概述
如RocketMQ源码阅读(二)中所述, RocketMQ的总体架构如下:
RocketMQ将注册中心单独提取出来封装成了一个可以单独部署的模块.
Name Server主要负责管理集群的路由信息, 包括Topic队列信息和Broker地址信息.客户端可以通过Name Server获取当前topic信息, 通过topic获取broker信息, 通过broker获取broker地址信息等等. 本文主要从三个方面分析Name Server的源代码:
- Name Server的启动
- 路由信息的管理(包括broker和topic)
- 心跳检查
在具体分析前线先上NameServer的类图:
Name Server的启动
Name Server的启动, 首先通过调用NamesrvStartup类的main方法进行执行. 该类首先加载系统默认配置文件, NamesrvConfig和NettyServerConfig, 顾名思义NamesrcConfig就是Name Server相关的配置信息, 例如rocketmq的home目录等, NettyServerConfig就是启动Netty服务端时的相关配置信息, 例如监听端口, 工作线程池数, 服务端发送接收缓存池的大小等. 源代码如下:
public static void main(String[] args) {
main0(args);
}
public static NamesrvController main0(String[] args) {
//设置RocketMQ版本号
System.setProperty(RemotingCommand.REMOTING_VERSION_KEY, Integer.toString(MQVersion.CURRENT_VERSION));
//设置数据发送缓冲区大小
if (null == System.getProperty(NettySystemConfig.COM_ROCKETMQ_REMOTING_SOCKET_SNDBUF_SIZE)) {
NettySystemConfig.socketSndbufSize = 4096;
}
//设置数据接收缓冲区大小
if (null == System.getProperty(NettySystemConfig.COM_ROCKETMQ_REMOTING_SOCKET_RCVBUF_SIZE)) {
NettySystemConfig.socketRcvbufSize = 4096;
}
try {
//PackageConflictDetect.detectFastjson();
Options options = ServerUtil.buildCommandlineOptions(new Options());
commandLine =
ServerUtil.parseCmdLine("mqnamesrv", args, buildCommandlineOptions(options),
new PosixParser());
if (null == commandLine) {
System.exit(-1);
return null;
}
//NameServer配置
final NamesrvConfig namesrvConfig = new NamesrvConfig();
//NettyServer配置
final NettyServerConfig nettyServerConfig = new NettyServerConfig();
nettyServerConfig.setListenPort(9876);
if (commandLine.hasOption('c')) {
String file = commandLine.getOptionValue('c');
if (file != null) {
InputStream in = new BufferedInputStream(new FileInputStream(file));
properties = new Properties();
properties.load(in);
MixAll.properties2Object(properties, namesrvConfig);
MixAll.properties2Object(properties, nettyServerConfig);
namesrvConfig.setConfigStorePath(file);
System.out.printf("load config properties file OK, " + file + "%n");
in.close();
}
}
if (commandLine.hasOption('p')) {
MixAll.printObjectProperties(null, namesrvConfig);
MixAll.printObjectProperties(null, nettyServerConfig);
System.exit(0);
}
MixAll.properties2Object(ServerUtil.commandLine2Properties(commandLine), namesrvConfig);
if (null == namesrvConfig.getRocketmqHome()) {
System.out.printf("Please set the " + MixAll.ROCKETMQ_HOME_ENV
+ " variable in your environment to match the location of the RocketMQ installation%n");
System.exit(-2);
}
LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory();
JoranConfigurator configurator = new JoranConfigurator();
configurator.setContext(lc);
lc.reset();
configurator.doConfigure(namesrvConfig.getRocketmqHome() + "/conf/logback_namesrv.xml");
final Logger log = LoggerFactory.getLogger(LoggerName.NAMESRV_LOGGER_NAME);
MixAll.printObjectProperties(log, namesrvConfig);
MixAll.printObjectProperties(log, nettyServerConfig);
//NamesrvController是Name Server真正的核心类
final NamesrvController controller = new NamesrvController(namesrvConfig, nettyServerConfig);
// remember all configs to prevent discard
controller.getConfiguration().registerConfig(properties);
//NamesrvController初始化
boolean initResult = controller.initialize();
if (!initResult) {
controller.shutdown();
System.exit(-3);
}
//添加java虚拟机关闭时的hook
Runtime.getRuntime().addShutdownHook(new Thread(new Runnable() {
private volatile boolean hasShutdown = false;
private AtomicInteger shutdownTimes = new AtomicInteger(0);
@Override
public void run() {
synchronized (this) {
log.info("shutdown hook was invoked, " + this.shutdownTimes.incrementAndGet());
if (!this.hasShutdown) {
this.hasShutdown = true;
long begineTime = System.currentTimeMillis();
controller.shutdown();
long consumingTimeTotal = System.currentTimeMillis() - begineTime;
log.info("shutdown hook over, consuming time total(ms): " + consumingTimeTotal);
}
}
}
}, "ShutdownHook"));
//NamesrvController启动
controller.start();
String tip = "The Name Server boot success. serializeType=" + RemotingCommand.getSerializeTypeConfigInThisServer();
log.info(tip);
System.out.printf(tip + "%n");
return controller;
} catch (Throwable e) {
e.printStackTrace();
System.exit(-1);
}
return null;
}
接下来看NamesrvController的initialize函数.
