一、Producer路由信息
从NameServer章节分析得知，路由信息存储在NameServer，生产端和消费端定时向NameServer获取topic相关的路由信息； 从生产者启动流程得知： 路由信息的动态更新源码在MQClientInstance#startScheduledTask定时任务里面 具体方法： updateTopicRouteInfoFromNameServer 下图为路由更新流程
接下来我们着重解析此段源码:
1 定时任务：频率-30s
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
//从nameServer更新路由信息 -定时任务：30s一次
MQClientInstance.this.updateTopicRouteInfoFromNameServer();
} catch (Exception e) {
log.error("ScheduledTask updateTopicRouteInfoFromNameServer exception", e);
}
}
}, 10, this.clientConfig.getPollNameServerInterval(), TimeUnit.MILLISECONDS);
2 updateTopicRouteInfoFromNameServer
public void updateTopicRouteInfoFromNameServer() {
Set<String> topicList = new HashSet<String>();
{ // Consumer 消费端，后续再分析
...省略....
}
{ // Producer 生产端
Iterator<Entry<String, MQProducerInner>> it = this.producerTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, MQProducerInner> entry = it.next();
MQProducerInner impl = entry.getValue();
if (impl != null) {
Set<String> lst = impl.getPublishTopicList();//1>获取所有 topic-list
topicList.addAll(lst);
}
}
}
//2>更新路由信息
for (String topic : topicList) {
this.updateTopicRouteInfoFromNameServer(topic);
}
}
分析如下:
1.1 getPublishTopicList getPublishTopicList 方法分析：
public Set<String> getPublishTopicList() {
Set<String> topicList = new HashSet<String>();
for (String key : this.topicPublishInfoTable.keySet()) {
topicList.add(key);
}
return topicList;
}
备注：
细心的你可能发现从启动流程中得知：
topicPublishInfoTable(ConcurrentHashMap)只会默认注册topic=TBW102的信息,那正常业务发送的topic是如何注册进去的呢，建议直接观看理解以下代码，在发送流程中会体现出如何注册到topicPublishInfoTable中；topicPublishInfoTable数据的初始化（value:第一次默认都是new TopicPublishInfo()）
//查找主题的路由信息的方法
private TopicPublishInfo tryToFindTopicPublishInfo(final String topic) {
TopicPublishInfo topicPublishInfo = this.topicPublishInfoTable.get(topic);
if (null == topicPublishInfo || !topicPublishInfo.ok()) {
this.topicPublishInfoTable.putIfAbsent(topic, new TopicPublishInfo());
this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic); //从NameServer更新topic路由信息
topicPublishInfo = this.topicPublishInfoTable.get(topic);
}
if (topicPublishInfo.isHaveTopicRouterInfo() || topicPublishInfo.ok()) {
return topicPublishInfo;
} else {
this.mQClientFactory.updateTopicRouteInfoFromNameServer(topic, true, this.defaultMQProducer); //从NameServer更新topic路由信息
topicPublishInfo = this.topicPublishInfoTable.get(topic);
return topicPublishInfo;
}
}
分析
-
如果生产者中缓存了 topic 的路由信息，如果该路由信息中包含了消息队列，则直接返回该路由信息，
-
如果没有缓存或没有包含消息队列， 则向 NameServer查询该 topic 的路由信息。
-
如果最终未找到路由信息，则抛出异常 : 无法找到主题相关路由信息异常 。
1.2 updateTopicRouteInfoFromNameServer 从NameServer更新topic路由信息
在分析之前，可先简单分析MQClientInstance核心属性：
public class MQClientInstance {
...省略...
//key:group, value: 生产者
private final ConcurrentMap<String/* group */, MQProducerInner> producerTable = new ConcurrentHashMap<String, MQProducerInner>();
...省略..
