java開發(fā)RocketMQ之NameServer路由管理源碼分析

更新時間：2021年11月15日 11:01:10 作者：又蠢又笨的懶羊羊程序猿

這篇文章主要為大家介紹了java開發(fā)中RocketMQ之NameServer路由管理源碼分析詳解，有需要的朋友可以借鑒參考下，希望能夠有所幫助，祝大家多多進(jìn)步早日升職加薪

1.前言

NameServer主要作用是為消息消費者和消息生產(chǎn)者提供關(guān)于主題Topic的路由信息，那么NameServer需要存儲路由的基本信息，還要管理Broker節(jié)點，包括路由注冊、路由刪除等。

2.路由元信息

路由元信息主要由RouteInfoManager來進(jìn)行管理，這個類在上一篇文章中已經(jīng)介紹過，這里再做一下簡單的介紹。

private final static long BROKER_CHANNEL_EXPIRED_TIME = 1000 * 60 * 2;	
private final ReadWriteLock lock = new ReentrantReadWriteLock();
private final HashMap<String/* topic */, List<QueueData>> topicQueueTable;
private final HashMap<String/* brokerName */, BrokerData> brokerAddrTable;
private final HashMap<String/* clusterName */, Set<String/* brokerName */>> clusterAddrTable;
private final HashMap<String/* brokerAddr */, BrokerLiveInfo> brokerLiveTable;
private final HashMap<String/* brokerAddr */, List<String>/* Filter Server */> filterServerTable;

BROKER_CHANNEL_EXPIRED_TIME：NameServer與Broker空閑連接時長，在2minNameServer之內(nèi)沒有收到Broker的心跳包，則NameServer會關(guān)閉與該Broker的連接并刪除Broker的路由信息。

lock：讀寫鎖，用來保護(hù)以下用于存儲關(guān)鍵信息的非線程安全容器HashMap。

topicQueueTable：Topic消息隊列路由信息，消息發(fā)送時根據(jù)路由表進(jìn)行負(fù)載均衡

brokerAddrTable：Broker基礎(chǔ)信息，包括brokerName、所屬集群名稱、主備Broker地址

clusterAddrTable：Broker集群信息，存儲集群中所有Broker名稱

brokerLiveTable：Broker狀態(tài)信息，NameServer每次收到心跳包會對該表進(jìn)行信息維護(hù)。

filterServerTable：Broker上的FilterServer列表，用于類模式消息過濾。

RocketMQ基于定于發(fā)布機制，一個Topic擁有多個消息隊列，一個Broker為每一個主題創(chuàng)建4個讀隊列和4個寫隊列。多個Broker組成一個集群，集群由相同的多臺Broker組成Master-Slave架構(gòu)，brokerId為0代表Master，大于0為Slave。BrokerLiveInfo中的lastUpdateTimestamp存儲上次收到Broker心跳包的時間。

3.路由注冊

以下是路由注冊的時序圖：

在這里插入圖片描述

RocketMQ的路由注冊功能是通過Broker與NameServer的心跳機制實現(xiàn)的。Broker啟動時向NameServer集群發(fā)送心跳信息，每隔30s向集群所有NameServer發(fā)送心跳包，NameServer接收到之后會對brokerLiveTable中的BrokerLiveInfo的lastUpdateTimeStamp屬性值進(jìn)行更新。此外NameServer會每隔10s掃描brokerLiveTable，如果檢測到有Broker連續(xù)120s沒有發(fā)送心跳包，則NameServer將移除Broker的路由信息同時關(guān)閉Socket連接。

源碼

3.1Broker路由注冊

BrokerController#start

//...進(jìn)行檢查
if (!messageStoreConfig.isEnableDLegerCommitLog()) {
        startProcessorByHa(messageStoreConfig.getBrokerRole());
        handleSlaveSynchronize(messageStoreConfig.getBrokerRole());
        //注冊Broker信息
        this.registerBrokerAll(true, false, true);
    }
    //創(chuàng)建定時任務(wù)線程池
    this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
        @Override
        public void run() {
            try {
                //每隔三十秒注冊Broker信息
                BrokerController.this.registerBrokerAll(true, false, brokerConfig.isForceRegister());
            } catch (Throwable e) {
                log.error("registerBrokerAll Exception", e);
            }
        }
    }, 1000 * 10, Math.max(10000, Math.min(brokerConfig.getRegisterNameServerPeriod(), 60000)), TimeUnit.MILLISECONDS);
    if (this.brokerStatsManager != null) {
        this.brokerStatsManager.start();
    }

    if (this.brokerFastFailure != null) {
        this.brokerFastFailure.start();
    }
}