public boolean initialize() {
//kvConfigManager是nameserver里管理kv数据的一个组件
this.kvConfigManager.load();
//启动一个NettyRemotingServer实例
this.remotingServer = new NettyRemotingServer(this.nettyServerConfig, this.brokerHousekeepingService);
this.remotingExecutor =
Executors.newFixedThreadPool(nettyServerConfig.getServerWorkerThreads(), new ThreadFactoryImpl("RemotingExecutorThread_"));
//注册处理请求的processor
this.registerProcessor();
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.routeInfoManager.scanNotActiveBroker();
}
}, 5, 10, TimeUnit.SECONDS);
this.scheduledExecutorService.scheduleAtFixedRate(new Runnable() {
@Override
public void run() {
NamesrvController.this.kvConfigManager.printAllPeriodically();
}
}, 1, 10, TimeUnit.MINUTES);
return true;
}
private void registerProcessor() {
if (namesrvConfig.isClusterTest()) {
//ClusterTestRequestProcessor与DefaultRequestProcessor的区别在于ClusterTestRequestProcessor无法从本地读取路由信息时会从集群中读取
this.remotingServer.registerDefaultProcessor(new ClusterTestRequestProcessor(this, namesrvConfig.getProductEnvName()),
this.remotingExecutor);
} else {
this.remotingServer.registerDefaultProcessor(new DefaultRequestProcessor(this), this.remotingExecutor);
}
}
NamesrvController的initialize过程主要就是初始化一个通信组件中的NettyRemotingServer实例(参考RocketMQ源码阅读(二)-通信模块).
NamesrvController的start函数非常简单就是启动定义好的NettyRemotingServer.
public void start() throws Exception {
this.remotingServer.start();
}
NettyRemotingServer启动后就可以接收请求了, 其中最主要的请求就是处理路由信息相关的请求, 例如broker的注册请求.
路由信息的管理
(在了解NameServer是如何管理TopicQueue之前先查看一下RocketMQ源码阅读附一TopicQueue的划分)
NamesrvController在创建时, 实例化了RouteInfoManager和BrokerHouseKeepingService两个对象. Name Server中最重要的就是RouteInfoManager类. Name Server所有的Topic和Borker信息都保存在RouteInfoManager中, RouteInfoManager保存所有的路由信息. Netty服务端接收到请求后, 回调请求处理程序DefaultRequestProcessor, defaultRequestProcessor根据请求类型RequestCode, 例如注册Broker或者新建Topic请求, 来更新RouteInfoManager路由信息.
