前言
在微服务盛行的当下,消息队列的使用越来越频繁,阿里的Rocketmq是使用频率较高的mq,本人对它的内在原理一直很感兴趣,今天来看看
脉络
我们先从一个整体的视角看Rocketmq
- NameServer保存了所有Broker的相关信息,为了保证NameServer的高可用,我们可以部署多台NameServer,但是多台NameServer服务器之间不会做信息同步,也就是说,每一台NameServer的broker信息都有可能不一样
- Broker分为Master与Slave,一个Master可以对应多个Slave,一个Slave只能对应一个Master,Braoker服务器在启动时会向所有NameServer注册信息,并且每隔30s会向NameServer发送一个心跳包。Broker本身主要负责消息的管理,可以说是Rocketmq的核心
- Producer会随机选择NameServer集群中的其中一个节点建立长连接,获取到Topic的路由信息进行消息的发送
- Consumer会随机选择NameServer集群中的其中一个节点建立长连接,获取到Topic的路由信息进行消息的获取
NameServer源码解析
路由管理
NameServer相当于一个注册中心,保存了所有Broker的相关信息,那么这些信息是如何保存?
秘密就在这些HashMap中
// 保存topic在每个broker的读写queue个数以及读写权限,key为topicName
private final HashMap<String, List<QueueData>> topicQueueTable;
// 保存每个broker所属的集群以及地址信息,key为brokerName
private final HashMap<String, BrokerData> brokerAddrTable;
// 保存集群中所有的brokerName,key为clusterName,value为brokerName
private final HashMap<String, Set<String>> clusterAddrTable;
// 保存每个broker的状态信息,key为brokerAddr
private final HashMap<String, BrokerLiveInfo> brokerLiveTable;
// key为brokerAddr,value为Filter Server
private final HashMap<String, List<String>> filterServerTable;
用一张图表示这些HashMap的关系
那么HashMap中的这些数据是如何产生的呢?
前面讲过,Braoker服务器在启动时会向所有NameServer注册信息,所以我们应该看Broker启动时做了什么,Broker和NameServer类似,启动类都是在StartUp这个类中
public void start() throws Exception {
......
// 定时向NameServer注册信息,延迟10s执行,间隔时间是计算出来的
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
try {
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);
......
}
一路往里追,关键代码是下面这一段
public List<RegisterBrokerResult> registerBrokerAll(
final String clusterName,
final String brokerAddr,
final String brokerName,
final long brokerId,
final String haServerAddr,
final TopicConfigSerializeWrapper topicConfigWrapper,
final List<String> filterServerList,
final boolean oneway,
final int timeoutMills,
final boolean compressed) {
final List<RegisterBrokerResult> registerBrokerResultList = new CopyOnWriteArrayList<>();
// 获取所有的NameServer地址
List<String> nameServerAddressList = this.remotingClient.getNameServerAddressList();
if (nameServerAddressList != null && nameServerAddressList.size() > 0) {
// 构造请求头
final RegisterBrokerRequestHeader requestHeader = new RegisterBrokerRequestHeader();
requestHeader.setBrokerAddr(brokerAddr);
requestHeader.setBrokerId(brokerId);
requestHeader.setBrokerName(brokerName);
requestHeader.setClusterName(clusterName);
requestHeader.setHaServerAddr(haServerAddr);
requestHeader.setCompressed(compressed);
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());
for (final String namesrvAddr : nameServerAddressList) {
brokerOuterExecutor.execute(new Runnable() {
@Override
public void run() {
try {
// 向NameServer注册信息
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;
}
那么NameServer是如何处理信息的呢?