BrokerController#registerBrokerAll

if (forceRegister || needRegister(this.brokerConfig.getBrokerClusterName(),
    this.getBrokerAddr(),
    this.brokerConfig.getBrokerName(),
    this.brokerConfig.getBrokerId(),
    this.brokerConfig.getRegisterBrokerTimeoutMills())) {
    //開始注冊
    doRegisterBrokerAll(checkOrderConfig, oneway, topicConfigWrapper);
}

BrokerController#doRegisterBrokerAll

//進(jìn)入brokerOuterAPI#registerBrokerAll
List<RegisterBrokerResult> registerBrokerResultList = this.brokerOuterAPI.registerBrokerAll(
    this.brokerConfig.getBrokerClusterName(),
    this.getBrokerAddr(),
    this.brokerConfig.getBrokerName(),
    this.brokerConfig.getBrokerId(),
    this.getHAServerAddr(),
    topicConfigWrapper,
    this.filterServerManager.buildNewFilterServerList(),
    oneway,
    this.brokerConfig.getRegisterBrokerTimeoutMills(),
    this.brokerConfig.isCompressedRegister());

BrokerOuterAPI#registerBrokerAll

final List<RegisterBrokerResult> registerBrokerResultList = new CopyOnWriteArrayList<>();
//獲取nameServer地址信息
List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
if (nameServerAddressList != null && nameServerAddressList.size() > 0) {
    //進(jìn)行請求頭的封裝
    final RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
    requestHeader.setBrokerAddr(brokerAddr);
    requestHeader.setBrokerId(brokerId);
    requestHeader.setBrokerName(brokerName);
    requestHeader.setClusterName(clusterName);
    requestHeader.setHaServerAddr(haServerAddr);
    requestHeader.setCompressed(compressed);
	//封裝注冊請求體
    RegisterBrokerBody requestBody = new RegisterBrokerBody();
    requestBody.setTopicConfigSerializeWrapper(topicConfigWrapper);
    requestBody.setFilterServerList(filterServerList);
    final byte[] body = requestBody.encode(compressed);
    final int bodyCrc32 = UtilAll.crc32(body);
    requestHeader.setBodyCrc32(bodyCrc32);
    final CountDownLatch countDownLatch = new CountDownLatch(nameServerAddressList.size());
    //遍歷nameServer地址 --->  分別向各個nameServer注冊Broker
    for (final String namesrvAddr : nameServerAddressList) {
        brokerOuterExecutor.execute(new Runnable() {
            @Override
            public void run() {
                try {
                    //向nameServer注冊Broker并返回注冊結(jié)果
                    RegisterBrokerResult result = registerBroker(namesrvAddr, oneway, timeoutMills, requestHeader, body);
                    if (result != null) {
                        registerBrokerResultList.add(result);
                    }

                    log.info("register broker[{}]to name server {} OK", brokerId, namesrvAddr);
                } catch (Exception e) {
                    log.warn("registerBroker Exception, {}", namesrvAddr, e);
                } finally {
                    countDownLatch.countDown();
                }
            }
        });
    }

    try {
        countDownLatch.await(timeoutMills, TimeUnit.MILLISECONDS);
    } catch (InterruptedException e) {
    }
}

return registerBrokerResultList;

BrokerOuterAPI#registerBroker

//如果是oneway發(fā)送 無需關(guān)注返回結(jié)果 直接返回null
if (oneway) {
    try {
        this.remotingClient.invokeOneway(namesrvAddr, request, timeoutMills);
    } catch (RemotingTooMuchRequestException e) {
        // Ignore
        log.error("RemotingTooMuchRequestException!!!");
    }
    return null;
}
//返回遠(yuǎn)程調(diào)用的響應(yīng)結(jié)果
RemotingCommand response = this.remotingClient.invokeSync(namesrvAddr, request, timeoutMills);

3.2NameServer處理路由注冊

以下是NameServer處理路由注冊的時序圖：

在這里插入圖片描述

請求發(fā)送至NameServer，會由默認(rèn)的網(wǎng)絡(luò)處理解析類DefaultRequestProcessor進(jìn)行處理解析，如果請求類型是REGISTER_BROKER則會將請求轉(zhuǎn)發(fā)至RouteInfoManager進(jìn)行路由的注冊。