先看注册Broker的源码:
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 {
//加锁
this.lock.writeLock().lockInterruptibly();
//根据clusterName获取brokerNames
Set<String> brokerNames = this.clusterAddrTable.get(clusterName);
if (null == brokerNames) {
brokerNames = new HashSet<String>();
this.clusterAddrTable.put(clusterName, brokerNames);
}
//brokerNames中增加当前注册的brokerName
brokerNames.add(brokerName);
//是否首次注册的标记
boolean registerFirst = false;
//根据brokerName获取brokerData
BrokerData brokerData = this.brokerAddrTable.get(brokerName);
if (null == brokerData) {
registerFirst = true;
brokerData = new BrokerData();
brokerData.setBrokerName(brokerName);
HashMap<Long, String> brokerAddrs = new HashMap<Long, String>();
brokerData.setBrokerAddrs(brokerAddrs);
this.brokerAddrTable.put(brokerName, brokerData);
}
String oldAddr = brokerData.getBrokerAddrs().put(brokerId, brokerAddr);
registerFirst = registerFirst || (null == oldAddr);
//如果topicConfigWrapper不为空, 并且发送请求的broker是master, 创建或者新建topicConfig
if (null != topicConfigWrapper //
&& MixAll.MASTER_ID == brokerId) {
if (this.isBrokerTopicConfigChanged(brokerAddr, topicConfigWrapper.getDataVersion())//
|| registerFirst) {
ConcurrentHashMap<String, TopicConfig> tcTable =
topicConfigWrapper.getTopicConfigTable();
if (tcTable != null) {
for (Map.Entry<String, TopicConfig> entry : tcTable.entrySet()) {
//根据topicConfigWrapper中携带的topicConfig跟新本地保存的topicConfig信息
this.createAndUpdateQueueData(brokerName, entry.getValue());
}
}
}
}
//更新broker存活信息
BrokerLiveInfo prevBrokerLiveInfo = this.brokerLiveTable.put(brokerAddr,
new BrokerLiveInfo(
System.currentTimeMillis(),
topicConfigWrapper.getDataVersion(),
channel,
haServerAddr));
if (null == prevBrokerLiveInfo) {
log.info("new broker registerd, {} HAServer: {}", brokerAddr, haServerAddr);
}
if (filterServerList != null) {
if (filterServerList.isEmpty()) {
this.filterServerTable.remove(brokerAddr);
} else {
this.filterServerTable.put(brokerAddr, filterServerList);
}
}
//如果发送请求的不是master, 读取master的HaServerAddr和MasterAddr, 并放入返回结果中
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;
}
简单来说,整个过程就是将brokerName和对应的addr保存到本地, 如果注册信息中同时包含了topicConfig信息, 并且发送请求的是master, 则更新topicConfig信息.
心跳检查
RocketMQ使用BrokerHouseKeepingService来处理broker是否存活. 如果broker失效, 异常或者关闭, 则将broker从RouteInfoManager路由信息中移除, 同时将与该broker相关的topic信息也一起删除. Netty服务端专门启动了一个线程用于监听管道的失效, 异常或者关闭等的事件队列, 当事件队列里面有新事件时, 则取出事件并判断事件的类型, 然后调用BrokerHouseKeepingService对应的方法来处理该事件.
NamesrvController初始化时会实例化一个BrokerHouseKeepingService对象.
public NamesrvController(NamesrvConfig namesrvConfig, NettyServerConfig nettyServerConfig) {
this.namesrvConfig = namesrvConfig;
this.nettyServerConfig = nettyServerConfig;
this.kvConfigManager = new KVConfigManager(this);
this.routeInfoManager = new RouteInfoManager();
//实例化一个BrokerHouseKeepingService对象
this.brokerHousekeepingService = new BrokerHousekeepingService(this);
this.configuration = new Configuration(
log,
this.namesrvConfig, this.nettyServerConfig
);
this.configuration.setStorePathFromConfig(this.namesrvConfig, "configStorePath");
}
BrokerHousekeepingService实现了ChannelEventListener接口, 并且NettyRemotingServer启动时会启动BrokerHousekeepingService(细节参考RocketMQ源码阅读(二)-通信模块).
//类NettyRemotingServer中
if (this.channelEventListener != null) {
this.nettyEventExecuter.start();
}
BrokerHousekeepingService会对连接事件, 连接关闭事件, 异常事件,闲置事件进行处理.
