.put(propertiesData);
   
    final long beginTimeMills = CommitLog.this.defaultMessageStore.now();
    // Write messages to the queue buffer 写入消息
    byteBuffer.put(this.msgStoreItemMemory.array(), 0, msgLen);

    AppendMessageResult result = new AppendMessageResult(AppendMessageStatus.PUT_OK, wroteOffset, msgLen, msgId,
        msgInner.getStoreTimestamp(), queueOffset, CommitLog.this.defaultMessageStore.now() - beginTimeMills);

    switch (tranType) {
        case MessageSysFlag.TRANSACTION_PREPARED_TYPE:
        case MessageSysFlag.TRANSACTION_ROLLBACK_TYPE:
            break;
        case MessageSysFlag.TRANSACTION_NOT_TYPE:
        case MessageSysFlag.TRANSACTION_COMMIT_TYPE:
            // The next update ConsumeQueue information
            CommitLog.this.topicQueueTable.put(key, ++queueOffset);
            break;
        default:
            break;
    }
    return result;
}