源碼

DefaultRequestProcessor#processRequest

switch (request.getCode()) {
    case RequestCode.REGISTER_BROKER:
        Version brokerVersion = MQVersion.value2Version(request.getVersion());
        //高版本進(jìn)入這個分支
        if (brokerVersion.ordinal() >= MQVersion.Version.V3_0_11.ordinal()) {
            return this.registerBrokerWithFilterServer(ctx, request);
        } else {
            return this.registerBroker(ctx, request);
        }     
}

DefaultRequestProcessor#registerBrokerWithFilterServer

//轉(zhuǎn)發(fā)到NameServerController中的RouteInfoManager進(jìn)行路由注冊
RegisterBrokerResult result = this.namesrvController.getRouteInfoManager().registerBroker(
    requestHeader.getClusterName(),
    requestHeader.getBrokerAddr(),
    requestHeader.getBrokerName(),
    requestHeader.getBrokerId(),
    requestHeader.getHaServerAddr(),
    registerBrokerBody.getTopicConfigSerializeWrapper(),
    registerBrokerBody.getFilterServerList(),
    ctx.channel());

RouteInfoManager#registerBroker

//加入寫鎖-保護(hù)HashTable線程安全
this.lock.writeLock().lockInterruptibly();
//維護(hù)clusterAddrTable
Set<String> brokerNames = this.clusterAddrTable.get(clusterName);
if (null == brokerNames) {
    brokerNames = new HashSet<String>();
    this.clusterAddrTable.put(clusterName, brokerNames);
}
brokerNames.add(brokerName);

//維護(hù)brokerAddrTable
//是否是第一次注冊 默認(rèn)為false
boolean registerFirst = false;
BrokerData brokerData = this.brokerAddrTable.get(brokerName);
//如果在brokerAddrTable沒有該Broker信息
if (null == brokerData) {
    //設(shè)置為第一次注冊
    registerFirst = true;
    //創(chuàng)建對應(yīng)的BrokerData信息
    brokerData = new BrokerData(clusterName, brokerName, new HashMap<Long, String>());
    this.brokerAddrTable.put(brokerName, brokerData);
}
//不是第一次注冊-對Broker信息進(jìn)行更新
Map<Long, String> brokerAddrsMap = brokerData.getBrokerAddrs();
//Switch slave to master: first remove <1, IP:PORT> in namesrv, then add <0, IP:PORT>
//The same IP:PORT must only have one record in brokerAddrTable
Iterator<Entry<Long, String>> it = brokerAddrsMap.entrySet().iterator();
while (it.hasNext()) {
    Entry<Long, String> item = it.next();
    if (null != brokerAddr && brokerAddr.equals(item.getValue()) && brokerId != item.getKey()) {
        it.remove();
    }
}

String oldAddr = brokerData.getBrokerAddrs().put(brokerId, brokerAddr);
registerFirst = registerFirst || (null == oldAddr);

//維護(hù)topicQueueTable
if (null != topicConfigWrapper
    && MixAll.MASTER_ID == brokerId) {
    if (this.isBrokerTopicConfigChanged(brokerAddr, topicConfigWrapper.getDataVersion())
        || registerFirst) {
        ConcurrentMap<String, TopicConfig> tcTable =
            topicConfigWrapper.getTopicConfigTable();
        if (tcTable != null) {
            for (Map.Entry<String, TopicConfig> entry : tcTable.entrySet()) {
                //具體細(xì)節(jié)在這個方法中
                this.createAndUpdateQueueData(brokerName, entry.getValue());
            }
        }
    }
}

//維護(hù)brokerLiveTable
BrokerLiveInfo prevBrokerLiveInfo = this.brokerLiveTable.put(brokerAddr,
    new BrokerLiveInfo(
        System.currentTimeMillis(),
        topicConfigWrapper.getDataVersion(),
        channel,
        haServerAddr));
if (null == prevBrokerLiveInfo) {
    log.info("new broker registered, {} HAServer: {}", brokerAddr, haServerAddr);
}