//topic-路由信息
private final ConcurrentMap<String/* Topic */, TopicRouteData> topicRouteTable = new ConcurrentHashMap<String, TopicRouteData>();
private final Lock lockNamesrv = new ReentrantLock(); //更新路由使用
private final Lock lockHeartbeat = new ReentrantLock(); //发送心跳使用
//broker信息，key:Broker Name, value:-key:brokerId,value:address
private final ConcurrentMap<String/* Broker Name */, HashMap<Long/* brokerId */, String/* address */>> brokerAddrTable =
new ConcurrentHashMap<String, HashMap<Long, String>>();
//broker版本信息，key:Broker Name, value:-key:address,value:version
private final ConcurrentMap<String/* Broker Name */, HashMap<String/* address */, Integer>> brokerVersionTable =
new ConcurrentHashMap<String, HashMap<String, Integer>>();
...省略...
}
备注：此处列出的属性仅跟生产端相关，其他的属性和方法大都我们会在消费端分析
接下来着重分析：updateTopicRouteInfoFromNameServer
/**
* 向-NameServer查询该 topic 的路由信息
* @param topic 主题
* @param isDefault 是否默认主题
* @param defaultMQProducer 默认MQProducer
* @return
*/
public boolean updateTopicRouteInfoFromNameServer(final String topic, boolean isDefault,
DefaultMQProducer defaultMQProducer) {
try {
if (this.lockNamesrv.tryLock(LOCK_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)) { //获取锁:3s
try {
TopicRouteData topicRouteData;
if (isDefault && defaultMQProducer != null) { //默认主题-'TBW102'，从NameServer查询-topicRouteData
topicRouteData = this.mQClientAPIImpl.getDefaultTopicRouteInfoFromNameServer(defaultMQProducer.getCreateTopicKey(), 1000 * 3);
if (topicRouteData != null) {
for (QueueData data : topicRouteData.getQueueDatas()) { //读写队列取最小值，getDefaultTopicQueueNums=4，getReadQueueNums=16
int queueNums = Math.min(defaultMQProducer.getDefaultTopicQueueNums(), data.getReadQueueNums());
data.setReadQueueNums(queueNums);
data.setWriteQueueNums(queueNums);
}
}
} else {//非默认主题，从NameServer查询-topicRouteData
topicRouteData = this.mQClientAPIImpl.getTopicRouteInfoFromNameServer(topic, 1000 * 3);
}
if (topicRouteData != null) {
TopicRouteData old = this.topicRouteTable.get(topic);
boolean changed = topicRouteDataIsChange(old, topicRouteData);//1> 判断：TopicRouteData 是否改变
if (!changed) { //未改变，
changed = this.isNeedUpdateTopicRouteInfo(topic);//2>继续判断是否需要更新：topic-路由信息
} else {
log.info("the topic[{}] route info changed, old[{}] ,new[{}]", topic, old, topicRouteData);
}
if (changed) { // 需要更新
TopicRouteData cloneTopicRouteData = topicRouteData.cloneTopicRouteData();
for (BrokerData bd : topicRouteData.getBrokerDatas()) {
this.brokerAddrTable.put(bd.getBrokerName(), bd.getBrokerAddrs());//维护brokerAddrTable地址信息
}
// Update Pub info
{ //topicRouteData 转换 TopicPublishInfo(isWriteable)-生产需要的数据
TopicPublishInfo publishInfo = topicRouteData2TopicPublishInfo(topic, topicRouteData); // 3>数据转换
publishInfo.setHaveTopicRouterInfo(true);
Iterator<Entry<String, MQProducerInner>> it = this.producerTable.entrySet().iterator();//迭代-producerTable
while (it.hasNext()) {
Entry<String, MQProducerInner> entry = it.next();
MQProducerInner impl = entry.getValue();
if (impl != null) {
impl.updateTopicPublishInfo(topic, publishInfo);//4-更新-路由发布信息
}
}
}
// Update sub info
{ //消费端--后续消费端讲解（ topicRouteData 转换 TopicPublishInfo(isReadable) 队列消息）
Set<MessageQueue> subscribeInfo = topicRouteData2TopicSubscribeInfo(topic, topicRouteData);//构建队列信息