//BrokerHousekeepingService
@Override
public void onChannelConnect(String remoteAddr, Channel channel) {
}
@Override
public void onChannelClose(String remoteAddr, Channel channel) {
this.namesrvController.getRouteInfoManager().onChannelDestroy(remoteAddr, channel);
}
@Override
public void onChannelException(String remoteAddr, Channel channel) {
this.namesrvController.getRouteInfoManager().onChannelDestroy(remoteAddr, channel);
}
@Override
public void onChannelIdle(String remoteAddr, Channel channel) {
this.namesrvController.getRouteInfoManager().onChannelDestroy(remoteAddr, channel);
}
所有事件调用的都是用一个函数, 接下来看一下RouteInfoManager的onChannelDestroy方法. 该方法的主要功能就是清理brokerInfo, filterServer和Queue中关于丢失连接的broker的信息. 代码如下:
public void onChannelDestroy(String remoteAddr, Channel channel) {
String brokerAddrFound = null;
//根据channel寻找brokerAddrFound
if (channel != null) {
try {
try {
this.lock.readLock().lockInterruptibly();
Iterator<Entry<String, BrokerLiveInfo>> itBrokerLiveTable =
this.brokerLiveTable.entrySet().iterator();
while (itBrokerLiveTable.hasNext()) {
Entry<String, BrokerLiveInfo> entry = itBrokerLiveTable.next();
if (entry.getValue().getChannel() == channel) {
brokerAddrFound = entry.getKey();
break;
}
}
} finally {
this.lock.readLock().unlock();
}
} catch (Exception e) {
log.error("onChannelDestroy Exception", e);
}
}
//无法根据channel找到就使用传入的remoteAddr参数
if (null == brokerAddrFound) {
brokerAddrFound = remoteAddr;
} else {
log.info("the broker's channel destroyed, {}, clean it's data structure at once", brokerAddrFound);
}
if (brokerAddrFound != null && brokerAddrFound.length() > 0) {
try {
try {
this.lock.writeLock().lockInterruptibly();
//移除brokerLiveTable中的信息
this.brokerLiveTable.remove(brokerAddrFound);
//移除filterServerTable中的信息
this.filterServerTable.remove(brokerAddrFound);
String brokerNameFound = null;
boolean removeBrokerName = false;
Iterator<Entry<String, BrokerData>> itBrokerAddrTable =
this.brokerAddrTable.entrySet().iterator();
//根据brokerAddrFound寻找brokerName
while (itBrokerAddrTable.hasNext() && (null == brokerNameFound)) {
BrokerData brokerData = itBrokerAddrTable.next().getValue();
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();
if (brokerAddr.equals(brokerAddrFound)) {
brokerNameFound = brokerData.getBrokerName();
it.remove();
log.info("remove brokerAddr[{}, {}] from brokerAddrTable, because channel destroyed",
brokerId, brokerAddr);
break;
}
}
if (brokerData.getBrokerAddrs().isEmpty()) {
//如果对应的brokerName再没有别的节点(即失去连接的节点是该brokerName拥有的唯一节点), 需要移除brokerName的信息
removeBrokerName = true;
itBrokerAddrTable.remove();
log.info("remove brokerName[{}] from brokerAddrTable, because channel destroyed",
brokerData.getBrokerName());
}
}
//移除brokerName的信息,在对应的cluster移除brokerName
if (brokerNameFound != null && removeBrokerName) {
Iterator<Entry<String, Set<String>>> it = this.clusterAddrTable.entrySet().iterator();
while (it.hasNext()) {
Entry<String, Set<String>> entry = it.next();
String clusterName = entry.getKey();
Set<String> brokerNames = entry.getValue();
boolean removed = brokerNames.remove(brokerNameFound);
if (removed) {
log.info("remove brokerName[{}], clusterName[{}] from clusterAddrTable, because channel destroyed",
brokerNameFound, clusterName);
//对应的cluster中再没有别的brokerName, 移除cluster
if (brokerNames.isEmpty()) {
log.info("remove the clusterName[{}] from clusterAddrTable, because channel destroyed and no broker in this cluster",
clusterName);
it.remove();
}
break;
}
}
}
//移除brokerName对应的queueData
if (removeBrokerName) {
Iterator<Entry<String, List<QueueData>>> itTopicQueueTable =
this.topicQueueTable.entrySet().iterator();
while (itTopicQueueTable.hasNext()) {
Entry<String, List<QueueData>> entry = itTopicQueueTable.next();
String topic = entry.getKey();
List<QueueData> queueDataList = entry.getValue();
Iterator<QueueData> itQueueData = queueDataList.iterator();
while (itQueueData.hasNext()) {
QueueData queueData = itQueueData.next();
if (queueData.getBrokerName().equals(brokerNameFound)) {
itQueueData.remove();
log.info("remove topic[{} {}], from topicQueueTable, because channel destroyed",
topic, queueData);
}
}
//如果对应的topicQueue下再没有别的queueData, topicQueue
if (queueDataList.isEmpty()) {
itTopicQueueTable.remove();
log.info("remove topic[{}] all queue, from topicQueueTable, because channel destroyed",
topic);
}
}
}
} finally {
this.lock.writeLock().unlock();
}
} catch (Exception e) {
log.error("onChannelDestroy Exception", e);
}
}
}
清理信息的过程没有什么难点, 只是细节比较多.
阅读完NameServer模块的整个代码比较奇怪的一点就是NameServer的各个节点之间是不会相互通信的. 那么假如一台NameServer宕机会造成什么样的影响呢? 相信这一点需要到broker和client模块中去分析. 此处作为遗留的问题.
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