//維護(hù)filterServerTable
if (filterServerList != null) {
    if (filterServerList.isEmpty()) {
        this.filterServerTable.remove(brokerAddr);
    } else {
        this.filterServerTable.put(brokerAddr, filterServerList);
    }
}
if (MixAll.MASTER_ID != brokerId) {
    String masterAddr = brokerData.getBrokerAddrs().get(MixAll.MASTER_ID);
    if (masterAddr != null) {
        BrokerLiveInfo brokerLiveInfo = this.brokerLiveTable.get(masterAddr);
        if (brokerLiveInfo != null) {
            result.setHaServerAddr(brokerLiveInfo.getHaServerAddr());
            result.setMasterAddr(masterAddr);
        }
    }
}

RouteInfoManager#createAndUpdateQueueData

//創(chuàng)建并封裝新的隊列信息
QueueData queueData = new QueueData();
//Broker名稱
queueData.setBrokerName(brokerName);
//讀寫隊列個數(shù)
queueData.setWriteQueueNums(topicConfig.getWriteQueueNums());
queueData.setReadQueueNums(topicConfig.getReadQueueNums());
//操作權(quán)限
queueData.setPerm(topicConfig.getPerm());
//同步復(fù)制還是異步復(fù)制的標(biāo)識
queueData.setTopicSysFlag(topicConfig.getTopicSysFlag());

//根據(jù)Topic從topicQueueTable中獲取隊列集合
List<QueueData> queueDataList = this.topicQueueTable.get(topicConfig.getTopicName());
//如果沒有獲取到
if (null == queueDataList) {
    //創(chuàng)建并將新的queueData添加到集合中
    queueDataList = new LinkedList<QueueData>();
    queueDataList.add(queueData);
    //放入topicQueueTable
    this.topicQueueTable.put(topicConfig.getTopicName(), queueDataList);
    log.info("new topic registered, {} {}", topicConfig.getTopicName(), queueData);
} 
//queueDataList不為空
else {
    boolean addNewOne = true;

    Iterator<QueueData> it = queueDataList.iterator();
    //對該主題已有隊列信息進(jìn)行遍歷
    while (it.hasNext()) {
        QueueData qd = it.next();
        //如果找到相同主題
        if (qd.getBrokerName().equals(brokerName)) {
            //已經(jīng)存在
            if (qd.equals(queueData)) {
                addNewOne = false;
            } else {
                //進(jìn)行更改-先刪除后新增
                log.info("topic changed, {} OLD: {} NEW: {}", topicConfig.getTopicName(), qd,
                    queueData);
                it.remove();
            }
        }
    }
	//添加一個新的隊列信息
    if (addNewOne) {
        queueDataList.add(queueData);
    }
}

3.3路由刪除

NameServer會每隔10s掃描brokerLiveTable狀態(tài)表，如果BrokerLive的lastUpdateTimestamp的時間戳距當(dāng)前時間超過120s，則認(rèn)為Broker失效，移除該Broker，關(guān)閉與Broker連接，同時更新topicQueueTable、brokerAddrTable、brokerLiveTable、filterServerTable。

刪除路由信息的兩個觸發(fā)條件：

NameServer定期掃描brokerLiveTable檢測上次心跳包發(fā)送時間與當(dāng)前系統(tǒng)的時間差，如果時間超過120s，則需要移除該Broker路由信息
Broker正常關(guān)閉，執(zhí)行unregisterBroker

3.3.1Broker異常關(guān)閉

在這里插入圖片描述

NamesrvController#initialize

//定時任務(wù)線程池--->每隔十秒掃描活躍狀態(tài)異常的Broker信息
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
    /**
     * 對Not Active Broker 進(jìn)行掃描
     */
    @Override
    public void run() {
        //在routeInfoManager中進(jìn)行路由刪除
        NamesrvController.this.routeInfoManager.scanNotActiveBroker();
    }
}, 5, 10, TimeUnit.SECONDS);

RouteInfoManager#scanNotActiveBroker

//遍歷brokerLiveTable 查看是否有broker狀態(tài)長時間沒有更新
Iterator<Entry<String, BrokerLiveInfo>> it = this.brokerLiveTable.entrySet().iterator();
//遍歷brokerLiveTable
while (it.hasNext()) {
    Entry<String, BrokerLiveInfo> next = it.next();
    long last = next.getValue().getLastUpdateTimestamp();
    //如果收到心跳包的時間間距超過120s
    if ((last + BROKER_CHANNEL_EXPIRED_TIME) < System.currentTimeMillis()) {
        //關(guān)閉連接
        RemotingUtil.closeChannel(next.getValue().getChannel());
        //移除broker
        it.remove();
        log.warn("The broker channel expired, {} {}ms", next.getKey(), BROKER_CHANNEL_EXPIRED_TIME);
        //維護(hù)路由表
        this.onChannelDestroy(next.getKey(), next.getValue().getChannel());
    }
}