Iterator<Entry<String, MQConsumerInner>> it = this.consumerTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, MQConsumerInner> entry = it.next();
MQConsumerInner impl = entry.getValue();
if (impl != null) {
impl.updateTopicSubscribeInfo(topic, subscribeInfo); //更新-消费端：队列信息
}
}
}
log.info("topicRouteTable.put. Topic = {}, TopicRouteData[{}]", topic, cloneTopicRouteData);
this.topicRouteTable.put(topic, cloneTopicRouteData); // 维护：topicRouteTable
return true;
}
} else {
log.warn("updateTopicRouteInfoFromNameServer, getTopicRouteInfoFromNameServer return null, Topic: {}", topic);
}
} catch (Exception e) { //异常吃掉了
if (!topic.startsWith(MixAll.RETRY_GROUP_TOPIC_PREFIX) && !topic.equals(MixAll.AUTO_CREATE_TOPIC_KEY_TOPIC)) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);//topic 非 RETRY 和 TBW102 失
}
} finally {
this.lockNamesrv.unlock(); // 释放锁
}
} else {
log.warn("updateTopicRouteInfoFromNameServer tryLock timeout {}ms", LOCK_TIMEOUT_MILLIS);
}
} catch (InterruptedException e) {
log.warn("updateTopicRouteInfoFromNameServer Exception", e);
}
return false;
}
备注：
-
判断：TopicRouteData 是否改变，topicRouteDataIsChange(old, topicRouteData); 代码很简单，直接分析如下：
(1) 判断 olddata 或 nowdata 是否为空
(2) TopicRouteData的equals方法比较
-
继续判断是否需要更新topic路由信息isNeedUpdateTopicRouteInfo(topic);
最终调用的代码为：
DefaultMQProducerImpl#isPublishTopicNeedUpdate(主要逻辑判断是 TopicPublishInfo是否存在，或者 TopicPublishInfo的messageQueueList是否为空)
-
topicRouteData2TopicPublishInfo数据转换，你一定感兴趣，内容相当简单，
分析如下：
public static TopicPublishInfo topicRouteData2TopicPublishInfo(final String topic, final TopicRouteData route) {
TopicPublishInfo info = new TopicPublishInfo();
info.setTopicRouteData(route);
if (route.getOrderTopicConf() != null && route.getOrderTopicConf().length() > 0) { // 此处可忽略，针对顺序消息
String[] brokers = route.getOrderTopicConf().split(";");
for (String broker : brokers) {
String[] item = broker.split(":");
int nums = Integer.parseInt(item[1]);
for (int i = 0; i < nums; i++) {
MessageQueue mq = new MessageQueue(topic, item[0], i);
info.getMessageQueueList().add(mq);
}
}
info.setOrderTopic(true);
} else {
List<QueueData> qds = route.getQueueDatas();
Collections.sort(qds);
for (QueueData qd : qds) {
if (PermName.isWriteable(qd.getPerm())) { // 写权限判断
BrokerData brokerData = null;
for (BrokerData bd : route.getBrokerDatas()) {
if (bd.getBrokerName().equals(qd.getBrokerName())) {
brokerData = bd;
break;
}
}
if (null == brokerData) {
continue;
}
if (!brokerData.getBrokerAddrs().containsKey(MixAll.MASTER_ID)) { // 不包含masterId，过滤
continue;
}
for (int i = 0; i < qd.getWriteQueueNums(); i++) {
MessageQueue mq = new MessageQueue(topic, qd.getBrokerName(), i);
info.getMessageQueueList().add(mq); //根据写队列个数，根据 topic+序号创建 MessageQueue，填充topicPublishlnfo 的 List<QuueMessage>。完成消息发送的路由查找 。
}
}
}
info.setOrderTopic(false);
}
return info;
}
4.更新-路由发布信息:updateTopicPublishInfo(topic, publishInfo); 调用的代码为：DefaultMQProducerImpl#updateTopicPublishInfo，本质就是维护Map-topicPublishInfoTable
二、结论
路由更新虽然相对简单，但对于生产者来说至关重要，生产端需要知道路由信息才能进行计算选择将消息发送到哪台broker； 但从源码分析中，可以看出更新路由信息以topic为维度，组装更新数据，本质还是维护Map(topicRouteTable、brokerAddrTable、topicPublishInfoTable)等，但是要注意是：ConcurrentHashMap。
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