关键代码在org.apache.rocketmq.namesrv.routeinfo.RouteInfoManager#registerBroker
public RegisterBrokerResult registerBroker(
final String clusterName,
final String brokerAddr,
final String brokerName,
final long brokerId,
final String haServerAddr,
final TopicConfigSerializeWrapper topicConfigWrapper,
final List<String> filterServerList,
final Channel channel) {
RegisterBrokerResult result = new RegisterBrokerResult();
try {
try {
// 先加上写锁
this.lock.writeLock().lockInterruptibly();
// 获取集群下所有的Broker,如果集群是首次出现,则新增键值对,否则将该BrokerName加入Set中,由于是Set,所以BrokerName不会重复
Set<String> brokerNames = this.clusterAddrTable.get(clusterName);
if (null == brokerNames) {
brokerNames = new HashSet<String>();
this.clusterAddrTable.put(clusterName, brokerNames);
}
brokerNames.add(brokerName);
boolean registerFirst = false;
// 获取Broker信息,如果是首次注册,则新建BrokerData并加入brokerAddrTable
BrokerData brokerData = this.brokerAddrTable.get(brokerName);
if (null == brokerData) {
registerFirst = true;
brokerData = new BrokerData(clusterName, brokerName, new HashMap<Long, String>());
this.brokerAddrTable.put(brokerName, brokerData);
}
// 非第一次注册,更新brokerAddrsMap
Map<Long, String> brokerAddrsMap = brokerData.getBrokerAddrs();
Iterator<Entry<Long, String>> it = brokerAddrsMap.entrySet().iterator();
while (it.hasNext()) {
Entry<Long, String> item = it.next();
// 将slave切换成master,先去掉nameServer中的<1,IP:PORT>,再添加<0,IP:PORT>
// 同一个IP:PORT,在brokerAddrTable中必须只有一条记录
if (null != brokerAddr && brokerAddr.equals(item.getValue()) && brokerId != item.getKey()) {
it.remove();
}
}
String oldAddr = brokerData.getBrokerAddrs().put(brokerId, brokerAddr);
registerFirst = registerFirst || (null == oldAddr);
// 如果Broker是Master节点
if (null != topicConfigWrapper
&& MixAll.MASTER_ID == brokerId) {
// 如果topic信息变更或者首次注册
if (this.isBrokerTopicConfigChanged(brokerAddr, topicConfigWrapper.getDataVersion())
|| registerFirst) {
ConcurrentMap<String, TopicConfig> tcTable =
topicConfigWrapper.getTopicConfigTable();
// 创建或者更新topicQueueTable
if (tcTable != null) {
for (Map.Entry<String, TopicConfig> entry : tcTable.entrySet()) {
this.createAndUpdateQueueData(brokerName, entry.getValue());
}
}
}
}
// 维护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);
}
// 维护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);
}
}
}
} finally {
this.lock.writeLock().unlock();
}
} catch (Exception e) {
log.error("registerBroker Exception", e);
}
return result;
}
看完源码,我们debug一下,感受一下路由信息是怎么样的,本人使用Rocketmq中的example来调试,topic名为TopicTest
topicQueueTable
brokerAddrTable
brokerLiveTable
clusterAddrTable
路由删除
路由既然会产生,那么一定会删除,在什么情况下会删除呢?秘密在NameServer的启动类中,NameServer启动类中有几个重要的方法,我们顺便来看看
NameServer启动的入口在NamesrvStartup
这个类
public static NamesrvController main0(String[] args) {
try {
// 设置nameServer监听端口号为9876,添加netty和nameServer的相关配置,创建NamesrvController对象
NamesrvController controller = createNamesrvController(args);
start(controller);
String tip = "The Name Server boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();
log.info(tip);
System.out.printf("%s%n", tip);
return controller;
} catch (Throwable e) {
e.printStackTrace();
System.exit(-1);
}
return null;
}
public static NamesrvController start(final NamesrvController controller) throws Exception {
if (null == controller) {
throw new IllegalArgumentException("NamesrvController is null");
}
// 初始化任务
boolean initResult = controller.initialize();
if (!initResult) {
controller.shutdown();
System.exit(-3);
}
// Hook方法,在JVM退出时释放资源
Runtime.getRuntime().addShutdownHook(new ShutdownHookThread(log, new Callable<Void>() {
@Override
public Void call() throws Exception {
controller.shutdown();
return null;
}
}));
controller.start();
return controller;
}
这个初始化方法是重点
public boolean initialize() {
this.kvConfigManager.load();
this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);
this.remotingExecutor =
Executors.newFixedThreadPool(nettyServerConfig.getServerWorkerThreads(), new ThreadFactoryImpl("RemotingExecutorThread_"));
this.registerProcessor();
// 线程池定时任务,延迟5s执行,每隔10s执行一次
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
// 扫描未活跃的broker的信息
@Override
public void run() {
NamesrvController.this.routeInfoManager.scanNotActiveBroker();
}
}, 5, 10, TimeUnit.SECONDS);
// 定期打印配置信息,每10分钟一次
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.kvConfigManager.printAllPeriodically();
}
}, 1, 10, TimeUnit.MINUTES);
......
return true;
}
public void scanNotActiveBroker() {
// 遍历brokerLiveTable
Iterator<Entry<String, BrokerLiveInfo>> it = this.brokerLiveTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, BrokerLiveInfo> next = it.next();
long last = next.getValue().getLastUpdateTimestamp();
// 这个判断是关键,如果这个brokerAddr的上次更新时间已经超过120s,就会删除这个brokerAddr
if ((last + BROKER_CHANNEL_EXPIRED_TIME) < System.currentTimeMillis()) {
RemotingUtil.closeChannel(next.getValue().getChannel());
it.remove();
log.warn("The broker channel expired, {} {}ms", next.getKey(), BROKER_CHANNEL_EXPIRED_TIME);
this.onChannelDestroy(next.getKey(), next.getValue().getChannel());
}
}
}
参考资料
B站黑马Rocketmq视频