RouteInfoManager#onChannelDestroy

//待刪除的BrokerAddress
String brokerAddrFound = null;
if (channel != null) {
    try {
        try {
            //加入讀鎖
            this.lock.readLock().lockInterruptibly();
            Iterator<Entry<String, BrokerLiveInfo>> itBrokerLiveTable =
                this.brokerLiveTable.entrySet().iterator();
            //遍歷查找待刪除的Broker
            while (itBrokerLiveTable.hasNext()) {
                Entry<String, BrokerLiveInfo> entry = itBrokerLiveTable.next();
                if (entry.getValue().getChannel() == channel) {
                    brokerAddrFound = entry.getKey();
                    break;
                }
            }
        } finally {
            //釋放鎖
            this.lock.readLock().unlock();
        }
    } catch (Exception e) {
        log.error("onChannelDestroy Exception", e);
    }
}

//加入寫鎖
//根據(jù)brokerAddrFound從brokerLiveTable和filterServerTable移除對應(yīng)的Broker信息
this.lock.writeLock().lockInterruptibly();
this.brokerLiveTable.remove(brokerAddrFound);
this.filterServerTable.remove(brokerAddrFound);

//維護(hù)brokerAddrTable
String brokerNameFound = null;
boolean removeBrokerName = false;
Iterator<Entry<String, BrokerData>> itBrokerAddrTable =
    this.brokerAddrTable.entrySet().iterator();
//遍歷brokerAddrTable
while (itBrokerAddrTable.hasNext() && (null == brokerNameFound)) {
    BrokerData brokerData = itBrokerAddrTable.next().getValue();
	//遍歷brokerAddress
    Iterator<Entry<Long, String>> it = brokerData.getBrokerAddrs().entrySet().iterator();
    while (it.hasNext()) {
        Entry<Long, String> entry = it.next();
        Long brokerId = entry.getKey();
        String brokerAddr = entry.getValue();
        //遍歷到匹配的broker
        if (brokerAddr.equals(brokerAddrFound)) {
            brokerNameFound = brokerData.getBrokerName();
            //根據(jù)broker地址移除broker
            it.remove();
            log.info("remove brokerAddr[{}, {}] from brokerAddrTable, because channel destroyed",
                brokerId, brokerAddr);
            break;
        }
    }
	//如果當(dāng)前BrokerData中的Broker列表為空
    if (brokerData.getBrokerAddrs().isEmpty()) {
        removeBrokerName = true;
        //從BrokerAddrTable移除該BrokerData
        itBrokerAddrTable.remove();
        log.info("remove brokerName[{}] from brokerAddrTable, because channel destroyed",
            brokerData.getBrokerName());
    }
}

//維護(hù)clusterAddrTable
if (brokerNameFound != null && removeBrokerName) {
    Iterator<Entry<String, Set<String>>> it = this.clusterAddrTable.entrySet().iterator();
    //遍歷clusterAddrTable
    while (it.hasNext()) {
        Entry<String, Set<String>> entry = it.next();
        String clusterName = entry.getKey();
        Set<String> brokerNames = entry.getValue();
        //根據(jù)brokerName刪除cluster集群中的broker并返回是否刪除成功
        boolean removed = brokerNames.remove(brokerNameFound);
        if (removed) {
            log.info("remove brokerName[{}], clusterName[{}] from clusterAddrTable, because channel destroyed",
                brokerNameFound, clusterName);
			
            //如果cluster已經(jīng)不包含任何broker則移除該集群
            if (brokerNames.isEmpty()) {
                log.info("remove the clusterName[{}] from clusterAddrTable, because channel destroyed and no broker in this cluster",
                    clusterName);
                it.remove();
            }
            break;
        }
    }
}

//維護(hù)TopicQueueTable
if (removeBrokerName) {
    Iterator<Entry<String, List<QueueData>>> itTopicQueueTable =
        this.topicQueueTable.entrySet().iterator();
    //遍歷TopicQueueTable
    while (itTopicQueueTable.hasNext()) {
        Entry<String, List<QueueData>> entry = itTopicQueueTable.next();
        //主題
        String topic = entry.getKey();
        //主題對應(yīng)的Broker信息
        List<QueueData> queueDataList = entry.getValue();

        Iterator<QueueData> itQueueData = queueDataList.iterator();
        //遍歷Broker
        while (itQueueData.hasNext()) {
            QueueData queueData = itQueueData.next();
            //通過brokerNameFound在queueData中查找對應(yīng)的Broker信息
            if (queueData.getBrokerName().equals(brokerNameFound)) {
                //移除該Broker
                itQueueData.remove();
                log.info("remove topic[{} {}], from topicQueueTable, because channel destroyed",
                    topic, queueData);
            }
        }
		
        //如果當(dāng)前主題已經(jīng)沒有任何Broker，則移除該主題Topic
        if (queueDataList.isEmpty()) {
            itTopicQueueTable.remove();
            log.info("remove topic[{}] all queue, from topicQueueTable, because channel destroyed",
                topic);
        }
    }
}

//釋放寫鎖
finally {
    this.lock.writeLock().unlock();
}

3.3.2Broker正常關(guān)閉

在這里插入圖片描述

關(guān)閉入口-BrokerController

//BrokerController#shutdown
this.unregisterBrokerAll();

//BrokerController#unregisterBrokerAll
this.brokerOuterAPI.unregisterBrokerAll(
    this.brokerConfig.getBrokerClusterName(),
    this.getBrokerAddr(),
    this.brokerConfig.getBrokerName(),
    this.brokerConfig.getBrokerId());

BrokerOuterAPI#unregisterBrokerAll

//獲取NameServerAddress列表
List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
if (nameServerAddressList != null) {
    //遍歷NameServer
    for (String namesrvAddr : nameServerAddressList) {
        try {
            //注銷指定Broker
            this.unregisterBroker(namesrvAddr, clusterName, brokerAddr, brokerName, brokerId);
            log.info("unregisterBroker OK, NamesrvAddr: {}", namesrvAddr);
        } catch (Exception e) {
            log.warn("unregisterBroker Exception, {}", namesrvAddr, e);
        }
    }
}

BrokerOuterAPI#unregisterBroker

//封裝注銷Broker請求頭
UnRegisterBrokerRequestHeader requestHeader = new UnRegisterBrokerRequestHeader();
requestHeader.setBrokerAddr(brokerAddr);
requestHeader.setBrokerId(brokerId);
requestHeader.setBrokerName(brokerName);
requestHeader.setClusterName(clusterName);
//封裝注銷請求
RemotingCommand request = RemotingCommand.createRequestCommand(RequestCode.UNREGISTER_BROKER, requestHeader);
//遠(yuǎn)程調(diào)用并發(fā)送請求-返回響應(yīng)結(jié)果
RemotingCommand response = this.remotingClient.invokeSync(namesrvAddr, request, 3000);
assert response != null;
switch (response.getCode()) {
    case ResponseCode.SUCCESS: {
        return;
    }
    default:
        break;
}
throw new MQBrokerException(response.getCode(), response.getRemark(), brokerAddr);

忽略Netty遠(yuǎn)程調(diào)用過程

DefaultRequestProcess#processRequest

//根據(jù)請求狀態(tài)碼-進(jìn)行不同的處理
switch (request.getCode()) {
	case RequestCode.UNREGISTER_BROKER:
        return this.unregisterBroker(ctx, request);
}

DefaultRequestProcess#unregisterBroker

final RemotingCommand response = RemotingCommand.createResponseCommand(null);
//解碼注銷Broker的請求頭
final UnRegisterBrokerRequestHeader requestHeader =
    (UnRegisterBrokerRequestHeader) request.decodeCommandCustomHeader(UnRegisterBrokerRequestHeader.class);
//轉(zhuǎn)發(fā)至RouteInfoManager注銷Broker
this.namesrvController.getRouteInfoManager().unregisterBroker(
    requestHeader.getClusterName(),
    requestHeader.getBrokerAddr(),
    requestHeader.getBrokerName(),
    requestHeader.getBrokerId());

//設(shè)置響應(yīng)狀態(tài)碼
response.setCode(ResponseCode.SUCCESS);
response.setRemark(null);
//返回響應(yīng)結(jié)果
return response;

RouteInfoManager#unregisterBroker

try {
    try {
        //加入寫鎖-保護(hù)HashMap線程安全
        this.lock.writeLock().lockInterruptibly();
        //由于是從BrokerController遠(yuǎn)程調(diào)用來的請求-故不對BrokerAddr進(jìn)行檢查-直接進(jìn)行移除
        //移除brokerLiveTable中的Broker信息
        BrokerLiveInfo brokerLiveInfo = this.brokerLiveTable.remove(brokerAddr);
        log.info("unregisterBroker, remove from brokerLiveTable {}, {}",
            brokerLiveInfo != null ? "OK" : "Failed",
            brokerAddr
        );

        //維護(hù)filterServerTable
        this.filterServerTable.remove(brokerAddr);
        boolean removeBrokerName = false;
        //根據(jù)brokername獲取對應(yīng)的BrokerData信息
        BrokerData brokerData = this.brokerAddrTable.get(brokerName);
        if (null != brokerData) {
            //刪除對應(yīng)Broker信息
            String addr = brokerData.getBrokerAddrs().remove(brokerId);
            log.info("unregisterBroker, remove addr from brokerAddrTable {}, {}",
                addr != null ? "OK" : "Failed",
                brokerAddr
            );
            //如果當(dāng)前BrokerData中已經(jīng)沒有其他Broker
            if (brokerData.getBrokerAddrs().isEmpty()) {
                //從BrokerAddrTable移除相應(yīng)的Broker
                this.brokerAddrTable.remove(brokerName);
                log.info("unregisterBroker, remove name from brokerAddrTable OK, {}",
                    brokerName
                );
                removeBrokerName = true;
            }
        }

        if (removeBrokerName) {
            //在clusterAddrTable中通過集群名稱獲取對應(yīng)的Broker集合
            Set<String> nameSet = this.clusterAddrTable.get(clusterName);
            if (nameSet != null) {
                //移除該集合中的Broker
                boolean removed = nameSet.remove(brokerName);
                log.info("unregisterBroker, remove name from clusterAddrTable {}, {}",
                    removed ? "OK" : "Failed",
                    brokerName);
                //如果該集群中的Broker集合為空-移除該集群
                if (nameSet.isEmpty()) {
                    this.clusterAddrTable.remove(clusterName);
                    log.info("unregisterBroker, remove cluster from clusterAddrTable {}",
                        clusterName
                    );
                }
            }
            //移除該Broker下的所有主題Topic
            this.removeTopicByBrokerName(brokerName);
        }
    } finally {
        //釋放寫鎖
        this.lock.writeLock().unlock();
    }
} catch (Exception e) {
    log.error("unregisterBroker Exception", e);
}

3.4路由發(fā)現(xiàn)

RocketMQ路由發(fā)現(xiàn)是非實時的，當(dāng)Topic路由出現(xiàn)變化后，NameServer不會主動推送給客戶端，而是由客戶端定時拉取主題最新的路由。

DefaultRequestProcessor#processRequest

switch (request.getCode()) {
    case RequestCode.GET_ROUTEINFO_BY_TOPIC:
         return this.getRouteInfoByTopic(ctx, request);	
}

DefaultRequestProcessor#getRouteInfoByTopic

//遠(yuǎn)程調(diào)用返回的響應(yīng)結(jié)果
final RemotingCommand response = RemotingCommand.createResponseCommand(null);
//解析獲取路由信息的請求頭
final GetRouteInfoRequestHeader requestHeader =
    (GetRouteInfoRequestHeader) request.decodeCommandCustomHeader(GetRouteInfoRequestHeader.class);
//調(diào)用RouteInfoManager中的方法,從路由表topicQueueTable、brokerAddrTable、filterServerTable中
//分別填充TopicRouteData的List<QueueData>、List<BrokerData>、filterServer
TopicRouteData topicRouteData = this.namesrvController.getRouteInfoManager().pickupTopicRouteData(requestHeader.getTopic());

//如果找到主題對應(yīng)你的路由信息并且該主題為順序消息
//則從NameServer KVConfig中獲取關(guān)于順序消息相關(guān)的配置填充路由信息
if (topicRouteData != null) {
    if (this.namesrvController.getNamesrvConfig().isOrderMessageEnable()) {
        String orderTopicConf =
            this.namesrvController.getKvConfigManager().getKVConfig(NamesrvUtil.NAMESPACE_ORDER_TOPIC_CONFIG,
                requestHeader.getTopic());
        topicRouteData.setOrderTopicConf(orderTopicConf);
    }

    byte[] content = topicRouteData.encode();
    //填充響應(yīng)體和狀態(tài)碼
    response.setBody(content);
    response.setCode(ResponseCode.SUCCESS);
    response.setRemark(null);
    return response;
}
//設(shè)置響應(yīng)碼-主題不存在
response.setCode(ResponseCode.TOPIC_NOT_EXIST);
response.setRemark("No topic route info in name server for the topic: " + requestHeader.getTopic()
    + FAQUrl.suggestTodo(FAQUrl.APPLY_TOPIC_URL));
return response;

RouteInfoManager#pickupTopicRouteData

//創(chuàng)建主題路由信息對象
TopicRouteData topicRouteData = new TopicRouteData();
//是否找到對應(yīng)隊列的標(biāo)識
boolean foundQueueData = false;
//是否找到對應(yīng)Broker的標(biāo)識
boolean foundBrokerData = false;
Set<String> brokerNameSet = new HashSet<String>();
List<BrokerData> brokerDataList = new LinkedList<BrokerData>();
topicRouteData.setBrokerDatas(brokerDataList);
HashMap<String, List<String>> filterServerMap = new HashMap<String, List<String>>();
topicRouteData.setFilterServerTable(filterServerMap);
try {
    try {
        //加入讀鎖
        this.lock.readLock().lockInterruptibly();
        //從topicQueueTable中通過主題topic查找Broker列表
        List<QueueData> queueDataList = this.topicQueueTable.get(topic);
        if (queueDataList != null) {
            //填充Broker信息到topicRouteData.QueueDatas
            topicRouteData.setQueueDatas(queueDataList);
            foundQueueData = true;

            Iterator<QueueData> it = queueDataList.iterator();
            while (it.hasNext()) {
                QueueData qd = it.next();
                brokerNameSet.add(qd.getBrokerName());
            }
            //遍歷Broker集合
            for (String brokerName : brokerNameSet) {
                //從brokerAddrTable中通過BrokerName進(jìn)行查找
                BrokerData brokerData = this.brokerAddrTable.get(brokerName);
                if (null != brokerData) {
                    BrokerData brokerDataClone = new BrokerData(brokerData.getCluster(), brokerData.getBrokerName(), (HashMap<Long, String>) brokerData.getBrokerAddrs().clone());
                    //填充BrokerData信息到brokerDatas
                    brokerDataList.add(brokerDataClone);
                    foundBrokerData = true;
                    for (final String brokerAddr : brokerDataClone.getBrokerAddrs().values()) {
                        List<String> filterServerList = this.filterServerTable.get(brokerAddr);
                        filterServerMap.put(brokerAddr, filterServerList);
                    }
                }
            }
        }
    } finally {
        //釋放讀鎖
        this.lock.readLock().unlock();
    }
} catch (Exception e) {
    log.error("pickupTopicRouteData Exception", e);
}

log.debug("pickupTopicRouteData {} {}", topic, topicRouteData);

if (foundBrokerData && foundQueueData) {
    return topicRouteData;
}
return null;

3.5總結(jié)

在這里插入圖片描述

路由注冊：Broker啟動之后會將自己的信息注冊到NameServer，NameServer收到Broker心跳包之后會更新BrokerLiveTable中對應(yīng)的Broker的相關(guān)信息，特別記錄lastUpdateTimestamp。

心跳機制：Broker會每隔30s向NameServer發(fā)送心跳包，告訴NameServer自己的運行狀態(tài)良好。

路由發(fā)現(xiàn)：NameServer中的主題Topic信息更新之后，NameServer并不會實時將數(shù)據(jù)推送給訂閱方Producer，而需要Producer自行通過Topic來查詢路由信息。

路由刪除：

Broker異常宕機：NameServer每隔10s掃描BrokerLiveTable，檢查表中各個Broker最新的發(fā)送心跳包時間，如果這個時間與當(dāng)前系統(tǒng)時間差超過120s，則該Broker會被視作已掉線，NameServer會將這個Broker從表中刪除，并且更新各個表中與該Broker有關(guān)的所有信息。
Broker正常下線：NameServer接受到BrokerController發(fā)送來的UNREGISTER_BROKER請求之后，會執(zhí)行上述步驟，對路由信息進(jìn)行更新。

本文僅作為個人學(xué)習(xí)使用，如有不足或者錯誤請指正！

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